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AN

INTRODUCTION

TO

ENTOMOLOGY;

OR

ELEMENTS

OF THE

NATURAL HISTORY OF INSECTS

WITH PLATES.

By WILLIAM KIRBY, M.A. F.R. and L.S.

RECTOR OF BARHAM,
AND

WILLIAM SPENCE, Esq. F.L.S.

"Hf

VOL. in.

LONDON:

PRINTED FOR

LONGMAN, IlEES, ORME, BROWN, AND GREEN,
PATERNOSTER ROW.

1S26.

auonJ5'

TBINXED BY HICHARD TAYLOR,
SHOE LANE, LONDON.

ADVEUTISEMENT.

X HE publication of the €0110111(11110; volumes of
the ^' Introduction to Entomology" has been un-
avoidably delayed by the continued ill health of
one of the Authors, which has devolved upon the
other a considerable increase of labour, and de-
manded a greater expenditure of time than would
otherwise have been required ; for though Mr.
Spence put every facility in Mr. Kirby's power,,
and had drawn up a rough copy of every Letter
belonging to his department ; yet, as most of
them had been written several years ago, many
curious facts, and a great variety of interesting
information subsequently derived from various
sources, were necessarily to be inserted, and the
whole to be prepared for the press.

When the thousands of objects that were to be
examined, and many of them repeatedly, in com-
posing the Letters on the External Anatomy of
Insects, are considered, it will not appear sur-

a2

IV ADVERTISEMENT.

prising- if some errors should have crept in; espe-
cially as Mr. KiRBY was deprived of the effectual
help formerly derived from the acumen, learning*,
and judgement of his esteemed coadjutor, by his
lamented and protracted indisposition : but it is
hoped that these errors will be found of minor
importance, and not to affect any general prin-
ciples advanced, l^he same remarks are also in
part applicable to the Anatomical and Orismolo-
gical Tables (Vol. III. p. 354—393, and Vol. IV.
p. 257 — 354), which were drawn up by the Au-
thors jointly many years ago, before any other
portion of the work was composed, but which
have, especially the former, required considerable
alterations and additions in consequence of sub-
sequent observations and information.

It will not be amiss here to state, in order to
obviate any charge of inconsistency in the pos^
sible event of Mr. Kirby's adverting in any other
work to this subject, that though on every material
point the authors have agreed in opinion, their
views of the theory of instinct do not precisely
accord. That given in the second and fourth
volumes is from the pen of Mr. Spence.

It was originally intended, as mentioned in the
Preface, to have giv^ a complete list of Entomo-

ADVERTISEMENT.

logical workS;, of which a large portion was drawn

up; but the great length to which more important

matters have extended, has rendered necessary

the intire omission of this list, — an omission in

some degree compensated by the catalogue of

Authors quoted, which comprises most of the

standard Entomological works.
m °

-vi,jo7bnB,eee~j^c5^. q i)

lariio ^fflB sioisd ,o^. .,j^ giorii

iflsidw jud .baaoqmo- mihoq

dldBisbianoa bairD

>dija 1o aonaiip^arroo at ^xiofUfabfi bn£ enotJBi9jI«
aoiisrti , j g noiijSTir^edo insupsi^

*a i^io Of /)jG)p ggiOTB 9d Ion lliw il

'8oq 9jJj ai pnajaigflo^m lo s^iurfa ^^ns aiBivdo
isdio yns nf ;^niii9vbjs ayaaiil iM loine^s aldie
bii9i£m yiavo no rf^^yodi isdi Joo'idus airiJ oi iliow
liarii .noiniqo nr bosi^xs 07Bri aioriJuu arii ioioq
ybaiosiq Jon ob JwtJam \o \rt«»As ^rfi \o bwsu
dho6> bne bnooaa ^dj ni nsn-^ istlT bioa^ji
33H3i8 iM )o nsq orii moit ei eomiilo/
oriJ ni bsnoilnsm 86 ,bobn3tni iilsni»ho86n il
omoina lo leil 9*3lqrno > f; ^^ /j;^ ^rsii r^jt >>,:) ^ .'f

ERRATA.

Page. Line.

29 27, for Pseudo-cordia read Pseudo-cardia.

33 1, for -^ read. \k.

35 7 and elsewhere, for Gigas read grandis.

46 16, /or number and situation read in some respects.

98 6, for Furtina read Jurtina.

121 note ^, for c read d.
135 note ^/or XXIV. read XXIII.
137 note ^, /or 17 read 18.
251 4, /or ten read nine.

„ ' i for froenum read fraenum.

359 21, S

422 note •>, for a' read a".

425 note ^ /or b" read h'.

471 1, dele Pelecotoma.

10, for orbicular read subtriangular.

512 antepenult, ^ter genera insert except in some ^crit/tr, as A.viri-

dissima.

562 note *, for -anu read wu/au

606 5, for Heteropterous read Homopterous.

Sd— i*

DIRECTIONS TO THE BINDER.

The Synoptical Table of the Nomenclature of the Parts of tKe
External Crust of Insects should be placed opposite to page 354.

Plates VI— XX. should be placed in this Volume, and the re-
mainder in the Fourth.

It is however suggested to Purchasers, that in binding complete
Sets of the Work, a separate Volume may be formed of the Synop-
tical Table, the Plates and their Explanations, and the Indexes.

CONTENTS OF VOL. III.

Letter. Page.

XXVIII. Definition of the Term /w5crf 1—51

XXIX. States of Insects. E^rg state 52—104-

XXX. The same Subject continued. Larva

state 105—237

XXXI. The same Subject continued. Pupa

state 238—290

XXXII. The same Subject continued. Imago

state 291—347

XXXIII. External Anatomy of Insects. Terms

aiul their Dejiniiion S'tS— 393

XXXIV. The same Subject continued. The Head

and its Parts 394<— 528

XXXV. The same Subject continued. The

Trimk and its Parts and Organs . . 529 — 697

XXXVI. The same Subject continued. The Ab-
domen and its Parts 698 — 720

NOTICE RESPECTING VOL. I. akd II.

It being judged expedient, since the publication of the last Edition of
the first and second Volumes of this Work, to adopt a new plan with
respect to the reference letters of the Plates, the Reader is requested to
make the following corrections in those Volumes.

Vol. I.
Page. Note.
1 25 *, for f, d read a".
273 ", far a read a.
395 *, for 29, 30 read 13.

Vol. II.

244 °, for a read a.

319 \ for 10 read 14.

348 ^, for a read e'".

353 ', for 7—. read 16—.

366 '', for a read s", v'".

'', for b read t".

405 % for 1.8. aa read 18. cf.
'', for bb read q".

406 *, /or bb read C".

407 % for cc read C"C", which represent the bundles of mus-

cles in connexion with the drums. In the above figure
the mirror is the part directly under those bundles.

AN

1"^ T /'\ XT

INTRODUCTION

TO

E N T O M O L O G Y.

LETTER XXVllI.

DEFIXiriOX OF THE TERM INSECT.

W HAT is an insect ? This may seem a strange ques-
tion after such copious details as have been given in my
former Letters of their history and economy, in which it
appears to have been taken for granted that you can an-
swer tliis question. Yet in the scientific road which you
are now about to enter, to be able to define these crea-
tures technically is an important first step which calls for
attention. You know already that a butterfly is an insect
— that a fly, a beetle, a grasshopper, a bug, a bee, a
louse, and flea, are insects — that a spider also and centi-
pede go under that name; and this knowledge, which
every child likewise possesses, was sufficient for compre-
hending the subjects upon which I have hitherto written.
But now that we are about to take a nearer view of tliem —
to investigate their iiuatomical and physiological charac-

VO[.. III. B

2 DEFINITION OF THE TERM IXSECT.

ters more closely — these vague and popular ideas are
insufficient. In common language, not only the tribes
above mentioned, but most small animals — as worms,
slugs, leeches, and many similar creatures, are known by
the name of iiisects. Such latitude, however, cannot be
admitted in a scientific view of the subject, in which the
class of insects is distinguished from these animals just as
strictly as beasts from birds, and birds from reptiles and
amphibia, and these again from fishes. Not, indeed,
that the just limits of the class have always been clearly
understood and marked out. Even when our corre-
spondence first commenced, animals were regarded as
belongmg to it, which since their internal oi'ganlzatlon
has been more fiilly explained, are properly separated
fi'om it But it is now agreed on all hands, that an
earthworm, a leech, or a slug, is not an insect ; and a
Naturalist seems almost as much inclined to smile at
those who confound them, as Captain Cook at the island-
ers who confessed their entire ignorance of the nature of
cows and horses, but gave him to understand that they
knew his sheep and goats to be birds.

You will better comprehend the subsequent definition
of the term Insect^ after attending to a slight sketch of
/the chief classifications of the animal kingdom, more es-
pecially of the creatures in question, that have been pro-
posed. That of Aristotle stands first. He divides ani-
mals into two grand sections, corresponding with the Vo-
tehrata and Invertcbrata of modern Zoologists : those,
namely, that have blood, and those that have it not^ : —
by this it appears that he only regarded red blood as
real blood ; and probably did not suspect that there was

* Ev«/^oj, .\uxtf<,u. Hist, Animal, 1. i. c. 6.

DKKINITK^N' OF THK TERM IXSECT. 3

.a true circuhitioii in his Mollusca and other w hitc-blooded
animals. His Enaima^ or animals that have blood, he
divides into Qjiadrupcdsy Birds, lus/ics, Ccfacca, and
Apods or reptiles ; though he includes the latter, where
they have four legs, amongst the quadrupeds*; and his
Anaivia, or animals without blood, into Malachia, Ma~
lacos/raca, Osfracodcrma, and Entoma. The first of
these, the Malachia, he defines as animals that are ex-
ternally fleshy and internally solid, like the E?iaima; and
he gives the (Sr^; /a as the type of this class, which ansAvers
to the Cephalopoda of the moderns. The next, the Ma-
lacostraca, synonymous with the Crustacea of Cuvier and
Lamarck, are those, he says, which have their solid part
without and the fleshy within, and whose shell will not
break, but splits, upon collision ''. The Ostracoderma, cor-
responding with the Testacea of Linne, he also defines as
having their fleshy substance within, and the solid with-
out; but whose shell, as to its fracture, reverses the cha-
racter of the Malacostraca. He defines his last class
Entoma, in Latin Insecta, with which we are principally
concernetl, as animals whose body is distinguished by in-
cisures, either on its upper or under side, or on both, and
has no solid or fleshy substance separate, but something
interinediate, their body being equally hard both within
and without*^. This definition would include the Anne-
lida and most other Vermes of Linne, except the Testacea,
w^hich accordingly were considered as insects by those
Zoologists that intervened between Aristotle and the lat-
ter author. The Stagyrite, however, in another place,

* Hist. Aniinal. 1. i. c. 5, G : compare 1. v. c. 3 and 83, and De
Partihus Animal. 1. iv. c. 1 and 11.

'' To 2£ aKh/i^ou otvruu a 3f«i/rov x'K'hat <p/«fov.
•^ Hist. Animal. 1. iv. c. 1 .

B 2

4 DEFINITION OF THE TERM IXSECT.

has expressly excluded all apods"". From other passages
in his works, it appears that he regarded the Vermes, &c.
either as larvcv, or as produced spontaneously and not
ex ovo^.

This definition of an insect, though partly founded on
misconception, as well as his primary division of animals
in general, is by no means contemptible. If you look at
a bee or a flv, you will observe at first sight that its body
is insected, being divided as it were into three principal
pieces — head, trunk, and abdomen "= ; and if you examine
it more narrowly, you will find that the two last of these
parts, especially the abdomen, are further subdivided.
And this character of insect ion, or division into segments,
more or less present in almost every insect**, is not to be
found (with tlie exception of the Crustacea, which Ari-

» K*To.«« cToXi^cToSet ftei> y*o e^i tuvtx. De Part. Animal. 1. iv, c. 6.

" Hist. Animal. 1. iv. c. 19.

"^ The insection that distinguishes these parts, the abdomen espe-
ciallv, is most visible in the majority of the Hymenaptera and Diptera
orders ; next in some Coleoptera, as the Laniel/icorri tribes, &c. and
the Lepidoptcra. Latreille is of opinion, that the two last segments
of the thorax in some insects ai"e represented by the first of the
abdomen, and that the upper half segment of this part in Coleoptera
also represents the same. Latr. De quclques Appendices, &c. An-
nales Geniralcs des Sciences Physiques. A Bruxelles, vi. livrais. xviii.
14. In fact, in the Lepidaptera, when the abdomen is separated from
the tnnik, this segment usually remains attached to the latter. In
the Myriapixis, the trunk is to be distinguished from the abdomen
only by its bearing the three first pair of legs.

** There is no general rule without exceptions, and no character is
so universal as to be distinctly cxhibitctl by every member of a class
or other natural group. Thus, in the majority of the mites {Acanu
h.) the body is marked by no segments, and the only articulation or
incision is in the legs, palpi, «ic. But as the exception does not make
void the rule, :>o neither does the extenuation or absence of some
primarv character at its {)oints of junction with others, in some indi-
viduals, annihilate the class or group.

niniMiioN or imk ikrm ixsect. 5

stotle distinguishes by the nature <>t tJieir intcginncnt
and its contents) in any of the other classes into which
he divided animals witliout blood. It was on account of
this most obvious of their characters, that these little
creatures were in Greek named Entoma, and in Latin
Insccta ; and from the former word, as yon know, our
favourite science takes the nante of Entomology.

Pliny adhering to the definition of Aristotle, as far as
it relates to the inscction of the animals we are speaking
of, expressly includes Apods, as well as Aptcra, amongst
them * ; and in this was followed, without any attemj)t at
unprovement, by all the entomolt)gical writers that inter-
vened between him and the great Aristotle of the mo-
derns, Linne.

This illustrious naturalist, aware of the incorrectness
of the primary divisions of the animal kingdom founded
upon the presence or absence of blood, establisljes Ids
system upon the structure of the heart, and upon tlie
temperature and colour of the circulating fluid. lie di-
vided animals into two great sections or sub-kingdoms^
each comprising two classes. Yl^x^Jirst section included
those having a heart with tvi'o ventricles, /x<? auricles,
and •j:arm and red blood, viz. the Mammalia or beasts,
and the Aves or birds. His second^ those having a heart
with one ventricle, one auricle, and cold and red blood,
namelv, the classes Amphibia, which included reptiles,
serpents, &c. and Pisces or fish. His third, tl)ose having
a heart with one ventricle and no anr'.cle, and cold VLhite
sanies in the place of blood, namely, his classes Insccta
et Vermes, including the Invertebrate animals of La-

■■ }Ikt. Xai. 1. \\. <•. 1.

6 DEFINITION 01' THE TERM INSECT.

marck. Thus the first of Aristotle's great divisions he
increased by the addition of a new and very distinct class,
the Amphibia^ by which some ground was gained in the
science ; but as much was lost by his compressing the
four classes of which the last consisted into two, by which
the natural classes o^ Cephalopoda and Crustacea merged
under Insecta and Vermes. Linne was not aware of the
extraordinary fact, that the Cephalopoda have three
hearts; and that though the Cnistacca and Arachnida
have a circulation, Insects have none, or he would never
have taken this retrograde step.

Indeed Linne's definition of an Insect is, in many
most material points, inapplicable, not only to the Crus-
tacea, but to many other animals included under that
denomination. This will appear evident from a very
slight examination. Thus it runs : " Polypod animal-
cxda, breathing by lateral spiracles, armed eveiy ijohei-e
"with an osseous skin, "whose head is furnished laith mov-
able sensitive antenna^." Now of this definition only
the first member can be applied to the whole class which
it is meant to designate; for the entire genus Cancer L.,
which, with some others, forms the class Crustacea of the
moderns, does not respire by spiracles at all, but by gills ;
and the same in some degree may be said of spiders,
scorpions, &c. With the last member of the definition
Linne himself must have been aware that a larsfe number
of what he conceived to be insects were at variance, as
mites, spiders, and many other of his apterous tribes :
though from some very recent observations of M. La-

= Animalcula polj-poda, sjnracitUs lateralibus respirantia, cute
ossea cataphracta; antennis mobilibus sensoriis iiistruuntur. St/st.
Nat. ed. 12. i. 533,

DKriMTION or THE TER.Ar IXSLCT. 7

ti'cillo*, there seems some fjrouncl for thinking, tlmt in
these tlie antcnnjc are ici)iescntecl by the majuhbles,
palpi, &c. ^f and to the soil flexible, coriaceous or mem-
branous skin of a vast number of insects, the term cutis
ossea is by no means applicable.

Evident as these incongruities arc, when the I lerculean
task which Linne imposed upon himself, and the vastness
and variety of his labours, are considered, they become
very venial. Indeed, unless he had divided his class Iii~
sccta into two or more, it was impossible to defuie it in-
telligibly to ordinary readers, otherwise than neiirly in
the terms which he actually employed ; and these clia-
racters, restricted and amended by qualifying clauses, are
still those to which recurrence must be had in a popidar
defmition of the chiss, when separated as it ought to be
from the Crmtacea and Araclinida.

Pennant, Brisson, and other zoologists, who, attending
to nature rather than system, saw the impropriety of unit-
ing a crab or a lobster in the same class with a bee or a
beetle, long since assigned the Crustacea their ancient
distinct rank. " But these changes," as Latreille Ob-
serves'^, " being only founded upon cxto'nal characters,
might be deemed arbitrary ; and to fix our opinion, it
was necessary to have recourse to a decisive authority —
the internal and comparative organization of these ani-

* Quoted by Mr. Win. MacLeay in his very remarkable and
learned work HorcE Ejitomologicce, in which he inclines to the same
opinion. .383.

'' Trcviranus ( Ucher dot inncrn Ban der Arachniden, Sec. 22.) aU
ways calls the palpi of spiders " Fullionier.^'' In Scorpio he regards
them as palpi {Palpcn).

' X. Did. d'llisf. XaL xvi. 181.

S DEFINITION or THE TERM INSECT.

mall). It results from tlie observations of the most pro-
f ound comparative anatomist of our age, M. Cuvier, that
the Crustacea and Arachnida differ from insects properly
so called, and particularly from those that are furnished
with wings, in having a complete system of circulation,
a different mode of respiration, and that they have a more
perfect organization. Influenced by these motives, both
Cuvier and Lamarck have considered them as forming
two classes separate from insects. Treviranus, led by
considerations founded on the organs of circulation, of
respiration, and of generation, is of opinion that spiders
and scorpions ought to form one class with the Crustacea :
he observes, however, that the nervous system of all three
is very dissimilar ; and that in an arrangement founded
on this circumstance, the organs of motion, and the ex-
ternal shape, even spiders and scorpions must be placed
in different classes^.

It is to be observed with regard to the Arachnida of
the French school, that the class as laid down by them
includes several animals that have no circulation, and
breathe by trachecr, of which description are the mites
{Acariis L.), and the harvest-men [Phalangium L.) &c. ;
and therefore it has been divided into two orders, Pul-
monaria and Tracheana ,• but if the definition from the
internal organization be adhered to, the latter should
eidier remain with the class Insecta, or form a new one by
themselves. Yet tjie animals that compose the Trachean
order of Arachnida^ their external form considered, are
certainly much more nearly related to the spiders and

" Treviranus, ut supra, 48. For the nervous system of scoipions,
sec /. i. /I 13; and for that of spjders, /. v./. 45,

nj.ijNnioN or 'iiiK ri;H.M ixs^cr. 9

scorpions than to any iiieiubci-s of the class Lisccla at
present known. This circumstance, perliaps, may seem
to throw sonic doubt upon the modern system o\' classi-
fication.

I must further observe, that the assertion ofTreviraiuis,
whicli appears to intimate that the respiration of the pul-
mojian/ Arac/niida is tlie same witli that of the Crustacea^
is not (juite correct, since in the latter the brayichicc or
gills arc cj.'tcrnal, and in tlie former internal^ the air en-
tering by spiracles bctbre it acts upon Uieiii^.

It may not be amiss in this place to lay before you the
jM'incipal points in which tlie Crustacea and Arachnida
agree with Insccta, and also those in which they differ.

Tlie Crustacea agree with Insccta in having a body
divided hito segments, furnished with jointed legs, com-
pound eyes, and antenna'. Their nervous system also is
not materially different, and they are both oviparou';.
They differ from them in having the greater insections
of the body less strongly marked; in the greater num-
ber of legs on t!ie trunk, tlie anterior ones perform-
ing the oflice of maxiike; in their eyes usually on a
moveable footstalk : their palpigerous mandibles ; and
their four antennye at least in the great majority. But
the principal difference consists in the internal organi-
zation and the fountains of vitality; for the Crustacea have
a double circulation, the fountain of which is a heart in
the middle of their thorax'^. Tiicy have too a kind of
gizzard and liver, at least the Decapods'^, and their re-
spiration is by gills. Genuine insects terminate tiieir

* Pi.ATL XXIX. Fig. 2. Treviramis, /. i./. 1.

••■ Cuvicr Aiiof. Com/), iv. J07. ' \. Did. <V Hist. Xol. ix. ];)().

lO DEriNlTION OF THE TEllM INSECT.

existence after they have laid their eggs^; but the Crus-
tacea hve longer, and lay more than once.

The Arachnida will be found to differ from insects
more widely than even the Crustacea. They agree in
their jointed legs and palpi ; immoveable eyes ; and in
being covered with a coriaceous or corneous integument:
but they differ in having a system of circulation; gills
instead of trachea? ; their organs of generation double ;
and the females lay more than once in their lives. Their
head also is not distinct from the trunk as in insects ;
they have no compound eyes ; and their antennas, if we
admit the opinion on this head of MM. Latreille and
Treviranus, that they have representatives of these or-
gans, differ totally in structure, situation, and use, from
those of the great body of insects. In the AraneidcB or
Spiders, their body seems to have no segments or incisure
but that which separates the abdomen from the trunk ;
and in the Scorpionidce they are observable only in the
abdomen. Other particulars might be enumerated in
which tliese two classes differ from insects; but these will
be sufficient to convince you that Aristotle and MM. Cu-
vier and Lamarck were justified in separating them.

The two last-mentioned authors made further improve-
ments in Zoology. The latter, from the consideration of
the general structure of animals, perceiving that Aristo-
tle's Enaima were distinguished from his A7umna, by
being built as it were upon a vertebral colimm, very ju-
diciously changed the denomination, which was indeed
improper, of " T/ieF/iiloso])he7-''s" two sub-kingdoms, into

* The females o^ DorfJiesia, however, a genus related to Coccus, are
said to survive laying their eggs. N. Diet. d'Hist. Xat. ix, 553.

DEFINITION OF THE TERM INSECT. 11

that of Vertebrota or animals that have a vertebral co-
lumn, and hivcrtehrata or those that have no vertebral
column. These he distributes into three primary divi-
sions according to their supposed degrees of intelligence
— Thus :

* Apathetic Animals. 1. Infusoria.

2. Polypi.

3. Radiata.

4. Vermes.

•• Sensitive Animals. . [Epizoaria,)

5. Insecta.

6. Arachnida.

7. Crustacea.

8. Annelida.

9. Cirrhipeda.
10. mollusca.

*** Intelligent Animals. 11. Pisces.

12. Reptilia.

13. AVES.

I'i. Mammalia.*
Profiting by the light afforded by the Aristotelian sy-
stem, this eminent zoologist improved, we see, upon that
of Linne, by resolving his Insecta into three classes, and
his Vermes into seven, interposing the Linnean Insecta
between the four first and three last, in which he was
not so happy, since as* to sense insects should certainly
occupy the place he has here assigned to the Mollusca.

In the work from which I have taken this statement
of Lamai'ck's system, that acute writer has given a sketch
of another method of arrangement, in which he has made
the first deviation from the beaten track of an unbroken

* Auim.sans Vcrlcbr. i. 1^81.

12 DEI'INITIOX OF THE TERM INSECT.

and unbranching series. In the Supplement to the first
volume, he has distributed the Invertebrata in a double
subramose series — one consisting oi articulate, and the
other o{ innrticulatc animals^.

Upon Lamarck's system, most of the modern ones,
with some variation, are founded. There is one, how-
ever, by a learned coimtryman of ours, that is more
unique, sui generis, and I may add profound, than any
that has yet appeared. I am speaking of that, you will
perceive, of which our friend Mr. Wm. MacLeay has
given a detailed statement in his Hoice Entomologicce.
In this he goes even far beyond what Lamarck has at-
tempted in the above sketch, and substantiates his claim
to be considered as one of those original thinkers, rari
n-antes in gurgite vasto, that do not appear every day.
The following are the principal bases of his system.

\. That all natural groups, whether kingdoms or any
subdivision of them, return into themselves; a distribu-
tion which he expresses by circles.

2. That each of these circles is formed precisely of
Jiiyc groups, each of which is resolvable into five other

wnaller groups, and so on till you reach the extreme term
of such division.

3. That proximate circles or larger groups are con-
nected by the intervention of lesser groups, which he de-
nominates osculant.

^. That there are relations of analogj' between the
corresponding points of contiguous cii'cles.

Tliis system he has represented by tables of circles
inscribed with the five primary divisions of each group.
His first table exhibits a general view of organized matter

' Aidm. sans Vcticbr. i, 4J>7<

DEFINITIOX OF THF. Tl-UAI /Ai'AY"/'.

13

as distributetl in the aniiiml and vegetable kingdoms —
Thus :

Our learned author here divides the animal kingdom
into what may be denominated five sub-kingdoms or pro-
vinces, in three of which (with the exception of the Cnoi^
tacca and Araclinida belonging to his Annulosn) no cir-
culation of blood is visible, but which obtains in the rest.
These he names —

1. AcRiTA, consisting of the Lifusor^y Animals^ the
Polypi^ the CorallincSy the TiV7ii(r, and the least organized
of the Intestinal Worms.

2. Radiata, including the Jelly-^sh^ Star^s/i, Echini,
and some others.

3. Annui-osa, consisting of Insecta, Arachnida, and
Cints tacca.

4:. Veutebra'I'a, consisting of Beasts, Birds, Reptiles^
Amphibia, and Fishes.

5. MoLi-uscA, including the numerous tribes of shell-
fish, land-shells, slugs, &c., which, from their mucous or
gelatinous substance, from their nervous system and the
imperfection of their senses, return again to the Acrila,

u

DEFINITION OF THE TERM INSECT.

though connected with the Veitebrata by having a heart
and circulation.

His next set of circles shows the sub-division of these
five sub-kingdoms into classes — Thus :

/*♦»

\

'\P.iiides

/■

iApcistna

\AcephaZa

.JSrtuliiopodc^

Unatantes/

ylmphihia

Jntesttna

ilfi

c^

-a^f

FisUilicia^

AH'

,Vfttt'

bolt*

yives^

l'^>^.

/AcalepltUUt

Mmxdi-
btilala

ito^

^cMnicUACmstacea

sMedusida

Stclleriih/

Saustd-
^Ai-acJiitider

In this scheme the oscula7it classes are those placed
between the circles. In the Mollusca circle two classes
are still wanting to complete the quinary arrangement
of that sub-kingdom. I am not sufficiently conversant

DKFIKITJON OK TltE TERM IXSi^CT. 15

with the details of the animal kingdom at large to hazard
any decided t)pinion upon Mr. MacLeay's whole system,
or to ascertain whether all these classes are sufiiciently
distinct*. My sentiments with regard to those of the
Anmdosa I shall state to you hereafter.

Upon a future occasion I shall consider more at large
the station to which insects seem entitled in a system of
invertebrate animals, which will not accord exactly with
that assigned by MM. Cuvier and Lamarck. But I am
now in a field in which I have no intention to expatiate
further, than as it is connected with the subject of the
present letter. I shall therefore confine myself in what
1 liave more to say to the definitions of Insccta that have
been given by modern authors, beginning with that of
the zoologist last mentioned. Insects form a part of his
second group, which he terms sensitive animals [animanx

sejisibles), which group he thus defines : " They arc sen-
tient, but obtain from their sensations only perceptions
of objects — a kind of simple ideas which they cannot
combine to obtain complex ones. Charact. No vertebral
column : a brain, and most commonly an elongated me-
dullary mass ; some distitict se7ises ; the organs of move-
merit attached under the skin : form symmetrical, by
parts, in pairs^\" Tliis division of animals, from the

' The number y?!'^', which Mr. MacLeay assumes for one basis of
his system as consecrated in Nature, seems to me to jielcl to the
number sei'cn, which is consecrated both in Nature and Scripture.
Metaphysicians reckon sei^cn principal operations of the mind ; mu-
sicians seven principal musical tones; and opticians seven primary
colours. In Scripture the abstract idea of this number is — comple-
tion— -fullness — perfection. I have a notion, but not yet sufiiciently
matured, that Mr. MacLeay's qninaries are resolvable into septcnaries.

^ Anini.saui Vertebr.\>ZS\.

16 DrFTN'ITIOX OF THF TER^f INSECT.

kind and degree of sense and intelligence that they pos-
sess, seems ratlier fanciful than founded in nature, since
many insects show a greater portion of them than many
vertebrate animals. Compare in this respect a bee witli
a, iorioise^. I.amarck divides his group o^ animaux sen-
sibles into two sections, nameh', Articulated animals, ex-
hihititiiO- seofments or articulations in all or some of their
parts; and Inarticulatcd animals, exhibiting neither seg-
ments nor articulations in any of their parts, hi sect a ^
Ararhnida, and Crusfoceo., belong to the first of these
sections, which he defines as " those xv/iose body is di-
vided into segments, ami 'isclnch are Jtirnished with jointed
legs bent at the artioilatiniis^y Insf.cta he defines —
" Articidate animals, undo going various nirfamorphoses,
01' acquiring new kinds of parts — having, in their perfect
state, six feet, txoo antenna', Itvo compound eyes, and a
corneous skin. The majoriti/ acquiring wings. Respira-
tion by spiracles (stigmates), and two vascular opposite
chords, divided by plexus, and constituting aei'iferous tra-
checc^ which extend every where. A small braiti at the
anterior extremity of a longitudinal knotty marrow, with
nen^es. No system of circulation, no conglomerate glands.
Generation oviparous : two distinct sexes. A single sex-
ual union in the whole course qflife'^." Arachnida he
defines — " Oviparous animals, having at all times jointed
legs, undei'going no m.etamorphosis, and never acquiring
new kinds of parts. Bespiration tracheal or bratichial .-
the openings for the entrance of the air spi)-aculijbrm
i^st igmatiform.es). A heart and circulation beginning in

^ Sec on this point MacLeay, Hor. Entomolog. 209 — .

'' A)um. .yrt'7M Vcrtchr. iii. 94^, '■' Ibid. iii. 24S

DEFINITION OV THE Tl'.HM IXSICCT. 17

many. The majovitif couple often in the course ojlife^r
I shall next add his definition of Crustacea : " Ovipa-
rous^ ar/iadated, apterous animals^ laith a crustaceous in-
tegument more or less solid^ having jointed legs ,- eyes
either pedunadate or sessile, and most commonly four
anteiincc, xvith a maxilliforous mmith seldom rostriform ;
maxillcc in many pairs placed one over the other ,- scarcely
any tmder-lip ; no spiractdij&rm openings for respiratio?i ;
five or seven pair of' legs -, a longitudinal knotty mayrow
termi7iated anteriorly by a small brain. A heart and ves-
sels for circidation. Respiration branchial xci/h extanal
branchicc, sometimes hid binder the sides of' the shell of the
thmax, or shut in promitient parts ,• sometimes u?icovered,
and in general adhering to particular legs or to the tail^
Each sex usually double^."

I have given Lamarck's definitions of tliese three classes,
all considered as Insecta by Linne, that by comparing
them together you may be better enabled to appreciate
the system of this author. On looking over the characters
of the Arachnida as here given, you will see at once that
it consists of heterogeneous animals — for in fact he in-
eludes in this class not only the Trachean Arachiida of
Latreille, but the Ametabolia of Dr. Leach, or the Hexa-
pod Aptera, and the Myriapoda.

I shall next copy for you Latreille's latest definition of
Insecta and Arachiida.

" Insecta : A single dorsal vessel representing the
heart : two tru?iks of trachea; runni?ig the whole length
of the body, and opejiing externally by numerous spira-
cles ; two antennce -, very often upper appendages for
flight, indicating the metamorphosis to which the animal

=* Aiiim, tans Vertehr. Hi. 245. '' Ibid.

vol.. ni. c

18 DEFINITION OF THE TERM IN'SECT.

is subject vohen young ,- legs most commonly reduced to
six, Arachnida : Distinguished from Crustacea by
having their respiratory organs always internal^ opening
on the sides of the abdomen or thoi-ax to receive the re-
spirable jluid. Sometimes these organs perform the office
of lungs, and then the circidation takes place by means of
a dorsal vessel, which sends Jbrth arterial, and receives
venose branches. Sometimes they are trachece or air-
vessels, which, as in the class Insecta, replace those of
circidation. These have only the vestige of a heart, m- a
dorsal vessel altertiately contracting and se7iding forth
no branch. The absence of antennce, the reunion of the
head with the thorax, a simple trachea but ramified and
almost radiating, serve to distinguish these last Arachnida,
or the most imperfect of insects, which 7'espire only by
trachecE^." Under this head he observes — " Of all
these characters, the most easy to seize and the most
certain would doubtless be, if there were no mistake in it,
that of the absence of antennae ; but later and compara-
tive researches, confirmed by analogy, have convinced
me, that these organs, under particular modifications it
is true, and which have misled the attention of naturalists,
do exist'':" and he supposes, from the situation and di-
rection of the matidibles of the Arachiida, corresponding
with that of the intermediate pair of antenncE in Crustacea,
that they really represent the latter organs. If this sup-
position be admitted, their use is wholly changed; the palpi,
in fact, executing the functions of antennae, which proba-
bly induced Treviranus to call them Fiihlhorner [Feeling-

* Des Rapports gcncraux, Sfc. des Anim, mvertebr. artic, Ann. du
Mus.

*■ Ibid. Hor. Entomaloa. 383.

DEFINITION OK THF TERM INSECT. 19

horns). Perhaps tliese last may be regarded as in some
sort representing the external antennae of the Crustacea ?
With regard to Insecta^ their antennae seem to disappear
in the Pupiparcc Latr,, or tlie genus Hijypohosca L.

The above definitions of the Arachnida by these two
celebrated authors, appear to me the reverse of satisfac-
tory. When we are told of animals included in it, that
some breathe by gills and others by tracheae, that some
have a heart and circulation and others not, we are im-
mediately struck by the incongruity, and are led to sus-
pect tliat animals differing so widely in the fountains of
life ought not to be associated in the same class. A
learned zoologist of our own country, Dr. Leach, seems
to have made a nearer approach to a classification in ac-
cordance with the internal organization, by excluding
from AracJmida the Jicari and Mijr-iapoda.

Sub-kingdom Annulata Cuv.

* Gills for respiration. Classes.

Legs sixteen: .... Antennae two or four 1 Crustacea.

** Sacs for respiration.
Legs twelve : .... Antennae none 3 Arachnoidea.

*** Tracheae for respiration.

a. Ko Antennae.
4 ACARI.

b. Two Antenna?.

Six thoracic legs : Abdomen also bearing legs 2 Myriapoda.

Sij: tlioracic legs : No abdominal legs 5 Insecta*.

Mr. MacLeay, on whose system I shall now say a few
words, divides his sub-kingdom Anmdosa into five classes,
namely, Crustacea, Amctabola, Mandibidata, Haustellata,
Arachnida. From the Crustacea he goes by the genus

* Leach in EnlomologisCs Useful Compendium, by Samouelle, 75.
C 2

20 DEFINITION OF THE TERM IXSECT.

Parcellio Latr. to lultis^, which begins his Ametabola :
tliese he connects with the Mandibulata, by Nh'mus,
which he thinks approaches some of the corticarious
Coleoptera°. This class he appears to leave by the Tri-
choptera Kirby, and so enters his Hattstellata by the Le-
pidoptera '^, and leaves it again by the Diptera by means
of the Pupipara Latr., especially Nycteribia, connecting
this class with the Araclmida^ which he enters by the
Hexapod Acari L.*^, and these last he appears to leave
by the Araneida, and to enter the Crustacea by the De-
capods ^ : thus making good his circle of classes, or a
series of Annulose animals returning into itself. Mr.
MacLeay's whole system upon paper appears very har-
monious and consistent, and bears a most seducing aspect
of verisimilitude ; but it has not yet been so thoroughly
weighed, discussed, and sifted, as to justify our adopting
it in toto at present : should it, however, upon an impartial
and thorough hivestigation, come forth from the furnace
as gold, and be found to correspond with the actual state
of things in nature, my objections, which rest only upon
some parts of his arrangement of Annidosa^ would soon
vanish. Some of those objections I will state here, and
some will come in better when I treat of the Systems
of Entomology. My first objection is, that his Ameta-
bola, Mandibidata, and Haustellata, approach much
nearer to each other than they do to the other two classes
of his circle, or than even these last to each other ; so
that under this view it should primarily consist of tJu-ee
greater groups, resolvable, it may be, into five smaller
ones. My next objection is, that he has also considered

» H«t^ Eittomotog. 348. " Ibid. 354. <^ Ihid. 373.

•» Ibid. mi. e /A/f/.389.

DEFINITION or Tin: TEIIM IXSECT. 21

the Trachcan and Pubnonary Arachnida as forming one
class. Whether an animal breathes by gills or trache.T,
or has a circulation or not, is surely as strong a reason
for considering those so distinguished as belonffinjr to dif-
ferent classes, as the taking. of tiieir food by suction or by
manducation is, for separating others to the full as nnich
or more nearly related as to their external structure.
But of this more hereafter. I cannot help, as a last ob-
jection, lamenting that our learned author has rejected
from his system a term consecrated from the most remote
antiquity, and which, even admitting his arrangement,
might have been substituted for Amiulosa, a name bor-
rowed by Scaliger from Albertus Magnus, neither of
whom, in Entomology, is an authority to weigh against
Aristotle, from whom we derive the term Ifiscc/a, in
Greek Evroiia.

As Fabricius did not alter Linne's class Insecta, but
merely broke up his orders into new ones, which he
named classes, I shall give you a detail of the alterations
he introduced into the science in a future letter.

Having stated what my predecessors have done in
classification, I shall next proceed to lay before you my
own sentiments as to — Whai is an insect. Since our
correspondence commenced, the Arachnida, principally
on account of their internal organization, have been ex-
cluded from bearing that name, carrying with them, as
we have seen, several tribes, which as yet have not
been discovered to differ materially in that respect from
the present Insecta .- for the sake, therefore, of conve-
nience and consistenc}', that I may, as far as the case
will admit, adhei'e to the Horatian maxim
Servetiir atl innini

Qnalis ab incepto proccssrrit ct sibi constct,

22 DEFINITION OF THE TERM INSECT.

I shall regard as Insects all those Annulosa that respire
by tracheae* and have no circulation, considering the
Trachean Arachnida and the Myriapoda for the present
as sub-classes, the one bordering upon the Arachnida, and
the other upon the Crustacea. Some of these I am ready
to own seem separated by an interval sufficiently wide
from the Hexapods, which may be regarded as more pe-
culiarly entitled to the denomination of Insects. The
most striking differences will be found in the coalition of
the head with the trunk in some [Phalaiigidce), and the
disappearance of the annulose form of the body in others
{Acarus L.), so that the legs only are jointed''. Yet an

■■' There is some reason for thinking, though the octopod and m}'-
riapod insects breathe by tracheae, that there is no small difference in
th»? distribution of these organs. The Trachean Arachnida have only
a pair of spiracles, from which the tracheae must radiate, if I may so
apply the term, in order to convey the necessary supply of air to every
part of the body. Scutigera, as far as I can discover, has only a sivgtc
series of dorsal spiracles (see Plate XXIX.Fig. 20) — an unusual situ-
ation for them : in these also, to attain the above end, each trachea
must also radiate, so as to supply each part of the segment it is in.
Those of lulus, according to the observations of Savi ( Osservaz. per
servire alia Storia di una Specie de Iulus,&c. 15 — ), consist of bundles
of parallel tracheae. Perhaps these circumstances would warrant the
considering of these Arachnida and the M^riajmda as primary classes?
The genus Galeodes is said to breathe hy gills similar to those of the
Araneidce, which structure, probably, carries with it a system of cir-
culation, and exhibits a third type in the Arachnida,\\\t\\ fom* palpi,
six legs, and a distinct thorax. This genus, then, is the corresponding
point in the Arachnida to the Hcxnpod Aptera, as the Scorpions are
to the Cheliferidte or Pseudo-Scorpions, and the Arancidce to the other
Octopnds ; and these analogies furnish a strong proof, that the Tra-
cheans belong rather to Insccta than Arachnida. Comp. N. Diet.
d'Hist. Nat. xxvi. 445 ; and Description de six Arachfiid. nouv, &c.
par Leon Dufour, 16.

'• Mr. MacLeay observes with regard to the Tardigrade, de-
scribed by Spallanzani and Dutrochet, that " it proves that an animal
may exist without antennae or distinct annular segments to the body,
but having two eyes and six articulate legs." {Hor. Entomolog. 350—.)
Many Acari prove the same thing, Dc Gccr. vii. /, vii./. 14.

DEFINITION OF THE TEltM IXSECT. 23

approach to such structure may be traced in some Hexa-
pods ; for instance, the coaUtion of the head and trunk
in Melophagus, Latr., and that of the trunk and abdomen
in Smmthuriis, Latr. * The Mi/iiapoda exhibit other re-
markable differences ; tliough their head and trunk are
distinct, the former antenniferous, and their body annu-
lose, the abdomen as well as the trunk is furnished with
legs, sometimes amounting to hundreds ; but even to this
a tendency has been observed in some Hexapods''. If
you examine a specimen of Mac/iilis jwlj/poda, an insect
related to the common sugar-louse [Lepisma saccharina)i
you will find that the abdomen is furnished with a double
series of elastic appendages, which, being instruments of
motion, may be regarded as representing legs. It is
worthy of notice, that the Myriapoda when first disclosed
from the egg have never more than six legs '^, and keep
acquiring additional pairs of them and additional seg-
ments to their abdomen as the}^ change their skins : and
it is equally remarkable, that many Hexapods are subject
to a law in some degree the very reverse of this, having
many abdominal legs in their first state, and losing them
all in their last. The union of the head with the trunk
in the Trachean Arachnida has been regarded as almost
an unanswerable argument, in spite of their different in-
ternal organization, for including them in the same class
with the Puhnonarij Arachnida ,- but the case of Galeodes,
which, though furnished with gills, (as an eminent Rus-
sian Entomologist Dr. G. Fischer is reported to have
discovered,) implying also a circulation, and evidently
belonmnff to the last-mentioned class, has nevertheless a
distinct thorax consisting of more than one piece, to which

■" Dc Geer, vii. t. iii./. 8. ■' Hor, Entomolog, 35'

' DeGeer, Ihid. 571, 583. /. xxxvi./. 20, 21.

24 DEFINITION or THE TERM IXSECT*

are affixed only six legs*, proves that even this circum-
stance possesses no weight when set against the organi-
zation. If it was a difference in this respect, that proved
the Crustacea classically distinct from Insecta — that like-
wise was the principal reason for the separation also of
the Arachiidu — it seems to follow that it ought also to
furnish an argument equally cogent for considering the
Trachean Arachnida, as well as the Mtjriapoda^ distinct
from the Pulmonary.

Another difference between the tribes in question is
that of their metamoiyhosis ; and tliis appears to have
had great weight with Lamarck, inducing him to include
in his Arachnida, not only the Tracheaus and Myriajpods,
but even the apterous Hexapods, except Pulex, or the
Afioplura and Thysanura of modern authors- But the
metamorphosis alone, unless supported by the internal
organization, will I think scarcely be deemed a sufficient
reason for separating from each other tribes agreeing in
that respect, and placing them with others with which
they disagree. The metamorphosis in some of the Hex-
apods [Lepidoptera) consists in the loss of legs, the ac-
quisition of wings, a great change in the oi'al organs and
in the general form; in others (some Coleoptera), in the
acquisition only of wings and a change of shape, the oral
organs remaining much the same; in others again [Cur-
adio L.), in the acquisition of six legs and wings and a
change of form ; in the flea, in the acquisition of six
legs and a change of form onl}' ; in the Orthoptera, He-
miptera, &c. in the mere acquisition of wings; in the
Libelkdida;^ in the loss of the mask that covers the mouth
^nd the acquisition of wings ; in the iXiptera^ in the ac-

^ Dnfour hM sapra. Hor. Entomolog. 38^,

DEFINITION OF THE TERM IXSECT. 25

qiiisition of six legs, wings, a change of the oral organs
and of the form ; in some of the Octopods {Acartis L.),
in the acquisition of a pair of legs ; and in others {Pha-
langium and Araiieah.), solely in a modification of tliem
as to their pro})ortions ; in the Mijiiapods^ the alteration
that takes place in this respect is considerable ; a large
number of pairs of legs is acquired and many additional
abdominal segments, and the proportion which the ab-
domen bears to the whole insect is quite altered. In all
these cases tliere is a change more or less, either partial
or general, of the original shape or organs of the animal;
and witli regard to their metamorphosis, there is a greater
difference between a young and adult Iidiis than between
a young and mdvXi grasshopper or bug: so that if the meta-
morphosis, per sc, be assumed as a principal regulator of
the class, the grasshopper or bug have as little claim to
belong to it as the Itdus.

M. Lamarck lays considerable stress upon another
character — That Insecta engender only once in the course
of their lives, and Arachnida more than once. But this,
if examined, will be found to be confined chiefly to the
Pidmonarxj Arachnida^ the Tracheans following the law
oi Insect a in this respect*.

You may perhaps object that the bringing of the Tra-
chean Arachnida and the Myriapoda into the class In-
secta will render the approximation of them to a natural
arrangement more difficult, since it will be impossible
at the same time to connect the Myriapods with the
Crustacea, and the Trachean with the genuine Arachnida.

' Male Insecta in sonic instances engender more than once. Mr.
MacLeay sen. has observed this with regard to Chrysomcla Po/i/goni,
and I have noticed it in Boinf)i/.v Mon.

26 DEFINITION OF THE TERM INSECT.

I admit the validity of your objection, but by no arrange-
ment of insects in a simple series can we attain this object :
the difficulty, however, may perhaps be obviated in this
way. The distribution of organized matter, to adopt
Mr. Wm. MacLeay's metaphor*, begins in a dichotomy,
constituting the animal and vegetable branches of the
great tree of nature, and from these two great branches, by
means of infinite ramifications, the whole system is form-
ed, and, what is remarkable, these branches unite again
so as to represent a series returning into itself, a disco-
very due to the patient investigation and acumen of our
learned friend just mentioned. Now, in considering
the Aptera order, we find at first setting out fi'om the
Hexapods, a dichotomy, where the Anoplura Leach
branch off on the one side, and the Thy&anura Latr. on
the other — the former, by means of the Pediculidce^ tak-
ing their food by suction, particularly Phthirus Leach,
or the Morpion (in which the segments of the trunk and
abdomen become indistinct^) approach the Octopods by
the hexapod Acarl L. — the latter by Machilis polypoda
tending towards the Myriapods. In the Octopod branch
a further dichotomy takes place, from which you proceed
on one side to the Araneidce in the Arachnida^ by Pha-
langium, &c, ; and in the other by Chelifer, &c. to Scorpio.
Again, the Myriapod branch also divides, going by the
Iidida; to one branch of the Isopod Crustacea, and by the
Scolopendridce to another.

But there is another view of this subject before alluded
to, which may be repeated here, and which seems to

> Hor. Entomolog. 134. 200.

''. Zoolog. Misccll. iii. t. 146. In this figure the segments are
made much more distinct than they are in my specimen.

DEFINITION OF THE TEKM INSECT. 27

prove that the types of form in one natural group or
class are reproduced in another ; this appears to result
from the following parallel series :

Kctiroptcrous Aptcra. Arachnlda. Crustacea.

Larva'.
Psocus Ilcxapoda Galcodcs Larunda.

Myrn.elcon Phalangium. . . . Aranea ....\ ^^cc^P^^a bra-

•' ° I chyura.

Octopoda rDecapoda ina-

Panorpa ? Chclifer Scorpio. . . . < ^'""'■^- ^ '^'''"^■

^ ■' 'I Ittssina Scorjno

v especially.

Ephemera INfyriapoda ***** Isopoda.

No type representing the Mi/riapoda has yet been
discovered in the Arachnida class; but I have little
tloubt of its existence. You will observe that the ana-
logies between the larva? of the "winged orders and the
Ajitera were first noticed by Mr. W. MacLeay*. It is
probable that these parallel series of representatives of
each other might be increased, as well as the numbers in
the respective columns.

What I have said w-ill, I trust, sufficiently justify me
for making at present no more material alterations in the
classification I long since proposed to you ^ ; I shall,
therefore, now proceed to define the objects I consider as
Lisectu; but I shall first observe — that as Latreille con-
siders the branchiapod Crustacea or Entomostraca of
Mliller as entitled to the denomination of Crustaceo-
Arachnida '^ ; so his Trachean Arachnida might be called
Arachnido^Insecta, and his Myriapoda, Crustaceo-Insecta.

» Hor. Entomolog. 422—.

^ See above, Vol. I. 4th Ed. p. (5G. Note \

•■ Surely the denomination ought to have hecn Ararhnido-Crttxtacea,
since the learned author considers them as belonging to the Crustacea
class.

28 DEFINITION OF THE TERM INHECT.

Sub-kingdom — Annulosa^'.
Class — Insecta.
Fiist Definition — From their external Organization.
Body — divided into Head — Tx*unk — Abdomen.

Head. — Principal seat of the organs of sensation.

Organs of sight. Immoveable eyes, simple or com-
pound, varying in number.

Organs of hearing uncertain, probably connected
with the antennas.

Organ of taste. Ligula or palate within the mouth,
accompanied by the organs of manducation — a pair
of mandibles and maxillae and an upper and lower
lip, or their representatives.

Organs of touch. Principally two jointed antennas
or their representatives, and four jointed feelers —
two maxillary and two labial.

Trunk. Principal seat of the organs of motion.
Organs of walking, nmning, or jumping. Six or

eight jomted thoracic legs, in pairs.
Organs of flight. Four wings or their representa-

* It may not be without use to give here a short definition of the
Anmdosa ; I mean excluding the Vermes, which Mr. W. iMacLeay
has inchjded ; and the Annelida, which Latreille has made the fifth
of his AnniUose classes. Ann. du Mus. 1821.

Anmdosa. Animal invertebrate, oviparous ; external integument of
a firmer consistence than the internal substance, serving
as a general point of attachment to the muscles; eijcs
immoveable; legs more than four, jointed.
Classes.

1. Crustacea. Gills external; more than eight legs.

2. Arachnida. Gills internal ; spiracles ; eight legs.

3. Insecta. Tracheae ; spiracles ; six to eight thoracic legs.

DLKINITION OF THli TI.U.M IXSECT. 29

tives, mostly with branching- nervures containing
air-vessels ; found in the majority of the class.
Organs [external) of respiration. A double set of
lateral spiracles, some for expiration.

Abdomen. Principal seat of the organs of generation.

Orga?is of' motion. In the Mj/riapods many pairs
of ac(|uired legs ; in the Thysanura elastic ventral
or caudal appendages.

Organs of respiration. A double series of lateral
sj)iracles for inspiration in the majority : in some
only a single series, and in others only a single
pair.

Organs of generation those common to the Ver-
tebrata, but retractile within the body, attended
usually by various anal appendages, particularly
a forceps in the males, and an ovipositor in the
females.

Second Definition — From their internal Organization.

Sensation.

Nervous System. A small brain usually subbilobed,
crowning a knotty double medullary chord ; nerves
proceeding from the brain and other ganglions to
all parts of the body.
Circulation.

Heart replaced by a simple alternately contracting
dorsal vessel or pseudocordia, without arteries or
veins, but filled with a white cold sanies.
Respiration.

Lungs replaced by tracheae, which receive the air
from the spiracles, and distribute it by bronchia^
infinilelv ramified.

30 definition of the term insect.

Digestion.

Liver and biliary vessels in most replaced by from
2 to + 150 floating hepatic filaments opening into
the space between the two skins of the intestinal
canal below the pylorus.
Generation.

Internal organs^ Males — Vasa deferentia, and vesi-
culae seminales, and the other ordinary organs. Fe-
males— Ovary usually bipartite, with palmate lobes;
genital organs single and mostly anal; one sexual
union impregnates the female for her life.
Development. In their passage to their adult state,
after they have left the egg, insects undergo several si-
multaneous changes of their integument or successive
moults, and the majority assume three distinct forms,
with distinct organs, which appear as rudiments in their
second state, and are completely developed in their last.

In defining the AracJmida I shall only mention those
particulars in which they differ from Insectce in their ex-
ternal anatomy.

Class — Arachnida.
Body.

Head and Trunk usually not separated by a suture.
Fyes. Two to eight, not lateral.
Mandibles cheliform or unguiculate, representing
the interior pair of the antennae of the Crustacea.
Palpi pediform or cheliform.

Trunlc. Legs eight or their representatives : tibiae
mostly consisting of two joints.
Abdomen with from two to eight spiracles.

definition of thk teum insect. 31

Sensation.

Nervous Sijstan. A small bilobed brain crowning a
double, knotty, medullary chord; nerves proceeding
iVom the brain and other ganglions to all parts of
the body.
Circulation.

Heart unilocnlar, inanrite, with a system of circulation
by arteries and veins ; blood a cold white sanies.
Respiration.
Lungs replaced by internal gills receiving the air by
s})iracles.
Digestion.

Liver^ consisting of conglomerate glands, and enve-
loping the intestines^ ; hepatic ducts.
Generation.

Genital organs double, ventral ; more than one sexual

union in the course of life.
The external characters in this class are the same al-
most in every respect as those which distinguish the
PhalangidcjC, the whole difierence consisting almost in
the systems of circulation, respiration, and digestion.
Perhaps some future anatomist may discover in the tribe
just mentioned, that there is a nearer agreement between
them and the AracJmida in these systems than is at pre-
sent suspected, which would prove them true Arachnida.
I am inclined to think that Phrijmis and Gonyleptes, &c.
breathe by branchial spiracles; but having no opportu-

* What L. Dufour regards as the liver in Scorpio {N. Diet. d'Hist.
N^at. XXX. 4:21.) Treviranus looks upon as an Epiploon {Fcttkorper)
both in Scorpio and Aranea. 6. t. If. 6. A A. t. Vi.f. 24. dd. Hepatic-
ducts: t. If. G. ii. t. u.f 24. /3. /3. /3, ,3.

32 DEFINITION or THE TERM INSECT.

tunity of examining living specimens, I dare not speak
with any confidence on the subject.

Having thus given j^ou a view of the most important
diagnostics by which what we have all along called In-
sects may scientifically be distinguished from other inver-
tebrate animals, it may not be without use, if, under
this head, I take a more popular and familiar view of
the subject, and say something upon those distinctions
which may attract the attention of the more common
observer.

The notion of diminutive size, particularly as com-
pared with vertebrate animals, seems more fi-equently
attached to the idea of an insect than any other ; and
this notion is generally correct, for one insect that is
bigger than the least of the above animals, thousands
and thousands are vastly smaller : but there exist some
that are considerably larger, whether we take length or
bulk into consideration, and this in almost every order.
To prove this most effectually, and that you may have a
synoptical view of the comparative size of the larger
insects of the different orders and tribes, I now lay be-
fore you a table of the dimensions of such of the largest
as I have had an opportunity of measuring, including
particularly those giants that are natives of the Britisli
isles.

DEFINITION OF THE TERM INSECT.

33

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VOL. in.

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DEFINITION OF THE TERM IXSECT.

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DEFINITION OF THE TERM JXSECT.

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DEFINITION OF THE TERM INSECT.

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38 DEFINITION OI THE TERM JXSECT.

From this table you see that several insects included
in it exceed some of the smallest Vertebrata in bulk. In
the Mammalia, the Sorex Araneus, called by the common
people here the Ranny, is not more than two inches
long excluding the tail ; and the Mus messorius, or har-
vest-mouse, peculiar to the southern counties of England,
is still more diminutive : so that to these little animals,
the larger Zh/nastida, Goliathi, and Prioni^ &c., appear
giants, and may compete with the mole in size. Even some
of the beetles of our own country, as the great Hydrophi-
Itis, the stag-beetle, &c., are more bulky than the two
first-named quadrupeds. Amongst the birds, many Piece,
PassereSi &c., yield to several insects in dimensions, and
their wings when expanded do not extend so far as those
of not a few Lepidoptera. The great owl-moth of Brazil
{Erebus Strioc) in this respect is a larger fowl than the
quail. Those beautiful little creatures, the humming-
birds [Trochilus L.), the peculiar ornament and life of
tropical gardens, which emulate the most splendid but-
terflies in the brilliancy of their plumage, are smaller
than a considerable nmiiber of insects in almost every
order, and even than some of those that are natives of
Britain. Various reptiles also are much inferior in size
to many of the insects of the above table. The smallest
lizard of this country would be outweighed by the great
British beetles lately mentioned, and the mole-cricket
{Gryllotalpa vulgaris); and some of the serpent tribe are
smaller than the larger Scolopendrce and luli. Amongst
theji'shes also, though some are so enormous in bulk,
others in this respect yield the palm to several insects.
The minnow and the stickleback that frequent our own
pools and streams are considerably inferior in size to
some ol" our water beetles.

DEFINITION Ol- THE TKU.M IXSIX'T. 39

In looking over the Uible, and comparing the different
species that compose it with each other, you will perceive
that the largest insects of the two sections of Ilemiptera,
of the Lcpidoptera as to their bodj/ merely, of the Ily-
menoptera and Diptcra, in general size fall considerably
short of those of the other orders ; and that certain indi-
viduals of the Orthoptera and Aptera bear away the
palm in this respect from all the rest. In the Coleoptera
the giants, with the exception of the Goliathi, are chiefly
to be found amongst the timber devourers in the Lamel-
licorn and Capricorn tribes. Of orthopterous insects the
Phasmidce present the most striking examples of magni-
tude; and in the Neuroptercy the Agrionidce of great
length.

It is worthy of remark here, that although the tropical
species of a genus usually exceed those of colder climates
in size, the Gryllotalpa of Brazil is very considerably
smaller than that of Europe: whether this is the case
with the rest of the cricket tribe I have not had an op-
portunity of ascertaining. The Lepidoptera^ though often
remarkable for the vast expansion of their " sail-broad
vans," if you consider only their bodies, never attain to
gigantic bulk. Even the hawk-moths {Sphinx L.), though
usually very robust, make no approach to the size of
the great beetles, or the length of some of the spectres
(Phasma) and dragon-flies [Agrionidce). With regard
to the superficial contents of their wings, a considerable
difference obtains in different species where they expand
to the same length — for the secondary wings are some-
times smaller than Xheprijuary^ and sometimes they equal
them in size. In some instances, also, the latter although
long are narrow, and in others they are nearly as wide
as long: regard, therefore, should be hud to their ex-

10 DEFINITION OF THE TEUM INSECT.

pansion both ways. In the Hymenoptera and Diptera,
the prhicipal giants are to be found in the predaceous or
blood-sucking tribes, as Scolia, the Sphecidcc^ Pomj)ilidce,
VespiddB, &c., belonging to the former order; and the
A»llid/E and Tahanidce to the latter. The true and false
humble bees [Bomhus and Xylocopa) and the fly tribe
(Muscidce), though they sometimes attain to considerable
size, scarcely afford an exception to this observation.
Amongst the Aptera none of the Hexapods strike us by
their magnitude, and few of the Octopods^ though the
legs of some of the Phalangida; inclose a vast area. That
in the table would with them describe a circle of six
inches diameter, though its body is little more than a
quarter of an inch in length. The Mijriapods exceed
most insects ii) the vast elongation of their body, which
with their motion gives them no slight resemblance to
the serpents. In the class Arachnida, the bird-spiders
{My gale) are amongst the principal giants, nor do the
Scorpio7is fall far short of them — both of them when alive
often alarming the beholder as much by their size as by
their aspect.

But as I have before observed, generally speaking, one
of the most remarkable characters of the insect world, is
the little space they occupy ; for though they touch the
vertebrate animals and even quadrupeds by their giants,
yet more commonly in this feature they go the conti'ary
way, and by their smallest species reach the confines of
those microscopic tribes that are at the bottom of the
scale of animal life. I possess an undescribed beetle,
allied to Silpha minutissima E. B. ^, which, though fur-

" S. minutissima of Marsham is synonymous with Dermestes ato-
mariiis De Geer, Scaphidium atomarium Gyllenh., and Latridiusfasd-
culaiis Herbst., but surely arranging with none of these genera, being

DEIINITION or THi: TEIl>r INSECT. ^l

iiishecl with elytra, wings, antennae, legs, and every other
organ usually found in the order it belongs to, is abso-
lutely not bigger than the full stop that closes this period.
In several other coleopterous genera there are also very
minute species, as in Cryptojjhagus, Anisoloma, Agathidi-
uni, 8:c. I know no orthopterous insect that can be called
extremely minute, except that remarkable one found on
the Continent in the nests of ants, the Blatla Acervorum
of Panzer *, but now called, I believe, Mi/rmecoj)hilus :
nor indeed any in the Hemiptera, Neuroptera^ and Di-
ptcra, that approach the extreme limits of visibility : but
in the Lcpidoptcra^ the pygmy Tinea occultclla is almost
invisible except in flight, being scarcely thicker tlian
a horse's hair, and proportionably short ; indeed, many
others of those lovely Lilliputians, the subcutaneous T'm<'^,
decorated with bands of gold and silver, and studded
with gems and pearls, that in larger species would dazzle
the beholder's eye, are in size not much more conspicu-
ous. In the Hymcnoptera order. Ichneumon Punctum of
Dr. Shaw, which forms so striking a contrast to his giant
Phasma dilatatum, being placed together in the same
plate; and another that I possess, under the trivial name
of AtomoSi would elude the searching eye of the ento-
mologist unless when moving upon glass. Linne named
the tribe of parasites to which these belong, Minuti,
on account of their generally diminutive size. But
these little minims, under the superintendence of Pro-
vidence, are amongst the greatest benefactors of the

sufficiently distinguished from them and every other insect by its
singular capillary wings. In my cabinet it stands under the name of
Tnchoptcryx K.

* Panz. Fn. Germ. Init. Ixii. 24. Conip. Hor. Entomolog. Addenda,
&.C. 533.

42 DEFINITION OF THE TERM INSECT.

human race, since they keep within due bounds the va-
rious destroyers of our produce.

The number of minute species of insects seems greatly
to exceed that of large ones, at least in Europe, of which
it may be asserted probably with truth, that two-thirds
are under a quarter of an inch in length, and one-third
not exceeding much a duodecimal of it. It might hold
good perhaps in Coleoptera, Hymenoptera, Diptera, and
Aptera : but in Orthoptera, Hemiptera, 'Neuroptera^ and
especially Lepidoptera, a large proportion would be found
to exceed three lines in length. Neither can it be af-
firmed of extra- European species, of those at least pre-
served in cabinets, amongst which it is rare to find an
insect less than the fourth of an inch long. This, how-
ever, must probably be attributed to the inattention of
collectors, who neglect the more minute species.

Though size forms a pretty accurate distinction between
insects and the great bulk o( vertebrate animals, it affords
less assistance in separating them from the invertebrate
classes, which are of every size, from the monstrous bulk
of some Cephalopoda (cuttle-fish) and Mollusca (shell-
fish, &c.) to the invisible infusory animalcule : but ex-
ternal characters, abundantly sufficient for this purpose,
may be drawn from the general covering, substance, form,
parts, and organs of the body. As I shall enter into pretty
full details upon this subject when I come to treat of the
external anatomy of insects, I shall here, therefore, only
give such a slight and general sketch of the distinctions
just mentioned, as will answer the end I have in view. I
must here repeat what I have before observed, and what it
is necessary that you should always bear in mind, namely,

DEFINITION OF THE TERM INSECT. -iS

tliat at the limits of classes and of every other natural
group, the characters begin to change, those peculiar to
the one group beginning gradually to disappear, and
those of the other to show themselves; so that it is im-
possible almost to draw up a set of characters so precise
as exactly in eveiy respect to suit all the members of any
natural group.

Whichever way we turn our eyes on the objects of
creation, above — below — athwart, analogies meet us in
every direction, and it appears clear, that the Book of
Nature is a Book of Symbols, in which one thing repre-
sents another in endless alternation. And not only does
one animal, &c. symbolize another, but even between the
parts and organs of one set of animals there is often an
analogy as to their situation and iise, when there is little
or no a^nity as to their structure — or again, the analogy
is in their situation^ without affinity in either structure
or use. Thus certain parts in one tribe represent other
certain parts of another tribe, though as to their structure
there is often a striking disagreement. This is particu-
larly observable between the vertebrate and invertebrate
animals. I shall therefore, in my remarks on the ge-
neral and particular structure of insects, contrast it in its
most important points with that of the first-mentioned
tribe.

The first thing that strikes us when we look at an
insect is its outside covering, or the case that incloses its
muscles and internal organs. If we examine it attentively,
we find that it is not like the skin of quadrupeds and
other Vertebrata, covering the whole external surface of
the body ; but that in the large majority it consists of
several pieces or joints, in this respect resembling the

44 DEFINITION OF THE TERM INSECT,

skeleton of the animals just named; and that even in those
in which the body appears to have no such segments, as
in many of the Mites {Acarus L.)j they are to be found in
the limbs. This last circumstance, to have externally
jointed legs, is the peculiar and most general distinction by
which the Insecta of Linne, including the Crustacea, may
always be known from the other invertebrate animals^.

If we proceed further to examine the substance of this
crust or covering, though varying in hardness, we shall
jfind it in most cases, if we exclude from our considera-
tion the shells of the Mollusca, &c., better calculated to
resist pressure than that of the majority of animals that
have no spine. In all the invertebrate tribes, indeed, the
muscles, there being no internal skeleton, are attached
to this skin or its processes, which of course is firmer
than the internal substance; but in insects it is very often
rigid and horny, and partially difficult to perforate, sel-
dom exhibiting that softness and flexibility which is found
in the cuticle of birds and most quadrupeds. From this
conformation it has been sometimes said, that insects
carry their bones on the outside of their body, or have
an external skeleton. This idea, though not correct in
all respects, is strictly so in this — that it affords a general
point of support to the muscles, and the whole structure
is erected upon it, or rather I should say within it. The
difference here between Insects and the Verteh^ata seems
very wide; but some of the latter make an approach to-
wards it. I allude to the Chelonian ReptUes ( Testudo L.),

® The Annelida have, however, sometimes jointed organs, which
facilitate their progressive motion whether vermicular or undulatory;
but they cannot be deemed legs, since they neither support the body
nor enable it to walk, &c. Latreille Anim. invertebr, Artie. 126. Ann.
du Mus. 1821.

DEFINITION or THE TERM I27SECT. 45

in which the vertebral cohimn becomes external or merges
in the upper shell. The cyclostomous fishes also are not
very wide of insects as to their integument. But on this
subject I shall be more full hereafter.

The forms of insects are so infinitely diversified that
they almost distance our powers of conception : in this re-
spect they seem to exceed the fishes and other inhabitants
of the ocean, so that endless diversity may be regarded
as one of their distinctions. But on all their variations
of form the Creator has set his seal of symmetry ; so that,
if we meet with an animal in the lower orders in which
the parts are not symmetrical, we may conclude in general
that it is no insect.

But it is by their j^arts and oj-gans that insects may be
most readily distinguished. In the vertebrate animals,
the body is usually considered as divided into head,
tnmk, and limbs, the abdomen forming no part of the
skeleton ; but in the insect tribes, besides the organs of
sense and motion, the body consists of three principal
parts — Head, Trunk, and Abdometi — the Jfist, as was
before observed, bearing the principal organs of sense
and mandiicatio?! ,- the second most commonly those of
motion; and the third those of peneratioji — the orojans of
respiration being usually common to both trunk and ab-
domen. These three primary parts, — though in some in-
sects the head is not separated from the trunk by any
suture, as for instance in the Arachnida ,- and in others,
head, trunk, and abdomen form only one piece, as in some
mites, — still exist in all, and in the great majority they are
separated by incisures more or less deeply marked : this
is particularly visible in the Hijmenojyfera and Diptcra,
which, in this respect, are formed upon a common model;

46 DEFINITION OF THE TERM INSECT.

and in the rest, with the above exceptions, it may be
distinctly traced.

The head of insects is clearly analogous to that of
vertebrate animals, except in one respect, that they do
not breathe by it. It is the seat probably of the same
senses as seeing, hearing, smelling, tasti?ig — and more pe-
culiarly perhaps of that of touch. The ej/es of insects,
though allowed on all hands to be organs of sight, are
differently circumstanced in many particulars from those
of the animals last mentioned ; they are fixed, have nei-
ther iris nor pupil, are often compound, and are without
eyelids to cover them during sleep or repose ; there are
usually two compound ones composed of hexagonal
facets, but in some instances there are four ; and from
one to three simple in particular orders. The antenncB
of insects in number and in situation correspond mth the
ears of the animals we are comparing with them ; but
whether they convey the vibrations of sound has not
been ascertained : that they receive pulses of some kind
from the atmosphere I shall prove to you hereafter — so
that if insects do not hear with them in one sense, they
may, by communicating information, and by ueroscopy, to
use Lehman's term, not directly in his sense ^, supply the
place of ears, which would render them properly ana-
logous to those organs. That in numbers these remark-
able organs are tactors is generally agreed, but this is not
their imiversal use. That insects smell has been often
proved ; but the organ of this sense has not been ascer-
tained. What has improperly been called the clypeus,
or the part terminating the face above the upper lip
{lahriim), is in the situation of the 7iose of the Vertebrataf
* De Antennis Insect, ii. 65.

DKiiM I'iON or rm: 'n:i{>[ ixsECT. 47

and therefore so far analogous to it, and in some cases
even in form : I therefore call it the 7iose. Whether this
part represents the nose by being fiirnished with what
answer the purpose oi nostrils^ residing somewhere at
or above the suture that joins it to the upper lip, I cannot
positively affirm; but from the observations of M. P.
Huber, with regard to the hive-bee, it appears that at
least these insects have the organ of the sense in question
somewhere in the vicinity of the mouth, and above the
tongue' : analogy, therefore, would lead us to look for
its site somewhere between the apex of the nose and the
upper lip ; and in some other cases, which I shall here-
after advert to, there is further reason for thinking that
it actually resides at the apex of the nose. The organ of
taste in insects, though some have advanced their j^^lpi
to that honour, is doubtless in some part within the
mouth analogous in a degree to the tongue and palate of
the higher animals. The organs of manducation, in
what may be deemed the most perfect description of
moutli, consist of an upper lip closing the mouth above,
a pair of jnaiidibles moving horizontally that close its
upper sides, and a Iffwe?' lip with a pair of viaxillce at-
tached to it, which close the mouth below and on the
under sides, both labium and maxillae being furnished
with jointed moveable organs peculiar to annulose pedate
animals, called palpi. In some tribes these organs as-
sume a different form, that they may serve for suction ;
but though in many cases some receive an increment at

• Noiiv. Obs. stir les AbeUles, ii. 376 — . It appears from M. Huberts
experiment, that it was only when the hair-pencil, impregnated with
the oil of turpentine, was presented " pres de la cavite, au dessus
de Vinsertion de la tronipe," that the bee was sensible of the odour.

48 DEFINITION OF THE TERM IXSECT.

the expense of others, and a variation in form takes place,
none, as M. Savigny has elaborately proved, are totally
obliterated or without some representative*. The organs
now described, except the upper lip, are formed after
a quite different type from those of Vei-tehrata^ with which
they agree only in their oral situation and use.

The second portion of the body is the Tninl"^ which
is interposed between the head and abdomen, and in
most insects consists of three principal segments, sub-
divided into several pieces, which I shall afterwards ex-
plain to you. I shall only observe, that some slight ana-
logy may perhaps be traced between these pieces and the
vertebree and ribs of vertebrate animals, particularly the
Chelonian reptiles. This is most observable in Gryllus L.
and Libellula L., in which the lateral pieces of the trunk
are parallel to each other''. In the Diptera and many
of the Aptera most of these pieces are not separated by
sutures. Each of the segments into which the trunk is
resolvable bears a pair of jointed legs, the first pair point-
ing to the head, and the two last to the anus. These legs
in their composition bear a considerable analogy to those
of quadrupeds, &c., consisting of hip, thigh, leg, and
foot ; but the last of these, the foot or Tarsus, is almost
universally monodactyle, unless we regard the Calcaria
that arm the end of the tibia, as representing fingers or
toes, an idea which their use seems to justify. Acheta
monstrosa and Tridactylus paradoxus, however *=, exhibit
some appearance of a phalanx of these organs. They
differ from them first in number, the thoracic legs being

* Anim. sans Vertehr. I. i. Mem. i.

" Plate VIII. Fig. 10—14; IX. Fig. G— 8.

<= Coquebert Illust. Ic\ iii, t. xxi./. 3.

nEFINITION OF THE TEHM INSECT. 49

invariably six in all insects, with the exception of the
Octopods or most of the Trachcan Arachnida^ which have
usually eight. In the Mi/riapods, though there are hun-
dreds o^ abdominal legs, only six are affixed to the trunk.
Next they difter with regard to the situation of their legs;
for though the anterior pair or arms are analogous in
that respect, the posterior pair are not, since in quadru-
peds these legs are placed hehind the abdomen, but in
insects before it — in fact, in the former the legs may be
considered as placed at each end of the body, excluding
only the liead and tail, but in the latter in the middle.
Though they correspond with those of quadrupeds in
being in pairs or opposite to each other, yet their direc-
tion witli respect to the body is different, the legs of
quadrupeds, &c. being nearly straight, whereas in insects
they are bent or form an angle, often very obtuse at the
principal articulations, which occasions them to extend
far beyond the body, and when long to inclose a propor-
tionally greater space. The ixings are the organs of
motion with which the upper side of the trunk is fur-
nished ; and these, though they are the instruments of
flight, are in no other respect analogous to those of
birds, which replace the anterior legs of quadrupeds, I ut
approach nearer, both in substance and situation, to the
fins of some fishes, and perhaps in some respects even to
the leaves of plants. M. Latreille is of opinion, That
the four wings or their representatives replace the four
thoracic legs of the decapod Crustacea'^. Upon this
opinion, which shows great depth of research and prac-
tical acumen, I shall have occasion to express my senti-
ments when I come to treat more at large on the anatomy

" Hor. Entomolog. 413—.
VOL. rii. F.

50 DEFINITION OF THE TERM IXSECT.

of the trunk and its members ; at any rate they do not
replace the two anterior pair of legs of the hexapod
Aptera. When merely used as wings, they commonly
consist of a fine transparent double membrane, strength-
ened by various longitudinal and transverse nervures, or
bones as some regard them, accompanied by air-vessels,
of which more hereafter, as well as of their kind and cha-
racters. I shall only observe, that insects are known
from all other winged animals, by havingyowr wings, or
what represent them, and this even generally in those
that are supposed to have only a pair. Another pecu-
liarity distinguishes the trunk of insects that you will
in vain look for in the vertebrate animals — these are one
or two pair of lateral spiracles or breathing pores. Though
the respiratory sacs, &c. of birds are almost as widely
dispersed as the tracheae and bronchiae of insects*, yet
tlieir respiration is perfectly pulmonary, and nothing like
these pores is to be discovered in them.

The principal peculiarity of the third part of the body,
the abdomen, is its situation behind the posterior pair of
thoracic legs, and its rank as forming a distinct portion
of what represents the skeleton. In most insects it is so
closely affixed to the posterior part of the trunk as to
appear like a continuation of it, but in the majority of
the Hymenoptera and Diptera, and in the Araneidan
Arachnida, or spiders, it is separated by a deep incisure ;
and in the first-mentioned tribe is mostly suspended to
the trunk by a footstalk, sometmies of wonderful length
and tenuity. In the Mainmalia the male genital organs
are partly external ; but in insects as well as in many of
the vertebrate animals, except when employed, they are

* N, Diet. (VHist. Nat. xxviii. ; compare 104 and 110,

DEFINITION OF THE TERM IXSECT. 51

retracted within the body. This part is the principal
seat of the respiratory pores or spiracles, many having
eight in each side, while others have only one.

Such are the principal external characters which di-
stinguish Insccta and Arachnida^ or what we have here-
tofore regarded as insects, to which here may be added
another connected with their internal organization. The
imion of the sexes takes place in the same manner as
amongst larger animals ; and the females with very few
exceptions, more apparent than real, are oviparous.
They are, however, distinguished by this remarkable pe-
culiarity already alluded to, that, except in the case of
the Arachnida, one impregnation fertilizes all the eggs
they are destined to produce. In most cases, after these
are laid, the females die immediately, and the males after
they have performed their office, though they wiU some-
times unite themselves to more than one female. One
other circumstance may be named here — that no genuine
insect or Arachnidan has yet been found to inhabit the
ocean.

Before I conchuie this letter, it is necessary to apprize
you, that evei'y thing which it contains relative to the
characters of insects, has reference to them only in their
last or perfect state, not in those preparatory ones through
which you are aware that the majority of them must pass.
The peculiar characteristics of them in these states — in the
egg^ the larva, and i\\Q jnipa^ will be the subjects of my
next letters, which will be devoted to a more detailed
view of the metamorphosis of insects than I gave you
before when adverting to this subject^.

^ See above, Vol.. I. Ed. 4. p. (j,'{ — .
E 2

LETTER XXIX.

STATES OF INSECTS.

EGG STATE.

On a former occasion I gave you a general idea of what
has been called, perhaps not improperly, the metavior-
phosis of insects * ; but since that time much novel and
interesting speculation on the subject has employed the
pens of many eminent Physiologists; and besides this,
the doctrine then advanced of successive developments
has been altogether denied by a very able Anatomist,
Dr. Herold, who, with a hand, eye, and pencil, second
only to those of Lyonnet, has traced the changes that
gradually take place in the structure of the cabbage-but-
terfly {Pier is Brassicce) on passing through its several
states of larva, pupa, and imago. It is necessary, there-
fore, that previously to considering separately and in

* The word fieru/i<,o^<pou, and its derivative fiiTu,uoQ(pco(ni, are not
extant in any Greek writer before the date of the New Testament.
They are used to express any external change of form or colour, and
metaphorically an inward change and progressive improvement of the
mind. Comp. Matth. xvii. 2. ^lian. Var. Hist. 1. i. c. 1. Rom. xiii. 2.
2 Cor, iii. 18. They are, therefore, not improperly applied, as some
have supposed, to the changes of insects.

STATES OF INSECTS. 53

detail the states of insects, I should again call your atten-
tion to this subject, and endeavour to ascertain whether
Dr. Herold's hypothesis rests upon a solid foundation ;
or whether that adopted from Swamnierdam by all tiie
most eminent Entomologists and Physiologists since his
time can be maintained against it.

I shall first give you a short abstract of the new hy-
pothesis.

According to Dr. Herold — The successive skms of the
caterpillar^ the jnipa-case, the future hutterjly^ and its
parts and organs, except those of sex "which he discovered
in the newly excluded larva, do not pi'eexist as germes, but
are formed stcccessively from the rate mucosum, "johich it-
self is formed anew upo7i every change of slcin from lihat
he denominates the blood, or the chyle after it has 2>assed
through the pores of the intestinal caTial into the general
cavity of the body, where, being oxygenated by the air-
vessels, it performs the nutritive functions of blood. He
attributes these formations to a vis formatrix (Bildende
Kraft).

The caul or epiploon (Fett-masse), the corps graisseux
of Reaumur, Sfc, which he supposes to be formed from the
supeifiwus blood, he allows, with most physiologists, to be
stored up in the larva, that in the pupa state it may serve
for the development of the imago. But he differs from
them in asserting that in this state it is desti?ied to two
distinct purposes— ;^rst, for the product io?i of the muscles
of the butterfly, which he affirms are generated from it in
the shape of slender bundles of fibres ; — and secondly, for
the development and nutrition of the organs formed in the
larva, to effect which, he says, it is dissolved again into
the mass tf blood, and being oxygenated by the air-vessels.

54 STATES or INSKCTS.

hecomesjitfor nutrition^ 'vohence the epiploon appears to
be a kind of concrete chijle^.

Need I repeat to you the hypothesis to which this
stands opposed — That every caterpillar at itsfrst exclu-
sion contains within itself' the getine of the future hutterjly
and of all its envelopes^ which successively p7'ese7iti7ig them-
selves are thrown off, till it appear in perfection and
beauty, with all its parts and. organs, when no further de-
velopment takes place.

I beheve you will agree with me, when you have read
and considered the above abstract of Dr. Herold's hy-
pothesis, that in it he substitutes a name for knowledge,
talks of a visformatrix because his assisted eye cannot
penetrate to the primordial essence or state of the germes
of being, and denies the existence of what he cannot dis-

• cover''. From ancient ages philosophers have done the
same, to conceal their own ignorance of causes under a
sounding name, when they have endeavoured to pene-
trate within the veil of the sanctum sanctorum, which it
is not permitted to vain man to enter. This has occa-
sioned the invention, not only of the term in question,
but of many others, as little meriting the appellation of
Signs of ideas ,- such as Plastic Nature, Epigenesis, Pan-
spermia, Idea seminalis, Nisus formativus, &c. But upon

* Entwickelungsgcschichte der Schmetterlinge 12 — 27. 10.5 — .

^ Dr. Virey's observations under the article Embryo {N. Hid.
(VHisl. Nat. X. 195.) deserve liere to be considered. " II y a done
quelque chose au dessus de Tintelligence humaine dans cette forma-
tion des etres; en vain on veut I'approfondir, c'est un abinie dans
lequel on ne voit que la main de Dieu. A quoi bon s'appesantir sur
le mystere de la formation des etres, sans esperance de I'expliquer ?
Ne vaut-il pas mieux observer les operations de la nature autant
qu'il est perniis a I'oeil humain de les appercevoir ? "

STATES or INSECTS. 55

this subject you cannot do better than consult \vhat the
learned Dr. Barclay has said in his admirable work On
Life, and Organization^^ in which he has placed the
inanity, the vox ct praterea nihily of such high-sounding
terms in their true light. The processes of nature in
the formation and development of ihafcctus in utcro, of
the chick in the egg, of the butterfly in the caterpillar,
we in vain attem})t fully to investigate ; yet we can easily
com])rehend that pre-existent germes, by the constant
accretion of new matter in a proper state, may be gra-
dually developed, but we find it impossible to conceive
liow, by the action of second causes, without the inter-
vention of the first cause, the butterfly should be formed
in the caterpillar, unless it preexists there as a germe or
foetus. " Is it not clear," asks Dr. Virey in his lively
manner, " as Blumenbach and other Physiologists main-
tain, that there is a formative power, a nisusformatixmSi
which organizes the embryo ? Admirable discovery ! "
says he, " which teaches us that the foetus forms itself
because it forms itself I As if you should afiirm that the
stone falls because it foils'' ! " Had Dr. Ilerold considered
what Bonnet says with as much good sense as modesty,
he would never have imagined that his discovering the
organs of the butterfly one after the other at certain pe-
riods in the caterpillar, was any sound argument against
their preexistence and coexistence as germes. " Or-
gans," says that amiable and excellent Physiologist,
" that have no existence as to us, exist as they respect
the embryo, and perform their essential functions ; the
term of their becoming visible is that which has been

' § xiv. b N. Diet. d'Hist. Xat. x. 103.

56 STATES OF INSECTS.

erroneously mistaken for the period of their existence'."
This has been Dr. Herold's grand error ; he mistook the
commencement of the appearance of the organs of the
butterfly for that of their existence, and yet the early ap-
pearance of the sexual organs ought to have led him to
a conclusion the reverse of that which he has adopted.

Dr. Virey has observed with great truth — that " Every
being has a peculiar and unique nature, which would be
impossible if the body was composed of parts made at
several intervals, and without a uniform power that acts
by concert^:" and every Physiologist acquainted with
the history of insects that undergo a complete metamor-
phosis will allow, that their developments and acquisition
of new parts and organs take place according to a law
which regulates the number, kind, and times of them,
differing in different species, and which has had an in-
variable operation, since the first creation, upon every
sound individual that has been produced into the world.
In consequence of this law, one species changes its
skin only Jbw times, and another^u^ or six ; — in some
cases the first skins shall be covered or bristled with
hairs or spines, and the last be naked and without arms ;
■. — that which forms the case of the pupae shall differ in
form and substance from the preceding skins, varying in
both respects in different species ; and finally the butterfly
shall invariably follow, when no other change but the

» (Euv. V. 279. " II n'est pas exact tie dii'e que le coeur, la tete, et
la moelle epiniere, sont formes les premiers dans les foetus iles ani-
maux a sang rouge et vertebres," says Dr. Virey ; " mais il faut dii'e
seulement que tel est I'ordre dans lequel ces organes commencent a
dcvenir visibles." N. Diet. d'Hist. Nat. x. 196.

b Ibid, 193.

STATES OF INSECTS. .57

last inortiil one shall take place. Can this law, so con-
stantly observed, be the result of a blind power? Or are
we to suppose that the Deity himself is always at work
to create the necessary organs in their time and place ?
Is it not much more consonant to reason and the general
analogy of nature, to suppose that these jiarts and organs
exist in embryo in the newly-hatched caterpillar, and
grow and are successively developed by the action of the
nutritive fluid ? In the pupa of many Z)/p^<*ra the in-
closed animal, even under the microscope, appears with-
out parts or organs, like a mere pulp ; but Bonnet tells
us, that if boiled, all the parts of the pupa appear^, which
proves the preexistence of these parts even when not to
be discerned, and that nothing but the evaporation of
the fluids in which they swim is wanted to render them
visible.

Mr. William MacLeay has with great truth observed:
*' The true criterion of animal as Avell as vegetable per-
fection is the ability to continue the species ^ ;" and in
their progress to this state certain changes take place in
the parts and organs of all animals and vegetables :
there is, therefore, an analogy in this respect between
them ; and this analogy also furnishes another argument
against Dr. Herold's hypothesis, as we shall presently
see. These changes are of three kinds : In the vege-
table kingdom, at least in the phaenogamous classes, tliere
is a succession of developments terminating in the ap-
pearance of the generative organs, inclosed in the flower ;
in this kind the integuments, or most of them, are usually
persistent. In insects and other annulose and some ver-
tebrate animals, there is a succession of spt^liation:^, or
■' (Euvr. \m. '^Ib. ^ Ihr. Kntvihnlo". 146.

58 - STATES OF INSECTS.

simultaneous changes of the whole integument, till the
animal appears in its perfect form with powers of repro-
duction ; in this kind the integuments are caducous. — In
man and most of the vertebrate animals there is a gradual
action of the vital forces in dilFerent organs till they are
fitted for reproduction ; accompanied, as progess is made
to the adult state, by the acquisition of certain organs,
&c. as of teeth, horns, pubes, feathers, &c. * Let us now
consider a little in detail the analogies that appear to exist
between the second and the first and third kinds. I shall
first consider the latter as the least obvious. That able,
judicious, and learned physiologist. Dr. Virey, has pointed
out no inconsiderable resemblance between the metamor-
phosis of the insect, and the changes, which he denomi-
nates a metamorphosis by metastasis, to which most ver-
tebrate animals are subject. In them, he observes, a state
analogous to the larva state begins at the exclusion of
the foetus from the womb ; it is deprived of teeth, and its
viscera are only accommodated to milk : in the cornute
species the horns are in embryo : the digestive system
now preponderates, and the great enjoyment is eating.
A second state, in a degree analogous to that of ^?mj9«,
commences at the period of dentition — the teeth now
produce another modification in the intestinal canal,
which becomes capable of receiving and digesting solid
food : during this period the vital forces are all tending
to produce the perfect state of the animal ; and in this
state, in man especially, the individual is educated and
fitted to discharge the duties of active life. Again, ana-
logous to the imago state is the age of puberty, in which

'"' See on this subject N. Did. d'Hisl. Nat. xx. article Metamor-
phosis.

STATES OF INSJiCTS. 59

the complete development of the sexual powers takes
place in both sexes, and the animal has arrived at its
acme, and can continue its kind^: now the digestive
powers diminish in tiieir activity, and love reigns para-
mount. When this state is fully attained, no further or
higher change is to he expected, and the progress is soon
towards decay and the termination of the animal's mortal
career. So we see that in fact man and other mammalia,
though they do not simultaneously cast their skins like
the insect ; or pass into a state of intermediate repose,
before they attain the perfection of their nature, like the
cateri)illar ; have their three states, in each of w hich they
acquire new parts, powers, and appetites.

But a more striking analogy has been traced between
the insects that undergo a complete metamorphosis and
the vegetable kingdom ; for though the jprimary analogy
seems to be between the Polypus and the Plant, yet the
secondary one with the Insect is not by any means remote.
There are circumstances to which I shall have occasion
hereafter to call your attention, which afford some ground
for supposing, that the substance of the insect and the
vegetable partakes of the same nature, at least approxi-
mates more nearly, than that of the insect and the verte-
brate animal ; and every one who has observed these little
creatures with any attention, will have observed amongst
them forms and organs borrowed as it were from the
kingdom of Flora; and vice versa the Botanist, if he
makes the comparison, will find amongst his favourite
tribes many striking resemblances of certain insects.
But the analogy does not stop here ; for the butterfly
and the plant appear to have been created with a parti-

^ .V. Dkt. d'Hist. Nat. xx. 349—.

60 STATES OF INSECTS.

cular reference to eacli other, both in the epoch of their
uppearance and the changes that take place in them.
Thus, as Dr. Virey has observed, the caterpillar is si-
multaneous with the leaf of the tree or plant on which it
feeds, and the butterfly with the flowers of which it im-
bibes the nectar*. Swammerdam, I believe, was the first
who noticed the analogy between the changes of the insect
and the vegetable, and has given a table in which he has
contrasted their developments, including other animals
that undergo a metamorphosis^: an idea which has been
generalized by Bonnet*^, and adopted and enlarged by
Dr. Virey ^. A state analogous to that of the larva in
the insect begins in the plant when it is disclosed from
the seed, or springs from its hybernaculum in the bulb,
&c., or is evolved from the gemma ; integument after in-
tegument, often in various forms, as cotyledon, radical,
cauhne, or floral leaves, expands as the stem rises, all
which envelopes incase the true representative of the
plant, the fructification, as the various skins do the future
butterfly. When these integuments are all expanded,
the fructification appears inclosed by the calyx or corolla
as the case may be, in which the generative organs are
matured for their office — this is the bud, which is clearly
analogous to the pupa state of the insect. Next the calyx
and corolla expand, the impregnation of the germen takes
place, and the seed being ripened, and dispersed by the
opening of the seed-vessel or ovary of the plant, the in-
dividual dies : thus the imago state of the insect has its
representative in the plant. " If we place," says Dr. Virey,
*' here the egg of the insect, next its caterpillar, a little

» JV. Dill. (THist. Nat. xx. 348.

f Bibl. Nal.EA. Hill. ii. 138. ' CEuir. v, 283--.

STATES OF INSECTS. 61

further the chrysalis, and lastly the butterfly — what is
this but an animal stem — an elongation perfectly similar
to that of the plant issuing from the seed to attain its
blossoming and propagation ?*

There being, therefore, this general analogy in their
progress to that state in which they can continue their
species between every part of animated nature, it holds
good, I think, that the same analogy should take place
in their developments. If the adult man or quadruped,
&c. is evidently an evolution of the foetus, as from mi-
croscopical observations it appears that they are^, if the
teeth, horns, and other parts, &c. to be acquired in his
progress to that state are already in him in their embryos,
we may also conclude that the butterfly and its organs,
&c. are all in the newl^'-hatched caterpillar. Again, if the
blossom and its envelopes are contained in the gemma, the
bulb, &c. where they have been discovered*^, it follows
analogically that the butterfly and its integuments all
preexist in its forerunner.

Perhaps after this view of the objections to Dr. He-
rold's hypothesis, it will not be necessary to say much
with regard to the argument he draws from the change
of organs — the loss of some and the acquisition of others
— since this may readily be conceived to be the natural
consequence of the vital forces tending more and more
to the formation of the buttei'fly, and the withdrawing
of their action more and more from the caterpillar; I
shall not, therefore, enter further into the question, espe-

» ^\ Diet. d'Hist. Nat. xx. 355.

'' Leeuwenhoek discovered in the incipient foetus of a sheep, not
larger than the eighth part of a pea, all the principal parts of the
future animal. Arc. Nat. I, ii. 165, 173.

«• Bonnet, CEuvr. v. 284.

C)2 STATES OF INSFXTS.

cially since the change of organs will come more regu-
larly under our notice upon a future occasion.

Winged insects, many branchiopod Crustacea, and the
Batracian reptiles, have been observed by Dr. Virey to
bear some analogy to the mammalia, aves, &c. in another
respect. In leaving their egg, they only quit their first
integument, answering to the chorion or external envelope
of the human foetus ; they therefore still continue a kind
of foetus, so to speak, more or less enveloped under other
tunics, and principally in their ajniiios, or the covering
in which the foetus floats in the liquor am?iii^. This the
buttei-fly does in the pupa case ; and its birth from this,
under this view, will be the true birth of the animal. In
the human subject, the ova upon impregnation are said
to pass from the ovary through the Fallopian tube into
the uterus. In the insect world, upon impregnation, the
eggs pass first from the ovaries into the oviduct, answer-
ing to the Fallopian tube, which in them terminates in
the ovipositor, or the instrument by which the parent
animal conveys the eggs to their proper station : there
is, therefore, nothing properly analogous to the uterus in
the insect, and the substance upon which the larva feeds
upon exclusion answers the purpose of a placenta.

After this general view of the most modern theories
with regard to the metamorphosis of insects, I shall in the
present and some following letters, treat separately of the
different states through which these little beings suc-
cessively pass.

The first of these is the Egg state, the whole class of
insects being strictly oviparous. Some few tribes indeed

" N. Dirt, d'lliil. Knt. xx. 352,

STATES OF INSECTS. t>L<

bring into the world living young ones, and have on that
account been considered as xnviparous^ but incorrectly,
for the embryos of none ol' those are nourished, as in the
true viviparous animals, within a uterus by means of a
placenta, but receive their development within true eggs
which are hatched in the body of the mother. This is
proved by the observations of Lceuwenhoek, who Ibund
eggs in the abdomen of a female scorpion^; and of
Reaumur, with regard to the flesh-fly [Musca cmiiaria)
and other viviparous flies as they have been called''. A
similar mode of production takes place in vipers and
some other reptiles, which have hence been denominated
ovo-vivi parous, to distinguish them from the true vivi-
parous animals — the class Mammalia. By far the larger
portion of insects is oviparous in the ordinary acceptation
of the term. The ovo-viviparous tribes at present known
are scorpions ; the flesh-fly and several other flies ; a
minute gnat belonging to Latreille's family' of Tipularicc'^ ;
some species oi Coccus-, some bugs [CimicidceY ; and most
Aphides, which last also exhibit the singular fact of indi-
viduals of the same species being some oviparous and
others ovo-viviparous, the former being longer in propor-
tion than the latter. — Bonnet, however, is of opinion that
the eggs of the first are not perfect eggs, but a kind of
cocoon, which defends the larva, already formed in some
degree, from the cold of winter*^.

* Select Works by Hoole, i. 132. The fact is coiifirmctl by M. L.
Dufour, who, havinj^ opened tlie abdomen ol'a female scorpion, found
in the midst of some eggs nearly mature a little scorpion a quarter
of an inch long; it lay without motion, with its tail folded under the
Iwdy. N. Diet. d'Hist. Xat. xxx. 43G.

^ Reaum. iv. 425—. ^ Ibid. 428—. t. xxix./. 10, 11.

"' Busch, a German author, affirms that many CiviicidcB are subject
to this law. Sclineid. i. 206.

•" Quoted iu Huber Fourmis, 20S. Some reptiles also are at one

64; STATES OF INSFXTS.

When excluded from the body of tlie mother, or from
the egg, as has been before observed, some insects appear
nearly in the form of their parents, which, with a very
slight alteration, they always retain ; others, and the
greater number, assume an appearance totally different
from that of their parents, which they acquire only after
passing through various changes. It is to these last, which
have chiefly engaged the attention of Entomologists,
that the title of metamorphoses has been often restricted.
As, hoAvever, those insects which undergo the slightest
change of form, as spiders do, undergo some change, and
almost all insects cast their skins several times ^ before
they attain maturity, Linne and most Entomologists, till
very recently, have regarded the whole class as under-
going metamorphoses, and as passing through ^owr dif-
ferent states, viz. the Egg — the Larva — the Pupa — and
the Imao;o.

It is obvious, however, that in ovo-viviparous species
three states of their existence only come under our cog-
nizance, as these, being hatched in the body of the
mother, come forth first under the form of larvae. There
is even one tribe of insects which presents the strange
anomaly of being born in the piipa state. This is the
Linnean genus Hippohosca [Pupipara fam. Latr.), to
which our forest-fly belongs, the females of which lay
bodies so much resembling eggs, that they were long
considered as such until their true nature was ascertained
by Reaumur (most of whose observations were confirmed
by De Geer), who, from their size, which nearly equals

time oviparous, and at another ovo-viviparous. N. Diet. (THist.
Nat. xii. 568.

^ I say almost all insects, because the larvae of Hyvienoptera and
Diptern are suppoFcd not to undergo this change. N. Diet. d'Hisf.
Nat. XX. 365.

STATES OF INSECTS. 6S

that of the parent fly — from their slight motion when
first extrudeil — from spiraculiform points which run down
each side of tliem — and histly, from their producing not
a larva, as all other insects' eggs do, but perfect flies in
the winged state — inferred, and doubtless with reason,
that they are not real eggs, but pupae, or larva? just ready
to assume the pupa state, which, however strange it may
seem, have passed the egg and larva states in the body
of the mother*.

Insects, therefore, as to their mode of birth, may be
divided into —

I. Ovo-viviparoiis, subdivided into —

1. Larvijmrons, coming forth from the matrix of the

mother in the state of larvae, as the Scorpion
(Scorpio), the Flesh-fly {Musca\ the Plant-louse
[Aphis\ &c.

2. Pupiparous, continuing in the matrix of the mo-

ther during the larva state, and coming forth in
that of pupa, as the Forest-fly [Hippohosca
equina), the Sheep-louse [Melopkagus ovinus),
the Bat-louse {Nyctcribia Vespertiliofiis), &c.

II. Oviparous. All other insects.

Our business for the remainder of this letter will be
with the latter description of these little animals.

The unerring foresight with which the female deposits
her eggs in the precise place where the larvae, when ex-
cluded, are sure to find suitable food ; and the singular
instruments with which, for this purpose, the extremity
of their abdomen is furnished, have been noticed in a
former letter^, and those last mentioned will be adverted
to in a future one. I shall now, therefore, confine myself

* Reaum. vi. Meni. xiv. De Geer, vi. 280.
'' See Vol. I. Lett. xi.
VOL. I J I. I

66 STATES OF INSECTS.

to other circumstances connected with the subject, ar-
ranged for the sake of order under several distinct heads,
as — their exclusion — situatio7i — substance — number — size
—^gure — colour — and period of hatching.

i. Exchision. The exclusion or extrusion of the im-
pregnated eggs takes place, when, passing fi'om the ovary
into the oviduct, they are conducted by means of the
ovipositor, in which it terminates, to their proper situa-
tion. By far the greater number of insects extrude them
singly, a longer interval elapsing between the passage of
each egg in some than in others. In those tribes which
place their eggs in groups, such as most butterflies and
moths, and many beetles, they pass from the ovaries
usually with great rapidity ; while in the Ichiieumonidce,
Sphegidce, CEstri, and other parasitic genera, which usu-
ally deposit their eggs singly, an interval of some minutes,
hours, or perhaps even days, intervenes between the ex-
trusion of each egg. One remarkable instance of the
former mode I noticed in my letter on the Perfect Socie-
ties of Insects * ; another may be cited, to which you may
yourself be a witness — I allude to that common moth,
vulgarly called the Ghost [Hepialus Humuli), which lays
a large number of minute black eggs, resembling grams
of gunpowder, and ejects them so fast that, according to
De Geer, they may be said to run from the oviduct, and
are sometimes expelled with the force of a popgun^. A
Tetrapterous insect, the genus of which is uncertain, is
said, when it is taken, to discharge its eggs like shot from
a gun '^. And a friend of mine, who had observed with at-
tention the proceedings of a common crane-fly ( Tipula),

^ See Vol. II. p. 36. " De Geer i. 494—.

" Called by M. I'Abbe Preaux, who observed it near Lisieux in
Normandy, Mouche Balisfe. N. Diet. d^Hist. N'at. xxi. 442.

STATKS Ol' INSKC rs. 67

assured iiio lliat several females which he caught pro-
jecteil tlieir eggs to the distance of more than ten inches.

A few Diptera extrude them in a sort of chain or
necklace, each egg being connected by a glutinous mat-
ter with that which precedes and follows it. In a small
species of a genus allied to Psi/choda (a kind of midge),
which one season was abundant in a window of my house,
this necklace is composed of eggs joined by their sides,
not unlike those strung by children of the seeds of the
mallow". Other TipnJidcv: on the contrary extrude their
eggs joined end to end, so as to resemble a necklace of
oval beads. Bcris clavipes and Sciura Thomcc^ two other
flies, produce a chain about an inch long, consisting of
oval eggs connected, in an oblitjue position, side by side ;
an arrangement very similar prevails in the ribband of
eggs which drop from some of the Ephemercv^ .

These esrcs, like those of the insects first mentioned,
though connected, are expelled in succession ; but other
tribes, as the LibelluUdce, with the exception of Agrioii,
many Ephemera, Trichopterous insects, &c. expel the
whole at once, as it were in a mass. In those first men-
tioned they are gummed together in an oblong cluster *=.
In one Ephemera mentioned by Reaumur'', they formed
two oblong masses, each containing from three to four
hundred eggs, and three and a half or four lines long.
Tliese animals as soon as their wings are developed eject
these masses by two orifices, and are aided in the process
by two vesicles full of air, wherever they happen to alight
or to fall ; in most instances it is the water, their proper
element, that receives them, but the animal does not ap-
pear to know the difference between a solid and a liquid,

"^ Plate XX. Fig. 20. '' Reaum. vi. TjOO. t. xlv./. 11, 12.

<• Reaum. vi. 434. '• Ihtd. vi. 494.

F 2

68 STATES OF INSECTS.

and seems only anxious how to free herself from a bur-
then that oppresses her ; all has been contrived that an
insect so short-lived may finish her diiFerent operations
with the utmost celerity : the term of her existence would
not have admitted the leisurely extrusion of such a num-
ber of eggs in succession'. Some Trichoptera^ or May-
flies, as Phyganea grandis L., exclude their eggs in a
double packet, enveloped in a mass of jelly, (a circum-
stance often attending the eggs that produce aquatic
larvae,) upon the leaves of willows^. A similar double
packet in tlie year 1 8 1 0 I observed appended to the anus
of a black species with long antennas, probably Phry-
ganea atrata F. *= Upon taking several of the females I
Avas surprised to find in the above situation a seemingly
fleshy substance of a dirty yellow. At first, from its an-
nular appearance, I conceived it to be some parasitic
larva, but was not a little surprised upon pulling it away
that it was full of globular transparent dusky eggs : it
was about two lines and a quarter in length and nearly
one in breadth. Being bent double it was attached to
the animal by the intermediate angle, and when un-
folded was constricted in the middle ''. Each half, which
was roundish, had about ten sharp transverse ridges,
the interstices of which appeared as if crenated, an ap-
pearance produced by the eggs which it contained.
Upon more than gentle pressure it burst and let out
the eggs. Though resembling the packet of P. grandis
in shape and other circumstances, it was nothing like

* The vesicles, which Reaumur thinks may be pulmonary vesicles,
^s well as assisting in the extrusion of the masses of eggs, he has
pgured t. xliv./. 10. uu.

■' De Geer ii. 534. t. xiii./. 13.

■= Coquebert Illustr. Ic. t. i./. A. B.

<" Pi,4TE XX. Fia. 25.

STATES Ol- INSECTS. C9

jelly, but had rather a waxy appearance, and seems to
have been covered by a membrane : so that the ex-
cluded larvae must probably have eaten their way out
of it. I have still by me, in 1822, s})ecimens of these
egg-packets, which, after the lapse of so many years, re-
tain their original form and colour. It is not improbable
that other species extrude their eggs in a similar case.
Scopoli says of P. hicaudata L., that the female carries
about under her belly her eggs united into a globe, like
Lycosa saccata^. The eggs oi Geometra Potamogata F.
are also enveloped in a gelatinous substance, and the
mass is covered with leaves^.

Insects of the Diptera order also, like frogs and toads,
commit their eggs to the water imbedded in masses of
jelly. Dr. Derham desci'ibes two different kinds of
them, in one of which the eggs were laid in parallel rows
end to end, and in another in a single row, in which the
sides were parallel*^. But the most remarkable and
beautiful specimen of this kind that I ever saw was one
that, many years ago, I took out of a pond at Wittersham
in Kent, from which I requested a young lady to make the
drawing I send you**. The mass of jelly, about an inch
and a quarter long, and rather widest in the middle, was
attached by one end to some aquatic grass, and from one
end to the other ran a spiral thread of very minute eggs,
the turns of the screw being alternately on each side.

The mode of exclusion of the eggs of the Blatta^v/hich.
are engaged for a whole week in the business of oviposi-
tion, is very singular: the female deposits one or two
large suboviform capsules, as large as half their abdomen,
rounded on one side, and on the other straight and ser-

" Ent. Carniol. 260. n. 705. *• Reaiim. ii. 401.

' In Rail Hist. Ins. 264. ^ Plate XX. Fig. 24.

70 STATES or INSECTS.

rated, wliich at first is white and soft, but soon becomes
brown and hard. This egg-case, as it may be called,
contains sixteen or eighteen eggs arranged in a double
series, and the cock-roaches when hatched make their
escape through a cleft in its straight side, which shuts so
accurately when they have quitted it, that at first it ap-
pears as entire as before*. The insects of the genus
Mantis also, or what are called the prai/ing insects, when
they deposit their eggs, eject with them a soft substance,
which hardens in the air and forms a long kind of enve-
lope resembling paichment, in which the eggs are ar-
ranged also in a double series. And the Locusts [Gryl-
lus Locusta L.) are said by Morier'' to deposit in the
ground an oblong substance, of the shape of their abdo-
men, which contains a considerable number of eggs ar-
rai)ged neatly in rows. The peristaltic motion observed
in the females of some insects during oviposition has been
before described '^.

ii. Situation. Under this head I include the situation
in which the female insect })laces her eggs when extruded,
whether she continues her care of them and carries them
about till they hatch, or whether she entirely deserts
them, placing them either without a covering within
reach of their food, or enveloping them in hair or other-
wise protecting them from accident or the attack of ene-
mies. I shall consider them under two views : Jirst, as
depositing their eggs in gy-oujn, whether covered or naked ;
and secondly, as depositing them singli/.

■■' Goeze Xaturf. xvii. 183—. /. iv./. 16 — 19. Comp. .V. Did.
cV H'lst. Nat. iii. 475. and xix. 239. Do Geer iii. 533.
'' Second Jounieij throngli Persia, 100 — .
■• Sec Vol. II. p. 3().

STATES (ir INSECTS. 71

1. Those that deposit their eggs in groi/j>s arc first to
be considered. I shall begin with those that protect them
with some kind oi' covering.

I have already mentioned in a former letter* the
silken bag with which Lycosa saccata Latr., a kind ot"
spider, surrounds her eggs, and in which she constantly
carries them about with her, defending them to the last
extremity. Many other spiders, indeed nearly the whole
tribe, fabricate similar pouches, but of various sizes,
forms, texture, and colours. Some are scarcely so big
us a pea, others of the size of a large gooseberry ; some
globular, some bell-shaped ; others, the genus Thomisus
Walck. in particular, depressed like a lupine ; some of a
close texture like silk ; others of a looser I'abric resem-
bling wool : some consisting of a single pellicle, but most
of a double, of which the interior is finer and softer'';
some white ; others inclining to blue ; others again yel-
low or reddish; most of them are of a whole colour, but
that of Fjpeira fasciaia is gray varied with black "^. And
while the parent spider of some kinds (the Lupi) always
carries her egg-bag attached to her anus, odiers hold
them by their palpi and maxillae; and others suspend
them by a long thread, or simply fasten them in different
situations, either constantly remaining near them (the
Telaricc), or wholly deserting them (the Rctiaricc). The
eggs of one of these last Lister describes as often fixed
in a very singular situation — the cavity at the end of a
ripe cherry ; and thus, as he expresses it — " Stomachi
maxime delicahdi qnotics hanc innocuam buccam non miiius
ignorantcr quam avide devora)-unt^."

» Vol. I. p. 359—.

" Latr. Hist. Nat. des Foitrmis, .334. ^V. Bk-f. d'HisL Xat. ii. 284.
' Lister I)e Aran. Tit. 13, 14. .V. Diet. d'Hist. Nat. ii. 284.
* Lister Ibid.od.Tn. l.i.

72 STATES OF INSECTS.

Herman informs us, that the species of the genus Che-
lifer carry their eggs in a mass under their belly ^.

Madam Merian gives an account of two species of
Blatta, which she affirms carry an egg-pouch about with
them — one species {B. gigantea P) she describes as car-
rying its eggs in a globular pouch of web like certain
spiders, and the other in a brown bag, which, when
alarmed, it drops and makes off*. But this admirable
paintress of natural objects was not always correct in her
statements ^ : it seems very improbable, from the habits
of those species of which we know the history, that any
of them should spin a pouch of web for their eggs.

The only insects certainly known to spin an egg-pouch
like the spiders, are the Hydrophili, a kind of water-
beetles. Some of these, as H, lividus, carry them about
with them, hke JLycosa saccata, attached to the under
side of their body, as M. Miger observed '* ; and others
when they are finished desert them. That of the great
water-beetle [Hydrophilus piceus) was long ago described
and figured by Lyonnet ^ ; and a more detailed account
of it has since been given by M. Miger '^. In form
it somewhat resembles a turnip when reversed, since it
consists of a pouch of the shape of an oblate spheroid,
the great diameter of which is three quarters of an inch ;
and the small, half an inch, from which rises a curved
horn, about an inch long and terminating in a points.
The animal is furnished with a pair of anal spinners,
which move from right to left, and up and down, with

e N. Diet. d'Hisf. Nat. xxvi. 447. •* Ins. Surinam, t. i.

^ A striking instance of this may be seen in her forty-ninth plate,
in which she has clapped the rostrated head of Fulgora laternaria
upon the ])ody of a Cicada Latr., affirming it to be the former fly in
its previous state ! This might be a trick npon her.

* N. Diet. d'Hist. Nat. xv. 489. * Lesser L. i. 300.

' Annates du Mitseum, xiv. 441. " Lesser L. i. t. n.f. xvi.

STATES Ol' INSECTS. ^S

much quickness and agility : from these spinners a white
and ghitinous fluid appears to issue, tliat forms the pouch,
which it takes the animal about three hours to construct.
The exterior tissue is produced by a kind of liquid and
glutinous paste, which by desiccation becomes a flexible
covering impermeable to water ; die second, which en-
velops the eggs, is a kind of light down of great white-
ness, that keeps them from injuring each other. The
tissue of the horn is of a silky nature, porous and shining,
and greatly resembling the cocoons of Lepidoptcra. This
part, contrary to what Lyonnet supposes, appears calcu-
lated to admit the air, the water soon penetrating it when
submerged. At its base is the opening prepared for the
egress of the larvse, when hatched, which is closed by
some threads, that, by means of the air confined in the
cocoon or pouch, hinder the water from getting in*.
This nidus does not float at liberty in the water till after
the eggs are liatched, the parent animal always attaching
it to some plant. By means of this anomalous process
for a beetle, which this insect is instructed by Providence
thus to perfect, the precious contents of its little ark are
secured from the action of the element which is to be the
theatre of their first state of existence, from the voracity
of fishes, or the more rapacious larvae of its own tribe,
until the included eggs are hatched, and emerge from
their curious cradle.

I shall next amuse you with a few instances, in which
the Allwise Creator instructs the parent insect, instead
of defending her eggs with a covering furnished by her
internal organs, to provide it from without, either from

=• Migcr Ann. du Mus. ubi sTipr. Conip. X. Diet. d^Hist. Nat. xv.

"7^ STA'J'ES OF INSECTS.

her own body or from some other substance. Most
commonly, indeed, the female leaves her cluster of eggs
without any other covering than the varnish with which
in this case they are usually besmeared. Either they are
deposited in summer and will soon be hatched, or they
are of a substance calculated to encounter and resist the
severities of the season. But many species, whose eggs
are more tender or have to resist the cold and wet of
winter, defend them in the most ingenious manner with
a clothing of different kinds of substance.

Cassida viridis, a tortoise beetle, Rosel tells us, covers
her group of eggs with a partially transparent membrane.
Arctia Salicis F., a moth, common on willows, wholly
conceals hers with a white frothy substance, which when
dry is partly friable and partly cottony, and being insoluble
in water effectually protects them from the weather^. The
female of Lophyrus Pini (a saw-fly), having by means
of her double saw made a suitable longitudinal incision
in the leaf of a fir, and placed in it her eggs in a single
row end to end, stops it up with a green frothy fluid
mixed with the small pieces of leaf detached by her saws,
which when dry becomes friable : a necessary precaution,
since these eggs are extremely brittle''. Arctia chry-
sorhcea, Hypogymna dispar, and several other moths, sur-
round theirs with an equally impervious and more singular
clothing — hair stripped from their own bodies. With
this material, which they pluck by means of their pincer-
like ovipositor, they first form a soft couch on the sur-
face of some leaf: they then place upon it successively
layers of eggs, and surround them with a similar downy
coating, and when the whole number is deposited cover
» De Geer i. 192. >> Ibid. ii. 982.

STATES OI" INSECTS. -75

tlie surface with a root" oF liairs, which cannot be too
much admired; for those used for the interior of tlie
nest are placed without order, but those employed ex-
ternally are arranged with as nuich art and skill as the
tiles of a roof, and as effectually keep out the water, one
layer resting partly on the other, and all having the same
direction, so that the whole resembles a well-brushed
piece of shaggy cloth or fur. When the mother has
finished this labour, which often occupies her for twenty-
four liours, and sometunes even twice that period, her
body, which before was extremely hairy, is almost wholly
naked — she has stri})})ed herself to supply clothing to her
offspring, and having performed this last duty she expires.
The female moths which thus protect their eggs are often
furnished with an extraordinary quantity of hair about the
anus fqr this express purpose ; and Reaumur conjectin'es,
that the singular anal patch of scales resembling those of
the wings, but considerably larger, which is foimd in the
female of Lasiocampa Pltyocampa, is destined for the
same purpose'.

Reaumur had once brouy-ht to him a nidus of eji'o-s
clothed still more curiously : they surrounded a twig in
a spiral direction, like those oi Lasiocampa Neustria, but
were much more numerous, and were thickly covered with
fine down, not pressed close, but standing off horizon-
tally, wiiich assumed much the same appearance as a
fox's tail would if tv/isted spirally round a branch''.

A procedure nearly similar was observed by De Geer
in some species of Aphides {A. Alni and A. Prwii\ which
covered their eggs wath a white cottony down detached

' Reaiim. ii. •)/. 159. ^ Iliid. 107—. /. iii./ lo.

76 STATES OF INSECTS.

from their belly by means of their hind legs*. In this
case, however, the eggs were separately coated with the
down, but there was no general covering to the group.

Several insects make the leaves and other parts of
plants serve as coverings for their eggs. Tenthredo
RoscE L., a saw-fly, and other species of the same genus,
with their saws make an incision in the green twigs of
shrubs and trees, and fill it with a line of eggs placed end
to end, taking care that, as the eggs grow after they are
laid, they are placed at such distances as to leave room
for their expansion''. Rhynchites BaccJms, a brilliant
weevil, well known to the vine-dressers for the injury it
does '^, rolls with much art the leaves of the vine, so as to
form a cavity, in which it places its eggs ; other species
practise similar manceuvres ; and some probably place
their young progeny in the interior of twigs, making an
opening for that purpose with their rostrum — at least, I
once saw Rhynchites Alliariee L. with its rostrum plunged
up to the antennae in the twig of a crab-tree. Others of
this tribe, as we know, place their eggs in the interior of
fruits and grain, as the nut, acorn, and common weevils.
It is pi'obable that most of the above coverings serve
another purpose besides the protection of the eggs from
wet and cold — that of sheltering them from the action of
too great light, which, as Dr. Michellotti by numerous
experiments has ascertained, is fatal to the included
germe*^. On this accoimt it is perhaps that so many in-
sects fasten their eggs to the under side of leaves. Those

» De Geer iii. 48. 51. >> Reaum. v. 122.

' See above, Vol. I. p. 196. 202.

'• Joum. de P/ii/s, Philos. Mag. ix. 344.

STATES OF INSECTS. 77

exposed in full day have usually an t)paque and horny
texture.

Some insects are spared all trouble in providing a
covering for their eggs, their own bodies furnishing one
in every respect adapted to this purpose. Not to mention
the Onisci., or wood-lice, since they rather belong to the
Crustacea^ which have a four-valved cell under the breast,
in which they carry their eggs, as the kangaroo does its
young in its abdominal pouch, the whole body of the fe-
male of those strange animals the Cocci becomes a cover-
ing for her eggs, which it incloses on every side. To make
this intelligible to you, further explanation is necessary.
You must have noticed those singular immovable tortoise-
shaped insects, which are such pests to myrtles and other
greenhouse plants. These are the young of a species of
Coccus {C. Hespeiidum L.), and their history is that of the
whole race. Part of them never become much bigger than
the size of which you ordinarily see them, and when full-
growTi disclose minute two-winged flies, which are the
males. The size of the females, which glue themselves to
a twig or leaf as if lifeless, now augments prodigiously,
and the whole body, distended with the thousands of eggs
which it includes to the bigness of a large pea, without
any vestige of head or limb, resembles a vegetable ex-
crescence or gall-apple rather than an insect. If you
remove one of them, you will perceive that the under
part of its abdomen is flat and closely applied to the
surfece of the branch on which it rests, only a thin
layer of a sort of cotton being interposed between them.
In laying her eggs the female Coccus does not, like most
insects, protrude them beyond her body into day-light ;
but as soon as the first egg has passed the orifice of her

78 STATES OF INSKCTS.

oviduct, she pushes it between her belly and the cottony
stratum just mentioned, and the succeeding eggs are de-
posited in the same manner until the whole are excluded.
You will ask how there can be found space between the
insect's belly and the cotton, to which at first it was close-
ly applied, for so large a mass of eggs ? To comprehend
this, you must consider that nearly the whole contents of
its abdomen were eggs ; that m proportion as these are
extruded a void space is left, which allows the skin of
the under side of the body to be pushed upwards, or
towards that of the back, affording room between it and
the cottony web for their convenient stowage. If you
examine the insect after its eggs are all laid, you will find
that they have merely changed their situation ; instead
of being on the upper side of the skin forming the belly,
and within the body, they now are placed between it
(now become concave and nearly touching the back) and'
the layer of cotton. As soon as the female Coccus has
finished her singular operation she dies ; but her body,
retaining its shape, remains glued upon the eggs, to
which it forms an arched covering, effectually protecting
them, until they are hatched, from every external injury.
Some species lay so many eggs, that the abdomen is not
sufficiently large to cover the whole mass, but merely
one side of it, the remainder being enveloped in cottony
web*.

I am next to consider the situation of those eggs that
are excluded by the mother in groups ^without any other
covering than the varnish with which they are usually
besmeared in their passage from the oviduct. The fe-

* Reaum. iv. Mem. i.

sTATr.s or INSECTS. 79

males only place them ui)on or nctir the food appropri-
ated to the youn^ larva^, to which they adhere by means
of the varnish just mentioned. These groups consist ot"
a greater or less number ; and when the eggs are hatched
by the heat of the sun, the larvae begin to disperse and
attack with voracity the food that surrounds thein. It
is thus that most butterliies and moths attach their eggs
to the stems, twigs, and leaves of plants ; that the lady
birds {Coccinell(s\ the aphidivorous flies {St/rphi Sac), and
the lace-winged flies {He?nerobii), deposit them in the
midst of plant-lice {Aphides); that the eggs of some flesh-
flies are gummed upon flesh ; those of crickets and grass-
hoppers buried in the earth ; those of gnats and other
Tipulidans set afloat upon, or submerged in, the water.

Frequently the whole number of eggs laid by one
female is placed in one large group, more commonly,
however, in several smaller ones, either at a distance
from each other on the same plant, or on distinct plants.
The object in the latter case seems to be, in some in-
stances, to avoid crowding too many guests at one table,
in others to protect the unhatched eggs from the voracity
of the larvae first excluded, which would often devour
them if in their immediate neighbourhood.

In the disposition of the eggs which compose these
groups much diversity prevails. Sometimes they are
placed without order in a confused mass : more fre-
quently, however, they are arranged in diflerent, and
often in very beautiful modes. The common cabbage-
butterfly [Pien's Brassica^) and many other insects place
theirs upon one end, side by side, so as, comparing
small things with sreat, to resemble a close column of
soldiers, in consequence of which those larvae which, on

80 STATES OF INSFXTS.

hatching, proceed from tlie upper end, cannot disturb
the adjoining eggs. Many indeed have a conformation
purposely adapted to this position, as the hemisphserical
eggs of the puss-moth {Cerura Vmula\ which have the
base by which they are gummed membranous and trans-
parent, while the rest is corneous and opaque. The
same ready exit to the larva is provided for in the oblong
eggs of the emperor moth {Saturnia Pavo7iia\ which
are piled on their sides in two or more lines like bottles
of wine in a bin *.

Where the larva does not emerge exactly from the
end of the egg other arrangements take place. The
whirlwig-beetle [Gyrimis natator) and the saw-fly of the
gooseberry &c. {Te7ithredoJlava h.) dispose theirs end
to end in several rows ; the former upon the leaf of some
aquatic grass, the rows being parallel, the latter gummed
to the main nerves of gooseberry or currant leaves, the
direction of which they follow •=.

But the lackey-moths [Lasiocampa Neustria^ castren-
sis, &c.) adopt a different procedure. As their eggs,
which are laid in the autumn, are not to be hatched until
the spring, the female does not, hke most other moths,
place them upon a leaf, with which they might be blown
by the winter's storms far from their destined food, but
upon the twig of some tree, round which she ranges them
in numerous circles. If you examine your fruit-trees,
you can scarcely fail to find upon the young twigs col-
lections of these eggs, which are disposed with such ad-
mirable art, that you would take them rather for pearls,
set by the skilful hand of a jeweller, than for the eggs of

» Rosel, ix. 157. t. 265? »> Ibid. iii. 197.

' See above. Vol. I. p. 195.

STATES OF INSECTS. 81

an insect. Each of these bracelets, as the French gar-
deners aptly call them, is composed of fi'om 200 to 300
pyramidal eggs with flattened tops', having their axes
perpendicular to the circumference of the twig to which
they are fastened, surrounding it in a series of from fif-
teen to seventeen close spiral circles, and having their
hiterstices filled up with a tenacious brown gum, which,
while it secures them alike from the wintry blast and the
attack of voracious insects, serves as a foil to the white
enamel of the eggs that it encompasses. It is not easy
to conceive how these moths contrive to accomplish so
accurately with their tail and hind feet an arrangement
which would require nicety from the hands of an artist ;
nor could Reaumur, with all his efforts and by any con-
ti'ivance, satisfy himself upon this head. He bred num-
bers of the fly from the egg, and supplied the females
after impregnation with appropriate twigs ; but these, as
though resolved that imprisonment should not force from
them the secret of their art, laid their eggs at random,
and made no attempt to place them symmetrically *'.

This illustrious Entomologist was more successful in
discovering the mode in which another insect, the com-
mon gnat, whose group of eggs is, in some respects, as
extraordinary as that last described, performs its opera-
tions. The eggs of this insect, of a long phial-like form,
are glued together, side by side, to the number of from
250 to 300, into an oblong mass, pointed and more
elevated at each end, so as considerably to resemble a
little boat in shape. You must not here suppose that I
use the term boat by way of illustration merely ; for it
has all the essential properties of a boat. In shape it

» Plate XX. Fig. 14. ^ Reaum. i 9;')— /. 1—13.

VOL. III. G

82 STATES OF INSECTS.

pretty accurately resembles a London wherry, being
sharp and higher, to use a nautical phrase, fore and aft ;
convex below and concave above ; floating, moreover,
constantly on the keel or convex part. But this is not
all. It is besides a life-boat^ more buoyant than even
Mr. Greathead's : the most violent agitation of the water
cannot sink it ; and what is more extraordinary, and a
property still a desideratum in our life-boats, though
hollow it never becomes filled with water, even though
exposed to the torrents that often accompany a thunder-
storm. To put this to the test, I yesterday (July 25, 1811)
placed half a dozen of these boats upon the surface of a
tumbler half full of water ; I then poured upon them a
stream of that element from the mouth of a quart bottle
held a foot above them. Yet after this treatment, which
was so rough as actually to project one out of the glass,
I found them floating as before upon their bottoms, and
not a drop of water within their cavity.

This boat, which floats upon the surface of the water
until the larvae are disclosed, is placed there by the female
gnat. But how ? Her eggs, as in other insects, are
extruded one by one. They are so small at the base in
proportion to their length that it would be difficult to
make them stand singly upright on a solid surface, much
more on the water. How then does the gnat contrive
to support the first egg perpendicularly until she has
glued another to it — these two until she has fixed a
third, and so on until a sufficient number is fastened to-
gether to form a base capable of sustaining them in
their perpendicular position ? This is her process. She
fixes her four anterior legs upon a piece of leaf, or a
blade of grass, and projects her tail over the water. She

STATliS OF INS1::CTS. $$

then crosses her two hind legs, and in the inner angle
which diey form, retains and snpports the first laid egg,
as it proceeds from the anus. In like manner she also
sup})orts tiie second, third, &c., all of which adhere to
each other by means of their glutinous coating, until she
feels that a sufficient number are united to give a stable
base to her little bark ; she then uncrosses her legs, and
merely employs them to retain the mass until it is of the
required size and shape, when she flies away, and leaves
it to its fate floating upon the water*.

It may not be out of place to mention here a re-
markable circumstance which not seldom attends a kind
of water-scorpion {Naucoris F.) occasionally to be met
with in collections of Chinese insects. Its back is often
covered with a group of rather large eggs, closely ar-
ranged; but whether these are its own eggs or those of
some large species of water-mite [Hydrachia Maill.) has
not been clearly ascertained. On the former supposition,
the ovipositor must be remarkably long and flexile to
enable the animal to place the eggs on its back. In con-
firmation of the latter it may be observed, that the spe-
cies of the genus Hydrachna usually attach their eggs
to the body and legs of aquatic insects, as for instance
H. abstergcjis to the water-scorpion {Nejm cinerea\ &c. ^

2. After having thus laid before you some of the pro-
cedures of those insects that usually deposit their eggs
in groups, either naked or defended by coverings of va-
rious kinds, I next proceed to a rapid survey of those of
the species that commonly deposit them singly. Some

* Reaum. iv. 615 — . t. xliv./..2 — 7-

•' N. Did. d' Hist. Nat. xv. 445. Ros. iii. 156.

G 2

84 STATES OF INSECTS.

of these, as for instance the Admiral Butterfly ( Vanessa
Atalanta), ghie each egg carefully to its destined leaf by
alighting on it for a moment. Another butterfly {Hip-
jparchia Hi/peranthus) whose caterpillar is polyphagous,
drops hers at random on different plants. In general it
may be observed, that all those larvae which live in so-
litude, as in the interior of wood, leaves, fruits, gram,
animals, &c., proceed from eggs laid singly by the female,
which is usually provided with an appropriate instrument
for depositing them in their proper situation. Thus the
nut-weevil [Balaninus Nucum Germ.) and also that of the
acorn [B. Glandium) pierce a nut or an acorn with their
long beak, and then deposit in the hole an egg^ from
which proceeds the maggot that destroys those fruits.
Leeuwenhoeck asserts that the common weevil (Calan-
dra granaria) adopts the same process, boring a hole in
every single grain of corn before it commits an egg to it,
and at the same time, by this manoeuvre, prepares a small
quantity of flour to serve for the food of the tender grub
when it is first hatched'. It is probable that the Rhyn-
cophorous or weevil tribe in general chiefly use their beaks
for the purpose of depositing their eggs in different vege-
table substances, and perhaps principally in fruit or grain.
The tribe of gall-flies (Ci/tiips) on the contrary, whose
economy, detailed in a former letter'', interested you so
much, bore an opening for the egg with their spiral ovi-
duct, which also conveys it.

Another large tribe of insects depositing their eggs
singly, are those which feed upon the bodies of other
animals, into the flesh of which they are either inserted,
or placed so as speedily to find their way into it. Some

» Epist. 1687. " Vol. I. p. 448-.

STATES OF INSECTS. 85

of these introduce tliem into living animals, and then
leave them to their fate, as the Ichneumons and gad-flies:
others deposit them along with the dead body of an in-
sect interred ui a hole, oltcn prepared with great labour,
as the different species of sand-wasps {Sphccida)^ spider-
wasps {Pompilidcc\ &c. : the manners of the latter of these
tribes have been already adverted to^*, and those of the
IchncumonidiV will come more fully under consideration
when I treat of the diseases of insects.

A similar labour in providing suitable habitations for
their eggs is undergone by various other insects whose
larvaj live chiefly on vegetable food, some inserting their
egg within the substance the larva devours, as those that
prey on timber, twigs, roots, or the like, and others on
its surface. One would suppose at first, that the exceed-
ingly small egg which produces the subcutaneous larva?
would, by the parent moth, be imbedded in the substance
of the leaf which is to exhibit hereafter their serpentine
galleries : but this is not the case, for she merely glues it
on the outside ; at least such was the situation of the only
egg of these veiy minute moths Reaumur had ever an
opportunity to observe''.

Other insects, belonging to the tribe which lay their
eggs singly, bury them in the ground. Of this descrip-
tion are many of the lamellicorn insects, the dung-chafers
[Scarabcsidcc MacLeay) particularly, which, inclosing
their eggs in a pellet of dung, deposit them in deep cy-
lindrical cavities. Concerning the proceedings of some
of these, as well as of the whole race of bees, wasps, &c.,
which all lay single eggs, I have before detailed to you

" See above, Vol. I. p. 344 — . '' Rcaiim. iii. 8—.

86 STATES OF INSECTS.

many interesting particulars'*. I must not conclude this
subject without observing, that the female Pycnogonidce,
an osculant tribe between Insects and Crustacea, carry
their eggs upon two pair of false legs ^.

iii. Substance. From this long dissertation on the sitti-
ation of the eggs of insects and matters connected with it,
I pass on to their substance or their external and internal
composition, giving at the same time some account of the
embryo included in them. The eggs of insects, like those
of birds, consist in the first place of an external coat or
shell, varying greatly, as to substance, in different genera.
Most commonly, particularly in those which deposit their
eggs in moist situations, as in dung, earth, and the like,
it is a mere membrane, often thin and transparent, and
showing, as in spiders, all the changes that take place in
the inclosed embryo, as the formation of the head, trunk,
and limbs'^. This membrane is sometimes so delicate
as to yield to the slightest pressure, and insufficient to
protect the included fluids fi'om too rapid an evaporation^
if the eggs be exposed to the full action of the atmosphere.
In most Lepidoptera, and several other tribes, this inte-
gument is considerably stronger, in those moths whose
eggs are exposed throughout the winter, as Lasiocampa
Neustria, &c., so hard as not to yield easily to the knife.
Even in these, however, its substance is more analogous
to horn or a stiff membrane than to the shell of the esrsfs
of birds. Nothing calcareous enters into its composition,
and it is not perceptibly acted upon by diluted sulphuric

^ Vol. I. 349—, 371—. ^ X. Diet. d'Hist. Nat. xxviii. 271.

" De Geer vii. 194.

STATKS Ol" INSECTS. 87

acitl The eggs of birds are lined by a fine membrane ;
but I have examined several of those of insects, and
have been able to discover nothing of the kind in them.
I will not, however, aflirm that it does not exist, though
the shell of the insect egg appears more analogous to the
membrane that lines that of the bird than to the outside
shell itself.

Within this integument is included a fluid, on the
precise nature of which, except that it is an aqueous
whitish fluid, few or no observations have been made, or
indeed are practicable; but it is reasonable to suppose
that like the white and yolk of the bird's egg, it serves
for the development of the organs of the germe of the
future insect.

But few observations are recorded that relate to the
embryo included in the egg. It is stated, that it is in-
vested with an extremely fine and delicate pellicle — sup-
posed by some analogous to the Chorion and Amnios of
the human foetus, though others think the shell of the
egg to correspond with the Chorion, and the successive
integuments of the larva with the Amnios^. When the
egg is first laid, nothing indeed is to be seen in it but the
fluid just mentioned ; the first change in this fluid is the
appearance of the head of the embryo, more particularly
in Coleoptera, of two points, the rudiments of the mandi-
bles, and of those apertures into the tracheae which I
have called spiracles '' ; the little animal we may suppose

» Compare K. Diet. d'Hist. Nat. xvi. 34G. with xx. 352 — ; but as
the Amnios immediately envelops the foetus, the pellicle seems most
analogous to it, and the shell to the Chorion.

'■ Swamm. Bibl. Nat. cd. Mill. 1. 133. a. Comp. N. Did. d'Hist.
Nat. xvi. 246.

88 STATES OF INSECTS.

then assumes its form and limbs. The embryo is usually
so folded in the egg that the head and tail meet*, and
the head, annuli, and other parts of the larva are often
visible through the shelP. Swammerdam even saw the
pulsation of the great dorsal vessel through the shell of
the egg of Oryctes nasicoj-nis.

Under this head I must notice another singular cir-
cumstance peculiar I believe to the eggs of insects, that
sometimes, though rarely, they are covered with down or
hair. Those of a singular little hemipterous insect, of a
genus I believe at present undescribed, the ravages of
which upon the larch have been before noticed '^, are co-
vered by a downy web, as is the case with the animal
itself. De Geer has described the eggs of a bug, not
uncommon in this country [Petitatoma juniperi7ia Latr.),
which are reticulated with black veins, in which very
short bristles are planted''. I possess also a nest of
brown eggs, probably of a species of the same genus,
found upon furze, which appear to be covered with very
short downy hairs. The top of these is flat, and sur-
rounded by a coronet of short bristles, each surmounted
by a small white ball, so as to wear the appearance of a
beautiful little Mucor. But hairy eggs are not confined
to the Hemiptera Order, for, according to Sepp, those of
the figure-of-eight moth {Bomhyx caeruleocephala) are of
this description^.

iv. Number. The fertility of insects far exceeds that of

•» Swamm. Ibid. '' Sepp. iv. t. iii./. i. c v. t. iv./. 2.

' See above. Vol. I. p. 208 : it is there called an Aphis, but it is a
distinct genus.

«" De Geer iii. 245. t. xiii./. 20—22.
« Sepp. \v.L xiii./. 2. 3.

STATES OF INSECTS. 89

birds, and is surpassed only by that of fishes*. But the
number of eggs laid by diiferent species, sometimes even
of the same natural family, is extremely various. Thus
the pupiparous insects may be regarded as producing
only a single egg ; Musca Mcridiana L., a common fly,
lays two'', other flies six or eight; the flea twelve; the
burying beetle {Necrophorus Vespillo^) thirty; May-flies
{Tn'chopera K.) under a hundred; the silk-worm moth
about 500 ; the great goat-moth (Co55?« ligjiipcrda) 1,000;
Acariis amcricamis more than 1,000 '^ ; the tiger-moth ( Ca/-
limoi'pha Caja) 1,600; some Cocci 2,000, others 4,000;
the female wasp at least 30,000^; the queen bee varies
considerably in the number of eggs that she produces in
one season, in some cases it may amount to 40,000 or
50,000 or more ^', a small hemipterous insect, resembhng
a little moth {Aleyrodes proletella Latr.) 200,000. But
all these are left far behind by one of the while ants
{Termes fatale F. bellicosus Smeath.) — the female of this
insect, as was before observed s, extruding from her enor-
mous matrix not less than 60 eggs in a minute, which
gives 3,600 in an hour, 86,400 in a day, 2,419,200 in a
lunar month, and the enormous number of 211,449,600
in a year : probably she does not always continue laying
at this rate; but if the sum be set as low as possible, it
will exceed that produced by any other known auimal in
the creation.

v. Size. The size of the eggs is in proportion to that of

* The sturgeon is said to lay 1,500,000 eggs, and the eod-fish
9,000,000.

*> Reaum. iv. 39;:J. " See above, Vol. I. p. 350.

" De Gecr vii. 159. « See above, Vol. II. p. 109.

f Ibid. 159. 166. E Ibid. o6— .

90 STATES OF INSECTS.

the insect producing them, thougli in some instances
small ones produce larger eggs than those laid by bigger
species. Thus the eggs of many Aptera, as those of that
singular mite Uropoda vegetans, and of the bird-louse
found in the golden pheasant, are nearly as large, it is
probable, as the parent insect ; while those of the ghost-
moth [Hepialus Hiimuli) and many other Lepidoptera,
&c. are vastly smaller. This circumstance perhaps de-
pends principally on the number they produce : the ma-
jority of them, however, are small. The largest tgg
known, if it be not rather an egg-case, is that of a spectre
insect {Pliasma dilatahim), figured in the Linnean Trans-
actions ^, being five hues in length and three in width,
which probably approaches near the size of that of some
humming-birds. The largest egg of any British insect
I ever savr was that of the common black rove-beetle
{Staphylinus olens) sent me by Mr. Sheppard — this is a
line and half long by a line in width. But we do not often
meet with insect-eggs exceeding a line in length. A vast
nuinber are much smaller : those of Ephemerae are more
minute than the smallest grains of sand'', and some almost
imperceptible, as those of the subcutaneous moths, to the
naked eye. Commonly the eggs laid by one female are
all of the same size ; but in several tribes, those con-
taining the germe of \hej'e7nale are larger than those that
are to give birth to a male. This appears to be the case
with those of the Rhinoceros beetle [Oryctes 7iasico7'nis'^\
and according to Gould with those of ants^. As the
female in a vast number of instances is much bigger than
the male, it is not improbable that this law may hold

» iv. t. xviii./. 4, 5. •> De Geer ii. 638.

^ Bibl. Nat. i. 132. b. ^ Gould 36.

STATES OF INSECTS. 91

very extensively. It is stated, however, by Ileuunuir",
that the reverse oi" this takes place in the eggs of the
liive-bee, those that are to produce males being larger
than the rest.

Another peculiarity connected with the present head is
the augmentation in bulk which takes place, after exclusion,
in the eggs of the great tribe of saw-flies ( Tenthredo L.), the
gall-flies [Ci/nij)s L.), the ants {Formica L.) and the water-
mites {IlijdracJma Maill. Atax F.). Those of the two for-
mer, which arc usually deposited in theparenchymous sub-
stance of the leaves, orof the young twigs, of various plants,
imbibe nutriment in some imknown manner, through their
membranous skins, from the vegetable juices which sur-
round them '', and when they have attained their full size
are nearly twice as large as when first laid. Except in the
eggs of fishes, whose volume in like manner is said to
augment previously to the extrusion of the young, there
is nothing analogous to this singular fact in any other of
the oviparous tribes of animals, the eggs of which have
always attained their full size when they are laid.

It is to M. P. Fluber that we are indebted for the
knowledge of the fact that the eggs of a7its grow after
being laid, a circumstance favoured probably by the
moist situation in which the workers are always careful
to keep them. By an accurate admeasurement he found
that those nearly ready to be hatched were almost twice
as big as those just laid*^. A similar observation was
made on the red eggs of a water-mite [Mydrachna abs-
tergens) by llosel, who conjectured that they draw their
means of increase from the body of the water-scorpions

' Iltaiiin. V. 477. '' Ibid. iii. .')7!). v. l^l. ■" Fourmis, 6.9 — .

92 STATES OF INSECTS.

{Nepa\ of which they form so singular an appendage *,
which opinion is confirmed by De Geer, who observes
that when the water-scorpions are covered by an unusual
number of the eggs of the water-mites, they grow weak
and languid, and endeavour to rid themselves of their
parasitic appendages^. It is most probable that the mite
lately named ( Uropoda vegetans), which is often found
planted as it were upon the bodies of various beetles, by
means of a long pedicle, through which, as the foetus by
an umbilical chord and placenta, it derives its nutriment
from the above animals, is at first so fixed in the egg
state, though before it is disengaged from the pedicle it
is hatched, since it is often found with its legs displayed
and quite active — this is the more probable, as the eggs
of the water-mite are fixed by a pedicle to the animals to
which they are attached '^. I have met with a remarkable
instance, in which pedunculated eggs seem to draw nu-
triment fi:'om the mother; which brings the pedicle still
near to the nature of the umbilical chord. Those of the
small heraipterous insect which infests the larch before
alluded to, are attached to the anal end of the mother by
a short foot-stalk not longer than the egg.

Dr. Derham seems to have observed, that the eggs of
some Diptera, of the tribe of Tipulidce, also increase in
size before the larva is excluded '^. It seems to me likely
enough, that in this and many of the above cases in which
the egg is supposed to grow, it is rather an extension of
the flexile membrane that forms their exterior propor-
tioned to the growth of the included embryo from food

" Rosel iii. 152. ^ De Geer vii. 145.

«= Ibid. 123—. See above, Vol. I. p. 393.
^ Rail Hist. Ins. 265.

STATES OF INSECTS. 93

it fiiuls within the egg, than from any absorption from
without.

■ vi. Shape. We are accustomed to see the eggs of dif-
ferent species of oviparous animals so nearly resembling
each other in form, that the very term egg-shaped has been
appropriated to a particular figure. Amongst those of
birds, with which we are most familiar, the sole variations
are shades of difference between a globular and oval or
ovate figure. The eggs of insects, however, are confined
by no such limited model. They differ often as much,
both as to their shape, sculpture, and appendages, as one
seed does from another; and it is not improbable that,
if duly studied, they would furnish as good indications
of generic distinctions as Gaertner has discovered in
those of plants. Their most usual form indeed is glo-
bular, oval, or oblong, with various intermediate modifi-
cations. We meet with them ovate, or of the shape of
the common hen's egg, flat and orbicular, elliptical, co-
nical, cylindrical, hemispherical, lenticular, pyramidal,
square, turban-shaped, pear-shaped, melon-shaped, boat-
shaped, of the shape of an ale-stand, of a drum, &c. ',
and sometimes of shapes so strange and peculiar, that
w^e can scarcely credit their claim to the name of eggs.
Thus the eggs of the gnat are oblong and narrow, or
nearly cylindrical, having at the top a cylindrical knob'',
so as to give them the precise form of the round -bottomed
phial sometimes used by chemists : those of the common

* Eggs of various shapes are given Plate XX. Fig. 3 — 23. See also
Brunnich. Entomologia 4. X. Diet. d'Hkt. Nat. xvi. 245. Reaum. ii.
/. iii. iv. xiv. xxvi. xxvii. &c.

" Pr.ATE XX. Fig. 18.

94 STATES OF INSECTS.

water-scorpion [Nepa cinerea) are oblong, and at the
upper end are surrounded by a sort of coronet, consisting
of seven slender rays or bristles of the length of the egg *,
•SO as to resemble somewhat the seeds of Carduus bene^
dictus [Cnicus acartia^) of the old botanists. One would
think this spinous circlet a very awkward appendage to
bodies which are to be gradually extruded through the
fine membranous ovaries and oviduct which inclose them :
but they are so admirably packed, the unarmed end of
each egg fitting closely into the space inclosed by the
spines of the one next below it, or, rather, the spines
which are moveable, embracing it closely, that not only
is no room lost, but the ovaries are perfectly secure from
injury. The eggs of another species of this tribe {Ra-
natra linearis) have only two of these spines or bristles
— they are inserted in the stem of a water-rush [Scirpus)
or other aquatic plant, so as to be quite concealed, and
are only to be detected by the two bristles which stand
out from it^. The eggs of the beautiful lace- winged flies
{Hemerobius\ those golden-eyed insects so serviceable in
. destroying the plant-lice {Aphicles^\ are still more sin-
gular. Those of iJ. Perla are oval, and each of them
attached to a filiform pedicle not thicker than a hair,
and seven or eight times as long as the egg. By this pe-
dicle (which is supposed to be formed by a glutinous
matter attached to one end, which the female draws out
by abstracting her ovipositor with the egg partly in it

» Plate XX. Fig. 23. Swanim. Bibl. Nat. t. iii. /. 7, 8. In a
specimen I opened of this insect the bristles converged so as to form
a kind of tail to the egg.

^ Darwin Phytolog. 512.

^ Geoffi-. Ins. Par. i. 480. /. x./. 1. ft. c.

'' See above, Vol. I. p. 261.

STATES OF INSECTS. 95

from the leaf, to which she has previously applied it, to
a proper length, when the gluten becoming suificiently
solid she wholly quits the egg,) the eggs are planted in
groups of ten or twelve on the surface of leaves and twigs,
from which they project like so many small fungi, to some
of which they have a remarkable resemblance. When the
included larva has made its way out of them by forcing
open the top, they look like little vases, and were actually
once figured by a Naturalist, as we learn from Reaumur,
as singular parasitic flowers growing upon the leaves of
the elder, for the origin of which he was extremely puz-
zled to account*. Eggs similarly furnished with a pedicle
are also laid by other insects ; but as most of these have
been before alluded to, it is not necessar}' to describe them
here ''. The cause of these differences of form is for the
most part concealed from us : in many instances it may
perhaps be referred to that will to vary forms, and so to
glorify his wisdom "^ and power, independently of other
considerations, which, as Dr. Paley has well remarked'*,
seems often to have guided the Great Author of Nature.
But in some cases the end to be answered is sufficiently
evident. The long footstalks of the eggs of the Heme-
rohius just mentioned, there can be little doubt, are meant
to place them out of the reach of the hosts of predaceous
insects which roam around them, from whose jaws, thus
elevated on their slender shaft, they are as safe as the

* Reaum. iii. 386 — . /. xxxii./. 1. t. xxxiii./. 5.

^ I allude to Op/iio7i luteiim F, {Ichneumon L.) V^ol. i. Ed. 3.
p. 269. figured Plate XX. Fig. 2-2; and the Hydrachnce- or Trom-
bidia. See above, and De Geer vii. 1 45.

•^ From this circumstance called ■KoXvTvout'hoi ao<ptcc by the Apostle,
JEphes. iii. 10.

^ Nat. Theol. Uth Ed. 375.

96 STATES OF INSECTS.

eggs of the tailor bird in its twig-suspended nest from
the attack of snakes. Reaumur has described the eggs
of a kind of fly, common upon the excrements of the
horse and other animals {Scatophaga vulgaris Latr.), or
one related to it, that requires to be immersed in the dung
to which it is committed, on which the future grubs are
to feed. He found that if not thus surrounded with
moisture, they infallibly shrivelled up and came to no-
thing ; but it is equally necessary that they should not be
wholly covered : if they were, the young larva would be
suffocated at its first exit from the egg. In what way is
this nice point secured ? In this manner. Each egg is
provided at its upper end, at which the animal when
hatched comes out, with two diverging horns'^; these
prevent it from being stuck into the excrement, in which
the female deposits the eggs one by one, more than three-
fourths of its length : and when examined they resemble
not badly, as Reaumur remarks (except that their colour
is white), a parcel of cloves stuck into a pudding, as they
are neatly inserted at due distances in the disgusting
mass''. The French Naturalists found these eggs in
swine's dung ; I have observed them in cow-dung. La-
treille thinks that the bristles above described attached
to the eggs of Nepa and Jlanatra have a similar use, as
the female plunges them all but these bristles into the
stems of aquatic plants ^ : but may not this have some-
thing to do with their oxygenation? Reaumur has
figured another egg of a dipterous insect which has a
longitudinal wing or lateral margin attached to it, giving

» Plate XX. Fig. 19. a «.

^ Reauni. iv. 376—. t. xxvii./. 9, 10.

' Hist. Nat. gen. et pnrtic. des Crust, et Ins. xii. 282.

STATES OF INSECTS. 97

it the form ot" an oblong square, the object of which, he
conceives, is to give a greater surface by which it may
be more firmly fixed to the substance against which the
fly attaches it".

Besides these more striking variations in figure, their
surface, tliough often smooth, is frequently curiously
and most elegantly sculptured, a circumstance that di-
stinguishes the eggs of no other oviparous animals. Some,
as the margined egg just mentioned, are only sculptured
on one side, the other being plain ; or, as those of the
Tusseh silk-worm'' [Atlacus Paphia) and other Bombyces,
which have orbicular depressed eggs with a central ca-
vity above and below, have their circumference crossed
with wrinkles corresponding with the rings of the inclosed
embryo'^. Others again are sculptured all over. Of
these, in some, the sculpture of the two sides is not sym-
metrical, as in those of a fly figured by Reaumur'' : but
in general there is a correspondence in this respect be-
tween the different parts of the egg. In those elegant
ones before alluded to of some bird-louse attached to the
golden pheasant, the shell resembles the purest wax, and
is scored with longitudinal striae, each distinguished by
a series of impressed points, which give it a beautiful ap-
pearance of net-work. In the others, as in a common
butterfly {Hipparc/iia ^geria) and moth [Geometra era"
tcegata), the whole surface is covered with hexagonal re-
ticulations*. Others, as those of another buttei-fly {Hip"

» Reaum. iv. 381. t. xxvi.f. 19, 20.
'• Roxburgh in Linti. Trans, vii. 34.

•^ Some of the Xoctiuv have suiiilar eggs, as A'^ Lapj^a, Sepp iv.
t. iii./. I.e. <" Reaum. ubi supr.f. 22, 23,

" Plate XX. Fig. C. 8.

VOL. III. H

98 STATES OF INSECTS.

parchia Hyper ant}ius\ are beset with minute granules or
tubercles*. Others again, like those of the cabbage and
hawthorn butterflies {Pieris Brassica and Cratcegi), are
remarkable for beautiful longitudinal ribs, often connected
by elevated lines crossing them at right angles'' ; and in
some, as in another butterfly [Hipparchia Furtina)^ crown-
ed by imbricated scales'^. Many other minor differences
in this respect might be noticed, but these will suffice to
give some idea of the infinite variety exhibited in this
respect by these little atoms. If the Creator has wrought
them with so much art and skill, can it be beneath his
reasonable creatures to examine and admire them, that
they may glorify those attributes which they serve to il-
lustrate ?

Some eggs after exclusion occasionally become slightly
corrugated : Malpighi supposed that this occurs only
when the eggs are barren, having observed that those of
the moth of the silk-worm which preserved their plump-
ness always produced caterpillars, while those which lost
their original rotundity and became wrinkled were con-
stantly unprolific. Bonnet, however, found exactly the
reverse take place in another moth ^, so that these ap-
pearances are scarcely to be depended upon. Kuhn as-
serts, that a virgin female of the puss-moth {Cerura
Vinula) having begun to lay eggs, which were yellow
above, green below, and depressed, he introduced to her
an hour afterwards a male, and some minutes subse-
quently to the union, she again deposited eggs, which
were \\ holly of a dark brown and convex '.

» Platk XX. Fig. 5. " Ibid. Fig. 3. 4. 7. 9. &c.

<= Ibid. Fig, 15. ^ Bonnet CEuvr. ii. 9. • Naturf. y:m, 229.

STATES OF INSECTS. 99

vii. Colour. The colour of the eggs of hisects is as va-
rious us their shape and sculpture. They are very often
white, those of some spiders like minute pearls*; some
are yellow, as those of the silk- worm ; others orange,
such are the eggs of the bloody-nosed beetle ( Timarcha
tenebi'icosa) \ others again of a golden hue; sometimes
they arc of a sanguine red. I remember once being
nmch surprised at seeing the water at one end of a ca-
nal in my garden as red as blood : upon examining it
further I found it discoloured by an infinite number of
minute red eggs, belonging probably to some dipterous
insect of the Tipulidan tribe. There are also eggs of
every intermediate shade between red and black ; some
again are blue and others green. They are not always
of whole colours, for some are speckled like those of
many birds, of which I can show you specimens, that
are also shaped like birds' eggs; these I think were
laid by a common moth [Odenesis potatoria)', others are
banded with different colours — thus the blue eggs of the
lappet-moth [Gastropacha qxiercifolia) are encircled by
three brown zones''; others are brown with a white
zone *=.

Many eggs assume a very different colour after being
laid a few days. In general upon their first exclusion
they are white. Those of the chameleon-fly [Stratyomis
Chamceleon) which I once found in great numbers, ar-
ranged like tiles on a roof one laid partly over another,
on the under side of the leaves of the water-plantain, from
white become green, and then change to olive green.
Those of the hemipterous enemy of the larch, more than

» N. Diet. d'Hist. Xat. xvi. 245. Reaum. ii. 286*.

«= Plate XX. Fig. 11. Sepp t. iv.f. 2.

H 2

100 STATES OF INSECTS.

once mentioned in this letter, are first mouse-coloured,
then they assume a reddish hue, and lastly a blackish
one. Those of the gnat from white in a short time as-
sume a shade of green, in a few hours they are entirely
green, and at length become gray^. Those of the silk-
worm, which at first are of a yellow or sulphur colour,
acquire a violet shade. The eggs of that rare moth En-
dromis versicolor^ are at first sulphur-coloured, then
green, next rose-coloured, and lastly blackish. The
colour of almost all eggs changes when they are near
hatching; but this change depends more frequently upon
the colour of the included larva, which appears through
the transparent shell of the egg, than upon any actual
alteration in the egg itself.

viii. Period of hatching. The general rule for the
hatching of the eggs of insects is the absorption by the
embryo of all the superabundant moisture included in
them ; but the time varies according to the state of the
atmosphere, to the action of which they are subjected.
Like those of other animals, they require a certain degree
of heat for the due evolution of the included larva. This
heat in much the greater number of instances is derived
from the temperature of the air, but often also from
other sources. The eggs of the gad-fly tribe are hatched
principally by the heat of the body of the animal to which
they are committed ; and doubtless the vital heat of va-
rious larvas, small as it may be, must contribute some-
thing to the hatching of the eggs deposited in them by
various Ichneumons. In the fermenting bark in which the
instinct of the rhinoceros beetles {Ori/ctes nasicornis &c.)
» Reaum. iv. 617.

J

STATES OF INSECTS. IQI

impels them to place theirs, the dung which the Scara-
baidce select for that purpose, and the decaying vegeta-
bles chosen by many other insects, a degree of artificial
heat must exist : and the eggs, or rather egg-like pupae,
of the spider-fly of the swallow {Ornil/iomj/ia Hinmdinis)
are hatched by the heat of those birds which sit upon
them along with their own eggs.

Fabricius says, " Insects never sit upon their eggs * ;"
but certainly, as I formerly related to you^, the female
earwig does this, and one would be induced to suppose,
from the circumstance of the you' g ones following their
mother, as chickens do the hen, that Pentatoma grisea
[Cimex Linn.), formerly mentioned, may do the same^.

"With these exceptions, the eggs of all insects are
hatched by atmospheric heat alone, the variations in
which determine the more speedy or more tardy disclo-
sure of the included insect. The eggs of such species as
have several broods in the year, as the nettle butterfly
( Vanessa U?'ticce\ when laid in summer are hatched in a
few days ; but if not laid till the close of autumn, they
remain dormant through the winter, and are only hatched
at the return of spring. That this difference is to be at-
tributed to the influence of heat has been often proved
by experiment: the autumnal eggs if brought into a
warm room may be hatched as soon as those laid in the
height of summer. Silk-worms' eggs naturally are not
hatched till they have been laid six weeks, but in coun-
tries where they are reared, the women effect their ex-
clusion in a much shorter period by carrying them in
their bosoms : yet to retard their hatching with particu-

» Philos. Ent. 76. •> See above. Vol. I. 358—.

•^ See above, Vol. I. Ibid.

102 STATES OF INSFXTS.

lar views is in many circumstances impossible. When
the heat of the atmosphere has reached a certain point,
the liatching cannot be retarded by cellars ; and M.
Faujas has remarked, that in June the silk-worm's eggs
would hatch in an ice-house*.

The period of exclusion does not, however, depend
solely upon temperature : the hardness or softness of the
shell, and possibly differences in the consistence of the
included flwid, intended to serve this very purpose, cause
some eggs to be hatched much sooner than others exposed
to the same degree of heat. Thus the eggs of many flesh-
flies are hatched in twen ty- four hours "^ ; those of bees and
some other insects in three days; those of a common
lady-bird [Cocchiella bipimctata) in five or six days;
those of spiders in about three weeks; those of the mole-
cricket in a month ; while those of many Lepidoptera and
Coleoptera require a longer period for exclusion. The
hard eggs of Lasiocampa Neustria and castrensis, noticed
above, remain full nine months before being hatched'^,
as do those of another moth [Hypogyiiiiia dtspa?^), which,
though laid in the beginning of the warm month of Au-
gust, do not send forth the included caterpillar till the
April following''. We know no more of the cause of

* Young's France, ii. 34. This author asserts, that no art will
hatch the eggs of the common silk-worms the first year, or that in
which they are laid ; but that there is a sort brought from Persia,
which are hatched three times a year, and which will hatch in fifteen
days in the proper heat. In 1765, it is said, the common sort hatched
in the first year. Ibid. 226 — .

t- In the N. Diet. d'Hist. Nat. xii, 564. the eggs of the flesh-fly
are said to hatch in two hours. This is true I believe in very warm
weather.

•^ Brahm. 310. <■ Rimrod Naturf. xvi. 131.

i

STATES OF INSECTS. 103

this difference than of that which lakes place in the
period of exclusion of the eggs of the different species of
birds.

Some eggs change considerably both their form and
consistence previously to being hatched. M. P. Huber
found that those of different species of ants when newly
laid are cylindrical, opaque, and of a milky white ; but just
before hatching their extremities are arched, and they
become transparent with only a single opaque whitish
point, cloud, or zone, in their interior*. An analogous
change takes place in the eggs of many spiders, which
just before hatching exhibit a change of form corre-
sponding with that which the included spider receives
when its parts begin to be developed, the thin and flexible
skin of the egg moulding itself to the body it incloses''.

In proportion as the germe included in the egg is ex-
panded, it becomes visible through the shell when trans-
parent: this is particularly the case with spiders, in
which, as was before observed, ever}' part is very di-
stinctly seen. At length, when all the parts are consoli-
dated so as to be capable of motion, which in spiders
takes place in four or five days after they begin to be
visible in the egg, the animal breaks the pellicle by the
swelling of its body and the movement of its legs, and
then quits it, and disengages all its parts one after the
other *=. In general, at least where the shell is harder
than that of spiders, insects make their way out by
gnawing an opening with their mandibles in the part
nearest their head, which, when the shell is very strong
(as in Lasiocampa Neustria, &c.), it is often several

» Fourmis. 69. ^ De Geer vii. 195. <^ Ibid. 196.

104 STATES Of INSECTts.

hours in accomplishing^. In many instances, however,
the larva is spared this trouble, one end of the egg being
furnished with a little lid or trap-door, which it has but
to force up, and it can then emerge at pleasure : such
lids are to be found in the eggs of several butterflies and
moths, as Satyrus Mcej-a, Saturnia pavotiia major, &c.
and the common louse ^. In those exquisitely elegant
eggs, before described, of some kind of bird-louse [Nir-
mus) found adhering to the base of the neck feathers of
the golden pheasant*^, there is a lid or cap of this kind
of a hemispherical form terminating in a tortuous style.
Those of a species of bug [Pentatoma Latr.), found by
our friend the Rev. R. Sheppard, besides a convex lid
are furnished with a very curious machine, as it should
seem, for throwing it off. This machine is dark-brown,
of a corneous substance, and of the shape of a cross-bow '*,
the bow part being attached to the lid or pushing against
it, and the handle, by means of a membrane, to the upper
end of the side of the egg.

When the included animal has made its way out of
the egg, it enters upon a new state of existence, that of
Larva, to which I shall direct your attention in the fol-
lowing letter.

* Reaum. ii. 167.

b Brahm. 249. Rosel. iv. 130. Swamm. Bibl. Nat. t. If. 2. -

•= By Mr. White, jun. cordwainer at Ipswich.

•^ Plate XX. Fig. 16. a.

LETTER XXX.

STATES OF INSECTS.

LARVA STATE.

1 HE Larva state is that in which insects exist imme-
diately after their exclusion from the egg (or from the
mother in ovo-viviparous species), in which they usually
eat voraciously, change their skin several times, and have
the power of locomotion, but do not propagate.

Almost all larvae, at their birth, are for a time in a very
feeble and languid state, the duration of which differs in
different species. In most it continues for a very short
time, a few minutes or perhaps hours, after which they
revive and betake hemselves to their appropriate food.
In others, as in the generality of spiders, this debility
lasts for seven or eight days, and in some species even a
month, during which the young ones remain inactive in
the egg-pouch *, and it is not till they have cast their first
skin that their active state of existence commences.
All larvae may be divided into two great divisions : —

I. Those which in general form more or less re-

semble the perfect insect,

II. Those which are wholly unlike the perfect in-

sect.

'* De Gcer vii. 197.

106 STATES OF INSECTS.

I shall begin by calling your attention to the charac-
ters of the Jirst of these divisions : the second, which is
by far the most numerous, will be afterwards considered.

I. The^r^^ division includes the larvae of Scorpions,
Spiders, Cockroaches, Grasshoppers, Lanthorn-^ies, Bugs,
&c. ; or generally, with the exception of the Flea and
Crustacea, the whole of the Linnean Orders Aptera and
Hemiptera. All these larvae, however remotely allied in
other respects, agree in the general similarity which they
bear to the perfect insects which proceed from them.
The most acute entomologist, untaught by experience,
could not even guess what would be the form of the
perfect insects to be produced from larvae of the second
division, while they can recognise the form of the spider,
the cricket, the cockroach, the bug, and the frog-hopper,
in that of the larvae. There are, however, differences in
the degrees of this resemblance, according to which we
may, perhaps, divide this tribe in their second state as
follows : —

i. Those that resemble the perfect insect, except in
the relative proportions and number of some
of their parts.

ii. Those which resemble the perfect insect, except
that they are apterous, or not yet furnished
with organs of flight.

i. Spiders, Phalangia, scorpions, lice, Podurce, sugar-
lice {Lepisma), mites, centipedes, millepedes, &c. come
under thejirst subdivision. The larvae of the first six
tribes here mentioned differ at their birth from the per-
fect insect, only in size and the proportions of their parts.

STATKS or INSECTS. 107

Tlius the larvae of spiders liave their legs of a different
relative length from that which they subsequently ac-
quire ; and the palpi in the males, which previously to
the discoveries of Treviranus were regarded as their
sexual organs, are not yet fully developed * : and a si-
milar difterence takes place in tlie legs of Phalangia.
The general form too of the body undergoes slight alter-
ations, and the colour very considerable ones, with each
change of the skin — a change to which all these tribes
are subject.

The larvae of the three last-mentioned tribes (the
mites, centipedes, and millepedes) differ from the per-
fect insect not only in the proportion but also in the
number of their parts. Leeuwenhoeck states (and De
Geer confirms his assertion, extending it to other species
of mites''), that the common cheese-mite, which in its
perfect state has eight legs, when first excluded from the
egg has but six^ the third pair being wanting ■=. Some
however are born with eight legs, for instance A. cniditus
of Schrank, which he saw come from the egg itself with
that number'*. Others again have never more than six
legs : this is the case with Latreille's genera — Caris,
Leptus, Atoma, and Ocypetes of Dr. Leach ^. In the
centipedes [Scolopendridcs) and millepedes {Iididcc) dif-
ferences still more remarkable, as I have stated in a for-
mer letter, have been observed by De Geer ; these ani-
mals, in their progress to the perfect state, not only gain
several additional pairs of legs, but also several additional
segments of the body. This illustrious Entomologist found
that Polly xenus lagurus [Scolopendra L.) was born a hexa-

» Dc Geer vii. 197. " Ibid. 85. «• Epht. lx^•ii. 1694. 390.
•* Enum. Ini. Auslr. 575. ' N. Bid. d'llisl. Xat. i. 74.

108 STATES OF INSFXTS.

pod, with but three segments and as many pairs of feet,
but successively acquired five additional segments with
other appendages, and nine more pairs of feet*. A spe-
cies of millepede [lulus terrestris L.), which he also
traced from its birth, and which begins the world at first
with only eight segments and six feet, by a successive
development at length acquires, in its perfect state, 50
segments and not less than 200 feet''. The nature of
these very singular accretions, which Latreille and Mr.
Wm. MacLeay have also observed in the centipedes *=,
seems not well understood. If, as is most probable,
though De Geer could not find any exuviae ■=, the larvae
cast a skin before each change, they do not essentially
differ from the metamorphosis of other insects. The
legs that these insects thus acquire are affixed to the
abdomen, the six that they set out with being attached
to the part representing the trunk, so that the former
may be regarded as analogous to the prolegs of cater-
pillars. These animals therefore, as I have before inti-
mated, invert the order of Nature, and from perfect de-
generate into imperfect insects.

ii. If you examine the coclroach, cricket, or grasshop-
per, in different stages of their growth, you will find that
the larva does not vary essentially from the perfect insect,
except in wanting wings and elytra. The case is the
same in almost all the Linnean genera of the modern
crder — Hemiptera ; and with Raphidia, Termes, and
Psocus, in the Neuroptera. Some of these, however, ex-

» De Geer vii. 576. " Ibid. 584.

"= Considerat. Gener. 21 . HorcB Entomolog. 353.
^ De Geer, Tbid. Mr. W. MacLeay observes of the Chilopoda, or
Centipedes, that they moult in the manner of Crustacea, ubi supr. 352.

STATES OF INSECTS. 109

hibit sligliter discrepancies in the proportion of some of
their parts, but without affecting the general resembhince.
Thus the hirva,' of the common ear-wig have at first only
eight, and subsequently niiie joints to their antennae,
whereas the perfect insect has fourteen *; and the forceps
is quite different, resembling rather two straight styles
than what its name implies. In those also of many bugs
[Corcus marginatus F. &c.), the joints of the antennae are
of a shape dissimilar to that which obtains in the perfect
insect. In that of the common water-scorpion, the anal
air-tube, which is so long in the miago, is scarcely visi-
ble ^. In the Cicada tribe, so celebrated for their song '^,
neither the larva nor the imago have the enormous thigh
armed below with strong teeth, the tibiae terminating in
a fixed incurved claw, probably for the purpose of dig-
ging the holes into which they retire till they disclose the
fly, which distinguish the pupae of some species, and is
particularly conspicuous in one commonly brought from
China''. These often exhibit also other minor differences.

II. In treating of the second great division of larva;,
those that are wholly unlike the parent insect, — which
includes, with few exceptions ^, the whole of the Linnean

* De Geer iii. 549. The figure of the forceps in De Geer (Ibid.
i. XXV. /. 21) is not quite correct. The styles do not taper to a point,
but are filiform and acute.

** Compare De Geer iii. t. xviii./. 2 and 12. q.

' See above, Vol. II. p. 401.

"* Plate XVI. Fig. 4. c. Reaum. v. /. xix./. 16. De Geer iJnsupr.
t. xxxii,/. 26. According to Reaumur, the larva as well as the pupa
of Chermcs Ficus has wing-cases (iii. 353).

^ These are in the female sex of some Coleoptera, as Lavipyris, &c.
which retain in the perfect state nearly the same fonn which they
had when larvae. The larvae of some Slaphylini are not very dissi-
milar in form to the perfect insect.

HO STATES OF INSECTS.

orders, Colcoptera^ Lepidoptera^ Hymenoptera, Diptei'a,
the majority of the Neuroptera, Cocais and Aleyrodes in
Hemiptera, and the genus Ptdex in Aptei-a, — I shall ad-
vert to their characters, under several distinct heads; and
to avoid unnecessary circumlocution, I shall in what fol-
lows wholly leave out of consideration Xh^Jirst division
already explained, and use the term larvce with reference
only to those of the second. The heads under which I
propose to treat of them are : The substance of their body,
its parts, shape, or figure, clothing, colour. Also the
lEiConomy or mode of life of these creatures : their ybcx/,
moultings, grotvth, age, sex, and their preparations for as-
suming the Pupa.

i. Substance, with the exception of the head and six
fore-feet, which are usually corneous, the exterior inte-
gument or skin of larvae is commonly of a membranous
texture, and the body is of a much softer consistence
than in the perfect insect. In those, however, of some
Staphylinidce and other Coleoptera, the dorsal part of
the three first pieces, which represent the trunk of the
perfect insect, is hard and horny. Some also have their
whole skin coriaceous, as the tortoise-shell butterfly
( Vanessa polychloros) ; and some few, as the wire-worm
[Elater segetum), and other Elateres, very hard. I pos-
sess a very remarkable larva from Brazil, from the ex-
treme flatness of its body, and from its having cavities to
receive its legs when unemployed, probably living under
bark, the skin of which is still harder than that of the
grub of the Elaters. Perhaps it has to resist great
pressure ; and on that account is gifted with this quality,
so seldom to be met with in other kinds of larvae. The

STATES OF INSECTS. 1 1 1

interior of the body of these animals is generally of a
softer consistence than in the perfect insect. Their in-
testines, and other internal organs, are usually wrapped
in a voluminous substance of a fatty nature, which is re-
garded as analogous to the epiploon, omentum, or caul,
which envelops the viscera of quadrupeds, &c., and is
called by Reaumur the corps graissacx. The use of this
general flexibility of larvae is obvious ; for, their bodies
being mostly long and narrow, a hard rigid covering
would have been very inconvenient, and a considerable
impediment to their motions. When a caterpillar is
feeding, it has occasion to apply its body to any part of
the margin of a leaf so as to support itself by its prolegs,
and when moving it wants to give it all the curves that
are necessary to enable it to avoid obstacles, and thread
its way through the sinuous labyrinths which it must
often traverse. On the other hand, the liardness of the
substance of its head affords a strong fulcrum to the
muscles which keep its powerful jaws in constant play.
The larvae, indeed, of some Diptera have a membra-
nous head; but their mandibles, which serve also as
legs, are not grinders, but merely claws, the muscles of
which require less powerful support *. Under this head
it may be proper to observe, that generally larva^ are
opaque ; but some, as those of ants, and a few Lepido-
ptera ^, are diaphanous. That of Corethra crystallina
( Tipula De Geer) is so beautifully transparent as to re-

* The larvae described in the first Section, whicli resemble the
imago, are usually covered with a skin not materially different from
that of the insect in that state.

'- Huber Fourmis. 7;>; N. Diet, (fllist. Xat. vi. 250.

112 STATES OF INSECTS.

semble a piece of crystal, and scarcely to be distinguished
from the water in which it lives *.

ii. Parts. The body of each larva consists of the head^
including its different organs, and of the succeeding seg-
ments, of which the three first may usually be denomi-
nated the trunk, and have the six anterior feet, when
present, attached to their under side : the remainder is
the abdomen. The latter includes in some species a vari-
able number of membranous feet, as well as various ap-
pendages affixed usually to its tail and sides. No larva
is ever furnished with wings ''. Each of these greater
divisions, and the organs which they include, require
separate consideration.

1. Head. This, as was lately observed, is exteriorly of
a horny substance, or at least harder than the rest of the
body, in most larvae ; and on this account, though rarely
separated from it by any visible distinct neck •=, is, if the

"" Reauni. v. 40. L vi./. 4—15.

** Miiller, the Danish zoologist, relates, that he once met with a
papilio which, with the true wings of the genus, had a head without
antennse or tongue, furnished with mandibles; and, in short, that of a
true caterpillar. It was a female, which deposited eggs that proved
barren. If this solitary instance was not a mistake, is it possible that
some parasitic larva had devoured only the inclosed head of the but-
terfly, or so injured it that it could not reject the hard skin of the
larva, and yet not be destroyed ?

*= The only larvae which have a visible distinct neck are those of
some Dytisci, Slaphylini, and a few others, in which this part is quita
distinct : proving the erroneousness of the opinion of those German
entomologists, who consider the thorax as analogous to the neck of
other animals, and hence call it Hnlsschild. In some lepidopterous
larvas, however, as in that of Pieris Brassicce, though no visible neck
presents itself, one is very perceptible when the insect stretches the
head forward considerably. Reaimi. i. 460.

STATES or INSECTS. 113

larva be of a tolerable size, distinguished at the first view.
In those of many Dipterous insects, however, the head is
covered with the same flexible membranous skin with the
rest of the body, from which it is often scarcely to be di-
stinguished. In these, except that it contains the organs
of manducation, it wears no more the appearance of a
head than any other segment of the body, and scarcely
so much as the last or anal one. The head of these larvae
is also remarkable for another peculiarity, — that it is ca-
pable of being extended or contracted, and assuming dif-
ferent forms at the will of the insect: a property which
the head of no superior animal can boast. It is probable
that there is a considerable variety in the shape and cir-
cumstances of the heads of larvae ; but since, with the ex-
ception of those of Lepidoptcra, they have had less at-
tention paid to them than they deserve (indeed in a vast
number of cases, from the difficulty of meeting with them,
these variations, except in a few instances, have not beeri
described), I will here mention a few of the most remark-
able. The head of the young larva at its first exclusion
from the Qg^^ is usually the most dilated part of the body,
but it does not often continue so. In that of Cicindela
campestris, however, — the beautiful green beetle some-
times found in sandy banks, — and also in several cater-
pillars of Lepidoptcra, it is much larger than any of the
following segments*; which, in conjunction with the
animal's formidable jaws, gives it a most ferocious ap-
pearance. In some lepidopterous larvae the head is of
the same diameter with the rest of the body, but in in-
sects in general it may, I think, be stated as less ; and

* Plate XVII. Fig. 13.

VOL. HI. I

\i^ STATES OF INSECTS.

occasionally it bears no proportion whatever to it. This
is the case with the subcortical one from Brasil lately
mentioned. It is more commonly longer than broad ;
but in some, as in the larvae of can-ion beetles {Silp/ia),
the reverse of this takes place. Its shape varies from
triangular to orbicular, the mouth of the animal forming
the vertex of the triangle. In some larvae of Hemerobii,
however, the head is narrowest behind. That of the grub
of a gnat noticed above [Corethra crijstallina) forms a
kind of sharp horn or claw, terminating the body ante-
riorly *. The contour of the head of larvae is usually
intire and unbroken ; but in the caterpillars of some Lepi-
doptera^ as the butterfly called the grand admiral ( Vanessa
Atalanta), the Glanville fritillary {Melitcea Cinxia\ &c.
it is divided into two lobes ^. In the Brazil flat larvae it
is trilobed, each lateral lobe being divided into three
smaller ones : in which circumstance it somewhat resem-
• bles the head of some subcortical Cimicidcs. Although
the part we are treating of is generally without horns,
yet in some tropical butterflies of the tribe of Nymphales,
it is singularly armed with them. Thus Papilio Anchises
is distinguished, according to Madame Merian *=, by two
in the occiput, which it has the power of retracting. In
the purple highflier [Apatura Iris), a British species, the

'■' Reauin. v. /, vi.f. 7. Lc.

•> In fact, in almost all Lepidopterous larvse the head may be re-
garded as divided into two lobes or eye-shaped portions, which in-
clude in the angle formed by their recession anteriorly from each
other, the nasus {clypeus Y.\ the labrum, and other instruments of
manducation. Posteriorly these lobes generally come into contact;
but I have a specimen in which there is a narrow space between
them.

'' Ins. Siir'innm. t. xvii.

STATES OF INSECTS. W!")

two lobes of the head, I am informed, termhiate behind in
two horns ; as they do Ukewise in the brilliant Morp/to
Menelaus *, the lobes assuming the form of a pear, and
the horn representing the stalk. In a caterpillar I found
amongst Mr. Francillon's larvae, the head is bilobed,
with a very long recurving subcapitate subramose spine.
In Safj/rns Cassia;, the head is armed with three occipital
stout spines ''. The larva of Nymphalis AmpJimome Latr.
{Limenitis F.) is crowned with a coronet of eight occipi-
tal stout acute spines, the intermediate ones being the
longest ^ ; and that of Morpho Teucer has a similar coro-
net, consisting of only seven blunt rays, seemingly, rather
than spines ''. With regard to the articulation of the
head with the trunk, it is generally by its wliole diame-
ter ; but in some instances, only by a part of it. This is
the case with one of a sphinx figured by Mad. Merian ^;
and I have another, probably belonging to the nocturnal
Lepidoptera [Phalccna L.)'^. In both these, the head is
vertical and triangular ; and in the latter (which is a re-
markable creatui-e, the tail itself being more like a head,
and furnished with what resemble two prominent black
eyes) the vertex of the triangle is considerably higher than
the back of the animal. Whatever may be the clothing of
the body, the head is usually naked. Sometimes, however,
it is itself beset with very small simple spines, as in the but-
terfly of the mallow [Hesperia Malvce) ; or with longer
compound ones, such as are found on the rest of the body.

* Ins. Surinam, t. liii. '■ Ibid. t. xxxii. *" Ibid. t. viiL

J Ibid. t. xxiii. « Ibid. t. xiv.

f I purchased this singular caterpillar from the collection of the
late Mr. Francilloii, with his other exotic larvae; but without any
indication of the fly to which it belonged.

I 2

IIG STATES OF INSECTS.

This is the case witli one of a butterfly named by RiJsei
Papilio viorsa. The most common colour of the head of
larvae, where it differs from the rest of the body, is a
darker or hghter reddish brown, or piceous. Tliis is
particularly observable in those of Coleopterous insects,
but it is very commonly in other tribes of the same hue.
Sometimes, amongst the Lepidoptera, the head is of a
different colour from the rest of the body ; especially
where a contrast renders it striking. I can show the ca-
terpillar of some insect, probably of the hawk-moth tribe
[Sphingida), from Georgia, remarkable for the length of
its anal spine, in which the body is black, and the head
red : another has a white head and a brown body. In
the larva? of some Lepidoptera^ Coleoptera^ and Diptera,
the head can be wholly or nearly withdrawn within the
first segment of the body. This may be readily seen in
that of the common glow-worm; and that of a small gnat
{Tipida replicata De Geer) withdraws it so completely
that the anterior margin of that segment closes the ori-
fice, so that the animal appears to have no head ^. —
The parts of the head which require distinct considera-
tion are, the eyes^ antennce^ and the mouth : consisting
of various organs, which will be specified. Some of these
parts and organs are peculiar to larvae of one order,
othei's to those of another, and some are furnished with
them all.

E^es. The larvae of many insects have no eyes. Those
with antennae which terminate in a lamellated clava
{Scarahaiis L.), and Capricorn beetles also [Ceramhijx L.),

" De Geer vi. 352.

STATES OF INSECTS. 117

junongst the Coleoptera^ are without them, and probably
several others ; and amongst the Diptcra, all those with
a membranous or variable head. Those of the remain-
ing orders, with the exception, perhaps, of some Hymen-
opterci •M\(\ Lepidoptcra, are furnished with these organs;
and in the Colcoptera all the predaceous tribes, as well
as most of those that are herbivorous or granivorous,
and the Gnats and other Tipulidans ( Tipiilarice Latr.) in
the Diptera^ are also distinguished by them. In the lar-
vae of the dragon-flies [Libellula L.), and other Neiiro-
ptera, they are composed of many facets as in those of
the perfect insect, from which they differ chiefly in being
smaller. But in the other insects of this description they
are simple, and resemble those of the Arachnida, and
many aptera. These simple eyes vary in their number,
in different genera and tribes, from one to six on each
side of the head. Thus the larva of Telephonis, and the
saw-flies, has only one *; that of Cici?idela three, the two
posterior ones being large with a red pupil surrounded
by a paler iris, which adds to the fierce aspect of this
animal; and the anterior one very minute. Those
of the tortoise-beetles also [Cassida) have three ^ ; of
&taph\jlinus, fmir ; of Timarcha (the bloody-nosed beetle)
Jive; of Carabus, and the Lepidoptera in general, six.
In the last they are of different sizes, and generally ar-
ranged in a circle: in that o^ Hemerohius there are five in
a circle, with one central one '^. The appearance of these

» De Geer iv. 66. ii. 922.

'' De Geer v. 1 70.

*■ De Geer says, he could not make out the number of eyes of the
larva of the whirlwig (Giji-inus): probably, as in that of D^jtiscus,
there are six. iv. 362. 385.

lis STATES OF INSECTS.

globules, which are often not visible but under a power-
ful lens, is so different from that of the eyes of a butter-
fly or moth, or other perfect insect, that it has been
doubted whether they actually perform the office of eyes,
but without reason. They occupy the usual station of those
organs, being situated in many instances upon a protube-
rance which appears to incase them ; and seem of a con-
struction closely analogous to that of the eyes of spiders,
and the stemmata or ocelli of Hymenoptera, which have
been satisfactorily proved to be organs of vision. In the
larva of a moth not yet ascertained to exist in this coun-
try, Attacus Tau, and probably other species, the eyes,
after the skin has been changed a few times, are no longer
to be seen ^.

AntenncB. Most larvae are provided with organs near
the base of the mandibles, which from their situation and
figure may be regarded as antennae. Fabricius has as-
serted that the larvae of the saw-flies ( Tenthredo L.) have
no antennae; but in this he was mistaken, for though
very short, they are discoverable in them, as he might
have learned by consulting De Geer ''. In the majority
of l^europterous larvae, they almost precisely resemble
those of the perfect insect. In all the rest they are very
different. The antennae of Coleopterous larvae are usu-
ally either filiform or setaceous, consisting of four or five
joints, nearly equal in length. Those of Lepidopterous
larvae are commonly conical, as are those likewise of
Chry&omela and Coccinella &c. amongst the ColeopterUf
and very short, composed of two or three joints, of which
the last is much thinner than the first, and ends in one or

« Pez. 188. '• ii. 923, /. xxxvj../: 4, hb, Fabr. PliUos. Enl. GO.

STATES OF INSECTS. 119

two luiirs or bristles. These antennae the larvii has the
power ol" protriuUng- or retracting at pleasure. Lyonnet
inl'orins us, that the caterjiilhu- of the great goat-moth
{Cossus lig7iipcr'da) can draw the joints of its antennae one
within the other, so as nearly to conceal the wliole •'.
The larva of the tonnnon gnat has two long inciu'ved se-
taceous antennae, fringed with hairs at some distance from
their apex, which consist only of a single joint ''. Tho
greater number of Dipterous larvae, however, all indeed
except the Tipulidans {Tipidaria; Latr.), and many be-
longing to the Coleoptcra and Hymenoptera orders (as
those of Curadio, Apion, Jph, &c.), are wholly deprived
of antennae. It is a general rule, that the antennae of
larvae are shorter than the same organs in the perfect in-
sect, the tribe Ephemerina perhaps affording the only
example in which the reverse of this takes place "=.

Mouth, All larvae have a mouth situated in the head,
by which they receive their food, and fiunished with one
or more instruments lor the purpose of mastication and
deglutition. These mstruments, in all the orders except
Lepidoptera, some Neuroptera and Diptera, bear a ge-
neral resemblance to the same parts in the perfect insect.
In iarv£E of the Coleopterous, Lepidopterous, and Hy-
men opterous orders, we can distinguish for the most part
an upper and under lip ; two pairs of jaws answermg to
the mandibulae and maxillae ; and two, four, or six pal-
pi '^ : and some of these instruments may be found in
mosi Diptcra. Each of these parts require separate no-
tice.

Upper-lip (Labrum). The mouth of almost all larvae,

'* Lyonnet 41. /. ii./. 1. c. '' De Geer vi. 307.

•■ Ibid. ii. /. xvi. Conip./. ~ a a with/. 14 aa.

'' In tlie l;u\ a of Ckindcia thcrfurc six pulpi, iis in the pcifccl insect.

120 STATES OF INSECTS.

except some of the order Diptcra, are provided with a
distinct upper-lip, for retaining their food during masti-
cation. As the construction of this part does not widely
differ from that of the perfect insect, which will hereafter
be more fully described, it is only necessary to observe,
that it is usually a transverse moveable plate, attached
posteriorly to the nasus [dypeiis F.), and situated just
above the mandibles ^.

Upper-jaws (MANDiBULiE). The most usual figure of
these, which are of a hard horny consistence ^, is that of
two slightly concave, oblong, or triangular plates, often
at their lower extremity of considerable thickness, and of
very irregular form, the base of which is filled with
powerful muscles, and planted in the side of the mouth
so as to move transversely. The other extremity can be
made to meet or diverge like the claws of pincers, and
are divided into one or more tooth-like indentations, by
means of which the food of the larva is cut '^. This is
their construction in the larvte of all Lepidoptera, and in
many of those of the other orders. They frequently,
however, assume a different form, though their situation
is always the same. Thus in the larvae of the Capricorn
beetles [Cerambyx L.) and of other wood-boring species,
they are shaped like the half of a cone, the inner sides of
which, applying close to each other, form a pair of power-
ful grindstones, capable of comminuting the hardest tim-

* Lyonnet, t. \.f. 7. e. In the larva of Callidium violaceum, how-
ever, this part is of a singular shape, being orbicular. ICirby Lin7i.
Trans, v. t. xii./. 13. a.

b It is affirmed (N. Diet, d' Hist. Nat. vii. 333) that the larvae of
those Coleoptera that live in carcases have mandibles almost mem-
branous : those, however, of that of Siiplia rugosa are horny and
hard.

? Lyonnet, t. ii./. 1. d d, and/. 2, 3, 4.

STATES OF INSECTS. 121

ber *. M. Cuvier has observed, with regard to the man-
dibulaj of those of stag-beetles (Lnca?ius), that besides
their teeth at the extremity, tliey have towards their base
a flat striated molary surtace ; so that they both cut and
grind their hgneous food ''. It seems to have escaped
him, that a similar structure takes place in many perfect
insects of the lamellicorn tribe, as I shall hereafter show
you. In the larvie of the water-beetles [Dytiscus L.),
ant-lions {Mijrmeleon L.), and lace-whiged flies [Hemero-
bitis L.), they resemble somewhat the forceps at the tail
of an ear-wig, being long and incurved; and, what is more
remarkable, hollow and perforated at the end, so as to
serve as a channel for conveying into the larva's mouth
the juices of the prey which by their aid it has seized.
Reaunnir even asserts, that the larva of Myrvideon has
no odier entrance into its throat than through these tu-
bular mandibles '^. That of the rove-beetles {Staphy-
limis L.), and of many other Coleopterous genera, have
these organs of this forcipate construction, without being
perforated'^. In the larva of the carnivorous flies, and
many other Diptera, are two black incurved subulate
parts, connected at the base, and capable of being pro-
truded out of, and retracted into, the head, through the
skin of which they are usually visible. As I informed
you in a former letter '^, these mandibles are vised for
'walking as well as feeding : they are pai'allel to each
other, and are neither formed for cutting nor grinding

* Kirby in Linn. Trans, v. /, xii.f. 7 b.
^ Cuvier Anat. Cumj). iii. 322. '' Reaum. vi. 340.

■* The larva o(" Cicindela camjieslris has mandibles of this descrip-
tion. Plate XVII. Fir.. 13. cr.
•^ See above, Vol. II. 275—.

122 STATES OF INSECTS.

like the mandibles of other insects, but merely detach
particles of food by digging into it and tearing the fibres
asunder. In this operation they are probably assisted by
an acutely triangular dart-like instrument of a horny sub-
stance, which in some species [Musca vomitoria) is
placed between the two. In others this part is wanting.
Some Dipterous larvae have two similar mandibles, but in-
stead of being parallel, they are placed one above the other;
others [Musca domestica and meridiana) have but one such
mandible, and some have no perceptible mandible of any
kind. Themandiblesof the larva of the crane-flies ( Tipida\
which are transverse and unguiform, do not act against
each other, but against two other' fixed, internally con-
cave and externally convex, and dentated pieces ^.

Under~j alios (Maxillae). These are a pair of organs,
usually of a softer consistence, placed immediately under
the upper-jaws ; but as they are usually so formed and si-
tuated as not to have any action upon each other, it is
probable that in general they rather assist in submitting
tlie food to the action of the mandibulae, than in the com-
minution of it. In Lepidopterous larvae they appear to
be conical or cylindrical (at least in that of the cossus
so admirably figured by Lyonnet ^), and to consist of two
joints ; which may, I imagine, be analogous to the upper
and lower portions of which the maxillae of perfect insects
usually consist. The last of these joints is surmounted
by two smaller jointed palpiform organs. If any part of
the maxillae can act upon each other, it is these organs
or palpi ; but it is evident they are not calculated for mas-
tication, although they may assist in the retention of the

^ Reauiu. v. 9. /. i./. 4. c c, //. '' Traile Aiiatom, I. n.f. 1. h h.

STATES or INSECTS. 123

substance to be masticated. In a figure given by Reau-
mur of the uniler side of the head of another lepitlopte-
rous larva [Enninea PomoncUa), the maxilla} consist of
a single joint, iuid appear to be crowned by chelate pal-
pi * : a circumstance which is also observable in that of a
common species of stiig-beetle [LucanusparallelipijJedus),
the weevil of the water-hemlock [Lixits paraplccticus^),
and other insects. In general the maxillae of larvae are
without the lobe or lobes discoverable in those of most
perfect insects, this part being usually represented by a
kind of nipple, or palpiform jointed process, strictly ana-
logous to the interior maxillary palpi of the predaceous
coleoptera ; but in most of the lamellicorn beetles the
lobe exists in its proper form % as it does likewise in that
of the capricorn-beetle before noticed {Callidiutn viola-
ceum^). In the former instance, it is armed with spines or
claws; but in the latter it is unarmed, and rounded at tlie
end. In the larva of Cicindela campestris, the base of the
maxilla runs in a transverse direction from the mentum,
to which, as is usually the case, it is attached. From this
at right angles proceeds the lobe, from the outer side of
which the feeler emerges ; and the inner part terminates
in an unguiform joint, ending in two or three bristles.
The structure in the larvae of water-beetles {Dytiscusl^.)
is different, for they appear to be without maxillae^; but
the case really seems to be, that these organs are repre-
sented by the first joint of what M. Cuvier calls their
paljn ^ ; from w Inch proceed the real palpi, the interior

" Reaum. ii. /. 40./. 4. ^ Qe Geer v. 229,

'" Ibid. iv. t. x'l.f. 16. pp. '' Lhm. Train: v. /. xii./. 10.

" Cuvier Anaf. Comp. iii. 323.

' Dc Geer iv. /. xv./. .9. b h. Tiie exterior and interior piilpi are
both rcjjrc^cntcd in this figure.

124 STATES OF INSECTS.

one being very short, and consisting only of a single
joint. These maxillae of larvae were regarded by Reau-
mur and other writers as parts of the under-lip, on each
side of which they are situated ; and indeed, as well as
those in the perfect insect, they form a part of the same
machine, being connected by their base with the mentum,
which is part of the labium, but they are clearly analo-
gous to the maxillae of the imago. They are not to be
found in the larvae of many Dipterous insects, and per-
haps in some species belonging to other orders. In some
Neuropterous larvae, as those of the Libellulina MacLeay,
the maxillae are of a substance quite as solid and horny as
the mandibles, which in every respect they resemble ^.

Under4ip (Labium). Between the two maxillae in the
larvae of most of the insects under consideration is a part
termed by Reaumur the middle division of the under-lip,
but which is in fact analogous to the whole of that organ
in the imago. This organ varies in shape, being some-
times quadrangular, often conical, &c. Interiorly it is
frequently connected with a more fleshy protuberance,
called the tongue by Reaumur ^, and supplying the place
of the ligula in the perfect insect. On each side of the
apex of the under-lip is a minute feeler, and in the mid-
dle between these in the Lepidoptera and many others, js
a filiform organ, which I shall call the spinneret {Fusuhis\
through which the larva draws the silken thread em-
ployed in fabricating its cocoon, preparatory to assuming
the pupa state, and for other purposes '^. This organ is

» Reaum. vi. t. xxxvii./. .5. e e. ^ Ibid. i. 125,

<^ Plate XXI. Fig. 9. The organ with which the larvae of Heme-
robius, Myrmeleon, and HydrophUui;, spin their cocoons, is situated
in the amis. The spinneret of the Cossus is figured by Lyonnet Ana-
tom. t. W.f. 1 . 1., QX\Afg. 9,

STATES OF INSECTS. 12.'J

found onlv in those larvae which liave the power of spin-
ning silk; that is, in all Lcpidoptera, most Ili/mcnoptcray
Trichoptei'a^ some Neuroptera^ and even a DijHcrous in-
sect ^. This tube, Lyonnet liad reason tobeheve, is com-
posed of longitudinal slips, alternately corneous and mem-
branous, so as to give the insect the power of contracting
its diameter, and thus making the thread thicker or
smaller. There is only a single orifice at the end, w hich
is cut obli(juely, somewhat like a pen, only with less obli-
quity, and without a point, the opening being below, so
as to be conveniently applicable to the bodies on which
the larva is placed. Reaumur conceived that this spin-
neret had two orifices ; but Lyonnet ascertained this to
be a mistake, the two silk tubes uniting into one before
they reach the orifice. From the contractile nature of
the sides and the form of the orifice, combined with the
power the insect has of moving it in every direction, re-
sults the great difference which we see in the breadth and
form of the threads, some being seven or eight times as
thick as others, some cylindrical, others flat, others chan-
nelled, and others of different thickness in different parts ^.
In the larvae of many Dipteia the under-lip is merely a
small tubercle, which can be protruded from the insect's
mouth by pressure '^.

One of the most remarkable prepensile instruments, in
which the art and skill of a Divine Mechanician are
singularly conspicuous, and which appears to be without
a parallel in the insect world, may be seen in the under-
lip of the various species of dragon-fly [Libdlula L.). In

" De Geer vi. .370. This species {Tiptda Agarici seticornis De Geer)
has two separate spinnerets. /. xx.y*. 8. m vi.

•> Lyonnet 55 — . * Reaum. iv. 16G.

126 STATES OF INSECTS.

other larvae this part is usually small and inconspicuous,
and serves merely for retaining the food and assisting in
its deglutition; but in these it is by far the largest organ
of the mouth, which when closed it entirely conceals ;
and it not only retains but actually seizes the animal's
prey, by means of a very singular pair of jaws with which
it is furnished. Conceive your under-lip (to have re-
course, as Reaumur on another occasion ^, to such com-
parison,) to be horny instead of fleshy, and to be elon-
gated perpendicularly downwards ^, so as to wrap over
your chin and extend to its bottom, — that this elongation
is there expanded into a triangular convex plate '^, at-
tached to it by a joint '^j so as to bend upwards again and
fold over the face as high as the nose, concealing not
only the chin and the first-mentioned elongation, but the
mouth and part of the cheeks ^ : conceive, moreover, that
to the end of this last-mentioned plate are fixed two other
convex ones, so broad as to cover the whole nose and
temples % — that these can open at pleasure, transversely
like a pair of jaws, so as to expose the nose and mouth,
and that their inner edges where they meet are cut into
numerous sharp teeth or spines, or armed with one or
more long and sharp claws s : — you will then have as ac-
curate an idea as my powers of description can give, of
the strange conformation of the under-lip in the larvae of
the tribes of Libellulina ; which conceals the mouth and
face precisely as I have supposed a similar construction
of your lip would do yours. You will probably admit

=* Reaum. v. 155. ^ Ibid. vi. t. xxxvii./. I.bp. '^ Ibid, m e e.

^ Ibid./. 6. p. « Ibid. Compare/. 4 with/ 6, 7.

f Ibid. t. xxxvi./ \2, s u e.

8 Ibid, n e, and xxxviii./. 7, dc. ; De Geer ii. t. xix./ 17. d g.

STATES OF INSF.CTS. 127

that your own visage would present an appearance not very
engaging while concealed by such a mask ; but it would
strike still more awe into the spectators, were they to see
you first open the two u}>per jaw-like plates, which would
project iVoni each temple like the blinders of a horse;
and next, liaving by means of the joint at your chin let
down the whole apparatus and uncovered your face, em-
ploy them in seizing any food that presented itself, and
conve3'ing it to your mouth. Yet this procedure is that
adopted by the lurvoe provided with this strange organ.
While it is at rest, it applies close to and covers the face.
When the insects would make use of it, they unfold it
like an arm, catch the prey at which they aim by means
of the mandibuliform plates, and then partly refold it so
as to hold the prey to the mouth in a convenient position
for the operation of the two pairs of jaws with which they
are provided. Reaumur once found one of them thus
holding and devouring alarge tadpole; — a sufficient proof
that Swammerdam was greatly deceived in imagining
earth to be the food of animals so tremendously armed
and fitted for carnivorous purposes. Such an under-lip
as I have described is found in the tribe of dragon-flies
{Libdlulina) ; varied, however, considerably in its figure
in the different genera. In the larva of Libclhda Fab.,
such as Libclhda depressa, &c. it is of the shape above
described ; so exactly resembling a mask, that if Ento-
mologists ever went to masquerades, they could not more
effectually relieve the insipidity of such amusements and
attract the attention of the demoiselles, than by appearing
at the supper table with a mask of this construction, and
serving themselves by its assistance. It would be difficult,
to be sure, by mechanism to supply the place of the mus-

128 STATES OF TNSECTS.

cles with which in the insect it is amply provided : but
MerUn, or his successor, has surmounted greater obsta-
cles. In the larva of the Fabrician JEshnce [Libellula
grandis, &c. L.), this apparatus is not convex but flat :
so that, though it equally conceals the face, it does not so
accurately resemble a mask ; and the jaws at its apex are
not convex plates, but rather two single conical teeth *.
It is, as to its general shape, similarly constructed in
Ag)ion Fab. [L. Virgo, &c. L.); but the first joint is
more remarkably elongated, the jaws more precisely re-
semble jaws than in any of the rest, and are armed with
three long, very sharp teeth : between them also there is
a lozenge-shaped opening, through which, when the ap-
paratus is closed, is protruded a circular sort of nipple,
apparently analogous to the ligula ''. Libellula (cnea, L,,
which is the tj'pe of another tribe [Cordulia Leach), has
a mask somewhat different from all the above, the jaws be-
ins: armed with a moveable claw and an internal tooth *=.
You will admire the wisdom of this admirable contri-
vance, when you reflect that these larvae are not fitted to
pursue their prey with rapidity, like most predaceous
animals ; but that they steal upon them, as De Geer ob-
serves ^, as a cat does upon a bird, very slowly, and as if
they counted their steps ; and then, by a sudden evolu-
tion of this machine, take them as it were by surprise,
when they think themselves safe. De Geer says, it is
very difiicult for other insects to elude their attacks, and
that he has even seen them devour very small fishes ^.

=" Reaum. vi. t. xxxvii./. 4 — 6. 8.

'' Ibid. t. xxxviii. First joint/. 8. bfp. ; jaws/. 7- c d.; opening o,
Ligula/. (5. /.

'■ De Geer ii./. 17- Jaws gg; clawf/; tooth//. '' Ibid. 674.
<■ Ibid. ii. 674.

STATES OF INSECTS. 129

As these animals are tbuiul in almost every ditch, you
will doubtless lose no time in examinhig for yourself an
instance of so singular a construction.

Feelers (Palpi). In the orders Diptcra and Hymeno-
ptera are many larvae in which these organs have not
been certainly discovered; yet Reaumur in that of a com-
mon fly {M. mcridiana L.) found four retractile nipples *
which seem analogous to them ; and Latreille has ob-
served, that below the mandibles of those of ants are
four minute points, two on each side ^ : but in all other
larvaj their existence is more clearly ascertained. The
maxillari) palpi vary in number, many having /wo on
each maxilla and others only one. In the perfect insect
the former is one of the distinguishing characters of the
predaceous beetles {Entomophagi Latr.), but in the larvae
it is more widely extended; since even in the caterpillars
of Lepidoptera the inner lobe of the maxilla which re-
presents this feeler is jointed, which is precisely the case
with the beetles just named. Cuvier has observed this
circumstance in the larva of the stag-beetle ^', and it be-
longs to many other Coleoptera that have only a pair of
maxiUary palpi in the perfect state. The labial palpi are
always two, emerging usually one on each side from the
apex of the under-lip. With regard to iheform of the
palpi, those of the Lepidoptera are mostly conical ; in
other orders they are sometimes setaceous and some-
times filiform. Their termination is generally simple,
but sometimes the last joint is divided. They are for the
most part very short, and the labial shorter than the

» Reaiim. iv. .376. •> K. Did. d'Hist. Nat. xii. 04.

<^ Anat. Comp. iii. 322.

VOL. III. K

130 STATES OF INSECTS.

maxillary. The latter never exceed yo?/r joints ^, which
seems the most natural number; and the former are limit-
ed to three. Both vary between these numbers, and one
joint. The joints, though commonly simple, are sometimes
branched. This is the case with one I met with in con-
siderable numbers upon the Turnip, in October 1808,
the second joint of the palpi of which sends forth near
the apex an internal branch. In the larva of the Cossus^
as Lyonnet informs us ^, the joints of the palpi are re-
tractile, so that the whole of the organ may be nearly
withdrawn.

After thus describing the head of larvae, and its prin-
cipal organs, we must next say something upon the re-
mainder of the body, or what constitutes the

2. Trunk and Abdomen : which I shall consider under
one article. These are composed of several segments or
rings, to which the feet and other appendages of the
body are fixed. The form of these segments, or that of
their vertical section, varies considerably: in many Lepi'
doptera, the wire-worm, &c., it would be nearly circular;
in others a greater or less segment of a circle would re-
present it ; and in some, perhaps, it would consist of two
such segments applied together. Their lower surface is
generally nearly plane. Their most natural numhei\
without the head and including the anal segment, is
twelve: this they seldom exceed, and perhaps never
fourteen. The three first segments are those which re-

* At first in the Dytisci they appear to have five joints ; but, as I
before observed, the first joint must be regarded as representing the
iliaxilla.

'' Lyonnet AnaUm. 55, 58.

STATES OF INSECTS. 131

present the trunk of the perfect insect, and to whicli the
six anterior legs when present are affixed. In general,
they differ from the remaining segments only in being
shorter, and in many cases less distinctly characterized;
but in Neuropterous larva;, those of Dytisci, and some
other Coleoptera, they are longer than the succeeding
ones, and pretty nearly resemble the trunk of the animal
in its last state. The surface of the trunk and abdomen
will be considered under a subsequent head ; I shall not,
therefore, describe it here. The co7ifarmation of the dif-
ferent segments varies but little, except of the terminal
one, or tail, which in different larva; takes various figures.
In most, this part is obtuse and rounded; in others acute
or acuminate ; in others truncate ; and in others emargi-
nate, or with a wider sinus, and with intermediate modifi-
cations of shape which it would be endless to particularize.
In some, also, it is simple and unarmed ; in others be-
set with horns, spines, radii, and tubercles of dii?'erent
forms, some of which will come under future considera-
tion. The parts connected with the trunk and abdo-
men which will require separate consideration, are the
legSf the spiracles, and various appendages.

Legs. It may be stated generally that the larvae of the
orders Colcoptera, Lepidoptera, and 'Ne^iroptera, have
legs ; and that those of the orders Hymenoptera and Di-
ptera have none. This must be understood, however,
with some exceptions. Thus the larvae of some Coleo-
ptera, as the weevil tribes [Curcidio L.) have no legs, un-
less we may call by that name certain fleshy tubercles be-
smeared with gluten, which assist them in their motions * ;

' De Geer v. 203;

K 2

132 STATES OF INSECTS.

\vhile those of Tcnthredo and Sirex in the order Hymen-
optera are furnished with these organs. At present I
know no Dipterous larva that may be said to have real
legs, unless we are to regard as such certain tentacula
formed upon a different model from the legs of other lar-
\x ^. Rosel has, I think, figured a Lepidopterous apode.
No Neuropterous one has yet been discovered.

The legs of larvae are of two kinds ; either horny and
composed of joints, or fleshy and without joints ''. The
first of these, as I observed in a former letter '^, are the
principal instruments of locomotion, and the last are to
be regarded chiefly as props and stays by which the ani-
mal keeps its long body from trailing, or by which it
takes hold of surfaces ; while the other legs, or where
there are none, the annul! of its body, regulate its mo-
tions. The former have been commonly called true legs
[pedes rrr/), because they are persistent, behig found in
the perfect insect as well as in the larva; and the latter
spurious legs (pedes spurii), because they are caducous,
being found in the larva only. Instead of these not very
appropriate names, I shall employ for the former the
simple term legs, and for the latter prolegs (jpropedcs) ^.

The legs, when present, are always in number six, and
attached by pairs to the underside of the three first seg-
ments of the trunk. They are of a horny substance, and
consist usually of the same parts as those of the perfect

* De Geer iv. 5. Legs of tliis kind are figured Plate XXIII.
Fig. 7.

** In the larva, however, of Sialis, or some kindred genus, in which,
like those of Scolopendra, the prolegs ai-e jointed, a pair distinguishes
each abdominal segment. See Reauni. iv. t. xv./. 1, 2. Compare De
Geer ii. t. xxiii./. 11.

' See above, Vol. II 28G— . -^ Ibid. 288.

STATES or IN.SKCTS. 13<{

insect; namely, farr/, troclianlet^fvmuf^ iihiu, iind/arsusy
suspended to each other by membranous ligaments: these
parts are less distinctly marked in some than in others.
Thus in the Icfrs of a caterpillar, or the grub of a capri-
corn-beetle, at ihstyou would think there were only three
or four joints besides tlie claw ; but upon a nearer inspec-
tion, you would discover at the base of the leg the rudi-
mentij of two others *, in the latter represented indeed by
the fleshy protuberance from which the legs emerge.
In the larvae of the predaceous Coleopicra, the hip and
trochanter are as conspicnous nearly as in the perfect
insect; and the tarsus, which still consists of only a sin-
gle joint, is ai-med with two claws''. In those of the
Neuroptera order, in which all the joints are very con-
sjiicuous, the tarsi are jointed, as well as two-clawed '=.
The legs of larva: are usually shorter than those of the
perfect insect, and scarcely differ from each other in
shape, for they all gradually decrease in diameter from
the base to the apex. This is the most usual conforma-
tion of them in Lepidopterous, Hymenopterous, and
some Coleopterous larvae, (those of the capricorn-beetles
are very short and minute, so as to be scarcely visible,)
in which they are so small as to be concealed by the body
of the insect ''. In Neuropterous larvae, however, and

" Lyonnet Analom. t. nuf. 8. Coxa b. Trochanter c. Femur d. Ti-
bia K. Tarsus Y. Claiv c.

*> Dc Gccr iv. /. xiii./. 20; and /. xv./. Ifi.

*" Ibid. ii. /. xvi./. 5, G, 7- d c: and t. xix./. 4. cfg h.

^ The larva of a scarce moth {Stauropus Fagi. See Plate XIX.
Fig. 4) is an exception to this. The first pair of its legs are of the
ordinary stature, but the two next arc remarkably long, and so thin
and weak as to be unable to Iicar the body. Pczold. 119. Another
jninutc calcr[)iUar described by Reaumur has the tliird pair of the

134 STATES OF JNSECTS.

several Coleoptera, as those of Dytlsciis, Staphylmus, Coc-
cinella, &c., they more resemble the legs of the perfect
insect, the joints being more elongated, and the femoral
one projecting beyond the body *.

You will find no other than true legs in most Coleo-
pterous, Neuropterous, and Hymenopterous larvae. But
those of the saw-flies {Tenthredo L.), and all caterpillars,
have besides a number ofprolegs : a few Dipterous larvae
also, are provided with some organs nearly analogous to
them. These prolegs are fleshy, commonly conical or
cyUndrical, and sometimes retractile protuberances, usu-
ally attached by pairs to the underside of that part of
the body that represents the abdomen of the future fly ''.
They vary in conformation and in number ; some having
but one, others as many as eighteen.

With regard to their conformation^ they may be di-
vided into two principal sections: first, those furnished
with terminal claws; and secondly, those deprived of
them. Each of which may be divided into smaller sec-
tions, founded on the general figure of the prolegs, and
arrangement of the claws or hooks.

legs apparently fleshy and singularly incrassated at the apex into a
pyriform figure, terminated by a pair of claws. This conformation
is for some particular purpose in the economy of the animal, since
they are the most busily employed of all in arranging the threads of
her web. Reaum. ii. 258. In the larva of a geometer {Gcometi'a hi-
naria) the third pair are remarkably long, lllig. Mag. 402. In that
of another moth, according to Kuhn {Naturf. xvi. 7H. /. iv./. 3), the
third pair of the fore-legs is remarkably incrassated, being twice as
thick and long as the other pair, though consisting of the same num-
ber of joints, the last of which has claws.

^ On the legs and prolegs see also what is said above, Vol.. II.
p. 286—.

*' In ?omc few instancet; these legs are dorsal. Ibid. 281.

STATES OF INSECTS. 135

i. Tlie prolegs of almost all Lepidopterobis larvae are
furnished with a set of minute slender horny hooks, crot-
chets, or cla'ii'S, of different lengths, somewhat resem-
bling fish-hooks; which either partially or wholly sur-
round the apex like a pallisade. By means of these
claws, of which there are from forty to sixty in each
prolcg, a short and a long one arranged alternately, the
insect is enabled to cling to smooth surfaces, to grasp
the smallest twigs to which the legs could not possibly
adhere: a circumstance which the flexible nature of
the prolegs greatly facilitiites *. Claws nearly similar
are found on the prologs of some Dij)fcrous larvae '', but
not in any of those of the other orders. These last, how-
ever, are seldom either so numerous, or arranged in
the same manner, as in caterpillars. When the sole of
the foot is open, the claws with which it is more or less
surrounded are turned outwards, and are in a situation
to lay hold of any surface ; but when the animal wishes
to let go its hold, it begins to draw in the skin of the sole,

* The claws or crotchets, though general, are not universal, in
Lcpiilopterous larv'ae. An exception is furnished to the rule by the
singular limaciform ones of Hepialm Tcstudo and Axe/lits of Fabricius,
two moths forming Haworth's genus Apoda, which have no distinct
prolegs, but in their stead a number of small transparent shining tu-
bercles without claws. The larva also of one of the subcutaneous
moths first discovered by De Geer in the leaves of the rose (i. 446),
but whose history is fully given by Goeze, Naturf. xv. 37 — 48, (who
has satisfactorily ascertained that it is the true larva of a T'lnoa of
Linne, but of a different habit from that of most subcutaneous ones),
has no true legs, and eighteen prolegs without any claws. Another
subcutaneous larva, for the history of which we are indebted to
M. Godeheu de Riville, is according to him entirely deprived of legs
of any kind (Bonnet ix. 19G — .); as is another of the same tribe that
feeds on the poplar, an account of which is given by Goeze Naturf.
xiv. 105. » Plate XXIV. Fig. 7- See also below, p. 13/,

136 STATES OF INSECTS.

and in proportion as this is retracted, the claws turn
their points inwards, so as not to impede its motion ^.

The prolegs with claws may be further divided into
four different kinds.

1. In the larvee of the great majority of butterflies
and moths they assume the form of a truncated cone,
the lower and smaller end of which is expanded into a
semicircular or subtriangular plate, having the inner
half of its circumference beset with the claws above men-
tioned ; and, from its great power of dilating and con-
tracting, admirably adapted for performing the offices of
a foot. Jungius calls these ]egs pedes elephantini^'; and
the term is not altogether inapplicable, since they exhibit
considerable resemblance to the clumsy but accommo-
dating leg and foot of the gigantic animal he alludes to.

2. The larvae of many minute moths, particularly of
the Fabrician genera Tortrix and Tinea — those which
live in convoluted leaves, the interior of fruits, &c., as well
as the Cossus, and Some other large moths, — have their
prolegs of a form not very unlike those of the preceding
class, but shorter, and without any terminal expansion ;
the apex, moreover, is wholly, instead of half, surround-
ed with claws '^ ; the additional provision of which, to-
gether with a centrical kind of nipple capable of being
protruded or retracted, in some measure, though imper-
fectly, supplies the place of the more flexible plate-like
expansion present in the first class.

3. The third class is composed of a very few Lepido-
pterous larvse which have their prolegs very thick and
conical at the base, but afterwards remarkably slender,

» Lyomiet Anatom. 84. t. iii./, 1 ], 1,2,

" Hist, \ermium, 130. ^ Plate XXIII. Fig. 1.

STATES OF INSECTS. 137

long, and cylindrical, so as exactly to assume the shape
of a wooden leg ". These, as in the first class, are ex-
panded at the end into a flat plate : but this is wholly cir-
cular, is surrounded with claws, and has also in the mid-
dle a retractile nipple, as in the preceding class. In
Cossus, at least in an American species {Cossus Rohini(c\
described by Professor Peck ^, the anal prolegs have the
claws only on their exterior half.

\'. The remaining description of imguiferous prolegs,
if the}' may not rather be deemed a kind of tentacula,
are those of certain DipUra, provided with no true legs;
which differ from the three preceding classes, either in
their shape, or the arrangement of their claws. In
one kind of those remarkable larvae, which from their
long respiratory anal tubes Reaumur denominates " rat-
tailed" tliat of Elophilus pcnduhis, there are fourteen of
these prolegs, affixed by pairs to the ventral segments,
the twelve posterior ones of which are subconical, and
truncate at the apex, which is surrounded with two cir-
cles of very minute claws, those of the inner being much
more numerous and shorter than those of the exterior
circle ; while the anterior pair terminate in a flat expan-
sion, and in shape almost exactly resemble those of a mole *=.
The prolegs of the larva; of a kind of gnat called by
DeGeer Tipida aynphibia, and of Si/ipJms mystaceus F.,
{Musca plumata De Geer,) are nearly of a similar con-
struction, but in the last arc armed with three claws
only''. Long moveable claws also distinguish the sin-

^ Plate XXIII. Fig. 17.

'' Account of Locusl-trce Insects, 69.

"= Reauiii. iv. 443. /. xxx./. G. //. /. xxii./. G. / /.

•• Dc Gcer vi. 383. and 137. /• viii./. «, 9.

138 STATES OT INSECTS.

gular prolegs before described =* of another gnat ( Tany-
pus maculatus Meig., Tipula De Geer). The case-worms
{Trichoptera K.) and some others, have two prolegs at
the anus, each fiirnished with a single claw ''.

ii. The prolegs deprived of clmsos are four^d in the
larva of the Hymenopterous tribe of saw-flies ( Tenthredo
L.), in those of some Lepidoptera [Hepialus F. &c.), and
in some few Ck)leopterous and Dipterous genera. Those
of the former are of the shape of a truncated cone, and
resemble the second class of unguiculate prolegs, except
in the defect of claws. In the latter they are a mere re-
tractile nipple-like protuberance, in some species so small
as scarcely to be perceptible. In all they aid in progres-
sive motion ; but it is by laying hold of surfaces, and so
enabling the body more readily to push itself forward by
annular contraction and dilatation, and not by taking
steps, of which all prolegs are incapable : to assist in this
purpose the protuberance sometimes secretes a gluten '^,
which supplies the place of claws. Some larvae have the
power of voluntarily dilating certain portions of the un-
derside of their body, so as to assume nearly the shape
and to perform the functions of prolegs. In a Coleopte-
rous (?) subcortical one from Brazil, before alluded to,
there are four round and nearly flat areas in each ventral
segment of the abdomen, but the last very little raised
above the surface, and rough, somewhat like a file; and
besides these, the base of the anal segment has ten of
these little rough spaces, but of a different shape, being
nearly linear, placed in a double series, five on each side.
Poubtless these may be regarded as a kind of prolegs^

^ See above, Vol. II. p. 2/8. De Geer ubi snpr. 376.

^ Rcaiim. iv. 184. t xv.f. 12. c c. "^ De Geer v, 303.

STATICS OF INSECTS. 13i)

which enable the animal to push itself along between the
bark and the wood '.

In considering, in the next place, the mimhcr and si-
ttuition of the prolcgs, it will contribute to distinctness to
advert to these circumstances as they occur in the diffe-
rent orders furnished with these organs.

To begin with the Lepidoptem. — Lepidopterous larvaj
have either ten, eight, six, or two prolegs, seldom more '',
and never fewer. Of these, with a very few exceptions,
two are attached to the last or anal, and the rest, when
present, to one or more of the sixth, seventh, eighth, and
7iinth segments of the body : none are ever found on the
fourth, fifth, tenth, or eleventh segments.

1 . Where ten prolegs are present, as is the case in by
far the greatest proportion of Lepidopterous larva^, there
is constantly an anal pair, and a pair on each of tlie four
intermediate segments just mentioned.

2. In caterpillars, which like those of a few species of
the genera Sphinx, Pijralis, and of the BombycidiC, &c.
have eight legs, they are placed in three different ways. In
those which have an anal pair, the remaining six are in
some fixed to the sixth, seventh, and eighth ; in others, to
tlie seventh, eighth, and ninth segments. In those which,
like Ccrura Vimda, and several other species of the
same family, have no anal prolegs; the whole eight
emerge from the sixth, seventh, eighth, and n-nth seg-
ments.

3. The Hemigeometers, as Nuciua Gamma, S:c. have

» See above, p. 110, 114.

'■ Sonic few suhcutaneous larvae liave more, as that, before men-
tioned, observed by De Gecr in the leaves of the rose j \\hich has
eighteen prolcgs, and no true ones.

140 STATES OF INSECTS.

only sioC legs : namely, an anal pair, and two ventral ones,
situated on the eighth and ninth segments.

4. The larvae of the Geometers {Gcometrce F.) have
hni four prolegs ; of which two are anal, and two spring
from the ninth segment. It should be observed, how-
ever, that the larvae of Hemigeometers, and even of some
of those that have ten prolegs, where the four anterior ones
are much shorter than the rest, move in the same way as
the Geometers. This even prevails in a few where these
organs are all of equal length.

5. Many of the larvae of Tinea L. which live in the in-
terior of fruits, seeds, &c., have but one pair of prolegs,
which are attached to the anal segment.

6. The larvae of Ha worth's genus Apoda [Hepialus
Testtido and Asellus F.), remarkable for their slug-like
shape and appearance, move by the aid of two lateral
longitudinal pustule-like protuberances, which leave a
trace of a gummy slime in their course.

ITj/}ne?ioptera. — The larvae of the different tribes of
Tenihredo L., almost the only Hymenopterous insects in
which prolegs are present, have a variable number of these
organs ; some sixteen, as the saw-fly of the willow ( T. lu-
iea L.), and this is the most numerous tribe of them, in-
cluding the modern genera, Cimbcx F., Pterophorus, &c.
Others have fourteen, as that of the cherry ( T. cerasi L.);
and many others with only nine joints to their antennae.
A third class have only twelve, as that of the rose ( T. Ro~
see L.), but this contains but few species. The last class
contains those that have no prolegs at all, but only the six
horny ones appended to the trunk. Of this tribe, the
caterpillars of which have a very different aspect from
the preceding, are those of the genus Lijda F. ( T. crij-

STATES OF INSECTS. 14-1

throccphala L.) \ Two of the prologs are anal, and tlie
rest intermediate, and none are furnislied with claws.
This circumstance, in conjunction with the greater num-
ber of prologs, except in the case of I^yda, will always
serve as a niark to distinguish these fausses chenilles., as
the French call the larvie of saw-flies, from true caterpil-
lars. Tlie dorsal prologs of a species of Cynips described
by lleaumiu" have been before noticed.

Coleoptcra. — The larvaa of insects of this order are so
little known or attended to, that no very accurate gene-
ralization of them in this respect is practicable. Many of
them, in addition to their six horny legs, have a proleg
at the anus ; which in many cases appears to be the last
segment of the abdomen, forming an obtuse angle with
the remainder of it, so as to support that pait of the body,
and prevent it from trailing; and in some instances, as
in Chrysomela Popidi, a common beetle, secreting a slimy
matter to fix itself*. In the larvae of Staphylinida; this
proleg is very long and cylindrical ; in that of Cicin-
dela it is shorter, and in shape a truncated cone rather
compressed ; it is very short, also, in those of the SilpJus
that I have seen. In the wire-worm [Elater Segetum) it
is a minute retractile tubercle, ])laced in a nearly semi-
circular space, shut in by the last dorsal segment, which
becomes also ventral at the anus. This space is in fact

* De Gecr ii. /. xl.y. 15, IG. Bergman has added to these four
classes of the larvae of saw-flies, a fifth; the msects belonging to
which, he affirms, thongh they have sixteen prolegs, are without the
anal pair. Ibid. 9.31. But as neither De Geer nor Reaumur ever met
with one of this description, it is probable he was mistaken. Reaumur
thought he had seen one with eighteen prolegs upon Eri/simum ciUi-
aria (v. 91), but he docs not speak positively.

'' De Gecr v. 28!S.

142 STATES or INSECTS.

tlie last ventral segment. This seems characteristic of
the genus '. From the underside of the body of the
common meal-worm ( Tenebrio Molitor), at the junction
of the two last segments, when the animal walks, there
issues a fleshy part, furnished below with two rather hard,
long, and moveable pediform pieces, which the animal
uses in walking''. In the larva of another beetle, whose
ravages have been before noticed, under the name of the
cadelle'^ [Trogosita mauritanica), a pair of prolegs are
said to be found under the anal segment ; and in that of
the bloody-nose beetle ( Timarcha tcnehricosa), that seg-
ment is bifid. That of llie weevil of the common water-
hemlock (Lixus jjciraplecticus F.) exhibits a singular ano-
maly: prolegs occupy the usual station of the true legs,
being attached to the three segments representing the
trunk ^. This insect, however, does not appear to use
them in moving. A pair in each of the tv/elve segments
of the body are found in the grub of another weevil
{Hi/pera Rianicis Germ.), the nine last pair being the
shortest, which all assist the insect in walking ^. But the
greatest number of prolegs is to be found in the Brazil
subcortical larva lately mentioned. Besides the six horny
legs of the trunk, this remarlcable animal has four pro-
les's on each of the seven intermediate abdominal sea;-
ments, and five on each side of the base of the last,
making the whole number of prolegs, if so they may
be called, amount to forty-four: a iar greater number
than is to be found in any larva at present known. When
I wrote to you upon the motions of insects, I informed

» DeGeer iv. 157. '' I1>h1- v. .%. f.ri.f. 11.

*•■ See above, Vot.. I. p. 171. '' De Goer v. 228.

* Ibid. 233.

STATES OF INSECTS. 143

you tliat some larvae moved by means of legs upon their
back *, but I was not then aware that any w^ere furnished
with them both on the back and the belly at the same
time. By the kindness of Mr. Joseph Sparshall of Nor-
wich, a very ardent and indefatigable entomologist, I am
in possession of the larva of Rhagiumfasciatum^ a timber-
feedinji: beetle. This animal on the ten intermediate sesr-
ments of the underside of the body, which in the centre
form a fleshy protuberance, has on it a double series of
rasps, as it were, consisting each of two rows of oblique
oblong prominences ; and on the seven intermediate dor-
sal segments there are also in the centre seven rasps of
three or four rows each, of similar prominences : so that
this animal at the same time can push itself along both by
dorsal and ventral prolegs. It is worthy of observation,
that a pair of these rasps is between the second and third
pair of true legs.

Diptera. — The larva of a little gnat, Tijmla steiTorU'
ria De Geer^ (C///>owo/;K«Meig.?), drags itself along by
the assistance of a smgle tubercle, placed on the under-
side of the first segment of the body, which the animal
has the power of lengthening or contracting <^. That of
another beautiful Chironomus {C. j)lumosus\ remarkable
for the feathered antennce of the male '*, has tiw short
prolegs, or pediform but not retractile tentacula in the
same situation '^. Others, as that of Tanypus maculattis,

>» See above, Vol, II. p. 281. »> De Gear ^-i. 388.

•^ Ibid. 389. «• Rcauni. v. t. v./. 10.

* Ibid. 31. This larva has also a pair of pediform processes at the
anus, surrounded at the end with claws {t. v. /'. 4, 5, s s), which he
saw the animal use in locomotion ; but which he suspects to be re-
spiratory organs (Ibid. 33), wliicii Lntrcille asserts the\' are. Gen.
Crust, ft Ills, iv 249.

l^^ STATES OF INSFXTS.

&c. have t-joo pairs, one attached to the anal and the
other to the first segment ^. Tipula amphibia De Geer
in this state has te7i prolegs, placed by pairs on the fourth,
fifth, eighth, ninth, and tenth dorsal segments^; and
Scceva Pyrastri F., one of the aphidivorous flies, has not
fewer iho.nforty-i'wo, arranged in a sextuple series, seven
in each row •=.

It may not be useless to close this long description of
the legs of larvae with a tabular view of them, founded
chiefly upon these organs; which afford very obvious
marks of distinction.

I. Larvae without legs.

i. With a corneous head of determinate shape (co-
leopterous and hymenopterous apods — Culicida,
some TipididoJ, &c. amongst the Dipt era).

ii. With a membranaceous heatl of indeterminate
shape [Muscida, Syrphidce^ and otlier Dip)te)-a).

II. Larvse with legs.

i. With legs only, and with or without an anal pro-
leg {Neuroptera, and many Coleoptera).

1. Joints short and conical [Elatei', Ceramh/ci-
dce^ &c.).

2. Joints long and subfiliform [Sfaphylinus,
Coccinella, Cicindela, &c.).

ii. Prolegs only (many Tipididce, and some subcu-
taneous Lepidopterous larvae, &c).

iii. Both legs and prolegs [Lepidop)tcra, Tenthredi-
7iida, and some Coleoptera).

1. Without claws [Tenthredinida, &c.).

2. With claws {Lepidopfera, Sec).

» De Geer Ibid. U xxw.f. 15—17. " Ibid. 383.

•^ Ibid. 111. /. vi./. 14— IG.

STATES OF INSECTS. 14l6

I should next say something upon the spiracles, or
breathing-pores, or any other external apparatus for the
purpose of respiration^ in larvae; but I think it will be
best to reserve the consideration of these for a subsequent
Letter. We will therefore conclude this detailed de-
scription of their parts in their first state, with some ac-
count of their other

iii. Appendages. The generality of larva) have no othei*
external organs than those already described ; but in se-
veral of them we observe various kinds of retractile ones
and others — protuberances — horn-like processes — rays,
&c. ; which, though not properly coming either under
any of the above parts^ or under the clothing of these
animals, yet require to be noticed. Upon these I shall
now enlarge a little.

You must have observed upon the back of the last seg-
ment but one of the caterpillar of the silk-worm a horn-
like process, rising at first nearly perpendicularly, and
then bending forward. A similar horn, though confined
in the genus Bomhijx to the silk-worm and a few others,
if we may believe Madame Merian, who, however, often
makes great mistakes, is found in the beautiful caterpillar
of one of the largest and finest moths that we know
[Erebus Strix^\ the glory of the Noctuidce, and in most
of those of the hawk-moths [Sphinx F.) \_S. Porcellus, Vi"
lis, and a few others excepted; in some of which, as
S. Lahrusca;, &c., this anal horn is replaced by a gibbo-
sity, and in others, as S. QLnothenc, by a callous eye-like
plate ^] in the same situation, but much longer '^, and

» Merian Ins. Sur. t. xx. '' Ibid. t. xxxiv.

•= I have a caterpillar, 1 believe from Georgia, in which this horn
is nearly an inch lonj;, filiform, slender, and tortuous.
VOL. Ill, L

14-6 STATES or INSECTS.

commonly curving backwards over the taiP. Some-
times, however, as in S. ocellata and S. Stellatarum, it is
perfectly straight. These organs towards the apex are
horny, and often end in a sharp point; nearer the base
they are fleshy. They are without any true joint ^, yet
the insect can elevate or depress them at pleasure. Un-
der a lens, they usually appear covered with spinous emi-
nences, arranged like scales. The use of these horns is
quite unknown : Goedart fancies that they secrete a po-
tent poison, and are intended as instruments of defence;
but both suppositions are altogether unfounded. It has
been remarked, that the body of those caterpillars which
have these horns, is firmer, and yields less to the touch
than that of those which have no such appendages '^. The
larva of a small timber-devouring beetle {Lymexylon der-
mestoides F.) has, like the above caterpillars, a long horn,
and in the same situation : it has also a singular protu-
berance on the first segment ^. Upon some other cater-
pillars, as in Bombyx Siigina F., a singular pair of horn-like
appendages arises from the back of the second segment of
the body, excluding the head. In a tawny-coloured one
from Georgia, with a transverse row of short black spines
on each segment, these horns are half an inch long,
black, covered with spinous eminences, rather thickest at
the base, and terminate in a little knob. They appear to
articulate with the body at the lower extremity. I have
another species, black, with narrow longitudinal yellow

» Plate XVIII. Fig. 12. c.

^ That of Sphinx latrophcR L. appears to be jointed, at least it is
moniliform. Merian Surinam, t. xxxviii. Compare also /. iii.
N. Diet. d'Hisi. Nat. vi. 252.
•^ Schellenberg Entomolog. Bei/tr. t. 1.

STATES OF INSECTS. 147

Stripes, in which these horns are of equal thickness at
base and apex, but with the same terminal knob. Da-
nais Archippus has a pair of tentacula at the head, and
another pair, but shorter, at the tail ; and D. Gylippiis
has, besides these, two in the middle of the body ^.

We are equally ignorant of the use of the upright horn
found upon the back of the fourth segment in the larva of
some \\\o\hs{Noctua Psi, and t}-idens F.) which is of a con-
struction quite different from that of those last described.
It is cylindrical, slightly thinner at the apex, which is
obtuse, fleshy, incapable of motion, of a black colour, and
about two lines long. On the same segment, also, in the
case-worms ( Trichoptera K.) are three fleshy conical emi--
nences, which the animal can inflate or depress, so that
they sometimes totally disappear, and then in an instant
swell out again. When retracted, they form a tunnel-
shaped cavity, varying in depth ^. Reaumur conjectured
that these eminences were connected with respiration,
and one circumstance seems in favour of this conjecture,
that this segment has not the respiratory threads observ-
able in the subsequent ones. Latreille mentions certain
fleshy naked emmences placed upon the ninth and tenth
segments of some hairy caterpillars, which, like those just
mentioned, the animal can elevate more or less. They
are often little cones ; but when it would shorten them,
the summit is drawn in, and a tunnel appears where be-
fore there was a pyramid '^.

In a former Letter I gave you a short account of the

^ Smith's Abbott\f Insects of Georgia, t. xiii.
*• De Geer ii. 507. t. xi./. 16. m v. t. xiv./. 7-
•^ a; Diet. (VHist. Nat. vi, 25fi.
L 2

148 STATES OF INSECTS.

remarkable Y-shaped, as it should seem, scent-organs
{Osmatei'ia) of the beautiful caterpillar of the swallow-
tailed butterfly [Papilio Machaon L.), and others of the
Equites ^ ,- I will now speak of them more fully. That
found in the former is situated at the anterior margin at
the back of the first segment, close to the head, from
which at first view it seems to proceed. At the bottom
it is simple, but divides towards the middle, like the let-
ter Y, into two forks, of a fleshy substance ^, which it can
lengthen, as a snail does its horns, to five times their or-
dinary extent, or retract them within the stalk, so as wholly
to conceal them. Sometimes it protrudes one fork, keep-
ing the other retracted ; and often withdraws the whole
apparatus for hours together under the skin, and its
place is only marked by two tawny-coloured dots, so that
an ordinary spectator would not suspect the existence of
such an instrument "=. Unfortunately this larva is rare
in this country, so that I can scarcely flatter you with the
hope of seeing this curious organ in a living specimen ^,
unless you choose to import a parcel of its eggs from the
south of Europe, where it is common. This you will
think rather a wild proposition ; but why should not En-
tomologists import the eggs of rare insects, as well as bo-
tanists the seeds of rare plants? But if you will be satis-
fied with the dissection of a dead specimen, I have seve-

* See above. Vol. II. p. 244 — .

•> Plate XIX. Fig. 1. a.

" Reaum. i. /. xxx./. 2. N. Diet. (THist. Nat. xxiv. 490, 497—.

^ Ray says he found it feeding on common fennel, about Middle-
ton in Yorkshire : Lett. 69. The indefatigable Mr. Dale recently
found many in the neighbourhood of Whittlesea-mere, feeding on
Selimim palustre. It will also eat the wild carrot.

STATES OV INSECTS. 149

ral, done by the inj^enious Mr. Abbott of Georgia, in
which this part is well exhibited ^.

Another small caterpillar, as it should seem, of a geo-
meter, prepared by the same gentleman, exhibits a pair
of similar horns on the fifth and sixth segments : in these
the common base from which the fork proceeds is very
short and wide, and each branch grows gradually more
slender from the base to the apex, where it is involute.
Whether these are retractile, or whether they correspond
with those of P. Machaon in their nature and use, cannot
be ascertained from a dead specimen : as they belong to a
larva of a quite different tribe of Lepidoptera, the proba-
bility is, that they essentially differ. Two globose re-
tractile vesicles issue from the ninth and tenth segments
of those of Arctia ch-yson-hea^ &c. ''

A great number of Lepidopterous larvae, particularly
those which are smooth and of a moderate size, have be-
tween the under-lip and fore-legs a slender transverse open-
ing, containing a teat-like protuberance of the same con-
struction as the furcate horn of the caterpillar of the beau-
tiful Yao\xr\Xa\n-h\xtteY^y i Parnassiiis Apollo ; and, like that,
can either be wholly retracted and concealed, or by pres-
sure be extended to the length of one of the legs. In some
larvse this part is of a subhemispherical figure, generally
single, but sometimes double. It is commonly, however,
more slender and conical ; and when of this shape, it is
sometimes quadruple '^. The use of this part is not very
clearly known : some have supposed it to be a second
spinneret, and to be of use in fabricating the cocoon; but

» This gentleman was remarkable for the admirable manner in
which he prepared caterpillars, so as scarcely to differ from life,
'' Reaum. i. 92. « Bonnet ii. 84-^-. iii, 1.

150 STATES OF INSECTS.

it is more probable that it secretes some other kind of
fluid, and is connected with defence.

The singular organ in a similar situation, evidently
for that purpose, with which the puss-moth endeavours
to annoy its assailants, has been described in a former
Letter, to which I refer you *. Bonnet, who was the first
that discovered this organ, ascertained that it might be
cut off without injury to either larva or imago. He also
remarked in a caterpillar found in the v/ild succory {Ci-
choriuvi Intyhus) another short, black, needle-shaped or-
gan between the conical part just described and the un-
der-lip ^. De Geer mentions a remarkable fleshy horn-
like style, which issues from the lower side of the first
segment, between the head and the legs of the case-worms
{Trichoptera) : he does not describe it as retractile, or it
might be regarded as analogous to those of LepidojJtcra
similarly situated, that I have just noticed ^. In that of
the emperor-moth {Saturnia Pavo7iia\ there are perfo-
rated tubercles, which when the animal is molested spirt
forth a transparent fluid'*.

The horn-like appendage of the puss-moth [Centra Vi'
nula) is situated at the tail of the insect, and is composed
of two distinct cylindrical diverging branches, each about
four lines long, not united at the base. Each of these is
hollow, and includes a smaller cylindrical piece, which
can be protruded at pleasure, and withdrawn again, as a
pencil within its case ; or, rather, as the horns of a snail.
The two outer horns are tolerably firm, moveable at their
base, and beset with black spines ; the interior tentacula
are fleshy, moveable in every direction, and in full-grown

* See above. Vol. II. 251—. >> Bonnet ii. 88.

<^ De Geer ii. 507. t- xi./. 16. c. -< Rds. iv. 162.

STATES OF IM SECTS. 151

larvae of a rose colour. The animal seldom protrudes
them, unless in some way disturbed ; and frequently it
approximates the two outer cases so closely that they re-
semble a single horn. It appears to use these inner horns,
when protruded, as a kind of whip to drive away the
flies, especially the Ichneumons, that alight upon its body.
When touched in any place, it will unsheath one of them,
and sometimes both, and with them strike the place where
it is incommoded ^. A similar organ is found in some
other BombycidiC, as B. Tau and Furcula F. Reaumur
mentions a caterpillar that to this kind of tail added the
resemblance of two ears, or two cylindrical bodies, ter-
minating in a point, which emerged from the first segment
behind the head ^. In another observed by the same au-
thor, the legs were replaced by a single horn, but which
did not appear to send forth an internal one : from the
back of its fourth segment also emerged a single conical
or pyramidal fleshy eminence or cleft, terminating in two
points *^. Some of the tropical butterflies also, as may be
seen in the figures of Madame Merian, have two diver-
ging anal horns instead of anal prolegs ; but it does not
appear that they incase tentacula'*. Wherever these
caudal horns are found, the above prolegs are wanting ^.

» De Geer i. 322—. See Plate XIX. Fig. % a a.

*' Reaum. ii. 275. t. xxii./. 3.

' Ibid. 276. t. xxii./. 4, 5.

"^ Ins. Surinam, t. vii. Nymphalis Amphinome xxiii. Morpho Teu-
cer t. xxxii. Papilio Cassice.

" This is not, however, universally the case, for the caterpillar of a
Geometer described by Reaumur (ii. 363. t. xxix./. 8.) (C. amatoria)
has a pair of fleshy anal horns, terminating, it should seem from his
figure, in a minute hook that the animal uses as a forceps; which has
at the same time the anal legs, of which indeed these horns seem to
be appendages.

152 STATES OF INSECTS.

Two conical anal horns also distinguish the caterpillar
of one of the moths called Prominents^ Notodonta ca-
melinu; but these are not terminal, but on the back of
the last segment but one *. In that of another Bri-
tish moth, N. ziczac F., there are three dorsal promi-
nences, one near the anus, and two more in the middle ''.
Some Geometers (G. fullginosa, &c.) have two erect
horns on the eleventh segment, and others (G. syringaria,
&c.) two recurved ones on the eighth *=. I must not here
omit to mention the curious hooks emerging from two tu-
bercles on the back of the eighth segment of the ferocious
larva of that beautiful tiger-beetle, the Cicindela campe-
stris L., not uncommon on warm sunny banks. This ani-
mal with incessant labour, as we are informed by M. Des-
marets, digs a cylindrical burrow, to the enormous depth,
the size of the animal considered, of eighteen inches. To
effect this, it carries out small masses of earth upon its large
concave head; and having often occasion to rest in ascend-
ing this height, by means of these hooks "^ it fixes itself
to the sides of its burrow, and, having finally arrived at its
mouth, casts off its burthen. When these insects lie in
wait for their prey, their head, probably in conjunction
with the first segment of the body, accurately stops the
mouth of the burrow, so as to form an exact level with
the surrounding soil ; and thus careless insects, walking
over it without perceiving the snare, are seized in a mo-
jnent and devoured •=.

Another kind of appendage, which is found in 5ome

* Sepp. iv. t. \.f. 6 — 8.

•> Plate XIX. Fig. 5. a b. Sepp. iv. t. xii./. 4—7.
•= Ros. iii. 69. •» Plate XVII. Fig. 13. v.

* .V. Diet. (CHist. Nat. vii. 93,

STATES OF INSFXTS. 153

larvjr, is the organ employed by them to carry the excre-
ment; with which, instead of letting it full to the ground,
they form a kind of umbrella to shelter and probably con-
ceal them. All the tortoise-beetles (Cassida L.) have in-
struments for this purpose, as well as an Indian genus
{Imatidium Latr.) very nearly related to them. This in-
strument is a kind of fork, half as long as the body, con-
sisting of two branches, growing gradually smaller from
the base to the summit, where they terminate in a very
fine point, of a substance rather horny, and attached to
the body near the anal orifice. They are armed on the
outside with short spines, from the base for about a third
of their length. When this fork, as it usually is, is laid
parallel to the back, with its points towards the head, the
anal aperture points the same way. When the animal
walks, the fork points the other way, and is in the same
line with the body, and the anus assumes a prone posi-
tion *.

The larvae of a genus of flies {Vohtcclla GeoJfFr.) re-
markable for inhabiting the nests of humble bees, are di-
stinguished on their upper side by six long, diverging,
pointed, membranous radii ; placed in a semicircle round
the anus ^: what the particular use of these organs may
be, has not been conjectured. Another in my collection
has only four upper radii, but below the anus are two
fleshy filiform tentacula. One of a Tipulidan described
by Reaumur, has also four upper teeth ; but instead of
two subanal tentacula, has six '^. The singular larva of
another of this tribe {Chironomus plumosiis) has on the

» De Geer v, 170— /. v./. 19—23. Compare Reaiim. Hi. 235—.
" Plate XIX. Fig. 11. ff. De Gecr vi. 137. Reauin. iv. 482.
•^ Reaiini. iv. t. xiv./. 9, 10.

154- STATES OF INSECTS.

two last segments four long, fleshy, filiform, flexible ten-
tacula, often interlaced with each other ; which, accord-
ing to the same illustrious author, are used by the ani-
mal to fix its caudal extremity, like the geometers, that the
other end may be at liberty. Besides these organs round
the anus, it has also four other oval ones, of uncertain
use : not to mention the two prolegs, which M. Latreille
thinks are air-tubes *. Jointed anal organs are observ-
able in other larvae : those in that of a saw-fly described
by De Geer {Lyda F.) consist of three joints''; in that
of Hister cadavemius, a carnivorous beetle, of two'=.
The larva as well as the pupa and imago of Ephemera
is furnished with three long diverging multiarticulate
tails, which are probably useful as a kind of rudder to
assist and direct their motions. That of the smaller
dragon flies [Agrioii F.) is furnished with three long ver-
tical laminae, by moving which, as fish do their tails,
from side to side, the animal makes its way in the water '*.
That singular one, also, with a hooked head, figured by
Reaumur, has a single swimming lamina, or fin, shaped
like a fan, and placed in a vertical position under the
tail^

The whole circumference of the body in some coleopte-
rous larvae, — for instance, in that of the tortoise-beetle
lately mentioned, — is surrounded with appendages like
rays. These are sometimes simple, rough with very
short spinous points ^ ; but I have a dipterous larva, in

a Reaum. v. 32. t. \,f. 3—5. Latr. Gen. Crust, et Ins. iv. 249.

•• De Geer ii. 1031. t. xl./. 13, 14. kk.

<: N. Diet. d'Hist. Nat. x. 430.

•< De Geer ii. 697- 1. xxi./. A,5.bb b.

*= Reaum. v. t. v'l.f. 7. n.

' Platk XVIII. Fig. 2.

KTATES OF INSECTS. 155

whicli these radii themselves are beautifully pinnated by
a fringe of longish spines on each side. Reaumur has de-
scribed the grub of a beetle, the genus of which is uncer-
tain, and which feeds upon the larva of Alci/rodcs Prole-
tclla, whose body is margined on each side by eight tri-
angular fleshy mammular processes, terminating each in
a bristle, which give it a remarkable aspect *. The cu-
rious scent-organs with which the larva of Chrysomela
Popnli is fringed have been before fully described ; and
therefore I shall only mention them here ''.

In the larvae of the lace- winged flies [Hcmerobius\ and
ant-lions {Mi/r?neleoti), the anus is furnished with a small
fleshy retractile cylinder, from which proceeds the silken
thread that forms the cocoon inclosing the pupa ^. Pro-
vidence has many different ways of performing the same
operation. From the structure of the oral organs of
these animals, the silk could not conveniently be fur-
nished by the mouth ; the Allwise Creator has therefore
instructed and fitted them to render it by a spinneret at
the other extremity of the body.

The respiratory anal appendages of many Dipterous
larva? will be fully described in a subsequent Letter : I
shall therefore now only further observe upon this subject,
that although there is seldom any alteration in the form of
these appendages &c. in the same species, the caterpil-
lars of two moths {Centra Vinula and Attacm Tau\ how-
ever, are exceptions. The former, when young, has two
hairy projecting ear-like protuberances, which it entirely
loses, as I have myself observed, before it assumes the
pupa; and the latter, in like manner, after its third

* Reauni. ii./. xxv./. 20.

^ See above. Vol. II. p. 245 — .

•^ Reaum. iii. 384, vi. 366. t. xxxii./. 7, 8.

1^6 STATES OF INSECTS.

change of skin, is deprived of its bent thorn-like points
which attend it when young*. It is remarkable that
these last larvae, when just excluded from the egg, are
also entirely destitute of these appendages; they soon,
however, appear, from slight elevations which mark their
situation, and rapidly acquire their usual form''. Changes
of a similar kind, hitherto unobserved, may probably
take place in other species.

iii. Figure. I am next to consider the general figure or
shape of larvae. All of them, with but few exceptions ^,
agree in having a body more or less constricted at inter-
vals into a series of rings or segmeiits ,- usually in num-
ber, twelve ; often nearly equal in length, but sometimes
in this respect very dissimilar ^. The general outline or
shape of the body is extremely various : most frequently
it approaches to cylindrical, as in most of the caterpillars
of Lepidoptera, and of the Hymenopterous tribe of saw-
flies (Tenthredo L.). The next most common figure is
that more or less oblong or oval one, sometimes ap-
proaching to conical, found in many of the larvae usually
called grubs; such as those of the weevil {Curadio L.) and

» Ros. iii. t. Ixviii./. 1. Meinecken Xaturf.vi. 120.

b Ibid. xiii. 175.

•= In the larva of Tenthredo Cerasi L., and some others, no traces
of segments are to be seen ; and in many coleopterous and dipterous
ones the folds of the skin prevent the segments from being distinctly
perceptible.

^ Reaum. ii. 361 . In the larva of a small common moth often met
within \vo\.\se9,{Aglossa jnnguinalis), every segment is divided into two
parts, and underneath has two deep folds, by means of which these two
parts can separate to a certain point, or approach again, according to
circumstances. Thus Providence has enabled them to prevent their
spiracles from being stopped by the greasy substances on which they
©ften ic&<\. N. Did. d'Hist. Nal. I 208.

STATES OF INSECTS. 157

ol' the Capricorn [Cerambyx L.), and other coleopterous
tribes ; of bees, and all Hymenopterous insects but the
saw-flies ; and also of a lar<re number of flies [Dipiera).
In some the figure approaches to fusiform, as in most of
the moths of the Fabrician genus Lithosia. In others,
as in those of the water-beetles {Dytiscus, &c.), it ap-
proaches to an obovate shape, being widest towards the
head, and terminating in a point at the anus. In others,
again, it is linear ; an example of which is that oiS/ap/ijj-
liniLs. Some are convex, and others gibbous, above, and
flat underneath ; as thost of Silpha, C/i)'i/so7nela and many
other beetles. Others are flat, both above and below,
and depressed like a leaf; a remarkable instance of which
has been before noticed *. I^'ome are very long, as those
of most Lepidoptera ; others very short, as that of the
ant-lion {Myrmeleoii). Many other peculiarities of form
in individuals might be instanced ; but a dry enumera-
tion of these would be of no great use to you. They can
only be advantageously leazned by the study of good
figures, and by watching the actual metamorphosis of the
singularly-formed larvae that you meet with.

Instead, therefore, of any further specification of indi-
vidual forms, I shall now endeavour to give you, as far
as my own knowledge of them and the information I can
collect from other sources will enable me, a larger and
more general view of the kinds of larvae ; for analytical
inquiries lose half their value and importance unless we
proceed to apply them synthetically, by forming, if pos-
sible, into groups the objects with which we are indivi-
dually acquainted.

Partial attempts at a synthetical arrangement with re-
* See above, p, 110.

15$ STATES OF INSECTS.

gard to the larvae of Lepidoptei-a and the saw-flies ( Ten-
thredo L.) have been made both by Reaumur and De
Geer. M. Latreille also has recently given a Tableau
metJwdique et general of articulated animals furnished
with jointed legs, considered in their first state *. The
former of these is chiefly founded upon the number of
the prolegs, and the latter upon the metamorphosis, pro-
legs, habits, head, and parts of the mouth, without any
other notice of the configuration. Mr. Wm. MacLeay,
who, though young in years, is old in science and critical
acumen, has started a perfectly new hypothesis upon this
subject. In the progress of his inquiries into the natural
arrangement of animals, particularly of insects in the
JLinnean sense, he has been the first to observe, that the
relation which organized objects bear to each other is of
two kinds ; one of real affinity^ and the other only of ana-
logy, or resemblance. This important distinction, upon
which I shall enlarge in a future Letter, when I come to
treat of Systems of Entomology, he has applied, in a way
quite original, to larvae in general, but more particularly
to those of the Coleoptera order. For the basis of his
system he assumes a relation of analogy between the
larva of Insects that in the progress of their metamor-
phosis assume wings, and those that do not, which form
his class Ametahola, so that the prototypes of the former
shall be found amongst the latter''. But though Mr.
MacLeay appears to consider the analogy between these
two as primary, he extends it in a secondary sense to the
Crustacea, at least in several instances '^. Upon this oc-

" N. Diet. d'Hist. Nat. xvii. 329.

" Hor. Enlomolog. 285. 397—. 422. 462—. Sec.

" Ibid. 399—401.

STATES OF INSECTS. 159

casiou lie very judiciously remarks, that " in terming
hirvae Chilogiiathiformes or Chilopodiformes^ it is not
meant that they are Scolopendrte or luli, or even near to
them in affinity ; but only that they are so constructed
that certain analogical circumstances attending them
strongly remind us of these Ametabola^.^' This remark
you will bear in mind while I am treating of this subject.
It should seem from another part of the same paragraph,
that the comparison which our learned Physiologist re-
commends, is between the yoimg of the Ametahola and
the larvae of the corresponding groups of Coleoptcra.
This must be understood to refer chiefly to the young of
the Chilopoda and Chilogiiatha, since they approach
nearer to them in that state, having then only six legs ;
but the rest of the Ametahola should certainly be brought
to this comparison in their adult state : and even the two
former orders in that state more strongly resemble nume-
rous coleopterous larvae, than when they are young and
much shorter. I before called your attention to the re-
markable circumstance that contrasts very many larvae
of Hexapod insects tliat become winged in their perfect
state with adult Myriapoda : namely, that in one the pro-
gress to this state is by losing their prolegs and shorten-
ing their body; while in the other, the reverse of this
takes place, numerous prolegs and additional segments
being gained before they arrive at maturity''. As the
multiplication of organs is a sign of imperfection, it may
be affirmed of the former of these tribes, that their pro-
gress is towards greater perfection ; while that of the
other may be called a degradation. As larvae may be
regarded as a stepping-stone by which approach is made

•' Hor. Entomolng. 433. ^ See above, p. 23;

160 STATES OF INSECTS.

from the apterous to the winged tribes of Insects, it seems
most consistent with general analogy that each should
connect with the other in that state in which the resem-
blance is greatest. Now the Myriapoda resemble larvae,
as we have just seen, most when in their adult state ;
therefore the comparison should be between larvae and
adult Myriapoda.

Mr. MacLeay divides coleopterous larvae into five tribes
thus characterized : —

1 . A car?iivo)'Ous hexapod larva^ with an elongate linear
Jlattened body^ having a large head armed isoith two sharp
falciform mandibles, andfo,rnished with six gramdar eyes

on each side. This kind he denominates Chilopodiform,
as having for its type in the Ametabola, Scoloj)endra L.
The examples he gives are Carabus and Dytiscus.

2. A herbivorous hexapod larva, with a long and al-
most cylindrical body, so fashioned that the posterior ex-
tremity being curved under the breast, the animal when at
rest necessarily lies like an luLUS on its side. This tribe
he denominates Chilognathifcnm, from hdus L. His ex-
amples are, the larvae of Petalocermis insects, as Scara-
bceus L., Lucanus L. &c.

3. An apod larva, having scarcely the rudiments of an-
tennce, but which is famished instead of fact with fat Jleshy
tubercles ; which, when continued along the back and belly,
give the animal a facility of jnovitig in whatever way it
may be placed. These he denominates Vermiform., from
certain of the Vermes intestina and Mollusca of Linne
which he has associated with Ill's Annulosa ^. His exam-
ples are, Curctdio L. and Cerambyx L.

4. A hexapod and distinctly antenniferous larva, with a

" The Inteitinaux cavUaires of Cuvier, and the Ephoarin of La-
marck. See Hor. Entomohs. 286 — .

STATES OF INSECTS. 161

subovate rather conical body, of isohich the second segment
is longer and of a different form from the others, so as to
gii'e the appearance of a thorax. His (lenoniiiiation for
these is Anopluriform, from Pediculus L., forming Dr.
Leacli's Anoplura. His examples are, Coccinella and
Chrysomela L.

5. A hcxapod antenniferous larva of an oblong form,
having like the former vestiges of a tharaxy besides two or
more articulated or inarticulated setaceous or cor?ieous ap^
pcndages to the last segment of the abdomen. This tribe
he calls Thijsanuriform, from Lepisma and Podura L.,
forming M. Latreille's order Thysanura. His example
is Meloc with a note of interrogation ^.

The system iiere stated, of naming and characterizing
larv« from the resemblance and analog}', in many cases
very striking, that they bear to the apterous tribes, is a
very happy and original one, and does its author great
credit; yet I think in some instances, as I shall soon
have occasion to point out to you, the application of it is
not so happy as the first idea. But this is always the
case when a new law of nature is discovered ; the proper
application of it is gradually developed, and it does not
at all detract from the merit of the first discoverer, that
all the bearings of such law do not strike him as it were
intuitively.

* Hor. Entomolog. 422. comp. 463. Mr. MacLeay's idea of the
larva of Meloc is taken from the animal which Frisch, Goedart, and
DeGccr imagined to be such; but upon this opinion there rest great
doubts. (See liirby iMon. Ap. Angl. ii. 168, and Latreille -.V. Diet.
(VHist. Kat. XX. lOJ).) At p. 464 he gives also Mordclla and many
Hctcromna as Iiaving Thysanuriform larvae. He thinks, that proba-
bly that of Citrus is of the same description ; to which he suspects
that many of Latreille's Malacodrrma likewise belong.

V(M., III. yi

162

STATES OF INSECTS.

Having, however, got the vantage-ground affoniecl by
this discovery of my fi'iend, let us see if by standing upon
it we cannot get a tolerable generalization of the larvaj
of all orders of insects that undergo a metamorphosis.
But first I must observe, that as in the perfect animals,
so in their larvae, the different groups are connected by
certain transition species, exhibiting characters common
to two or more of them ; and likewise that in many cases,
which you will see as we proceed, the analogy is as strong
or stronger between them and the Crustacea (and in a
few instances Arachnida, and even Molhisca) than the
Ametahola. My denominations, therefore, will be taken
from those tribes where the analogy appears to me the
most striking, and not from the Ametahola alone.

I shall begin by drawing up for j-ou a list of the Pri-
mary forms that I seem to have observed, and their cha-
racters ; and then going through the orders, shall give
you the examples of each, with such observations upon
them as the case may require.

Primary Forms of Larvcr.

APTERA.

Anopluriform.
Thysanuriform.
Chilopodiform,
Chilognathiform.

ARACHNIDA.

Araneidiform.

CRUSTACEA.

isopodiform.

Onisciform.

Idoteiform.

Amphipodiform.

Stomapodiform.

Decapodiform.

Branchiopodiform.

MOLLUSCA.

LiMACIFORM.

ANNELIDA.

Vermiform.

Characters.
1. Anopluriform. Carnivorous; hexapod; antenniferous:
with a shortish oblong depressed body, an<l distinct

STATES or INSECTS. 163

tlioracic shield. Example: Psociis, Coccmella, most
HcmijHcra ".

2. Thi/smiuriform. Polyphagous; liexapod; antenniferous:

body with segments of trunk distinctly marked; anus
often furnished with seta; or mucro. Ex. Meloe^?
Thrips, Aj)//is.

3. Chilopodijhrm. Carnivorous; subhexapod; antennife-

rous : body depressed, elongate, linear, with falcate
acute mandibles, a distinct thoracic shield, and an
anal proleg. Ex. Cicindela '^ i Carahus L.

4. Chilognathiform. Herbivorous : body subcylindrical,

elcngate, linear; no thoracic shield; often many pro-
legs, sometimes a retractile one, and sometimes none.
— Ex. Elater, Pctaloccra, most Lepidoptera^ Ten-
thrcdo L. '^

5. Va'mijhrm. Polj'iihagous ; apod or hexaj^od : with

very short legs; antennie nearly obsolete; body
fleshy, plicate, with sides often plicato-papillose ;

' Pi.ATF. XVIII. Fig. 1. as to the tlioracic shield.

'' Mmf 27, 18.-22. This day, T. Allen, Esq. F.L.S. bronght mc in
a phial a vast niinibcr of the little insect which Goedart, Frisch, and
De Goer took for the larva of Meloc V rosvarabcEus, which he found
on the leaves of Achillea MillcfoUum. These little animals were
coursing each other with wonderful velocity over the sides of the
phial. To assist them in their motions, they ajjplied to the surface
of the glass the end of their abdomen, using it, like many larvae of
Colcoptera, as a seventh leg. This circumstance excited a suspicion
in the minds of both Mr. MacLeay sen., then visiting me, and my-
self, that after ail they might be coleopterous larvae. One, amongst
other circumstances, however, seemed to militate strongly against
this opinion ; namely, that in this infinite number none aj^peared to
differ in size.

<= Plate XVII. Fig. 1.3.

■I Ibid. Fig, 12.; Plate XVIII. Fig. 4, 11, i;?. c^c.
I\l2

I64f STATES OF INSECTS.

no distinct thoracic shield. Ex. Curculio L., Ce-
ramhyx L., Musca L., and many other Diptera *.

6. Araneidifo7-m. Carnivorous ; hexapod : body very

short ; mandibles long, suctorious ; animal lying in
wait for its prey in a pitfall it has prepared; motion
retrogressive. Ex. Myrmeleon L. ^ Cici7idela ?

7. Isopodiform. Saprophagous; hexapod; antenniferous,

with longer antennae : body oblong ; thoracic shield
distinct; anus styliferous or laminiferous. Ex.
Blatta L. Silpha L. ?

8. Omscifo7'm. Herbivorous; polypod; antenniferous:

body short, oblong, depressed, margined. Ex. Ejy-
cina, Lycana, in the Lepidoptera, and some species
of Tenthredo L. *^

9. Idoteiform. Subcortical; hexapod; antennae obso-

lete : body much depressed, with the last segment
elongate, terminating in three or more mucros. Ex.
Larva from Brazil. Perfect insect at present un-
known.
I have placed this larva, which was described above '',
amongst crustaceous forms, because of the remarkable
resemblance which the last segment of the body bears to
that of the Idoteidce ; but I do it with considerable hesi-
tation, since in other respects its type seems to be in the
Ametabola. In its want of antennae, very short legs, and
ventral asperities, it resembles some of the Vermiform
larvae ; in its small head, distinct thoracic shield, and ob-
long shape, it approaches the Anopluriform ,- and in its

» Plate XVIII. Fig. 3, 9. ^ Plate XIX. Fig. 8.

' /iirf.FiG..3. Reauni. v. 97, t. xii./. 17, 18.; De Geer ii. 1004.
t. xxviii./. 12.
" See above, p. 110, 114, 138, 142.

STATES OF INSECTS. 165

very depressed body, but not at all in other respects,
the Chilopodijorm. At any rate, it appears of a primary
Type.

10. Lccmodipodiform. Herbivorous; hexapod; an tenni-

ferous, with long antennas: body elongate, subcylin-
drical ; second segment of the trunk the longest ;
anterior pair of legs distant from the other two. Ex.
Phasma.

11. Amphipodiform. Herbivorous; hexapod; antenni-
ferous, with long antennjE: body shortish, com-
pressed, saltatorious. Ex. Gtyllus L. *

12. Stomapodiform. Carnivorous or saprophagous; hex-

apod; antenniferous, with long antennas: body elon-
gate, subdepressed, with raptorious hands, and ab-
domen wider than the trunk ; in aquatic species fur-
nished with lateral gills. Ex. Mantis, Ephemera ?
Sialis ?

13. Decapodiform. Carnivorous; hexapod; antenniferous:

body elongate, narrow, convex, compressed, taper-
ing towards the tail ; tail with natatorious laminae.
Ex. Dj/tisais L., Agrion F. ^

14-. 3rancliiopodiform. Carnivorous?; aquatic; apod;
antenniferous: head distinct: body transparent, flex-
ile, furnished with a respiratory tube just above the
tail. Ex. Ctdex *=.

1 5. Limaciform. Herbivorous ; apod, or with very short
legs : body ovate or obovate, slimy. Ex. Apoda
Haw., Tenthredo Cerasi L.

Plate XVIII. Fig. 7- '' Plate XVIII. Fig. 5.

Plate XIX. Fig. 9.

166 STATES OF INSECTS.

The above are the principal forms that appear to me
Primary (though some doubt may rest upon the ninth
and tenth); and probably others will hereafter be disco-
vered, since at present our knowledge of the larvae of
most of the Orders is very limited. And now having given
you this generalization of them, as far as they are known
to me, I shall next, in a slight survey of those of the dif-
ferent orders, lay before you what I have further to ob-
serve upon this subject.

Coleoptera. The Anopluriform coleopterous larvae, ac-
cording to Mr. W. MacLeay's view of them, include
both those of Coccinella L., Chry&omcla L., and Cas-
sida L. ; but this appears to me to admit of further con-
sideration. With regard to the two former — those of
Coccinella are carnivorous, those of Chrysomela herbi-
vorous ; the first is also usually more flat and depressed.
As to the latter, Cassida =^, it seems to me to belong to a
peculiar type, distinguished not only by its radiated mar-
win, but by the remarkable deflected anal fork on which it
carries its excrement. At present I know no analogous
form amongst the apterous tribes ; I must therefore leave
this without a denomination. Perhaps the larva of Hispa
or Alurnus, when known, will throw light upon this sub-
ject. The larva of Endomychusi agrees with that of Coc-
cinella.

There are very few known larvae that approach to a true
Thysanuriform type in this order: that most celebrated is
the one supposed to belong to Meloc; but the claim of this
to be so considered, is, as we have seen, rather dubious,
Should this point at last be satisfactorily asc-ertained, it

■• Platl XVIII. Fig. 2.

STATES OF INSKCTS. 167

will })robably cany with it the whole tribe of vesicatory
beetles. But even this animal in its general structure is
njioplwijhnn : the only circumstance that gives it any ana-
lo<ry to the Thtjsamira being its anal setae. Mr. William
MacLeay is inclined to regard some of the larvae of the
Malacodcrmi Latr., but which of them he does not state,
as probably belonging to the tribe in question ^. Those of
Lampyris and of Tclcphorus, as described and figured by
De Geer ^\ appear to me intermediate between the Alio-
pluriform and Chilopodiform Types : they have no anal
setiform or styliform appendages, their mandibulae are
falcate, and their habits seem carnivorous.

Examples of Chilopodijhnn coleopterous larvaj are
more numerous. Of this description are those of Gy-
riniiSj Cicindcla, Carabus^ and Staphjlinus. That of the
first, indeed, appears to be the most perfectly Scolopcn-
dr'iform of any yet known; yet the gills or respiratory
laminae, a pair of which issues from each abdominal seg-
ment, and two pair from the last *=, prove that there is
no slight analogy between it, and indeed many other
aquatic larvae, and the Stomajyoda amongst the Crustacea.
A remarkable instance of analogy with the Decapoda of
the same Class is presented by the larva of Dytiscus^ &c.
which Mr. MacLeay considers as Chilopodiform^ but
which exhibits no other resemblance to Scolopendrce than

=* Hor. Entomolog. 4G5. '' De Gecr iv. 66. t. ii./, 5—8.

'■ Iliid. t. xiii. /'. 16 — 19. A very singular larva, which preys ui)on
that of Alei/rodcs prulctclla Latr., if Reaumur's figure be correct (ii.
t. wv.f. 18 — 20), is of a perfect Clulopodifomi type, the abdomi-
nal legs being represented by a tubercle crowned by a bristle : yet
even this, which turns to a minute beetle (Ibid./. 21), has some ten-
dency to the Anoplunfurm ty[)c.

168 STATES Ol- INSECTS.

ill its predaceous habits and threatening aspect. Its
convex, compressed, tapering body, terminating in setae
or laminae, is certainly much more like that of a shrimp
or a prawn ; to which the older Entomologists thought it
was akin ', and after which they named it. As Mr. Mac-
Leay's object was, to take all his forms from the A7neta-
bola, perhaps these larvae will best fall in with his Chilo-
jpodiform type ; though in the general form of their body
they most represent a section [Lepisma L.) of the Thy-
sanura.

Chilognathiform forms are equally numerous in the
Coleoptera with the preceding. The wire-worm, or larva
of JLlater Segetis, as to shape best represents the full-
grown lulus^, and those oi' the Petalocera [Scarabceus L.,
Lucanus L.) the young one.

The most abundant of all forms in this order, is, I
think, the Vermiform, upon which I have nothing further
to remark.

With regard to Crustaceous forms in Coleoptera, be-
sides the Decapodiform just noticed, I possess two speci-
mens of larvae of Silphidce which seem to exhibit a con-
siderable analogy with the Isopodous Crustacea, one rather

" " Squilla insectum a sl{U\\\-a jiisce pariim d'lffcrty Mouffet, 319.

*• A remarkable difference obtains between the larva of the wire-
worm and that of Elater iindidatm. In the former, the last segment
is longer than the preceding one, terminating in a small acute mucro
at the apex, with a deep cavity, perhaps a spiracle, on each side, at
the base. In the latter, this segment is shorter than the preceding
one, forming above a nearly circular plate ; the margin of which is a
little elevated, and armed on each side with three teeth, and at the
apex with a pair of furcate recurved horns, and without any basal
spiracle. De Geer iv. 156. /. v./. 25. I have a similar larva, but not
the same species.

STATIS Ol INSKC'IS. 169

convex ami the other flatter, so as to give the idea of an
Annadillu and of an Oniscus.

Slrcpsiptera. Larva Vermiform.

Dcrmaptera. I^arva Thysanuriform. 'I'ype Pudura or
Sminthurus.

Orthoptcra. Mr. MacLeay considers tlie larvae of this
Order as primarily Thysanuriform *, though he allows
the resemblance between them and Amphipoda to be par-
ticularly striking ''. For my own part, their prototypes ap-
pear tome to be in the Crustacea, m\{[ their analogical re-
lations to the Thysamira nmch more distant. I trust this
will a})pear to you the reverse of dubious in a progress
through the Crustaceous Orders. I begin with the Iso-
jpoda. Take the larva of a Blatta, and place it between
a Lepistna, or Machilis, and an Oniscus, or Pmcellio ;
you will find that in shape and width, and the form of its
anal styles, it resembles the latter much more than it does
the former, with which it possesses scarcely any character
in common, except its nuiltiarticulate antennae. It is re-
markable, that amongst the Blattida; we meet with spe-
cies that represent both the Oniscidce and Armadillo or
Glomeris ^, the latter being more convex than the former.
In their habits the Blattae certainly agree with Lepisma ,-
and Dumeril, who thought the latter and Podura sub-
ject to a metamor{)hosis, imagined they were related ^.

The Spectres of Stoli [PJiasma F.) are so strikingly
analogous to another crustaceous tribe, the Lcemodipoda,
particularly the genus Caprclla, that Montagu gave one
species the Trivial name o^ Phasma^. The jumping Am-

" Hor. Entomolog. 397. ^ Ifnd. 399. '■- Ibid. 438. Note *.

•^ Traitc Element, ii. .35. n. 577 •

" Trans. Linn. Soc. vii. OH. i. \uj'. 3.

170 STATES OF INSECTS.

jiliipodijorm Crustacea are represented extremely well by
Gnjllus L., and the Stomapodifotm, particularly Sqiiilla
Mantis, by Mantis. The resemblance in this last instance
is so very striking, that it cannot escape the eye of the
least intelligent observer. Orthopterous insects may per-
haps one day be discovered analogous to the two other
crustaceous orders, ^e Decapods and Branchiopods ; but
at present I know of none of that description.

Heyniptcra. The larvae of this order, which in general
resemble the perfect insect, except that they have no
wings, seem most commonly to belong to the Anopluri-
form type ^ ; but the Aphides, Chcrmcs, and Thrips may,
I think, be regarded as more analogous to the genera
Podura and S?nint/iurus in the Thysanura ^. I have some
suspicion that the Nepidce, Naucoris, and the remipedes,
Noto7iccta, Sigara, &c. may find their prototypes amongst
the Crustacea ,- but my confined knowledge of the latter
does not enable me to point to any individual genera or
tribes that they may be presumed to represent.

Neuroptera. As the kinds of larvae of the different tribes
composing this order, as it now stands, are very various,
it is to be expected that the analogical forms they repre-
sent are equally so. The Libellulina MacLeay {whose
metamorphosis that gentleman has denominated suh-
semico7nplete, a term warranted by their losing in their
perfect state the mask before described'^) in their oral
organs, particularly by their galeate jna.villa and distinct
ligida '^, have some relation to the Orthoptera, the proto-
types of whose larvae we have found amongst the Cn«>-

" Compare De Geer iii. /. xi./. 3. and t. xvii./. 14. &c.

'^ Ibid. i. If. 4, 9. /. ii./. 15, /. ix./. 4. ' See above, p. 125—.

'' Compare Platk VI. Fig. 6. witli Fig. 12 e, d, d.

STATES OK INSKCTS. 171

lacca : probably, theretore, those ot" tlie Uibc in question
lurk ill that class; a suspicion that receives strong con-
firmation trom the larva of Agrion =>, which in its taper-
ing boch' and anal natatorious lainiiuu represents a shrimp.
The larvaj of that very peculiar and distinct tribe, the Ej^hc-
jnerina, appear to be intermediate between the Sloinapo-
iliform and Tliijsanuriform types. Their natatory respira-
tory abdominal Inmina; seem copied from the former, and
their anal diverging seta? from the latter ''. The Mijrmc-
leonina, as well in their general form as in their motions
and habits, present a most singular analogy with the tribe
of sjMders, as does also in some respect that of Cicindcla,
With regard to Pmiorpa, which Mr. MacLeay remarks
is related to Mtjrmelcoii ^, and is a most ferocious insect '',
as its larva has not yet been discovered, nodiing certain
respecting its analogical form can be asserted; but should
it, like the male fly, represent the scorpion, both orders
of Arachnida v> ill have their representatives in the class
we are considering. The Corijdalina, as far as the larva
of Hcmcrobiiis instructs us, is Cliilujwdiform, but with a
tendency to the Araneidzform Type. The Ametabola
also furnish the prototype of the next tribe, the Termi-
thia, which, as is evident both from Psocns and TermeSy
are perfectly Anoplurijotm. The Sialina, or Plicipenncs.
of Latreille, excluding Trichoptera Kirby, appear to me
to be intermediate between the Chilopodifoiin and Stoma-
podiforni Types, and not without some relation to the
T/iysanuriform. Their pediform, jointed, respiratory ab-
dominal appendages, their head and falcate mandibles,
seem copied from the first tribe. The same appendages

•' Do Gecr ii. /. xxi. /. 4, 5. '• Swiinini. Bihl. Xnt. I. xiii./. 1.
' //();•. Entiimulog. 43^. '' Sec above, Vol. II. p. 25(5.

172 STATES or INSECTS.

considered as organs of respiration, and their taper forks,
are moulded upon the plan of the Stomapodifoi'm Crus-
tacea, and the long seta which terminates the abdomen is
upon the TJiysanuriform plan ^.

Trichoptera. The larvae of this order appear also to
be constructed upon a double plan. The respiratory
threads observable in both the upper and under sides of
the abdomen connect it with the Sioniapoda, and its cy-
lindrical elongate body with Chilognathiform types in the
Lepidoptei'a ^.

Lepidoptera. The great majority of larvae in this or-
der are Chilognathiform, but there are exceptions to this
remai'k. Those of the Geometrce recede from this type,
both in their motions and the distance and number of
their legs. In both these respects they represent the Lae-
modipoda in the Crustacea ^. Other caterpillars are 0)iis-
cifo?'m ; and a third sort seem to leave the Anmdose type,
and imitate that of the Mollusca, and one is figured by
Madame Merian° which appears to tend even to the
Chilopodifo7^m type.

Hymenoptera. In this order the larvae of the saw-flies,
TenthredolL., are in general Chilognathiform, though some
are Onisciform, others Limaciform, and those of Lyda F.
{Cephaleia Jur.) and Sirex^ have a Vermiform tendency,

" De Geer ii. t. xxiii. /. 9 — 14. Comp. Reaum. iv. t. xv.
/. 1,2.

'' De Geer ii. /. xiv./. 7. &c. The caterpillar of P. G. Scratiotata
L. like those of Phryganece, has these respiratory threads. Ibid. i.
t. xxx^di./. 2 — 6. De Geer has described the larva of a Phryganeu L.
which is without any respiratory threads, ii. 569. t. xv.y. 10.

■^ Hor. Entomolog. 401. Montagu in Linn. Trans, vii. 67.

'' Ins. Surinam, t. xxviii. Compare Ibid, t, xix. right-hand figure.

* Plate XVIII. Fjg. 10.

STATES OF INS>F.CT.S. 173

and are a stepping-stone to those of the rest of the order,
which are all I'crmiJ'orm and apods.

Diptera. The majoiity of this order may be set down
as Vermiform, thongh it is not improbable that some of
them bear an analogy to animals that appear far removed
from the Atnudosa. Thus, the larva of Stratyomis Cha-
meleon seems to exhibit no small resemblance to some of
the Polypi vaginati in the Aa-ita subkingdom of Mr. W.
MacLeay ^. That of Culex and some others is con-
structed on a (|uite diflerent type from the rest, and seems
to possess some analogy to the Branchiopod Cmsfacea.

Though some of these analogies are more striking than
others, yet in almost all that I have stated there is that
kind of resemblance that could not be the result of what is
called mere chance; and Mr. MacLeay, by first pointing-
out this plan of tlie All-wise Creator, and by laying down
the doctrine of analogies in general, as distinguished from
affinities in the animal kingdom, has furnislied the be-
liever with a new argument against those attacks of the
infidel, that would render null those proofs of the wasdom
and goodness of the Author of nature with which the ani-
mal and vegetable creation furnish us ; by affirming most
absurdly, and under the most stultifying blindness of
mind, that the orafures w'ere in a manner their own cre-
ators, their wants under local circumstances stimulating
them to efforts that in a long course of years produced
all the different forms and organizations that are now to
be found in our globe. The affinities and close connexion
of beings with each other, so that the ascent from low to
high is usually by the most gentle gradations, is the cir-

» Swanini. Jii/j/. Xnl. t. xxxix. Pi.ATE XIX. Fig. 13.

174 STATES OF INSECTS.

cumstance on which they build this strange and impious
theory. Bat the fact, that certain animals of one tribe
were created with a view to certam animals of another,
so as to present a striking aspect of correspondence, pa-
rallel almost with that of type and antitype, without any
real affinity or approximation; — this triumphantly proves
a Power above and without them, who has associated
them not only in a complex chain of affinities, but has
caused them, to represent and figure each other, even
when evidently far removed, so as to give a mutual cor-
respondence and harmony to the whole, which could be
produced only by a Being infinite in power and wisdom,
who made all things after a general preconceived plan
and system.

iv. We are now to consider the clothing with which
larvae are furnished. Many are quite naked, and smooth
or rough only with granular elevations or tubercles or-
derly arranged; but a very considerable number, espe-
cially of the Lepidoptera order, are clothed with hair or
bristles of different kinds, in greater or less abundance,
and arranged in different modes ; and a proportion still
smaller have their, skin beset with spines or a mixture of
spines and hairs. Lyonnet found that the hairs of the
caterpillar of the great goat-moth [Cossus ligni2:)erda) were
hollow, though not to the apex : probably this is the case
with those of other larvae, as well as with their spines.
In this instance they were set, he observes, in a corneous
ring, or very short cylinder, elevated a little above the
skin. The hair passes through this ring, and appears to
be rooted in a soft integument, which clothes the skin
within, and upon which the nerves form a reticular tissue,

STATI'.S OF INSECTS. 175

some of which he thinks lie has even seen enter the root
oftlie hairs, which perliaps are organs of touch ^.

Of the pilose larva?, some, like most of those of the
smaller moths {Gcomrfra, 7o)in'x, Pijralis, ^c), have
merely a few scattered short hairs, scarcely perceptible ex-
cept through a lens: o{hcv<, {Odnicsis jwluloria, Lasiocam-
2>a Bubi) are covereil with down more or less thick : in
others {Eriogasfcr lanesh-is, Laaiocampa Netistria) the
hair is slenderer, and more like wool; the body of two spe-
cies which I purchased from the collection of Mr. Fran-
cillon is covered with woolly hairs, so long as to give
them the api)earance of a shock-dog; and Madam Merian
has figured a similar one, which she could not bring to the
j)erfect state ^\ The hairs of many B<mhycida\ known
commonly by the name of hairy caterpillars, as Arctia er~
viinea, &c. are stifFer, resembling bristles ; sometimes, as
in Arctia c/nysor/wa, mixed with shorter ones. The
hairs either spring immediately from the skin [Nortua
Aceris, leporina), or, as is more general, proceed only
from certain tubercular elevations, usually subhemisphe-
rical, but sometimes conical ; of which a number varying
from four to twelve are found on each semnent of diffe-
rent species. They seem to issue from these tubercles,
as little diverging streams from the rose of a Avatering-j^ot.
In both cases, they form a coating usually so dense as
to conceal the body, but sometimes more thinly set, and
admitting the skin to be seen more or less between them.
In a caterpillar of the beautiful Arctia ocidaria, the hairs
are set upon tubercles alternately nearer the anterior and
posterior margin of each segment, so as to form a dense

" r.yonnct GO — . '■ Siirbuim, I. Ivii. ridit-Iiand figure.

1 76 STATES OF INSECTS.

band, the rest being naked ; and in the lovely green and
black one of Satmmia Pavonia, each tubercle bears but
six hairs, diverging like a star, the central one being the
longest and capitate, so that the chief part of the body
appears naked. This diverging position of the hairs is
most common in the thick-clothed larvae also, but many
have them placed differently : thus, in those of Callimor-
pha Caja and Arctia xnllica ^ they are all directed towards
the tail, like the quills of a porcupine : in some otheis
the anterior ones point towards the head : in that of
Eriogaster Quercus half of the tuft of hairs of each tu-
bercle is directed downwards, the other half upwards :
in that of At'ctia Salicis all the hairs point downwards,
so that the belly is thickly covered, while the back is
bare. Another variation is, that the hairs of half the
tubercle are sometimes very long, while those of the
other half are very short, and even of a different colour ^.
In the larva of Tussuck moths [Laria pudihunda, fasce-
I'lna^ &c.) the hairs are collected into tufts of a singular
appearance, those on the intermediate segments of the
back being quite level at the top, so as to resemble so
many brushes; while those on the first and last segments
are longer, and composed of feathered hairs converging
to a point at their extremit}'^, like a common camel-hair-
pencil '^. This last mode of arrangement prevails also in
the larva of Noctua Aceris ,- but in this the pencils are
shorter, exactly wedge-shaped, and distinguished by an-
other particularity, that of springing directly from the

* Sepp iv. t. ii.f. 3. t. xvi./, 2, 3.
^ iV. Diet. cVHist. Nat. vl. 254.

'' Plate XIX. Fig. 6. One of these larvse was t;iken at Mel-
ville Island. See Parry's Voyage, Appendix No. x. 37.

STATES Ol INStLCTS. 177

skill, iiiul iu)l I'roin a tuheixlc. This is also the caso with
the large caterpilhirs of Odcucsis j^olatoria, wliich has a
double row of short bundles of black hairs on the back,
intermixed with larger ones: at each end of the body is
a pencil of coiiverging hairs, and the sides are s]>otted
with bundles of wiiile ones, which with longer tawny
ones itfe bent downwartls, so as to cover the sides of the
creature ^. Some have the anterior aigrettes disposed like
tile arms of a cross, of which the body of the caterpillar
is the stem '\ But not only is there considerable variety
in the geneial arrangement of the hairs that clothe our
little larva^, the hairs themselves differ much in their kind
and structure, of which I will now, before I jjroceed to
consider spines, give you some account. Several of them
are feathered like the plumes of a bird : this is the case
with those of Morp/io Idomcnciis, on each segment of the
body of which are three blue tubercles, like so many little
tui quois beads, from each of which proceeds a long black
plume •=. Other hairs terminate in a club; those of the
larva of Nuclna Alni^ a specimen of which I jiossess taken
in England, are flat and incrassated at the apex, some-
thing like the antennae of some Sphingida;. Mad. Merian
has figured the caterpillar of another moth which feeds
upon the Papaw-tree [Caricu Papaya)\\\ih. similar hairs'*.
But the most remarkable larva for the shape of its hairs
is that of Anthrenus Miisceoriim, the little pest of our ca-

" Sepp. iv. i. viii. /. 4. Some species have three, others four,
and others even five of these brushes. i\". Dki. iVHist. Nat. vi.
255.

'■ Ibid. Merian Ertic. xxxiv. upper left hand figure.

' Merian Ins. Suriiiaiii. t. Ix.

•' Ibid. f. xl.

VOL. III. N

178 STATES OF IXSECTi.,

binets, which I noticed in a former letter =*. All the hairs
of its body are rough with minute points ; but those of
six diverging long tufts or aigrettes, laid obliquely on
the anal extremity of the body, which the animal when
alarmed erects as a porcupine does its quills, are of a
most singular structure : every hair is composed of a se-
ries of little conical pieces, placed end to end, the point
of which is directed towards the origin of each hair, which
is terminated at the other exti-emity by a long and large
conical mass, resembling somewhat the head of a pike''.
Besides the one lately mentioned, other caterpillars
are rendered striking by the brilliant colour of the tuber-
cles fi'om which their hairs emeige. A remarkable in-
stance of this is the thick large caterpillar of a Bombyx,
which feeds upon the Psidiiim pyriferiim, or white Guava,
figured by Madame Merian. This caterpillar, which is
white, with transverse black stripes, aiid which has two
angular long converging curved bunches of hairs near
the tail, is splendidly adorned on each side with fifty red
tubercles, shining like coral, from which proceed six or
seven long diverging hairs. Leeuwenhoeck took these
tubercles for eyes ^. Another figured by the same lady,
who mistakes it, with her usual inaccuracy, for the larva
of a Lygaits F., and which seems by her description to
be between the onisciform and limaciform types, has the
apparently fleshy mamillse that project from its sides and
back crowned with little hairy red globes, which give the
animal a most singular and unique appearance ^. Hav-
ing thus described some of the principal modes in which

» See above, Vol. I. p. 238.

" De Geer iv, 207. t. viii./. 4—6.

* Im. Siir. t, xix. right hand caterpillar. '' Ibid. xli.

STATtS Ok INSECTS. 170

the All-wise Creator has decked and defended these
creatures with hairs, I shall next give you a shojt ac-
count of the spi?ics with which he has armed others.
The spinous larva; are prhicipally Icpidopterous, and more
particularly conspicuous in some tribes of the genus Pa-
pilio L., though some saw-flies and Diptoa are also di-
stinguished by them. Vanessa lo ', Atalanta and UrticUy
Argj/nnis Paphia, Urania Lcilus, and many other But-
terflies, &c. arc clothed with long sharp points, which
claim the denomination of spines, rather than that of
hairs or bristles ; being horny and hard, and so stiff at
the point as readily to pierce the skin. Those of the last-
mentioned species, Madame Merian says, are as stiff" as
iron-wire ''. They are sometimes entirely simple, and
look like spikes rather than spines, as in the caterpillar
of Nymphalis Amphinome and Morpho Menelaus '^ ; but
ordinarily they are beset with hairs, or more commonly
with shorter spines, which often give them the appearance
of plumes, as in Urania Leilus]\\simiii\\xoned: sometimes
these lateral spines are so long as to have the appear-
ance of a branch of a tree; this is strikingly the case with
a small caterpillar which Captain Hancock brought from
Brazil ; its body is so thickly planted with spines of this
description, that it absolutely wears the appearance of
a forest or thicket in miniature. A singular circum-
stance attends the spines of this species : in many cases
a smaller and very slender hair-like spine issues from
them, resembling a sting ; and this accounts for an ob-
servation of Abbott's, that many American caterpillars
sting like a nettle, raising little white blisters on the skin

^ Plate XVIll. Fig. 13.

^ Tns. Siir. t. xxix. • Ibid. t. vii. liii.

N 2

180 STATES OF INSECTS.

when accidentally or slightly touched =*. Lewin has de-
scribed the caterpillar of a moth found in New Holland,
which he names Bomhjx vulnerans, that, like these Ame-
ricans, has also the power of wounding, but in a different
way. It darts out, he says, when alarmed by the ap-
proach of any thing, from as many knobs or protube-
rances in its back eight bunches of little stings, with
which it inflicts a very painful and venomous wound ''.
The caterpillar of Papilio Protesilaus F., if Madame Me-
rian's account and figure of it are correct, has its body
armed with hairy spines, the extreme point of which is
surmounted by a star-shaped appendage *=. Those of a
few saw-flies {Tenthredo Priini L.), and another figured
by Reaumur **, are covered with a little forest of spinas
without lateral branches, but divided into a fork at the
apex. Some spines are merely rough, with very short
points, as those round the head, which give so terrific an
appearance to the caterpillar of the Bomhyx regalis^ of
some proceedings of which I gave you an account in one
of my former letters ^.

I must now say something upon the arrangement of
these spines. Though in a few instances so thickly set
as entirely to conceal the bod}' of the animal, as in the
case of the Brazil one lately mentioned, yet generally
speaking, even when they are most numerous, they per-
mit the skin to be distinctly seen. Their arrangement
is various, though always orderly : in the majority they

* Smith's Abbott^s Ins. of Georg. Pref. vi.

'' Prodromus Entomologi/.

"^ Ins. Sur. t. xliii. The figure represents only the two spines near
the head as thus circumstanced.

0 Reaum. v, i. xii./. 8, 14. Platje XVIII. Fig. 11.

^ See above, Vol. II. p. 238. This, wilh B. imperaloiia, &c. in the
modern system, should form a genus.

STATE."^ OF INSECTS. lyl

are planted singly, but in some caterpillars in bunilles.
In that o( Sa/urfiia In, on eacli segment there are six bun-
dles of longish, quill-shaped, sharji, slender, diverging
spines, which also appear to sheath aculei. Madame
INIerian has figured this larva, or one very near it, as the
grub of a Euglossa *, with which, though she affirms she
traced it to the fly, it can have no connection. With re-
gard to mimbc}\ some larvae have only four spines on
each segment; others five, others again six, and others
seven, or even eight : they are planted on the sides and
back only, never on the belly. They are often more nu-
merous on the intermediate than on the anterior and
posterior segments; but sometimes the reverse of this
takes place ; in that of Attacus ErythritKE only the head
and tail are armed with spines, the rest of the body being
without any''; and in that of Moj-pho Teucei' there is
only a single spine on the four intermediate segments ^.
They are usually all nearly of equal length ; but in some
cases those of the head and tail are much longer than
the rest, and remarkably so in the caterpillar of Urania
LeiluSj also beautifully plumose, and gracefully waved ^.
Those hi the second and third segments are much longer
than any of the rest in that of Bomhyx rcgalis .- which
circumstance gives it the terrific appearance lately al-
luded to. In the family to which Argyn7iis Paphia be-
longs, the larva is adorned with two on the back of the
first segment twice as long as the rest, and resembling
at first sight two antennae.

The spines, as well as the hairs of the new skin, are
concealed under the old one, and not incased in its spines;

* Ills. Sur. t. xlviii. ri^ht hand figiiie. '' Ihid. I. xi.

* Ib'ul. t. xxiii, '^ Ihid. I. xxi.v.

182 STATES OF INSECTS.

but Bonnet ascertained, that if cut off very closely, the
larva sometimes died in consequence, whilst no such re-
sult followed a similar operation on hairy larvae. We
learn from Reaumur *, that some spinous larvae of saw-
flies ( Tenthredo L.) lose their spines at the last change of
their skin ; and from Madame Merian, that that of Atta-
cus Erythrince before mentioned loses also at the same
period the six tremendous black spikes that arm its black
and yellow larvae. The grubs of ants that are destined
to pass the winter in the larva state are hairy, but are not
so in summer ^. The spines found in the grubs of some
gad-flies {(Estrus L.) are of a different kind from those
above described, being very minute triangular flat plates,
arranged in different and contrary directions '^, and serv-
ing the insect merely to change its place and fix itself''.

Two other kinds of clothing, if so they may be called,
neither coming under the description of hairs nor spines^
are found in some other larvae, not only amongst the Le-
pidoptera, but also in some of the other orders. Nym-
phalis Populi and others of the same family have larvse
furnished on the back of each segment with cylindrico-
conical processes of a fleshy substance, obtuse at the apex
and surrounded with capitate hairs. In that of N. Sy-
billa, which has on each segment two fleshy protube-
rances, they are bifurcate or trifurcate, and also encir-
cled at the base with a hairy tuft ^. Others, as those of
Melitcea Artemis^ Cynthia, &c. have each segment beset
on the back with from seven to nine fleshy, pubescent,
wedge-shaped protuberances ; two larger ones projecting

* Reaum. v. 95. ^ Iluber Mceurs des Four mix, 79.

•" See above, Voi.. IF. p. 276—. *• Reaum. v, 72. /. ix./. 2—4. ,
' Rds. /;211.

STATES OF INSPECTS. 183

over the head. Under this head, too, may be noticed,
tlie glutinous secretion which clothes the grub of Cionus
Scrophulari(r, a little weevil ; and of Tcnthredo Cerasi L.
a saw-fly, and that waxy or powdery substance which
transpires through the skm of the larvae of several Aphi-
des, Chermes, Cocci, Hylotoma ovata F., &c. The Apkisy
whose extensive ravages of our apple-trees [A. Ia7iata)
were before described to you ', is covered and quite con-
cealed by this kmd of substance, so that the crevices in
the bark which they inhabit look as if they were filled,
not with animals, but with cotton. The insect, also,
that forms those curious galls produced upon the spruce
fir, and which imitate its cones {Cheiines Abietis L., Aphis
De Geer) secretes a similar substance. In these and
other cases of the same kind, this matter seems to be, if
I may so speak, wire-drawn through numerous pores in
certain oval plates in the skin, more depressed than the
rest of the back, arranged regularly upon the segments,
and exhibiting minute tuberosities. When young, these
animals have more of this secretion than when more ad-
vanced : it then hangs from their anal extremity in
locks''.

But the insects most remarkable for a covering of this
nature are those Coccida of which Bosc has made a ge-
nus under the name of Dorthesia. De Geer is the first
author that notices them, and has given a description
and figure of one species under the name of Coccus floc-

■' See above, Voi,. I. p. 29, 198—.

•• De Geer iii. 111. Comp. 121. It would be as well to adopt the
French word fioco-n, instead of locks or flocks, which strictly mean
very diflTeient thingj.

184 STATES or INSFXTS.

cosus^. It was discovered by Modeer upon some seve
fir-leaves in a thick bed of moss. Panzer has figured a
second found upon Geranium sarigiti)icum, which from
the figure appears distinct fi'om De Geer's, under the
name of Coccus duhiiis ^. Fabricius regards this as syno-
nymous witli the Dorthesia cliaracias of Bosc, inhabiting
Euphorbia characias in South Europe ^. Ohvier found
a species upon the bramble '^. I once took one, which
appears to differ in some respects from the preceding spe-
cies, upon Melampyrum cn'stafmn, and our indefatigable
friend Mr. Sheppard has sent me another, on what plant
found I do not remember, which does not agree with any
that I have mentioned. The body of the animals of this
genus is covered by a number of cottony or waxy laminge
which partly cover each other, and are arranged usually
in a triple series : in De Geer's figure the series appears
(juadruple, the lateral ones being placed obliquely. The
anterior one in my specimen covered the head, and they
are all canaliculate. Above the anus are four diveroinor
ones: the whole are of the most dazzling whiteness.
When these lamina are removed, the body appears di-
vided into segments.

With respect to those larvae which imitate slugs by the
viscid covering that besmears them and issues from their
pores, we learn from Professor Peck that this exudation
takes place as soon as they are Hatched ; that the animal
retains its humidity although exposed to the fiercest heat
of the sun, and that at the last moult the skin becomes

' vii. G04. t. xliv./. 26. •' Fn. Germ. Inif. xxxvi. 21.

■'■ Si)iit. Rln/ng. 311. 29. ^ N. Did. d'Hifst. Nat. ix. 554.

STATES OF INSFXTS. IS.*)

ijuite clean, ami iVoo iVom all viscidity' It is prohaMo
that the other limaciform larvae are similarly circum-
stanced. Madame Merian has figured an onhciform one,
the legs of which, she says, are covered with a viscid skin:
this produced a Noctiia. Those o'^ Papilio A/ic///srs also
are slimy, and adhere to each other ''.

V. Amongst other qualities which attach to larvae, we
must not omit to say something concerning their Colour.
Vov though those which live in darkness, in the earth,
in wood, in fruits, 8lC. are, with few exceptions '^, of an
uniform whitish colour, j^et such as are exposed to the
influence of the light are usually adorned with a vast va-
riety of tints, sometimes the most vivid that can be ima-
gined. That the white colour of the fornKU' may be at-
tributed to the absence of light is proved by an experi-
ment of M. Dorthes, who having forced some to live un-
der glasses, exposed to the light, found that they gradu-
ally became brown'*. To attempt any classification of
coloured larvae would be in vain, since they are tinged
with almost every possible shade that can be conceived,
of many of which it would be difficult to find examples
elsewhere; and infinitely diversified as to the arrangement
and figure of their multiform markings and spots. A few
general remarks, therefore, are all that you will expect
on this head. Many ai*e of one uniform colour ; while a
variety of tints, very different, and very vivid and distinct,
ornament others. Sometimes they are distributed in

" Nalurrtl Histort/ of the Slug-worm, 7.

'' Ins. Sunnani. I. xv. xvii.

' The larva? o\' Carnhua L. form one, I)eiiif generally black.

■■ Aiinnlci de CMmif ii.

18G STATES OF INSECTS.

longitudinal rays or bands, at others in transverse ones.
Sometimes they are waved or spotted, regularly or irre-
gularly; at others they are sprinkled in dots, or minute
streaks, in every possible way. Various larvae are of the
colour of the plant on which they feed, whence they are
with difficulty discovered by their enemies. Thus, a large
proportion of Lepidoptera are green of different shades,
sometimes beautifully contrasted with black bands ; a cir-
cumstance which renders the caterpillars of two of our
finest insects of this order as lovely as the fly : I mean
that of Papilio Machaon and Saturnia Pavonia. Very
frequently the larvae of quite different species resemble
each other so exactly, in colour as well as shape, as
scarcely to be distinguishable : this sometimes takes
place even where they belong to different genera, as in
those of Bomhyx versicolor a moth, and Smeri7ithus Po-
puli a hawk-moth. And it sometimes happens, very for-
tunately for distinguishing allied species, that where the
perfect insects very nearly resemble each other, the lar-
vae are altogether dissimilar. Thus, the female of Pieris
Rapa is so much like the same sex of Pieris Brassicce,
that it might be taken for a variety of it, did not the
green caterpillar of the one, and the spotted one of the
other, evince the complete distinction of these butterflies.
Noctua Lactuca, N. umbratica^ and several other species
of the same tribe, which includes N. Absinthii^ Verbasci,
Chamomillce^ Abrotani, are so extremely alike, that the
most practised eye can scarcely discover a shade of dif-
ference between them, though their larvae in colour and
markings are constandy distinct *. The markings of

» JVifti. Veyz. 2 J 9.

STATES or INSECTS. 187

species belonging to the same family are usually dlfle-
rent; but in some cases the latter maybe prejudged from
the former. The larvae of many of the genus Sphina: L.,
for example, have their sides marked by oblique streaks
running from the back in a direction towards the head ;
and by this last circumstance they are distinguished from
those of Bomhi/x versicolor, Attacus Tau, and others of
the same tribe, which have also lateral oblique stria?, but
running from the back towards the tail ^. The colours
of individual larvas of the same species are usually alike,
but in Sphinx Fdpcnor and some others they vary exceed-
ingly-. Many, like those of Lasiocampa Bubi, Saiurnia
jnino7\ &c., are of one colour when first disclosed, and
assume others quite different in riper age. Just previ-
ously to changing their skin^ the tints of most larvae be-
come as dull and obscure, as they are fresh and vivid when
the change has fully taken place ; and in some instances
the new skin is quite differently marked from the old one.
This is remarkably the case with the last skin of some of
the larvae of the genus Tenthredo L., which is entirely
different from all the preceding ones. As people when
they advance far in 3'ears usually become more simple in
their dress than when they were young, so the larvae in
question change an agreeably variegated skin for one oi"
a uniform and less brilliant colour ''. Madame Merian
has observed with respect to Attacus Erythrincr, that its
caterpillar is at first yellowish, with nine black striae
on each side: when arrived at one third of its size,
they become orange ; the striae are obliterated, and in
(heir place a round black spot appears on each of the

'■ Wien. Veiz. 4. ^ Reauni. v. 92.

188 STATES OF INSECTS.

eight intermediate segments '. Mr. Slieppard has re-
marked to me, that the skin of that of SpJtinx Ligustri.,
after being under ground foiu* days, was changed from a
vivid green to a dull red. Very rarely, however, it be-
comes of a more brilliant hue just before entering the
pupa state : thus, that of another hawk-moth {Smeriu/Zius
Tilice) changes to a bright violet ; and the yellow hairs
of that of Laria pzidihunda then become of a lovely rose
colour. And here I may observe, that the hairs and
spines also, of larvae, vary greatly in colour. They are to
be met with brown, black, red, yellow, violet, white, &c.
De Geer found, that in the larva of Cimhex iiitcns the
two sides of the body were of a different colour, the
left being of a deep green, whilst the right side and the
rest of the body were paler ^ ; but as he saw only a single
individual, this was probably an accidental circumstance.
Though the caterpillars, as I lately said, of one of the
most beautiful butterflies and moths that inhabit Britain
contend with the perfect insect in loveliness, yet in gene-
I'al no judgement can be formed of the beauty of the fu-
ture fly from the colour of the larva ; and the young Au-
relian must not flatter himself always with the hope, be-
cause the caterpillar excites admiration by its colours and
their arrangement, that the butterfly or moth it is to pro-
duce will do the same ; nor ought he to despise and over-
look a sombre or plain-coloured individual of the former,
under the idea that it will produce one equally plain of
the latter, for it often happens that the splendid cater-
pillar gives a plain butterfly or moth, and vice versa.
De Geer, however, gives us two instances of conformity

' Ins. Siirimw. f.\i. ^ u. 101 7.

STATES OF INSECTS. 189

beUvccu the colours of the caterpillar and those of the
future moth ; the one is that of the common currant-
moth [Phalccna G. grossulariata L.)? the caterpillar of
which is white, ornamented with several black spots va-
rying in size. At the two extremities it is yellowish, with
a longitudinal ray of the same colour on each side, the
head and legs being black. These colours are all to be
found in the lly, the ground of its wings being white or-
namented with many black spots of diflerent sizes. Its
upper wings are traversed by a yellowish band; and
towards their base is a spot of the same colour. Its body
is yellowish, with black spots ; but the head and legs are
black ^. The other is that of a green caterpillar, which
gives a green moth, figured by Reaumur [Pyralis prasi-
naria Fab.)^ Sometimes, also, the sex of the future per-
fect insect may be predicted from the colour it exhibits in
its first state : thus, the brown caterpillars of Noctua Pro-
nuba produce males, and the green ones females ^. The
sexes, also, of N. cxoleta and Pcrslcaruc differ in that
state.

vi. To the full account of the Food of insects given in
a former letter'^, which had reference chiefly to their
larva state, it is only necessary in this place to add a few
particulars not there noticed. Many larvse when first
excluded, as those of Picris Craiccgi, &c. devour the
shells of the eggs from which they have proceeded '^; and

» DeGeer i. 57. '' lbid.b%. Reaum. i. /. xxxix./. 13, 14.

«= De Gcer ii. 400. ^ See above. Vol.. I. Letters xii. xiii.

• Bonnet (ii. 18) mentions, that the yoiintj larvae of a butterfly
{Picris Cralcpgi), after devouring tlic exuviae of the eg^s fioniv.hich
they wcic halthtd, guawcd ihobc which were not so : not, however,

190 STATES OF INSECTS.

Others {Cerura Vinula, Sphinx Euphorbia^ Noctua Ver-
basci), though their usual food is of a vegetable nature,
eat with great apparent satisfaction the skins which they
cast from time to time, not leaving even the horny legs.
This strange repast seems even a stimulating dainty,
which speedily restores them to vigour, after the painful
operation by which they are supplied with it. Under
this head it will not be out of place to mention, that some
larvse of insects, which feed only on the juices of animals,
or the nectar and ambrosia of flowers, have no anal pas-
sage, and of course no feces. This is said to be the case
with the grubs of bees, wasps, the larvae ofMi/rmeleon, &c. *

vii. You will require no stimulus to induce you to at-
tend to the subject I am next going to enter upon, — the
Moulting, namely, of Larvae ; or their changes of skin.
This, indeed, is a subject so replete with interest, and
which so fully displays the power, wisdom, and goodness
of the Creator, affording at the same time such large oc-
casion for nice investigation, that a pious and inquisitive
mind like yours cannot but be taken with it. In the
higher orders of anunals, though the hairs of quadrupeds
and the feathers of birds are in many cases annually
renewed, the change, or scaling and increment of the
skin, is gradual and imperceptible ; no simultaneous re-

so as to destroy the included animal, but rather to facilitate its egress.
Those also of Coccinella bijncnctata which I lately bred from the egg,
as soon as hatched began to devour the unhatched ones around them,
which they seemed to relish highly. I am inclined to believe, how-
ever, that this unnatural procedure was to be attributed to the cir-
cumstance of the female not having had it in her power to place her
eggs in the midst of Aphides, their proper food.
' .V. Did. d'Hisi. Nat. xx. 359.

STATES OF INSLCTS. 191

jection of it, in which it is stripped ofl' by the aiumul it-
self Hke a worn shirt, being observable, till you descend in
the scale to the Serpent tribe ', which at certain periods
disengage themselves from their old integument, and start
forth with that new and deadly beauty so finely described
by the Mantuan bard : —

" So from Iiis ilen, the winter slept away.
Shoots forth the burnished snake in open diiy ;
A\ ho, fed with every poison of the plain,
Sheds Ills old spoils and shines in youth again :
I\oud of his golden scales rolls tow'ring on,
And darts his i'ovky tongue^, and glitters in the sun."

Pitt.

In these the new skin, I imagine, is fonuetl under the
old from the rdc mitcosum; but in insects, as I formerly
stated *^, since tlie time of Swammerdam it has generally
been believed by entomologists, that the larva includes a
series of cases or envelopes, one within the other, con-
taining in the centre the germe of the future perfect insect,
whose devclo})ment and final exclusion take place only
when these cases have been successively cast off". This
hypothesis, as was explained to you on a former occasion**,
has been controverted by a late writer. Dr. Herold ; who
affirms that the skins of caterpillars are also successively
produced out of the rete miicosum, I have however, I
hope, satisfied you that the old system is most consonant

" In the human species, after certain fevers a simultaneous and
total moult, if the term may be so applied, takes place. I experi-
enced this myself in my boyhood; when convalescent from Scarlatina,
the skin of my whole body, or nearly so, peeled off'.

'' The translator, more ignorant of natural history than his author,
has turned the '* Unguis micat ore trisulcis " of Virgil, into " darts his
forky sting"

'' Vol. I. p. 70. ^ See above, p. b2 — .

192 STATES or INSECTS.

to nature and probability : but as we are now to enter
at large upon the Moults of insects, it will not be without
use if I add a few additional reasons which seem to me
still further to prove the correctness of Swammerdam's
system, as far as it relates to that subject. With regard
to the mere formation of the skin from the rctc mucosuni^
were this the whole question few would hesitate to adopt
the sentiments of M. Herold ; but when we come to con-
sider further — that the number of moults of individuals
of the same species is always the same, and that it varies
in different species, and takes place at certain periods, —
we begin to suspect that something more than the mere
formation of a new skin upon an old one being cast is to
be accounted for ; and that the law which prescribes its
own definite number of skins to each species, must begin
to act in the primordial formation of the larva. Again,
the hairs observable in the higher animals do not take
their origin from the epidermis solely, but are planted
below it in the 7-ete nmcosum, or deeper ^ ; so that the
change of skin does not affect them ; but in the larvae of
insects they are a continuation of that integument, since,
when the moult takes place, they always remain on the
rejected skin ^ : this is the case, also, even with spines.
If you shave a caterpillar ready to change its skin, either
partially or generally, you will find that the parts in the
new skin that correspond with those that are denuded,
are equally hairy with those that were uot '^ ; and if
you pay attention to the new-clad animal, you will find
farther, that the hairs never grow after a moult. From

' Cuvicr Anal. Conqy. ii. 59G. N. Did. iVHhl. Nal. xxvi. 165.
^ Cuvicr Ibid. 624. ^ Rcaum. i. 182.

STATES OF INSECTS. 193

lience it follows, that the hairs have their place and take
their whole irrowth between the new skin and the old *.
Whether the spines, simple or compound, lately described
to you, that arm some larvae are similarly circumstanced,
seems not as yet to have been ascertained ; but as the
spinous ones of certain Tenthredines L. and Lcpidoptera
at their last moult have no spines, the presumption is,
that, whether incased or not, they are mere appendages
of the skin on which they appear. A new set of hairs,
therefore, and probably of spines in spinous larvae, ac-
companying each skin, and these varying very much in
size, composition, &c. though a ncAv membrane may be
admitted to be formed from an action in the rete mucosum
without a pie-existent germe of it, it seems not easy to
conceive how these hairs and spines can spring up and
grow there, each according to a certain law, without ex-
isting previously as a kind of corcidum ovpunctum saliens;
and that the germes of the tubercles, in which the hairs
are so generally planted, according to a certain arrange-
ment and in a given number, should also pre-exist, seems
most consonant to reason. These and the several skins may
all co-exist in their primordial germes, and remain be-
yond the discovery of our highest powers of assisted vi-
sion, till a certain period when they may first enter the
range of the microscope-aided eye. It does not therefore
follow, because these primoi'dia sernina rerum are not
discoverable, that therefore they may not exist. Our
faculties and organs are too limited and of too little power
to enable us to see the essences of being.

Upon the supposition that the hypothesis of Swam-

» X. Diet. d'Hist Xaf. vi. 290.
AOL. III. o

194 STATES OF INSECTS.

merdam is the true one, we may imagine that the enve-
lope that Ues within all the rest is that which covers the
insect in its pupa state. Above this are placed several
others, which successively become external integuments.
These changes or casting of the skin in larvae, analogous,
as before observed, to that of serpents, are familiar to
every breeder of silk- worms, in which J'oia- such changes
occur : the first at the end of about ttvelve days from its
birth, and the three next each at the end of A«//' that time
from the moulting which preceded it. With some ex-
ceptions ', similar changes of the skin take place in all
larvae, not however in the same number and at the same
periods. Most indeed undergo this operation only three
or four times ; but there are some that moult oftener,
from five up to eight [Arctia villica), nine [CalUmorpha
Domimda), or even ten times; for so often, M. Cuvier
informs us, the caterpillar of the tiger-moth [Callimorpha
Caja) casts its exuviae. It has been observed that the
caterpillars of the day- flying Lepidoptet-a [Papilio L.)
usually change only three times, while those of the night-
flyin'g ones {Phalcena L,.) change Jbu7'^. The periods
that intervene between each change depend upon the
length of the insect's existence in the larva state. In
those which live only a few weeks or months, they are
from eight to twenty days ; while in those that live more
than a year, as the cockchafer, &c. they are probably
proportionably longer : though we know very little with

* Those Dipiera whose metamorphosis is coarctate (Vol. I. p. 67),
bees, the female Cocci, &c. do not cast their skin in the larva state.
Reaiim. iv. 364. iV. Diet. d'Hist. Nat. xx. 365.

b N. Did. d'Hist. Nat. vi. 289. xx. 372. Cuvier Aruti. Comp. ii.
648. M. Cuvier {Ibid. 547.) asserts, that most Papilioncs and Bom-
hyces moult seven times.

sTATKs or iN'siars. 195

regard to the moult ot" any insects besides the Lepido-
ptcra.

A day or two previously to each change of its skin,
the hirva ceases eating altogether; it becomes languid
and feeble, its beautilul colours fade, and it seeks for a
retreat in which it can undergo this important and some-
times dangerous and even fatal operation in security.
Here, either fixing itself by its legs to the surface on
which it rests, or, as is the case with many caterpillars,
by its prolegs, to a slight web spun for this purpose, it
turns and twists its body in various directions, and alter-
nately swells and contracts its different segments. The
object of these motions and contortions seems to be, to
separate the exterior skin, now become dry and rigid,
from the new one just below it- After continuing these
operations for some hours, resting at intervals without
motion, as if exhausted by their violence, the critical mo-
ment arrives : the skin splits in tlie back, in conse-
quence of the still more violent swelling of the second or
third segment : the openhig thus made is speedily in-
creased by a succession of swellings and contractions of
the remaining segments : even the head itself often di-
vides into three triangular pieces, and the inclosed larva
by degrees withdraws itself wholly from its old skin.
All larvae, however, do not force their way through this
skin in precisely the same place. Thus, those of the haw-
thorn buttei'fly (Pien's Cratcegi), according to Bonnet ',
make their way out by forcing off what may be called their
skull, or the horny part of their head, without splitting the
jskin, which remains entire ; others have been observed
to make their way out at the side and the belly. Reau-

* G\uvr. ii. 71-
o 2

196 STATES OF INSECTS.

mur noticed the larva of Zygccna Filijoauhda, previoiisly
to its last moult, actually biting off and detaching several
portions of its old skin; and before this, drops of a fluid
resembling water were seen to exude from it ^.

The skin when cast is often so entire, that it might be
mistaken for the larva itself; comprising not only the
covering of the main trunk with the hairs which clothed
it, but of the very skull, eyes, antennae, palpi, jaws, and
legs; which, if examined from within, are now found to
be hollow, and tb have incased, like so many sheaths,
similar parts in the new skin. That the feet of the newly-
coated larva were actually sheathed, as fingers in a glove,
in the same parts of the exuviae, may be proved by a
yery simple experiment : if a leg of one just ready to
cast its skin be cut off, the same limb will be found mu-
tilated when that change has ensued. The anal horns,
also, of the larvse of the hawk-moth [Sphinx L.) and other
similar protuberances, are incased in each other in like
manner ; but hairs are laid flat between the two skins,
and contribute considerably towards their more easy se-
paration. Thus, if you saved the skins cast by the larva
of CalUmorpha Caja^ for instance, you would appear to
have ten different specimens of caterpillars, furnished
with every external necessary part, and differing only in
size, and the colour perhaps of the hairs, and all repre-
senting the same individual.

But further changes than this take place. Swammer-
dani says, speaking of the moult of the grub of Oi-yctes
nasicornis, a beetle common in Holland, but not satis-
factorily ascertained to inhabit Britahi, " Nothing in all
nature is in my opinion a n)oi"e wonderful sight than the

■■ Ktaiuu. ii. '^o.

STATKS OF INStCTS. 197

change of" skin in these and other the hke worms. This
matter, therefore, deserves the greatest consideration,
and is worthy to be called a specimen of nature's mira-
cles; for it is not the external skin only that these worms
cast, like serjients, but the throat and a part of the sto-
mach, and even the inward surface of the great gut,
change their skin at the same time. But tliis is not the
whole of these wonders; for at the same time some hun-
dreds of pulmonary pipes within the body of the worm
cast also each its delicate and tender skin. These seve-
ral skins are afterwards collected into eighteen thicker,
and, as it were, compounded ropes, nine on each side of
the botly, which, when the skin is cast, slip gently and
by degrees from within the body through the eighteen
apertures or orifices of the pulmonary tubes before de-
scribed, having their tops or ends directed upwards
towards the head. Two other branches of the pulmo-
nary pipes that are smaller, and have no points of respi-
ration, cast a skin likewise." ..." If any one separates
the cast little ropes or congeries of the pulmonary pipes
with a fine needle, he will very distinctly see the branches
and ramifications of these several pipes, and also their
annular composition '." — Bonnet makes a similar obser-
vation with regard to caterpillars; but he appears to have
observed it more particularly, at least the change of the
intestines, previously to the metamorphosis of the insect,
when he says with the excrements it casts the inner skin
of the stomach and viscera ''. Both these great men ap-
pear to have recorded the result of their own actual ob-
servations with regard to the proceedings of two very dif-

» Bibl. Xal. E. Trans, i. 135. col. b. /.xxvii./. 6.
'° (E tares, viii. 303.

198 STATi:S OF INSFXTS.

ferent kinds of insects ; the one the grub of a beetle, and
the other the caterpillars of Lepidoptera. The account of
the former is given quite in detail, as that of a person who
is describing what he has actually seen : yet by a later and
very able physiologist. Dr. Herold, it is affirmed that the
inner skin of the intestinal canal is never cast, that canal
constantly retaining its two skins. He further affirms, that
they are only the la7-ge trunks of the Tracheae that cast
their skins, none being detached from their 57rt«Z/er rami-
fications *. When men so eminent for their anatomical
skill and nicety, and for their depth and acumen, dis-
agree, the question must be regarded as undecided till
further observations throw sufficient weight into one scale
or the other.

The larva which has undergone this painful process is
at first extremely weak: all its parts are soft and tender;
even the corneous ones, as the head and the legs, are then
scarcely more than membranous, and are all bathed with
a fluid, which, before the moult, intervenes between the
two skins, and facilitates their yeparation ^ : and it is
only after some hours, or in some cases even days, du-
ring which it lies without motion, that this humidity eva-
porates, all its parts become consolidated, and it reco-
vers its strength sufficiently to betake itself to its wonted
food. Its colour, too, is usually at first much paler than
before, and its markings indistinct, until their tints have

" ETitwickelungsgeschiclite, &c. 34, 88. Swammerdam on the con-
trary affirms, that " on the hinder part of the cast skin where it is
twisted and compHcated, whoever accurately cxannne!i the skin it-
self may still observe the coat that was cast by the intrstwum rectum,
Ubi supr, 136. col. a.

" .V. Diet. (rHisl. Xat. vi, 290,

sTAri:s Of iNSKCi's. J9y

been enlivened by exjjosure to the air, when tliey become
more fresh, vivid, and bcantiful to a})pearance than ever.
When a tew meals have invigorated its languid powers,
the renovated animal makes up tor its long abstinence
by eating with double voracity.

A similar preparatory fast, and succeeding state of
debility, accompany every change of the larva's skin.
Eacli time except the last, the old skin is succeeded by
a new one, with few exceptions, similar to the one it has
discarded. Previously to the final change, which discloses
the pupa, it quits the plant or tree on which it had lived,
and appears to be quite unsettled, wandering about and
crossing the paths and roads, as if in quest of some new-
dwelling. It now abstains from food for a longer time
than before a common moult, empties itself copiously,
and as I have just said, if Swammerdam and Bonnet are
to be depended upon, casts the skin that lines the sto-
mach and intestines, as well as that of the Tracheae.

I have observed above, that all larvas, with few excep-
tions, change their skins in the manner that I have de-
scribed. These exceptions aie principally found in the
order Diptera, of which those of the Linnean genera
Musca, Qislrus, and probably all that, like the maggot
of the common flesh-fly, have membranous contractile
heads, never change their skin at all, not even prepara-
tory to their becoming pupae. The skin of the pupa,
though often differing greatly in shape from that of the
larva, is the same which has covered this last from its
birth, only modified in figure by the internal changes that
have taken place, and to which its membranous texture
readily accommodates itself. The larvas of the Dipte-
rous genera Tipula, Cider, and those which liave come-

200 STATES OF INStCTS.

ous heads, like other larvae change their skins several
times previously to becoming pupae ". The grubs, also,
of bees, wasps, ants? and probably many other Hymeno-
jptera, do not change their skin till they assume the pupa,
nor the larva of the female Coccus ^.

If you feel disposed to investigate the reasons of that
\a.vf of the Creator which has ordained that the skins of
the higher animals shall be daily, and imperceptibly, and
as it were piece by piece renewed, while those of insects
are cast periodically and simultaneously, — the proximate
cause must be sought for in the nature of the two kinds
of skin, the one being more pliable and admitting a
greater degree of tension than the other, and being so
constructed as to scale off more readily. If, ascending
higher, you wish to know why the skins of insects are so
differently circumstanced from our own, the most appa-
rent reason is, to accommodate the skin to the very rapid
growth of these animals, which a gradual and slower
change would have impeded too much, or the skin have
suffered constant dilapidation and injury ; therefore their
Beneficent Creator has furnished them with one which
will stretch to a certain point, and during a certain period,
and then yield to the efforts of the inclosed animal, and
be thrown aside as a garment that no longer fits the
wearer.

viii. And this leads me to a subject to which I am de-

* Reaum. iv. 604.

b Ibid. 364, N. Did. d'Hist. Nat. xx. 365. Huber Fourmk 78.
M. Huber does not say expressly that the grubs of ants do not change
their skin ; but his account seems to imply that they change it only
previously to their metamorphosis.

STATKS oi" iNsixrrs. 201

sirous now to bespeak your attention, — tlie Growth^ I
mean, and size of Insects in this state. As to sizc^ larvae
tllfler as much as insects in their perfect state : these last,
however, never grow after their exclusion from the pupa,
while larvif increase in bulk in aproportion, and often with
a rapidity, almost without a parallel in the other tribes of
animals. Thus Lyonnet found, that the caterpillar of
the great goat-moth {Cossus ligyiiperda F.) after having
attained its full growth is at least 72,000 times heavier
than wlien it was first excluded from the egg * ; and of
course had increased in size in the same proportion.
Connected with the size of larva^, is the mode in which
their accretion takes jilace. This, with respect to the
more solid parts, as the head, legs, &c., is not, as in other
animals, by gradual and imperceptible degrees, but sud-
denly and at stated intervals. Between the assumption
of a new skin and the deposition of an old one, no in-
crease of size takes place in these parts, while the rest of
tlie body grows and extends itself, till, becoming too big
lor these solid parts, nature restores the equilibrium be-
tween them by a fresh moult'', in which the augmenta-
tion of bulk, especially in these parts, is so great, that we
can scarcely credit the possibility of its being cased in so
small an envelope. Malpighi declares, that the head of
a silk-worm that has recently cast its skin is four times
larger than before the change *^. It is very probable,
also, that when the outer skin becomes rigid, it confines
the body of the larva within a smaller compass than it
would expand to if uuconfined, so that, when this com-
pression is removed, the soft and elastic new integu-

•• Lyonnet 11. ^ X. Did. d'Hisl. Xat. vi. ;^90.

* De Bombi/cibus, 6S.

202 STATES OF INSECTS. ,

merit immediately swells out, and the animal appears all
at once much larger than it was before the moult. In
fact, the proximate cause of the rupture and rejection of
the old skin is the expansion of the included body, which
at length becomes so distended as to split its envelope,
aided, indeed, as before described, by the contortions of
the creature itself.

The larvffi most notorious for the rapidity of their
growth are those of Musca carnaria and other flesh-flies :
some of which Redi found to become from 140 to more
than 200 times heavier in twenty-four hours ^ : an increase
of weight and size in so short a time truly prodigious,
but essential for the end of their creation — the rapid re-
moval of dead and putrescent animal matter. As the
skins of these larvae are never changed, we may conclude,
if the cause of the change of skin in other larvae above
surmised be accurate, that their skins are more contrac-
tile and capable of a greater degree of tension than those
of larvae that are subject to moulting. And two peculi-
arities observable in them confirm this idea : in the first
place, their head is not hard and corneous, as that of
the others, but capable of being shortened or lengthened ;
and in the next, their breathing-pores are not in the sides,
but at the extremities of the body, while in the moulting
larvae there are two in almost every segment, which must
form so many callous points that impede the stretcliing
of the skin to the utmost. The hairs, spines, and tuber-
cles, that are so often found on caterpillars, must also
form so many points of resistance that prevent that full
extension of the integument which it might otherwise
admit,

■' Opusc. i. '2'J,

KTATEiJ OF 1NS1;CI?5. 203

There is not always that pic)poitit)n between the size
of larvae and of the insects that proceed from them that
might have been supposed, some small larvae often pro-
ducing perfect insects larger than some of those proceed-
ing from such as are of greater size.

ix. As insects often live longest in the state we are
treating of, I shall say something next upon the age of
larvae, or the j)eLi'iod intervening between their exclusion
from the egg and their becoming pupae. This is exceed-
ingly various, but in every case nicely adajited to their
several functions and modes of life. The grubs of the
flesh-fly have attained their full growth, and are ready to
become pupje, in 5/0' or seven days ; the cater})illar of Ar-
gynnis Paphia, a butterfly, in Jourteen days ; the larvae of
bees in t-jocnti/ days ; while those of the great goat-moth
{Cossus ligiiiperda) and of the cockchafer [Melolontha vul-
garis) live three years, or at least survive three winters, be-
fore the same change. That of another lamellicorn beetle
{Oryctes nasicornis F.) is said to be extended to Jour or
Jive ; that of the wire-worm [Elater segetum) to Jive.
That of the stag-beetle (Lucanus Cervus) is affirmed by
R()sel to be extended to six years ; but the most remark-
able instance of insect longevity is recorded by Mr. Mar-
sham in the Ijifmean Transactious ^. A specimen of Bu-
prestis splendida, a beautiful beetle never before found in
this country, made its way out of a deal desk in an oflice
in London in the beginning of the year 1810, which had
been fixed there in the year 1788 or 1789; so that ac-
cording to every appearance it had existed in this desk

* Linn. Tram. x. 'i'JO.

204- STATES or INSECTS.

more than twenty years. Ample allowance being made
for its life as a pujsa, we may conclude that it had existed
as a larva at least half the above period. The grubs of
the species of the genus Cynips L. attain their full size
in a short time ; but they afterwards remain five or six
months in the gall before they become pupae ^.

With few exceptions it may be laid down, that those
larvae which live on dead animals, in fungi, in dung, and
in similar substances, are of the shortest duration in this
state; and that those which live under the earth, on the
roots of grass, &c. and in wood, the longest: the former
becoming pupa^ in a few days or weeks, the latter requir-
ing several months, or even years, to bring them to ma-
turity. The larvae which live on the leaves of plants
seem to attain a middle term between the one and the
other, — seldom shorter than a few weeks, and rarely
longer than seven or eight months. Aquatic larvae ap-
pear to be subject to no general rule: some, as the larvaj
of Gnats, becoming pupae in two or three weeks; and
others, as those of the Ephemera', which are thus com-
pensated for their short life as flies, in as many years ^.
The cause of all these difi^erences is obviously dependent
on the nature of the food, and the purposes in the eco-
nomy of creation to which the larvae are destined.

X. The last part of the history of larvae relates to their
Preparations for assuming the pupa state. When they
have acquired their full size, after having ceased to take

» N.Dict. (THist. Nat. vii. 129.

'' As the larvae of Epliemerce usually live in the submerged part of
the banks of rivers, perhaps they may be regarded as following the
economy of subterranean tcnentr'uil larva*.

STATES OF INSECTS. 205

tbod, by a copious evacuation they empty tlie intestinal
canal, even rejecting the membrane that lines it and the
stomach ' ; their colours either change totalh', or lade ;
and they make themselves ready for entering upon a
new stage of their existence. Some merely rest in a
state of inactivity in the midst of the substances in which
they feed, as if conscious of their inability to select any
safer abode. Of this description are most Coleopterous,
Hymenopterous, and Dipterous larvae, that feed under
ground, or in the interior of trees, fruits, and seeds.

But a still larger tribe, those which feed on leaves, ani-
mals, &c. act as if more sensible of the insecurity of this
to them important epoch. They are about to exchange
their state of vigour and activity for a long period of death-
like sleep. The vigilant caution which was wont to guard
them from tlie attack of their enemies will be hencefor-
ward of no avail. Destitute of all the means of active
defence, their only chance of safety during their often
protracted night of torpor must arise from the privacy of
their place of repose. About this, therefore, they exhibit
the greatest anxiety. Many, after wandering about as if

* A caterpillar nearly answering to the description of tliat of
Bombyx camelina, which I found upon the hazel, after a few days
produced sixteen grubs of some Ichneumon. At first these grubs were
green, but they became gradually paler ; and after a day or two be-
came pupae. But I mention this circumstance here for another rea-
son : upon examining them after this last occurrence, I observed that
they adhered to the lid of the box in which I kept the larva, arranged
somewhat circularly ; and at a little distance from the anus of each
was a pea-green mass, consisting of about eight oval granules, which
appeared like so many minute eggs. These were the excrement eva-
cuated by each grub previously to its becoming a pupa. The appear-
ance of this little group, with their verdant appendage, formed tt cu-
rious spectacle : they arc still pupie, July .^t^, 1^22.

206 STATES OF INSECTS.

bewildered, retire to any small hole on the surface of the
earth, covering themselves with dead leaves, moss, or the
like, or to the chinks of trees, or niches in walls and other
buildings, or similar hiding-places. Many penetrate to
tlie depth of several inches under ground, and there form
an ap])ropriate cavern by pushing away the surrounding
earth; to which they often give consistence by wetting it
with a viscid fluid poured from the mouth. The larvae
of other insects undertake long and arduous journeys in
search of appropriate places of shelter. Those of flesh-
flies, now satiated with the mass of putridity in which
they have wallowed, leave it, and conceal themselves in
any adjoining heap of dust. The grubs of the gad-fly
[CEstrus) creep some of them out of the backs of cattle,
in tumours of which they have resided, and suffer them-
selves to fall to the earth ; while others, which have fed
in the stomach of horses, quit their hold, and by a still
more extraordinary and perilous route are carried through
the intestines the whole length of their numerous circum-
volutions, and are discharged at the anus. And without
enumerating other instances, various aquatic larvae, as
that of a common fly (Elophilus pendulns), &c. leave the
water, now no longer their proper element, and betake
themselves to the shore, there to undergo their metamor-
phosis.

Most of these, having reached their selected retreat,
require no other precaution ; but another large tribe of
larvae have recoui'se to further manoeuvres for their de-
fence before they assume the pupa. Those of the aphi-
divorous flies [Syrphus F. &c.), of the various lady-birds
{Coccmella h.\ and tortoise-beetles {Cassida L.), &c. fix
themselves bv the anus with a p'ummv substance to the

^STATES Ol- IXSF.CTS. 207

leaves or twigs undei* which tliey propose to conceal ihem-
selves during their existence in that state. Others previ-
ously suspend themselves by a silken thread fixed to the
tail, or passing-round the body; by which also, when become
pupae, they are afterwards pendent in a similar position;
and lastly, a very great number of larvas wholly inclose
themselves in cases or cocoons, composed of silk and va-
rious other materials, by which during their state of re-
pose they are protected both from their enemies and the
action of the atmosphere. As these two last-mentioned
processes are extremely curious and interesting, I shall
not fear tiring you by entering into some further detail
respecting them : explaining /^V^^ the mode by which lar-
vae suspe?id themselves, both before and after they are
become pupae, by silken threads ; and next, the various
cases or cocoons in which others inclose themselves, and
their manner of operating in the formation of them.

1. The larvae which suspend themselves and their pu-
pae, with the exception of the tribe of Aluciice, and some
GeometrcE of the family of G. pendularia, punctaria, &c.
are almost all butterflies^. No others follow this mode.
They may be divided into two great classes — those which
suspend themselves perpendicularly by the tail, and those
which suspend themselves horizontally by means of a

' Except some species oi Poti/mnmatu.i Latr. {Thecla,Argynnis¥.),
P. Argiolus, Corydon, &c., and Hesperia Rttbi, BetitlcB F., &c. Some
of the larvae of the former become pupae within the stalk of some
plant, or partly under the earth : those of the latter usually in a leaf
to which the abdomen is fastened by various threads. These last
are the rouleiises of the butterfly-tribe, living, like some moths, in
leaves that they have rolled up. N. Diet. d'Hist. Nat. xxiv. 499.

208 STATES OF INSECTS.

thread girthed round iheir middle. In both cases it
should be observed, that tlie suspension of the pupa is
the object in view; but as the process is the work of the
tarva, this seems the proper place for explaining it. To
begin with the^;;<f/ case.

You are aware that all Icpidoptcfous larvae have the
faculty of spinning silk threads from their mouths, and
it will readily occur to you that it is by means of these
threads that they suspend themselves. But how ? How
is a caterpillar to hang itself by the tail to threads spun
from the mouth ? Even suppose this difficulty overcome,
others still greater remain. Suppose the caterpillar to
be suspended by its tail, — this is but a preparatory ope-
ration,— what is required is, that the pupa shall hang in
the same position : now when you take into consideration
that it is incased within the skin of the larva, and without
feet or other external organs; that it has to extricate it-
self from this skin ; to hang itself in its place, and to de-
tach the skin from the threads which hold it — this will
appear no trifling task. Indeed at first view it seems
impossible. Country-fellows for a prize sometimes amuse
the assembled inhabitants of a village by running races
in sacks : take one of the most active and adroit of these,
bind him hand and foot, suspend him by the bottom of
his sack with his head downwards, to the branch of a
lofty tree ; make an opening in one side of the sack, and
set him to extricate himself from it, to detach it from
its hold, and suspend himself by his feet in its place.
Though endowed with the suppleness of an Indian jug-
gler, and promised his sack full of gold (or a reward, you
would set him an absolute impossibility : yet this is what

STATES OF INSECTS. '209

our caterpillars, instructed by a beneficent Creator, easily
perform. Their manoeuvres I shall now endeavour to
explain.

When the caterpillar has selected the under-side of
the leaf or other object to which it purposes suspending
itself, its first process is to spin upon it a little hillock of
silk consisting of numerous loosely interwoven threads ;
it then bends its body so as to insinuate the anal pair of
prolegs amongst tliese threads, in which, by a slight ex-
ertion, the little crochets which surround them * become
so strongly entangled as to support its weight with ease.
It now suffers the anterior part of the body to fall down,
and it hangs perpendicularly from its silken support with
its head downwards. In this position it remains often for
twenty-four hours, at intervals alternately contracting and
dilating itself. At length the skin is seen to split on the
back near the head, and a portion of the pupa appears,
which by repeated swellings acts like a wedge, and ra-
pidly extends the slit towards the tail. By the continu-
ance of these alternate contractions and dilatations of the
conical pupa, the skin of the caterpillar is at last collected
in folds near the tail, like a stocking which we roll upon
the ancle before withdrawing it from the foot. But now
comes the important operation. The pupa, being much
shorter than the caterpillar, is as yet at some distance
from the silken hillock on M'hich it is to be fastened ; it
is supported merely by the unsplit terminal portion of
the latter's skin. How shall it disengage itself from this
remnant of its case, and be suspended in the air while it
climbs up to take its place? Without arms or legs to

»- Platf; XXIII. Fic. \.a.
VOL. Ill, P

210 STATES OF INSECTS.

support itself, the anxious spectator expects to see it fall
to the earth. His fears, howevei*, are vain ; the supple
segments of the pupa's abdomen serve in the place of
arms. Between two of these, as with a pair of pmcers, it
seizes on a portion of the skin; and bending its body once
more, entirely extricates its tail from it. It is now wholly
out of the skin, against one side of which it is supported,
but yet at some distance from the leaf. The next step it
must take is to climb up to the required height. For this
purpose it repeats the same ingenious manoeuvre, making
its cast-off skin serve as a sort of ladder, it successively
with different segments seizes a higher and a higher
portion, until in the end it reaches the summit, where
with its tail it feels for the silken threads that are to sup-
port it. But how can the tail be fastened to them ? you
ask. This difficulty has been provided against by Crea-
tive Wisdom. The tail of the pupa is furnished with nu-
merous little hooks pointing in different directions ^, as
well adapted to the end in view as the crochets of the
larva's prolegs, and some of these hooks are sure to fast-
en themselves upon the silk the moment the tail is thrust
amongst it. Our pupa has now nearly completed its la-
bours ; it has withdrawn its tail from the slough, climbed
up it, and suspended itself to the silken hillock — manoeu-
vres so delicate and perilous, that we cannot but admire
that an insect which executes them but once in its life,
should execute them so well : nor could it, as Reaumur
has well and piously observed, had it not been instructed
by a Great Master. One more exertion remains : it
seems to have as great an antipathy to its cast-off skin,

^ Plate XXIII. Fig. 8. a.

STATES OF INSECTS. 2lj

as one of us should, when newly clothed after a long im-
prisonment, to the filthy prison garments we had put off.
It will not suffer this memento of its former state to re-
main near it, and is no sooner suspended in security than
it endeavours to make it fall. For this end — it seizes,
as it were with its tail, the threads to which the skin is
lastened, and then very rapidly whirls itself round, often
not fewer than twenty times. By this manoeuvre it ge-
nerally succeeds in breaking them, and the skin falls
down. Sometimes, however, the first attempt fails : in
that case, after a moment's rest, it makes a second, twirl-
ing itself in an opposite direction ; and this is rarely un-
successful. Yet now and then it is forced to repeat its
whirling, not less than four or five times : and Reaumur
has seen instances where the feet of the skin were so firmly
hooked, that after many fruitless efforts the pupa, as if
in despair, gave up the task and suffered it to remain '.
After these exertions, it hangs the remainder of its exist-
ence in this state imtil the butterfly is disclosed.

We are now to consider the second mode of suspen-
sion, in which larvae by means of a silken girth round
their middle, fix themselves horizontally under leaves, &c.
These follow the same process with that of those last de-
scribed, in spinning a small hillock of silk to which they
fasten their hind legs ; and if the operation concerned the
larva state alone, this would be sufficient, as by means of
this support, and of their prolegs, they could easily re-
tain themselves in a horizontal position. But these lar-

* Bonnet is of opinion that this twirling process is not with any
view to get rid of the exuvise, but is caused only by the irritation oc-
casioned by the spines of the skin of the caterpillar when they touch
that of the pupa. Q^uv. ii. 109.

p 2

212 STATES OF INSECTS.

vae act as if they foresaw the assumption of a state in
which they will be deprived of legs. It is the suspension
of the forthcoming pujoa that is the object in view ; and
though this can be hung by the tail in the same way with
those of the first class, yet it is plain that it cannot be re-
tained in a horizontal position, which for some unknown
reason is essential to it, without some support to its an-
terior extremity. It is necessary for the larva, therefore,
not only to fix its posterior legs amongst a collection of
silken fibres, but to spin a girth of the same material
round its body. This girth, though apparently of a sin-
gle thread, will be found on examination to be composed
of several, often as many as fifty or sixty ; and is fastened
on each side of the body of the larva about the middle,
to the surface under which it is placed. Three different
modes of fixing these girths are adopted by the caterpil-
lars of different butterflies. Some, as those of the com-
mon cabbage-butterfly [Pier is Brassicce), which have re-
markably pliable bodies, bend them almost double on
one side, then fix the thread and carry it over to the
other in the same position, repeating this operation as
often as is necessary. Others, as that of L.yccena Argus
and many more of the Papiliones Rurales and Urbico-
Ice L., which have a short and more rigid body, after
having bent the head on one side so as to fix one end of
the thread, bring themselves into a straight position, and,
by a manoeuvre not easily described, contrive to intro-
duce the head under the thread, which they then bend
themselves to fasten on the other side, pushing it to its
proper situation by the successive tension and contrac-
tion of their segments. But the most curious mode,
though indeed that which seems most natural, is adopted

STATES OF INSECTS, 213

by the caterpillar of tlic beautiful swallow-tail buttcifly
{Papilio Machaoii) and otliers of the same family. This
first forms the loop which is to serve for its girth, and
then creeps under it. But the difficulty it has to surmount
is, to keep itself from being entangled in the fifty or sixty
fine distinct threads of which the girth is composed, and
to preserve them all extended so as to be able to intro-
duce its body beneath them. For tliis purpose it makes
use of the two first pair of its fore-legs, employing them
as a woman does her hands in winding a skein of cotton,
to collect and keep all the threads of its card unentangled
and properly stretched ; and it is often with great diffi-
culty, towards the end of the process, that it prevents
them from slipping off. Wlien a sufficient number of
threads is completed, the animal bends its head between
its legs, and insinuates it under the collected loop, which
by its annular contraction it easily pushes to the middle
of the body.

In about thirty hours after the larvae which girth them-
selves have finished their operations, the skm splits, and
the pupa disengages itself from it by those contractions
and dilatations of its segments which have been before
described, pushing the exuviae in folds to the tail, by dif-
ferent motions of which it generally succeeds in detach-
ing them. One would have thought there would be con-
siderable difficulty in slipping the skin past the girth ;
but this, according to Reaumur, seems to be easily ef-
fected =•.

If you are desirous of witnessing for yourself the manoeu-
vres by which these curious modes of suspension are

* For the above account see Reauni. i, Mem. x. xi.

214 STATES OF INSECTS.

effected, you may be readily gratified. It is only neces-
sary to collect and feed until their metamorphosis the
black spinous caterpillars of the common peacock-but-
terfly (Vanessa lo)^ which in most places may be found
upon nettles, or those of the Pieris Brassicco, which swarm
in cabbages or brocoli in every garden. The former will
exhibit to you a specimen of vertical, the latter of hori-
zontal suspension. It should be observed, however, that
to hit the precise moment when these processes are go-
ing on, it is necessary to feed a considerable number of
the larvae of each kind; some one of which, if you watch
them narrowly when they have attained their full growth,
you will scarcely fail to surprise in the act.

I must observe here, that although the vertical and
horizontal are the two principal positions in which cater-
pillars suspend themselves, yet that others are inclined at
various angles; and some are attached with less art, ap-
pearing only to be fastened by some part of their abdo-
men to the body upon which they are fixed \

2. The larvae whose procedures I am in the next place
to describe, are those which, previously to assuming the
pupa state, inclose themselves in cases or cocoo?is of diffe-
rent materials. For the sake of method, I shall divide
these into two great classes : First, those which form their
cocoons entirely or principally of silk; and secondly,
those which form them chiefly of other substances.

To begin with the ^rst. The larvae which inclose
themselves in silkeji cocoons are chiefly of the Lepido-
pterous tribes of Bcnnhjcida and Noctuidcc ; but a few

» K. Diet. d'Hist. Nal. vi. 291—.

STATES Ol- INSECTS. 215

Geometra (G. papiliofiiaria, lactearia, &c.); most of the
Hymcnoptera ; some Colcoptera, as certain of the weevil
tribe {Hi/pera Arator, Rumicis Germ.), and those bril-
hant beetles frequenting aquatic plants constituting the
genus Donacia F. ; the Neuropterous genera Hcmerobius
and Mp-tneleoji ; Mycetophila and a few others in the
Diptera ; and Pulex in the Aphaniptera fabricate cover-
ings of the same material. In all, with the exception of
Myrmcleon and Hcmerobius (and perhaps Hypera Rumi-
cis, &c.?) which have their spinning apparatus at the
extremity of the abdomen, the silken thread employed in
forming these coverings proceeds from the middle part of
the under-lip, as before explained ; and is in fact com-
posed of two threads gummed together as they issue from
the two adjoining orifices of the spinner.

Of the larvae which inclose themselves in silk, the most
familiarly known is the silk-worm : the cocoon of this
consists exteriorly of a thin, transparent, gauze-like coat-
ing, through the interstices of which can be seen an in-
ner, smaller, oval ball of a more close and compact tex-
ture. The whole is m fact composed of one single
thread, but arranged in two distinct modes. To form
the cxterioi' envelope, which is merely the scaffolding by
means of which the imier and more solid covering is con-
structed, the caterpillar, after fixing upon a space between
two leaves or twigs or angles suitable for its purpose,
begins by glueing one end of its thread to one of the ad-
joining surfaces. This thread it next conducts to another
part and then fastens, repeating this process and inter-
lacing it in various directions, until it has surrounded it-
self with a slight and loosely spun netting. In the cen-
tre of this, when contracted into a space sufficiently small.

216 STATES or INSECTS,

it lays the foundation of the interior cocoon. Fixing it-
self by its prolegs to some of the surrounding threads,
it bends its body, and by successive motions of its head
from side to side spins a layer of silk on the side oppo-
site to it : when this is of the requisite thickness, the larva
shifts its position, and repeats the same process in another
quarter, covering each layer in turn with a new one
until the interior cavity is reduced to the size desired.
Thus, the silken thread which forms this new cocoon is
not, as might have been supposed, wound circularly as
we wind the thread of a ball of cotton; but backwards and
forwards in a series of zigzags, so as to compose a num-
ber of distinct layers. Malpighi could distinguish six of
these layers^, and Reaumur suspects there is often a
greater number ^. The former found the length of the
thread of silk coafnposing them when wound off, without
including the exterior case, to be not less than &30 feet*^;
but others have computed it at more than a thousand '^ :
consequently the threads of five cocoons united would be
a mile in length. Estimating by the weight, — the thread
of a pound of cocoons, each of which weighs about two
grains and a half, would extend more than 600 miles %
and ^ch is its tenuity, that the threads of five or six co-
coons require to be joined to form one of the thickness
requisite in the silk manufacture. It is the continuous
thread of the inner cocoon which is most valuable ; the
outer loose coating from its irregularity cannot be

a De Bombyc. 24. •* i. 498.

" Dc Boinbyc. 43. ^ N. Diet. iVHisl. Nat. vi. 294.

* Lesser. L. ii. 150, note 22. Boyle says an English lady found that
the silk of a single cocoon would extend 300 English leagues or 900
miles. But this must be a mistake.

STATUS or INSECTS. 217

wound off, and is known in comniercc by the name oi'Jloss
silk.

Manoeuvres in their general principle similar to those
of the silk-worm are Ibllowed by most of those larvge
which inclose themselves in silken cocoons. Many spe-
cies, however, adopt variations in the mode of procedure
all of which it would be tedious to particularize, but some
of them are worth mentioning. The larvae of Tortrix
jyrasi7iana, and other species of moths which form co-
coons resembling a reversed boat, arrange their threads
in layers, so as to construct two parallel walls gradually
inclining towards the top and ends, where they finally
force them to approach each other by means of an appa-
ratus of silken cables ^. And the larva of Saiiirtiia Pavo-
nia^ though it forms the base of its flask-shaped cocoon by
spinnmg like the silk-worm a number of interwoven zig-
zags, places the threads which compose the interior fun-
nel-like opening of the aj^ex nearly straight, parallel to
each other, and converging towards the same point in
the centre ^.

These last, as well as almost all larvae, constantly re-
main in the inside of the cocoon during its construction.
But De Geer has given us the history of a minute cater-
pillar of a species of moth {Tinea L.) which feeds on the
under side of the leaves of the Rhamnus Frajigula, or
Black Alder, that actually weaves half of its cocoon on the
outside. This cocoon, which is very small, is beautifully
fluted, consisting of several longitudinal cords, with the
intervals filled by fine net-work, and shaped like a re-
versed boat ^. The animal begins by laying the founda-

■•' Reaum. i. 555—. ^ Platl XVIJ. Fig. 5._b.

•" De Gccr i, t. xxxii./. 3 — 6".

218 STATES OF INSECTS.

tions of one of the ends of her cocoon, she adds new
threads to this small beginning, and so proceeds. As
the work advances she retreats backwards, and her body
is situated nearly in the same line with the cocoon she
has begun, and quite out of it ; she only touches with her
head and legs its anterior margin. When half the co-
coon, or rather of its exterior layer, is finished, she sus-
pends her operations for some moments. She then for
the first time introduces her head iiito this demi-cocoon,
and turns herself in it by doubling her supple body, and
passing one part over the other, so that at last she ma-
nages to bring her tail into the pointed end of the cocoon,
the head and the anterior half of her body remaining
without. Thus situated, she commences her operations
afresh. At a distance from the margin of the demi-co-
coon, equal to its length, she begins to spin the pointed
end of the other moiety, the length of her body serving
her as a measure that enables her to begin at the proper
distance from it. This new portion she spins in the same
manner as the other ; but as she is prevented by the demi-
cocoon in which the posterior part of her body is lodged
from retreating backwards, she contracts her body more,
which answers the same purpose. When the new work
is so advanced that she can no longer contract her body,
she bends the anterior part of it considerably, and re-
verses her head. When the distance between the mar-
gin of the two halves of the cocoon is very small, so as no
longer to admit the head between them, in order to unite
them she is obliged to have recourse to another manceu-
vre. Withdrawing her head, she extends silken longitu-
dinal threads between the two margins, and thus unites
them. This part is more clumsy, and not so regular as

STATliS OF INSECTS. 219

the rest of the cocoon, so that the point of union is always
discoverable. These caterpillars do not always divide
the cocoon into two cqtial portions, for often they will
finish three quarters of the cocoon before they enter it,
and begin at the other end *.

The general rule is, — that each larva spins for itself a
separate cocoon; but amongst those ol Arctia clirysorhca
and others which live in society, two or three sometimes
begin their operations so close together that they are
under the necessity of forming one common cocoon, which
serves for a covering to the whole number. The same
thing happens to silk-worms, the double or treble cocoons
of which are called Dupions by the breeders. The larvsB
of some Ichneumons, besides forming each its separate
cocoon, spin a joint cottony covering for the whole ^,
which is effected thus: — After they leave the caterpillar
they have devoured, they fix themselves side by side at a
little distance from it, and begin to spin each a cocoon ;
and in order to defend its end and side that is not covered
by others, they spin further an envelope of loose silk,
and thus this exterior covering is formed.

The size, figure, colour, substance, and textiu'e of
silken cocoons are extremely various. Their size indeed
is usually proportioned to that of the included larva or
pupa ; yet it is by no means always so. Some large ca-
terpillars spin cocoons so small, that the observer can
hardly conceive how they can be contained in so narrow
a compass ; Eriogaster Catax is a moth of this descrip-
tion *=. And others smaller in size lodge themselves in

=> Dc Geer i. 463—,

'' Reaum. ii. Mem. xi. Coinp. De Geer ii. 162. Reaiini. ii. 434.

' B. Catax — Pupa arete folliculata. Fab.

220 STATES OF INSECTS.

apartments apparently much more spacious than neces-
sary. The transparent hammoclc-hke cocoons of Uepi-
alus Hitmidi and Arctia vUlica, two other moths, would
contain several of their pupae. I possess one in which
the pupa is suspended in the centre, that is ten times its
size, and not very short in dimensions of that of Atfaacs
Paphia^ a giant silk-moth. The largest cocoon I ever
read or heard of, is that thus described by Mr. Hobhouse
in his Travels: "Depending," says he, "from the boughs
of the pines, near the Attic mountain Parnes, and stretch-
ing across from tree to tree so as to obsti'uct our passage,
were the pods, thrice as big as a turkey's egg ! and the
thick webs of a chrysalis, whose moth must be far larger
than any of those in our country." * If this statement
is correct, and I am not aware that there is any reason
for doubting it, the cocoon must be vastly larger than the
pupa, or the moth it produced would far exceed in size
any yet known. Perhaps, however, as this gentleman is
probably no entomologist, what he took for a cocoon
might be a nidus, in which many larvae were associated,
of the nature of those formerly described ^.

With regard io^gure, the majority are like those of
the silk-worm, of a shape more or less oval or elliptic :
some, however, vary from this. That of Lasiocampa
Huhi is oblong. I have one from New Holland some-
what resembling an acorn, fixed to the twigs of some tree
or shrub, of a very close silk, and covered by a circular
operculum, which the animal pushes off when it assumes
the imago; this is ovate or conico-ovate; others again are
globose*^; others are conical "^j as that of Gastropacha

■ Traveh in Greece^ 285. '' See above, Vol. I. p. 476 — .

* Merian Surinam, i. xv, '* Reauni. ii. t. xxiii./. 5.

STATES OF INSFXTS. 221

quercifolia ,- othei's almost tusH'onn* [Odenesis potatoria).
lieauniiir received one from Arabia wliich was iieaily
cylindrical ''. Those of T. lirusinana before noticed, and
many other Tortrices, are shaped like a reversed boat *= ;
that of Saturnia Pavonia and others of the same tribe,
like a Florence flask with a wide and short neck. The
cocoon of Lijgicna Filipcnduhc resembles a grain of bar-
ley. Another cocoon in my cabinet, of very slight net-
work, is shaped something like an air-balloon. But the
most remarkable one for its form and characters, is one
that I received from the rich cabinet above quoted. This,
which is of an unusually close texture, is suspended by
a thread more than two inches long from the point of a
leaf; it then swells into a perfect cone, at the base about
four-fifths of an inch in diameter and half an inch in
length, and covered with scattered setiform appendages :
from the centre of the base projects a large hemispherical
protuberance, which terminates in a long stalk, much
thicker than the thread that suspends the cocoon. There
is commonly no difference between the shape of cocoons
spun by larvae which are to give birth to different sexes of
the same species. The silk-worm cocoons, however,
which will produce male moths, have more silk at the
ends, and consequently are more round than those which
are to produce females : but the difference is not strik-
ing.

The most usual colon)- of silken cocoons is white, yel-
low, or brown, or the intermediate shades. The whites
are very pure in the general envelope of some species
of Iclnieumotiidcr^ and yellows often very brilliant. But

* Sepp. iv. t. viii./. 5. '' Reauin. i. t. xiiv./. 2.

' Pi.ATi:XVII. FiG.7.

222 STATES OF INSECTS.

besides these more general colours, some cocoons are
black ^, some few blue or green, and others red ^. Some-
times the same cocoon is of two different colours. Those
of certain parasites of the tribe of Ichneumones minuti L.
the motions of one of which I noticed on a former occa-
sion *^, are alternately banded with black or brown and
white, or have only a pale or white belt in the middle,
which gives them a singular appearance. In both cases
the difference in colour depends upon the different tints
with which the silky gum is imbued in the reservoirs :
the first portion of it is white, and with this the larva
first sketches the outline of its cocoon, and then thickens
the layers of silk considerably in those parts where the
white bands appear : when these are finished, its stock
of white silk is exhausted, and the remainder of the inte-
rior of the cocoon is composed of brown silk ''. The cir-
cular operculum above mentioned as covering an acorn-
shaped cocoon, is paler than the latter, and also orna-
mented by a zone within the margin of deep brown.
The pale cocoon also of Attacus PajpJiia is veined with
silk of a deep red.

I have very little to say on the substayice of the silk of
cocoons. Though that of the silk-worm is composed of
such a slender thread, that of many others is still finer,
scarcely yielding in tenuity to the spider's web. On the
other hand, the silk of the cocoons of Satur7iia Pavonia
and of several foreign species is as thick as a hair.

With regard to the texture of their cocoons — in some,
as in that of the silk-worm, the threads are so slightly

^ I have a black one from Mr. Francillon's cabinet.

b .V. Diet, d'llhf. Xat. vi. 294.

«^ See above, Vol. II. p. 298—. '' Reaum. ii. 438.

STATES OF INSECTS. 223

glued to each other, ns to separate with facility ; but in
that of the eniperor-moth just mentioned they are inti-
mately connected by a gummy matter, furnished, as
Reaumur conjectures, from the anus ^, with which the
whole interior of the cocoon is often plastered. Some,
as that of the silk-worm, are composed of an exterior
loose envelope, and an inner compact ball ; others have
no exterior covering, the whole cocoon being of an uni-
form and thick texture. The larva of Cossus RobinicB
Peck, in spinning its cocoon, makes the end next the
openmg to the air, by which the imago is to emerge, of a
slighter texture than the rest of it ^, The exterior case
is sometimes, as in Laria pudibu?ida, very closely woven,
so as to resemble a real cocoon *= : its form is usually
adapted to that of the inner one ; but in some which fix
them under flat surfaces {Laria Jascelina, Callimorpha
Caja,) it resembles a hammock''. Cocoons of a close
texture have generally no orifice in any part; but that of
Eriogaster lanesiris is spun with openings, as if bored
from without, the use of which, however, does not seem
to have been ascertained*^.

Many silken cocoons are of so close a fabric, as, when
finished, entirely to conceal the included insect; but a
very considerable number are of a more open texture,
composed of a much smaller quantity of silk, and that
woven so loosely, that the larva or pupa may always be
discovered through it. Of this description are the co-
coons of Hi/pogymna dispar, Arctia Salia's, &c., which
consist only of a few slight meshes. Those of some others

* Reaum. i. 503. •> Peck on Locust-tree Insects, 60.

•^ Bonnet ii. 260. "^ Sepp. iv. /. ii,/. 4.

' Brahm. Ins. Kal. x'89.

224 STATES OF INSECTS.

resemble gauze or lace ^. Of the first description is one
in my cabinet before alluded to, shaped somewhat like
an air-balloon ; the meshes are large and perfectly square.
The pupa hangs in the centre, fixed by some few slight
threads which diverge from it to all parts of the cocoon —
so that it looks as if it was suspended in the air, like
Mahomet's coffin, without support. Of the second de-
scription is a black one with very fine and nearly circular
meshes : the threads that form these are thick, and seem
to be agglutinated. In our own country, the cocoons of
some beetles, as oiHypera Arator, Galeruca Tanaceti^ and
of some little Tinecc, also resemble gauze. Many of the
larvae, however, which spin these cocoons, whose thin-
ness is probably attributable to the smallness of their
stock of silk, seem anxious for a more complete conceal-
ment ; and therefore commonly either hide them between
leaves tied together, in some with a certain regularity,
in others without art''; or thicken their texture, and
render it opaque, by the addition of grains of earth *=,
or of other materials with which their bodies sup-
ply them. These are principally of two kinds. The
larvae of Lasiocampa Neustria, Arctia Salicis, &c. after
spinning their cocoons, cast from their anus three or four
masses of a soft and paste-like matter, which they apply
with their head all round the inside of the cavity ; and
which, drying in a short time, becomes a powder that
effectually renders it opake. This is not, as might be
conjectured, an excrement, but a true secretion, evidently

^ Plate XVII. Fig. 8.

^ The thick cocoons of Attacus Faphia, Polt/'phevuis, Sec. are also
thus fastened between leaves.
'^ Merian Eiirup. ii. /. ix.

STATES OF INSECTS. 225

intended tor this very purpose: iind, according; to Reau-
mur, a similar powder, but white, derived from the vari-
cose intestines, is used by the caterpillars of Gastropacha
quercifulia, &c. * The other niateritil, which is still more
frequently employed, and which is occasionally mixed
widi the former, is the hair which every one has observed
to cover so thickly the bodies of some caterpillars. This,
after spinning a sufficient envelope, they tear, or in some
instances cut off with theii mandibles, and distribute all
round them, pushing it with their lieatl amongst the in-
terstices of the silk, so as to make the whole of a regular
thick texture. After this process, which leaves the body
completely denuded, and often seems to give them great
pain, they conclude by spinning another tissue of slight
silk, in order to protect the forthcoming pupa from the
sin-rounding prickly points. It should be observed, how-
ever, that though many hairy larvae, as those of Noctua
Aceris, Arctia Caja, and others, employ their hairs in the
composition of their cocoons, the rule is not general,
several never making any such use of them. Nor do all
that do so employ them distribute them in the same man-
ner as those above described, which rarely attempt to
arrange them in any regular position. Reaumur has no-
ticed a small hairy caterpillar that feeds on lichens, which
is more methodical : this actually })laces its hairs upright,
side by side, as regularly as the pales in a palisade, in
an, oval ring around its body, connecting them by a slight
tissue of silk, which forces them to bend into ti sort of
roof at the top ; and under this curiously-formed cocoon
assumes its state of pupa ''. Home larva; make so much

• Reaiiin. ii. 284. '' Ibitl. i. 524.

VOL. m. o

22G STATES OF INSECTS.

hair aiid so little silk enter into the composition of their
cocoons, that on the first inspection they would be pro-
nounced wholly composed of it * ; others, thickening the
interior of their cocoon with hair, line the whole with a
viscid matter like varnish ''.

The larvae of some saw-flies {Tenthredo L.) are re-
markable for inclosing themselves in a double cocoon, in
which the inner is not, as in the silk-worm &c., connected
with the outer, but perfectly distinct from it. Some spe-
cies, as T. RoscE [Cryptus Jm*.), which have but a small
stock of silk, compose the outer cocoon of thick silken
<!ords crossing at right angles, and forming an oval net;
which at the same time that it protects them effectually
from the ants, which are always ready to attack them, de-
mands much less silk than a covering of a closer texture.
But the tender nymph itself requires to be inclosed in a
case of a softer and more delicate substance ; and accord-
ingly the inner cocoon is composed of fine silk, woven
so closely that the threads are scarcely perceptible under
a microscope '^. Reaumur mentions a hymenopterous
larva belonging to Latreille's Fossores [Sphex L.) which
thickened its cocoon with the legs, wings, and other relics
of the flies which it had devoured'': trophies — like the
drinking- cups of some savages, made of the skulls of their
enemies, or the skull pyramid near Ispahan — of its
powers of devastation.

It is a general rule, that those larvae which spin co-
coons, never in ordinary circumstances become pupee
without having thus inclosed themselves. An exception,
however, is met with in the larva of a species of ant no-

•» Bonnet ii. 297. " Ibid, ix. 181.

'■ Reauni. v. 102. ^ Ibid. iv. 2G9.

STATES OF INSECTS. 227

ticed by De Geer [Formica J'usca L.), some of the indi-
viduals of wliich inclose themselves in cocoons; while
others neglect this jirecaution, and undergo their meta-
morphosis uncovered ^. Rosel also made^ nearly the
same observation on the larva of the flea ''.

I must say something with regard to the situation,
often very remote from their place of feeding, in which
larvae fabricate their cocoons. A very considerable num-
ber, probably the majority, form them either partially
{Arctia lubricipeda) or wholly under ground; others
beneath dead leaves, moss, or in the chinks of the trees ;
others within the wood in substances on which they
have fed ; the larva of Cossus leaves in these a communi-
cation with the open air by which the imago emerges ;
and a lar^e number attach them to the leaves and
branches of trees and plants ; the cocoon of Donaciafas-
ciata(?) is fastened by one side to the roots or surculi of
Typha latifolia. There is usually nothing very remark-
able in the mode of fixing them, the exterior threads
being merely gummed irregularly to different portions of
the objects which support them. But some effect this with
greater art. I have one from New Holland, very long,
which is suspended from a twig by a long riband, as it
were, which entirely girths the twig. The larva of the
magnificent silk-moth, Attaais Papliia, actually forms a
solid silken stalk to its cocoon, an inch and half in length

* De Geer ii. 1084. Comp. Ray Hist. his. Praef. xi. It is the opi-
nion of M. P. Huber, that in this case the naked pupae are deprived
of their cocoons by the neuters : he states, indeed, that he has often
seen them pulled off by them, and also by those of F. cunicularia ;
and he seems to think that these larvae are never developed. Moeurs
des Fourmis, 84. note 1.

'' II. viii. 16.

Q2

228 STATES OF INSECTS.

and a line in diameter, fastened by the other extremity
to a twig, which it closely surrounds as if with a ring,
at first sight resembling a fruit of a very singular ap-
pearance ^. I have specimens of this cocoon with both
stalk and ring. A bell-shaped cocoon fastened by a foot-
stalk, but of softer consistence, to a blade of grass, found
by Mr. Sheppard, I can also show you ; and my friend
Mr. Wilkin had a similar one out of the late Mr. Hud-
son's collection. Most larvae spin their cocoons in soli-
tude: some of those, however, which live in society do it
close together under their common tent.

There are other cocoons that should be noticed here,
such as those formed by the larva of Zygcena Filipendnlte,
and some Bomhyccs, saw-flies [Tenthredo L.), and bee-
tles [Curculio, Donacia F.), &c. These are formed of
a substance which seems more analogous to gum than
silk, yet furnished from the silk reservoirs, and usually
present the appearance externally of parchment or mem-
brane. That of the insect first mentioned is coated,
however, with a slight interior silken lining; as indeed
are almost all cocoons, of whatever substance.

The seco?i(I class, into which I have divided larvae that
inclose themselves in cocoons, includes those which form
their coverings not solely or principally of silk, but in
which other materials are mixed more or less. The co-
coons of some of these larvae are merely composed of a
few leaves slightly tied together, either irregularly, or ar-
ranged, particularly when they are of a linear figure, with
considerable symmetry. The grubs of many beetles, as of

' Linn. Trans. \ii. /. \\.f. 5, G.

STATF-S «)1. INSECTS. 229

the rose-beetle, Cetunia a/na/u, Ike, prepare themselves a
cocoon, composed of earth, pieces oi rotten wood, and any
substances within their reach; whicli tliey iasten togetlier
with a ohitinons secretion. The same material is employed
by others in forming a cocoon wholly of earth; v\hicii
is sometimes, as that of the stag-beetle, Lucaniis Ccr-
vtis, exceedingly hard ; at others, as tliat of some moths,
Noclna ambigua, &c., so slight as to fall to pieces as soon
as touched •\ Other cocoons are formed of grains of
earth. Reaumur has given a very interesting account of
the proceflures of a larva in repairing one of these co-
coons, from which he had broken off" the top when just
completed. Without quitting the interior of the walls
that remained, it put out its head from the breach, and
for more than an hour employed itself in selecting one
by one grains of earth, which it conveyed with its mandi-
bles and deposited within its case : it next spun all round
the opening threads of silk, to which it attached grains
of earth taken from the previously-stored heap, uniting
tliem compactly by means of other silken threads. After
employing three hours in this laborious process, the in-
dustrious Httle mason had reduced the diameter of the
breach to a few lines. Reaumur was very curious to
know how it would fill u}) this orifice, which would no
longer admit the protrusion of its head outside the walls,
as in its previous operations. He concluded, that while
the rest of the cocoon was exteriorly formed of earth,
this opening would be merely closed with silk. He was
mistaken, however: the artist knew how to vary its

•' Witfu. Vcrz. I possess a cocoon of this kind fioin New Hol-
land, even now (juite solid, and retaininir its form. No silk appears
to have been used in il^ coni|)ositioii.

230 STATES OF INSECTS.

manoeuvres, and make its vault of one uniform texture.
It spun across the opening a little net of silk, between the
meshes of which it thrust grains of earth so dexterously
that they projected as far as the outer surface, retained
there probably by silken lines previously attached and
fastened within. It then finished its habitation by forti-
fying the inside of the orifice with another layer of earth*.
The ant-lion [Myrmeleon) spins a globular cocoon with
its anus, which it covers with grains of sand ''. One that I
took in the forest of Fontainebleau, in the quarry that pro-
duces the crystallized sandstone called the Fontainebleau
Jbssil, was covered with large and shining grains. Instead
of the grains of earth or sand employed by these larvae,
those of another tribe substitute grains of stone detached
from the softer walls, upon whose lichens they previously
feed, which they unite into solid oval cocoons *=. Those
of a fourth form their cocoons of patches of short moss
arranged with the roots downwards, and forming a vault,
as it were, of verdant turf, admirably adapted for con-
cealment ^. The larvae of some moths form their cocoons
of irregular pieces of bark tied together with silk, and
resembling when completed a knotty protuberance of the
twig on which they are fixed. That of Pyralis tuhercu-
lana constructs a panniei'-shaped one of the parenchyma
of the leaves of plants ^.

All these cocoons, however, must yield in point of
singularity of construction, materials, and ingenuity, to
one formed by a small caterpillar, described by the illus-
trious naturalist lately quoted, which feeds upon the oak.
This cocoon is wholly composed of small rectangular

■' Reaum. i. 579. ^ Ibid. vi. 368. ' Ibid. i. 542.

•< Ibid. 543. '■ Linn. Trans, i. 196.

STATES Ol- IN. SIX IS. 2Sl

strap-shaped pieces of the fine upper skin, or epidermis
of tlie twig upon which it rests, regularly fastened to each
other in a longitudinal direction with very slender silken
cords. But the mode of its construction is even more
remarkable than the substance of which it is fabricated.
The caterpillar's first process is to form its slips of bark
into two flat triangular wing-like pieces, projecting oppo-
site to each other from each side of the twig, somewhat
like the feathers of an arrow. It does not, perhaps, re-
quire any gi'eat degree of intelligence in a larva to give
its cocoon the usual oval form, when it begins to arrange
its materials in that shape from the very first, and round
so good a mould as its own bent body; but we surely must
admit that it is a task to which no stupid artist would be
competent, to form first a multitude of strap-shaped la-
minae into two triangular plates, and then to bend these
plates into a case resembling the longitudinal section of a
cone, with an elliptical and protuberant base, — the figure
which the cocoon of this insect assumes. All the minu-
tiae of the manoeuvres which it employs in this nice ope-
ration could not be comprehended without a more diffuse
explanation than I have here room to give : suffice it to
say, that the caterpillar fastens silken lines to each exterior
opposite and longer side of the laminae, and by applying
all the weight of its body forces them to bend and ap-
proach each other, in which position it secures them by
other shorter lines. It next repeats the same process
with the upper and shorter sides of the plates; which
when joined form the base of the cocoon. Both these
tasks are accomplished in less than an hour, and the seams
are so nicely joined as to be imperceptible. A fine inner
tapestry oi\silk, covering all the asperities of (he exterior

232 STATES OF INSECTS.

walls, concludes its laboiirs ^. It is to be lamented that
Keamiiur was unacquainted with the moth that proceeds
from the pupte inclosed in these ingenious cocoons ;
which being small, and precisely of the same colour as
the bark of the twig that supports them, are not to be
discovered but by a very narrow inspection. It would
seem, however, to be Nochia Sfrigtda of Berkhausen,
Pj/ralis strigulalls of Hubner ^. The larva, he informs
us, is found in May : its body is flatter than common, of
a yellowish flesh-colour, clothed with tufts of red hair on
each seiiment, and furnished with fourteen feet. Should
this description enable you to detect it upon your oaks,
a view of its ingenious procedures would amply repay
you for the trouble of seeking for it. The larvae of Ce-
i-ura xnnula, Sfaiavjms Fagi, and several other moths,
form their cocoons of grains of wood gnawed from the
trees on which they feed. These grains they masticate,
mixed with a glutinous fluid secreted from the mouth,
into a paste, which forms a covering of an uniform smooth
texture, and so hard as not readily to yield to a knife.
Of a substance apparently nearly similar is composed
the cocoon of a weevil related to Liparus Pini ; which
with its inhabitant was given me by the ingenious Mr.
Bullock. A little moth, whose ravages have been before
noticed % lines the interior of the grain of barley, of
which it has devoured the contents, with silk ; divides it
into two apartments, into one of which it pushes the ex-
crement ithad voided, and in theother assumes thepupa'^.
These, and the other larva? mentioned above, com-

•' Reaum. i. 545—. ^ Pt/ral. 8.3. /. iii./. 16.

'■ Sec above, Vol. I. p. 1/2 — .
'• Reaum. ii. 4U1.

STATES OK INSECTS. 233

monly iorm their cocoons of the substances I have indi-
cated ; but when by an}- cause they are prevented from
access to them, they often substitute such other materials
as are at hand. Reaumur fed a larva that formed its
cocoon of minute fragments of paper, which with its
mandibles it had cut from the piece that covered the glass
vessel that contained it ^ : and the same circumstance
happened to Bon)iet.

Upon a former occasion I tlescribed to you the cases
of various kinds formed and inhabited by the insects of
the Trichoptcra Order {Phtyganea L.) commonly called
case-worms ''. As these serve for the pupa as well as
the larva, they may be regarded as a kind of cocoon. I
shall not repeat here what 1 then said ; but having pur-
chased from the collection of the late Mr. Francillon
some that seem to belong to this or some cognate tribe,
that are of a curious construction, I shall give you some
account of two or three of them in this place. The first
is not quite three inches long, of a sublanceolate sluipe,
but rather widest towards one end. It consists of an in-
ternal tough and thick bag or cocoon, of a silk resem-
bling fine wool of a dirty white colour, which is closely
covered transversely by })ieces of the stalk of a plant,
about three-fourths of an inch in length, and crossing
each other at an obtuse angle. The next is thicker and
shorter: the internal bag is just covered with small frag-
ments of wood like sawdust ; over these are fastened ir-
regularly, short stout pieces of a pithy stick or stalk, and
tlie whole is clothed with a very close- woven ash-co-
loured web. It seems diflicult to conceive how the in-
closed animal could contrive to cover her habitation with
' Reauni. i. 540. ^ See ab^'V'% \\n.. I. 167 — . 11. -t»t.

234- STATES OF INSECTS.

this web without going wholly out of it. The third is
the most curious and remarkable of all. It is nearly six
inches long, and about four-fifths of an inch in diameter.
It consists of a bag of thick cinereous silk web, to which
are fastened, in a sextuple series, pieces of stick about an
inch long, the end of one mostly resting upon the base of
another: between each series a space of about three-tenths
of an inch intervenes, but at the apex they all converge.
This probably imitates the branch or stem of some tree
or plant, in which the leaves are linear, and diverge but
little from the stem. A label upon it states its country to
be New Holland. I suspect the inhabitants of the two
last cocoons to be terrestrial animals : the first is proba-
bly a true aquatic case-worm.

The same purpose for which the cocoons above de-
scribed serve, is answered in the case of numerous Di-
pterous insects, by a humble and less artificial contriv-
ance— the skin, namely, of the larva; which, as was be-
fore observed *, is never cast, but, whe^ the insect is about
to enter into the pupa state, assumes a different form and
colour; becomes of a thicker and more rigid texture;
and defends the included pupa, which is separate from it,
till its exclusion. In this case the mouth of the larva is
constantly different from that of the perfect insect, or at
least has not with it those relations as to number and
kind of organs, which have been observed in the mouth
of other larvae compared with the insects that they pro-
duce. The animal, immediately after it is clothed with
this skin, if it is opened, exhibits only a soft gelatinous

■■• See above. Vol. 1. j). (i7.

STATES OF INSECTS. 235

pulp, in the surface of which the exterior organs of the
adult insect cannot yet be detected. Nature requires
more time for their elaboration, or at least for the ap-
pearance of their outline, and to consolidate them. This
pulp first takes an oblong iorin [Baide allongce Ileaum.),
and afterwards that of the insect it is destined to give
birth to =*. The skin of the larva also serves for a cocoon
to the pupa? of male Cocci ^. The grub of the genus An-
ihrenus, so destructive to our cabinets of natural objects *^,
when it assumes the pupa does not quit its skin, but only
splits it open longitudinally on the back, and when it
becomes an imaijo makes its exit through the orifice '^.
Some Lepidopterous larva? even [Ahicita licntadactyla^
Callimorpha 7'osea, &c.) assume the pupa state within
their last skin ^

When a larva has finished its cocoon, — which with

» N. Did. (THist. Kat. xvi. 269—. xxii. 76.

'' Reaura. iv. 32. The author here quoted asserts that the grub of
Ichneumon Lurvarum L. retains its skin, which, he says, is so trans-
parent that the form of the nymph can be seen through it. Ibid. ii.
447. Dc Gecr, however, found that this really did cast its skin,
which is so transparent as to be scarcely visible, by pushing it gradu-
ally towards the anus, wHere it soon dries up and cannot then be dis-
covered. De Geer ii. 893 — . According to Rosel the same circum-
stance attends the transformation of Coccinella renipiistidata Illig.
(C. Cacti Ent. Brit.), which at first perplexed him not a little. It is
probable that in this case the retention of the skin was accidental ;
for some of the grubs of a MyceiophtLa, the transformation of which
I observed, became pupae within their last skin, while others wholly
disengaged themselves from it. The cause of this variation, I con-
jectured, arose from the former being too weak to extricate them-
selves from the skin.

•^ See above, Vol. I. p. 238. Byrrhus Musceorum belongs to this
genus.

•< .V. Did. d'Hid. Nat. ii. 161. *• Pczold. 102.

236 STATES OV INSECTS.

some species, that proceed so earnestly as though they
had not a moment to lose, is the work of a few hours, of
others about two or three days, — after a certain interval
it casts its last skin, which is usually suffered to remain
in the cocoon (but which one moth, Geometra lacertinaria,
ejects through an opening purposely left in its bottom),
and the pupa makes its appearance ^. This interval is
exceedingly various. Most larvae assume the pupa state
within a few days after they have formed their cocoons ;
but some not for several weeks, or even months. The
caterpillar of ^ow^yj:' cceruleocephala, according to Riisel,
lies three weeks in the cocoon before this change is ef-
fected ; those of many Pupivora and Diploleparicc Latr.,
according to Reaumur, six months '' ; that of Phalcena
urticata nine months "^ ; and that of Cimhex lutea, accord-
intr to De Geer, sometimes eighteen months ^. Brahm
observes, that such larvae of the double-brooded moth,
Hepialus Testudo, as form their cocoons in autumn, do
not become pupae until the following spring ; while those
which form them in summer undergo this change in a
few days^. From this fact it might be conjectured, that
the degree of heat pi'evailing at the time the insect in-
closes itself determines the period of the pupa's appear-
ance ; but this supposition seems contradicted by what
Reaumur observed of a brood of the larvae of Phalceyia
urticata, just mentioned, which, though they formed
themselves cocoons in September, did not become pupae
till the June following ^ I am unable, therefore, to as-
sign any plausible cause for these extraordinary varia-

» De Geer i. .339—. " Reaum. ii. 423, and iii. 497-

' Ibid. i. 605. '' De Geer ii. 941.

' Brahm Insek. 72. ' Reaum. nbi .supra.

STATES OF INSECTS. 237

tions. The diiliculty of coniprchcnclino; liow animals be-
fore so voracious can live so loii<^ without food may be
partly surmounted, by adverting to the circumstance of
its having attained its full growth, and laid up a store of
nutriment for the development of the perfect insect. It
is consequently no more wonderful that it should not
liave need oi' any further supply without casting off its
upper integument, than that it should not eat after liav-
ing done so and become a pupa.

LETTER XXXI.

STATES OF INSECTS.

PUPA STATE.

We have now traced our little animals through their
egg and larva states, and have arrived at the third stage
of their existence, the Pupa State. This, to include all,
can only be defined, — that state intervening between the
larva and iniago, in which the parts and organs of the
perfect insect, particularly those of sex, though in few
cases fully developed, are prepared and fitted for their
final and complete development in the last-mentioned
state; and in which the majority of these animals are
incapable of locomotion, or of taking food.

Pupae, like larvae, may be separated into two great di-
visions : —

I. Those which, in general form, more or less resem-
ble the larvae from which they have proceeded.
II. Those which are wholly unlike the larvae from
which they have proceeded.

I. To the first division belong, with some exceptions*,

* In the Hemiptera the male Cocci (Reaum. iv. 32.) and Aleyrodes
(Ibid. ii. 311.) belong to the second division.

STATES or iNsr.cTs. 239

\\\cl)ermciptt)a, Orlhoptera^Hcmiptera^an^X most Aptern^
witli the iieuropteroas tribes of Libellulina, l')phemerina^
and the genus Termes, in the qlass Insectu; and the majo-
rity of the Arachnida. This, Hke the first division of
lacvie, may be subdivided into two corresponding smaller
sections ; the first inchiding those pupa; which resemble
the larvos, except in the relative proportion and number
of some of their parts; and the second those that resem-
ble them, except in having the rudiments of wings, or of
wings and elytra.

i. The first subdivision will include the pupae, if they
may be so called *, of insects of the Aptcra order, and of
the class Arachnida : as, lice, Podurce, LepismidcE^ centi-
pedes, millipedes, mites, harvest-men, spiders, scorpions,
&c. These mostly differ from their larvae only in that
the relative length or number of their legs, the number of
the segments of the body in some, or the development of
their palpi, more nearly approach the characters of the
perfect msect ; and in that while in their larva state they
have two or more skins to cast, previously to their assump-
tion of the imago, in their pupa state they have but one.
In fact, this last circumstance is the only one which,
strictly speaking, characterizes the pupae of this subdivi-
sion ; as the changes which take place in the number and
proportion of the organs are partly produced with each
change of the larva's skin. And hence, as it is not easy
to ascertain what number of skins a spider, for example,
has yet to cast, and as both the larva and pupa differ so
little from the perfect insect, it is very difficult to deter-
mine in what state insects of this division are. From

' • The terms larva aaA pupa, applied to the insects of this subdivi-
sion, arc perhaps not strictly proper.

240 STATES OF INSECTS.

this difficulty has {)r()bably arisen the too great multipli-
cation of species in some of these tribes, particularly the
AracJmida, the larva and })upa having been mistaken for
perfect insects. The pupa; of this subdivision were
named by Linne complete, from the near resemblance
which they bear to the imago.

ii. The second subdivision will include the pnpa? of
the Dennaptci'a, Ortkoptera and Hemiptera orders, with
few exceptions ; as likewise the Libellulina, Ephemcriiia,
and Termitina ? amongst the Neuroptera : including the
well-known tribes of earwigs, cockroaches, crickets,
grasshoppers, locusts, lanthoi'n-flies, froghoppers {Ci-
cada L.), bugs, plant-lice, dragon-flies, day-flies, white
ants, &c. Of these, as in the former subdivision, the
pupae are equally cai)able of eating and moving with the
larvae, which they resemble, except in having the rudi-
ments of wings, or of wings and elytra. The pupae of
the three orders first enumerated differ from those of the
Neuroptera in resembling the perfect insect in most in-
stances, both as to shape and the organs for taking their
food ; and in all other respects, except in not having their
wings and elytra fully developed ^. The resemblance of
the pupae of the Libelhdina and Ephemerina to the per-
fect insects is more distant, and the above organs in the
two states are very dissimilar ; for the pupae of the former
are furnished with a prehensory mask similar to that .of
the larvae before described ^, which the perfect insect has

^ The larvas iind pupae of many of the homopteroiis section o( Hemi-
ptera differ often from the imago, not only in their fore-legs (Plate
XVI. Fia. 4.), but also in other respects. I have the larva of a Ce7i-
trotus from Canada, given me by Dr. Bigsby, which has a long anal
process or tail. '' See above, p. 125— .

STATES OF INSECTS. 24<1

not; and those of the hitter with the usual oral oriraus of
masticntinf^ insects, of which the imago has scarcely the
rudiments.

I have applied the term rudiments to the wings and
elytra in this state, not in a strict sense, but merely to
denote their appearance; for in fact the wings, &c. are
complete, but only folded up longitudinally and trans-
versely, and inclosed in membranous cases, which when
the last change takes place remain attached to the pupa-
rium or pupa-case. The tegmina or hemelj'tra in this
state usually cover the wings, and the upper wings the
under ; but in the Libellulina both are usually visible.
Though commonly very small compared with the instru-
ments of flight in the perfect insect, some of these rudi-
ments, contrasted with the majority, are of considerable
magnitude. This is the case with those of some species
of Chermes, as we learn from De Geer ^.

II. The second grand division comprises by far the
largest number of pupas : those of all coleopterous, strepsl-
pterous, lepidoptcrous, hymenopterous, dipterous, and
aphanipterous, and by far the majority of ncnropterous in-
sects, as well as the hcmiptcrous genus Aleyrodcs, and one
sex of Coccus of the same order. These pupae, however,
though agreeing in the circumstance of being unlike the
larvse from which they proceed, differ from each other in
several respects, and require to be divided into three
great sections, as under: —

i. Those pupas in which the parts of the future insect,
being folded up under a membranous skin closely apply-
ing to each, are distinctly xnsible. To this head belong

» Hi. 135.

VOL. III. R

24-2 STATES OF INSECTS.

generally, the pupae of coleopterous * and hymeriopterous
insects ; those of the neuropteroiis genera Myrmeleo7i and
HemerohiuSy &c. ; the Trichoptera; amongst the Diptera,
Culex, Tipula L., Tahajius, Bombylius, &c.; and that of the
flea [Pulex). These were the incomplete pupae of Linne.

ii. Those pupae in which the parts of the future insect,
being folded up under a harder skin, are less distinctly
discoverable. To this subdivision belong the pupae of all
Lepidoptera^ and of them alone. These are what Linne
termed obtected pupae.

iii. Those pupae which are inclosed in the thick and
opaque skin of the larva, through which no trace of the
perfect insect can be discovered. These, which Linne
termed coarctate pupae, include a large proportion of the
dipterous genera; as (Estrus L., Musca L., Etnpis L.,
Conops L., &c. &c. '*

* The pupae of Cassida, Imaticliuni, &c. seem to vary somewhat from
this type, the upper part being neither membranous nor exhibiting
distinctly the form of the inclosed imago.

*> The following arrangement of pupaD is perhaps in some respects
better than that above given. But it is scarcely possible to propose
one free from objections.

I. Capable of eating and walking.

i. Like the perfect insect, except in proportion and number
of parts.

1. Except in proportion {Lice, Podurce, Mites, Spide/s,

Scorpions, &c.).

2. Except in proportion and number {Centipedes, mille-

pedes').
ii. With rudiments of the organs of flight.

1 . With oral organs resembling those of the perfect in-

sect {Heiniptera).

2, With oral organs differing from those of the perfect

insect {Libellula L., Ephemera L.).

II. Incapable of eating and walking.

i. Incomplete pupae,
ii. Obtected.
iii. Coarctate.

STATES or INSECTS. 21-3

I shall next advert, chiefly to the pupae ot" the oiaml
division last described, under the distinct heads of" si/h-
stance, ^figure, anil parts ,• colour, age, sex, juo/iofis, and
extrication of the perfect insect

i. As to their substance — at first interiorly all pupre
consist of a milky fluid, in which the unformed members
of the future perfect insect mx\y be said to float, and in

Lamarck tlivide^ the pupae of insects that undergo a metamorphosis
into three kinds, wliich he names — C/uysalis, Mumia, and Ki/in2)h(t.

i. Chrysalis. Under this denomination he includes all inactive
pupae inclosed in an opaque puparium which entirely conceals them.
These he further subdivides into two kinds.

1. C/n-i/salis signata. This term is synonymous with the Pi/pa
obtectn of Linne, or the Clirysalis of Lepidoptrrct and some Diptera.

2. Chri/salis dolioloides. Equivalent to the Pupa coarctata \X\\\\.
peculiar to those Diplera that assume this state in the skin of the
larva.

ii, Mumia. All inactive pupa2 which are covered by a transparent
skin, through which all the parts of the inclosed imago may be seen,
subdivided also into two.

1. Mumia coarctata. Cofresponding with the Pupa incomplcta
Linn., which includes the Colcoptcra and most of the Hymenojitera.

2. Alumia pscudnnympJia, confined to the Pupa of Phryganea and
some others. This might be named Pupa subincomplcta.

iii. Xtjmpha. Under this denomination are included all insects
that undergo only a partial metamorphosis, and are active in their
pupa state, corresponding with the Pupasemicomplctahmn. and also
suJ)scmicomplcta MacLeay. See Anim. sans Vertcbr. iii. 285 — .

M. Latreille has started an ingenious idea on this subject with re-
gard to these kinds of metamorphosis, which comprehends both larva
and pupa under a distinct denomination : as thus —

1 . Dcmilnrvc and Demiui/mjih, synonymous with the Semicomplcte
Metamorp/iosis.

2. Larvc and Kympli, answering to Incomplete Metamorphosis.

3. Caterpdlar and Chrysalis, answering to Obtccted Metamorphosis.

4. Fermi tarve and Pupa, answering to Coarctate Metaviorpfiosis.
N. Diet, d'llisf. Xaf. xvi. 272.

R 2

244. STATES OF INSECTS.

which they may be discerned, and separated with the
point of a pin *. In proportion as these acquire consist-
ency, and are more and more developed by the absorp-
tion of the surrounding fluid, they occupy its place, and
fill up the cavity of the puparium. The rest of this fluid
passes off by transpiration ^. Reaumur is of opinion that
it is from the epiploon, or corps graisseux, that this matter
is prepared, which he regards as analogous to the white
of an egg'^. In coarctate pupae the included annual, or
the pulp that contains its germes (in which the limbs and
body at first are not discernible), fills at this period the
whole skin-cocoon ; but in proportion as the above eva-
poration takes place, and the consolidation of the body
and parts proceeds, it shrinks at each end, so that when
near assuming the imago, a considerable cavity appears
both at the head and tail of the cocoon ^. At this period
of its existence, from the quantity of fluid included in the
puparium, the animal weighs usually considerably more
than it does when become a perfect insect ^.

The exterior integument or skin of pupae, which is usu-
ally lined with a very thin white pellicle, is of different
consistence in different orders. In the Coleoptcra and
Hymenoptera it is, with a few exceptions, of a soft and
membranous texture; in the Lepidoptera (especially those
that are not defended by cocoons), and Diptera, it is more
rigid and harder, being either coriaceous or corneous.
Lepidopterous pupae, however, are not excluded from

a N. Did. d'Hixt. Nat. vii. 57. ^ De Geer ii. 105.
" Reauni. ii. 428 — .

<* Swamm. Bibl. Nat. Engl, Tr. ii. ?,2. t. xli./. 2. Comp. Reaiim.
iv. t. XXV. y. 1.
" Jbid.\. 144.

STATES OF INSKCTS. 2i5

the last skin of the larvae with this hard coveriii";. At
the iDonient of this change the envelope is nearly as soft
and membranous as in the order first mentioned. But
they are besides covered with a viscous fluid, which ap-
jiears to ooze out, chiefly from untler the wings, and
which very soon drying, forms the exterior hard shell ^.
At first the antennae, wings, and legs, like those of Coleo-
ptera and Hijmenoptcra, can be each separated from the
body; and it is only after these parts have been glued to-
gether by tlie fluid just mentioned, which takes place in
less than twenty-four hours ^, that they are immoveably
attached to the body of the })upa, as we usually see them.
In fact, the essential difference between incomplete and
obtected pupa? seems to be, that in the former the limbs
and body are only covered each with a single membranous
integument, whereas in the latter they are besides glued
together by a substance which forms an additional and
harder envelope. It is not easy to explain the alteration
that takes place in the texture of the skin of such dipte-
rous pupae as retain the skin of the larva. In the latter
this is generally a transparent and very fine membrane :
yet the very same integument becomes to the pupa an
opaque and rigid case.

The surface of the skin of the greater number of pupae
is smooth, but in those of many Papilionidcc it is rugose
and warty: this you may see, particularly in that of Pa-
pilio Machaon. In many of the hawkmoths [Sphinx L.)
it is covered with impressed puncta. In Attaais lo the
upper side of the channels that separate the intermediate
segments of the abdomen are curiously striated with trans-

' Rcauin. i. 355. ^ N. Dirf. cVHist, Nal. ubi sup. 59.

246 STATKS OF INSECXy.

verse striee, formed of very minute granula, the lower side
being transversely sulcated. In some few instances, as
in Arctia Salicis, Laria piulibimda and Jasceli7ia, the skin
of the pupa is clothed with hair * : as is also that of Ue-
speria Bixce^ according to Madame Merian ^. De Geer
has described a little beetle under the name of Tenebrio
lardcij-ius [Lati'idins Latr., Corticaria Marsh.), the pupa
of which is beset with very fine hairs, terminating in
a spherical or oval button *=.

ii. I shall include under the same head both ihejigure
or shape, and pai'ts of pupae, as the latter in most kinds
are either the same or nearly the same as those of the
larva, or merely incasing those of the imago, so as not to
require that detailed notice that I judged necessary when
treating of the parts of larvae.

With regard to incomplete pupae, nothing further can
be said of their extremely various^o-?^r^, than that it has
a general resemblance to that of the perfect insect. The
head, trunk, abdomen, and their respective external or-
gans, are alike visible in both; but in the pupae, the latter,
instead of occupying their natural situation, are all closely
folded under the breast and abdomen : or, as in the case
of the long ovipositors of some Ichneumons, laid along the
back. In a specimen of some coleopterous insect now
before me, the following is the order of the arrangement
of the parts: — The head is inflexed; the mandibulse are
open ; between them are seen the labium and labial palpi;
these appear to cover and conceal the maxillae, and the
maxillary palpi extend on each side beyond them ; the

^ Plate XVI. Fig. 14. N. Diet. d'Hist. Nat. vii. 59.

•> Ins. Surinam, f. xliv. ' De Geer v. 47. t. ii./. 29—31.

STATES OF INSECTS. 2i7

antennae pass above the thighs ot" the two anterior pair
of legs, and then turning down over the breast between
them and the posterior Jegs, repose upon llie base of the
wings ; wliich also are turned down between the inter-
mediate and posterior pair of legs, and rest upon the lat-
ter; the tibiae are bent in and Tolded upon tlie thigh,
and the tarsi turn outwards '*. In another coleopterous
species, the wings and elytra are placed under the hind-
legs. In Hymenopteroiis pupae the antennae appear usu-
ally to lie between the legs ''. In many Tipulcc the long
legs are bent into three folds in the pupse ; but the tarsi
are extended, and lie close to each other, the anterior
pair being the shortest '^. In a specimen belonging to
this tribe in my cabinet, which I think contained Cteno-
cera pcctinicornis^ the six leg-cases are of the same
length, exactly parallel and adjacent, and being annu-
lated wear the appearance of tracheae ^. These parts
have each their separate case, so that a pin may be intro-
duced between them and the body : which cases, as well
as the general envelope, are usually formed of a fine soft
transparent membrane ; but sometimes, as in the lady-
bird {Coccinella), the tortoise-beetle (Cassida), the crane-
fly (Tipula), &c. it is harder and more opaque, so that
though it is usually easy for a practised Entomologist
from an examination of the pupa, particularly in the Jly-
menoptera, to predict to what genus the insect to be dis-

^ In the pupa of IlydrojMliis picctts (Lesser L. i. n.f. 13, 14), the
arrangement of the parts is nearly the same, but the tarsi are not re-
flexed.

'' Ihld.f. 0, 10. De Geer ii. t. xxxii./. 5. Reaum. v. /. xxxvi,/. 14.

" Reaum. Ibid. t. ii./. 9.

^ The legs of Tipula rcplicata L. are placed in a similar way. De
Geer vi. t. xx./. 1 2. /.

248 STATES OF IN.SECTS.

closed from them will belong, yet in these cases the organs
bemg not so conspicuous, a less experienced examiner
might be perplexed, and unable to come to a conclusion.
Although hymenopterous pupee have usually no parts
but what are afterwards seen in the perfect insect^ this is
not the case with sever^ coleopterous and dipterous ones,
which are furnished with various temporary appendages,
indispensable to them to bring about their final change,
or for other purposes. Thus, the pupa of the male of
Lucanus Cervus has two short, jointed anal processes *.
That of Hijdrophilus ccu-aboidcs has a pedunculated lunu-
late one ; and moreover, the sides of the abdominal seg-
ments, and the top of the thorax, are beset with hairs,
which are not seen in the perfect insect ^. The abdomen
of many, also, is armed with spines. That, the arrange-
ment of whose organs I lately described, has a quadruple
series in the back of this part; viz. on each of the first five
segments, 3, 2, 2, 3. The five first ventral segments also
have on each side three spines; the inner are incurved, the
intermediate nearly upright, and the outer one recurved.
These spines, except those of the innermost ventral series,
terminate in a bristle. In another coleopterous species the
back part of the head is armed with a pair of lateral spines,
and that of the thorax with three processes, the external
ones armed with a single spine, and the intermediate one
with a pair. De Geer has figured the pupa of an Asilus,
the head of which is armed with eii^ht spines — two ro-
bust ones in front, and three smaller ones, connected at
the base on each side. The abdominal segments, also,
are fringed with spines '=. The abdomen of the pupa of

■> Ros. /. 81 . '' Ibid. I. 95. ' De Geer vi. 237. /. xiv./. 8.

STATES OF INSECTS. 249

Ctenoccra pcctinicornis is armed with several strong co-
nical spines, pointing mostly towards the tail, which is
likewise the case with that of Tipida lunata *. As the
above pupa? are usually subterranean or subcortical, the
spines assist in pushing them out oi" the ground, &c.
The respiratory horns that proceed from the thorax of
the pupa? of many of the aquatic gnats will be noticed
in another place. Those of Corethra adiciformis and of
some other aquatic gnat-like Dij)tcra, have their anus
furnished with a pair of oars, or natatory laminae, by
which they rise to the surface''.

The figure of obtectcd pupie, or chrysalises, is more
uniform. 1 hey arc commonly obtuse at the anterior ex-
tremity, and gradually contracted to a point at the poste-
rior, or tail. The outline usually inclines to a long oval
or an ellipse ; but in some, as Attacus lo and Luna^ the
pupa is shorter and more spherical. In Gcomctra sani'
hucaria it re})resents an elongated cone, and in Hejnalus
it is nearly cylindrical. In the butterfly tribe [Pajnlio L.)
the outline is frequently rendered angular by various pro-
tuberances.

In all these pupa? may be distinguished the following
parts :—3/?r5^, the Head-case [Cephalo-theca), or anterior
extremity; secondly, the TrunJc-case {Cyto-thcca\ or inter-
mediate part; and thlrdli/, the Abdomen-case (Gasiro-
thcca).

1. The Head-case covers and protects the head of the
inclosed imago. From its sides behind proceed the an-

* Rcaum, v. t. n.f. 7. The anal and ventral spines of Tipula re-
plicatci arc also remarkable. De Gcer vi. i. xx./. 14,

^ De Geer Ibid. 377- i. xxiii./. 8, 9. n. Reaum. v, 42. t. vi.f. 9. m n.

250 STATES OF INSECTS.

tennae-cases {Cera-theca)\ and before from the middle,
the tongue-case ( Glosso-theca). Just below the base of the
antennae-case you may discern the eye-cases [Ophthalmo-
theca), surrounded on their inner side by a crescent-
shaped laevigated piece, which may perhaps transmit
some light to the inclosed prisoner.

2. The Trunk-case, divided into the thorax, or upper
surface, extending from the head to the dorsal segments of
the abdomen, and consisting of three pieces, answering to
the protkorax, mesothorax, and metathorax of the perfect
insect : the first answering to the prothorax small, the
second covering the mesothorax very large, and the two
next representing the metathorax, at first appearing to
belong to the abdomen, but having no spiracle ; and the
breast [pectus) or under-surface reaching fi'om the head
to the ventral abdominal segments, from which proceed
the wing-cases [Ptero-theca) and leg-cases [Podo-theca\
which organs, with the antenna-cases and tongue-case,
entirely cover, or rather form, the breast. The arrange-
ment of the whole is as follows : — The wing-cases, which
are more or less triangular, and exhibit the larger ner-
vures of the wings, are a lateral continuation of the me-
sothorax, which turn downwards from the sides of the
breast, and cover, or replace, the three first ventral seg-
ments of the abdomen. The antenna-cases, united to the
anterior portion of the head just behind the eye-cases,
repose immediately next to those of the wings running
parallel with their inner margin. Then follow the legs,
the tibiae forming an angle with the thigh, and the case
of the anterior pair being innermost, and representing the
breast-bone in the pupa. The tongue lies over the fore-

STATES OF INSECTS. 251

legs, except in the case of some sphinxes, wliich 1 shall
notice afterwards : so that the glosso-theca covers both
them and it.

3. The abdomen-case consists of tc7i segments when
viewed on the back, and of only six when viewed below;
so that it might be said to have ten dorsal and six ven-
tral segments : but the fact is, that the place of the three
anterior ventral segments, or rather ventral portions of
the segments, (for they form complete rings without any
lateral suture,) are replaced by the wings and other or-
gans : in consequence of this, the fourth segment, which
is less covered than the three first, at its posterior margin
forms an annulus or ring. In counting the abdominal
segments of a pupa, you must be careful not to include
tlic piece that represents the metathorax, which looks as
if it belonged to the abdomen ^. In the pupaj oi buttei-
jlies you will discover evident traces of ten dorsal seg-
ments ; but in many moths^ and some hwisok-mothSf you
will perceive at first only eighty or even seven, but a closer
examination will enable you to discover the line that
marks out the others ; and if you divide the puparium
longitudinally, and inspect its internal surface, you will
see very visible sutures between them. The intermediate
segments are sometimes separated from each other and
the preceding and subsequent ones by deep channels.
In the pupa of Papilio Machaon there is one such chan-
nel between the third and fourth segments. In Bombyx

' The caterpillar consists of twelve segments (Lyonnet t. \.f. 4,5),
excluding the head; on each of which, except the 2d, 3d, and 12th,
there is a pair oi' spiracles. The chrysaHs usually exhibits an analogy
to this structure, though the first, second, and last pair of spiracles
are more or less obsolete in most.

252 STATES OF INSECTS.

rcsalis the channel is between the sixth and seventh, and
in B. imperatoria there are three, namely, a channel be-
tween the third and fourth, and fourth and fifth, and fifth
and sixth segments. The way in which insects with an
exserted sting fold it in the pupa seems not to have been
noticed ; but from an observation of De Geer upon one
species of Ichneumon^ it appears to be turned up over the
back of the abdomen =».

These little animals, thus swathed and banded, exhibit
no unapt representation of an Egyptian mummy ; though
Lamarck applies the term Miimia to incomplete pupae ^^
to which it seems less happily applicable.

Chrysalises, as to the modifications of their general
fio-ure, maybe conveniently divided into two great classes:
Jirst, those that have no angular projections, the anal
mucroof some excepted, on different parts of their body;
and secondly^ those which have such projections. Each
of these classes affords variations in its peculiar charac-
ters which require to be noticed.

1. The first of these are called angular pupae '^, and
are confined to the Butterjli) or diurnal tribes. In some
the head projects into one short conical protuberance :
this you may see in the chrysalis of the common cabbage
butterfly [Pieris Brassica), and others of the same ge-
nus'^; in the brimstone-buttei'fly {Colias Rhamni^)^ and
in the beautiful purple emperor or high-flier [Apatura
Iris F. ^): though in this last it is not conspicuous. But

* De Geer ii. 847. t. xxix./. 7. a b.
^ Animaitx sans Vertebres, iii. 287.
'^ N. Diet. cVHist. Nat. vii. 57.
<! Sepp ii. t. If. 4. t. ii./. 4. t. iv.f. 5.
« Plate XVI. Fig. 12.
' Plate XVI. Fig. 10.

STATES OF INSECTS. 253

the most remarkable instance of a single eminence trom
the head is oxliibited by the pupa of a tropical butterfly
{Morpho Idomcncus Latr.), figured by Madame ISIerian.
In this the head projects into a long incurved obtuse
horn =*. In others the head is armed with two mucros,
or conical eminences. This is the case with the common
butterfly of the nettle ( Vanessa Urticce F. ''), and with that
of the beautiful Papilio Machaon •=. In these the promi-
nences are trigonal. These processes, which in some, as
in the peacock-butterfl}^ [Vanessa To), stand upright'',
and in others diverge [Papilio Machaon), form the eye-
cases of the included imago; and in their outer base
is planted the crescent-shaped piece I lately mentioned,
which seems intended to convey light into it. In many
the prothorax, besides a lateral angular projection, has
in the mitUle another triangular or trigonal one, some-
what resembling a Roman nose ; on each side of which
is a smaller elevated black point : so that it re(juires no
great stretch of imagination to find out in it a sort of re-
semblance to the human face, which, though not quite
so striking as honest Goedart figures it ^, is however very
considerable. In the pupa of Morpho Menelaiis, figured
by Madame Merian ^, this nasiform prominence of the
prothorax is extended into a long arched horn, reaching
to the middle of the abdomen. The pupa of the silver-
washed fritillary [Argynnis Paphia F.), and others of the
same genus, exhibit beneath this nasiform prominence

" Im. Surinam, t. Ix. It is singular that the chrjsaHs of its congener,
Mor])lio Teucer, which she figures t. xxlii., exhibits no such process.
The larvae also widely differ. '' Plate XVI. Fig. 11.

"■ Sepp ii. /. iii./. 5. •' Srpp i. L vii./. .5.

* De l>isrrtis,ed. Lister. /.I. ' Ins. Sunna»i. t. liii.

254 STATES OF INSECTS.

a very deep depression, itself beset with one or more se-
ries of smaller angular elevations. The back of the ab-
domen is often furnished with two rows of protuberances,
in some species larger, in others smaller ^ ; sometimes
sharp and conical, and sometimes flat, and in some in-
stances resembling the fins of fishes^. These bosses
usually decrease in size towards the tail.

2. The second kind of chrysalises are denominated
conical <^. These, which include the crepuscular and noc-
turnal Lepidoptera^ and the butterflies with oriisciform
larvae, have no protuberances, and are less variable in
their form — their anterior extremity being almost con-
stantly oval and rounded, and their posterior conical and
acute. An exception to this form is met with in the pupa
of a moth long celebrated {Lasiocampa Pithy ocampa)^,
which has the head acute and the tail obtuse, and armed
with two points ^. Another occurs in that of the Cossus,
which has two points on the head, by which it makes
an opening in its cocoon : when it assumes the imago,
one of these is placed below the other K And some
few have the anterior end nearly flat instead of rounded.
The pupa of the orange-tip butterfly [Pieris Cardamines)
seems intermediate between the angular and conical
kinds: it is somewhat boat-shaped, and distinguished
by a fusiform process from the head and tail s. Other
modifications of the usual figure are met with, but are
for the most part so slight as not to require notice. One

» Sepp i. t. ii./. 6. ^ N. Diet. d'HisL Nat. vii. 60.

<" Ibid. 57. '' See above, Vol. I. p. 131.

' Reaum. ii. 158. t. viii./. 4,5.
f Lesser L. i. 160. note. t. ii./. 19.

s N. Diet. d'Hist. Nat. xxvi. 165, Reaum. i. ."47. Rosel says this
is present only in some individuals, I, ii. 4/.

STATES OF INSECTS. 255

or two, however, should not be passed over. The pupae
of many hnwk-nioths (Sphinx L.) have the anterior piece
ot" the head-case elongated into a sort of cylindrical pro-
boscis, which is incurved beneath the breast : you will
find this formation in aS'. Convolxndi and Ligmtri ^. \i\
some, as in a species figured by Madame Merian, that
feeds upon the Annoiia squamosa, it is rolled up like a
serpent in many folds ''. In Noctua Linarice the tongue-
case turns upwards, and is prominent laterally beyond
the body '^. This singular appendage is one of those
beautiful instances of compensating contrivances, as Dr.
Paley calls them, which perpetually occur in the insect
tribes. The tongue of these hawk-moths is of very great
length, often three inches, while the pupa itself is scarcely
two ; it could not possibly, therefore, have been extended
at length, as it is in common cases, but is coiled up
within the above protuberance. When the tongue is but
a little longer than the breast, the ordinary plan is ad-
hered to, but the apex of the breast projects a little over
the abdomen into a sort of nose, in which the end of the
tongue is contained. This conformation may be seen in
the pupa of Noctua Gamma, Verbasci, and many other
species. Sometimes, as in N. Linarice F., this projection
is recurved into a short horn.

I have before adverted to the adminiciila or short spmes
looking towards the anus, with which the dorsal segments
of the abdomen of some pupae are armed ; and by which,
when the time for their exclusion is arrived, they are
enabled to push themselves upwards or outwards from

" Plate XVI. Fig. 1,3. a. ^ Ins. Surinam. /. iii.

^ De Geer ii. 433. /. viii./ 4. (.

256 STATES OF INSECTS.

their several places of confinement ^ : you will find these
in the pupa of the great goat-moth [Cossus ligniperfJa);
and in the cylindrical pupa of the moth called the ghost
[Hepialus Huimili F.) there are two rows of sharp trian-
gular spines on the back of each segment. These are not
laid flat, but, as they do also in the Cossets, form an acute
angle with the bod}' ; which gives them greater power of
resistance. Those that constitute the row nearest the
base of the segment are longer than the anterior row,
the middle spines than the lateral ones. The first and
last segment are without them, and the last segment but
one has a sharp ventral transverse ridge, armed with
many sharp teeth ^. The abdominal spines lately men-
tioned, of semicomplete pupae, are also admiiiiada.

The tail of this description of pupae is in many ii>
stances armed with a mucro, or sharp point, emerging
from its upper side. You will see this in most hawk-
moths. In the pupa of Hesperia Proteus the muci'o is
truncate at the apex ; in that of Bomhyx imperatoria it is
long, and terminates in two diverging points. In the
majority of chrysalises of both descriptions the tail is
acute, and usually furnished with hooks of different kinds.
These are so various in shape and number, &c. that they
would probably afford good characters for discriminating
many allied species. In some there are but two or three,
in others five or six, in others they are more numerous '^.
Sometimes they are quite straight ^^ but most commonly
recurved, so as to form a hook. The hawk-moths, and a

» See above, Vol. II. p. 300.

'' This description was taken from Rpuparium in my own cabinet;
it is siiTiilarly described by De Geer i. 41.*0. /. vii./. 2.

'■ Plate XXIII, Fig. 8, 9. ^ Klkmnnn Beilrage, .104,

STATES OF INSECTS. 257

few others, as Bomhijx Piui^ Cerura Vi)iula, &c., have no
anal hooks whatever. Under this head I shall observe,
that in many conical pupte below the anal angle or mu-
cro, is the ap})earance of a vertical foramen or passage :
this is particularly conspicuous in Ilcpialus^ in which it
is surmounted by a bifid ridge, and has under it a pair of
minute black tubercles.

A pretty accurate judgement of the division to which
the perfect insect when disclosed will belong, may usually
be formed from the figure of its chrymlis. All the angu-
lar ones, with scarcely any exception, inclose butteijiies.
The converse, however, does not hold ; for some that are
not angular, as those of Parnass'ms Apollo and Mne-
mosyne, and most of the Linnean Pleheii urhicohv, also
inclose flies of that description. With these exceptions,
all conical chrysalises give birth to moths or haisokmoths.
An idea even of the family or genus under which the
perfect insect will arrange, may be generally formed from
the figure of the chrysalis; less distinctly, however, in
the conical or rounded, than in the angular kinds, in
which the prominences of the head and trunk, as before
explained, usually vary in difTerent families. Even the
sex of some moths may be judged from the pupas: those
of females being thicker; and those also of the females that
have no wings, or only the rudiments of them, will of
course vary somewhat from the ordinary form : but there
is a still more striking difference in that of Callimorpha ?
vestita F., and others of the singular tribe before no-
ticed^, called by the Germans jScrc/iYrfl-o-^- (sack-bearers),
from the sack-like cases in which the larva resides. The

* See above, Vol. I, 464.
VOL. in. s

258 STATES OF INSECTS.

females of these having not only no wings, but no anten-
nae, and legs not longer than those of the larva, their
pupa more resembles that of a dipterous than of a lepi'
doptei-ous insect, it being not easy to determine which is
the head and which the tail*.

In these too we can often learn from the outline of the
wing-cases, whether the uihabitant of the chrysalis has
these organs indented or intire. If the former, the mar-
gins of these cases are sinuate, as in that of Vanessa
C. album; if the latter, they are intire, as in Pieris Bras-
siccc. Even in conical pupae, — the size, the shape of the
antennae, which may be distinguished through the skin
that covers them, and slight modifications of the ordi-
nary form, — give indications of the genus of the included
insect sufficiently conclusive to a practised eye.

The true figure of coarctate pupae when they are ma-
ture, the parts of the future fly being very visible, and
each being included in a separate case ^, is that of those
that belong to the incomplete division ; but as this is a
character not cognizable without dissection, it is customary,
in speaking of pupae of this description, to refer solely to
the shape of the exterior covering, which is in fact a cocoon
formed of the dried skin of the larva moulded into a dif-
ferent form. In this sense the figure of coarctate pupae is
extremely various. The majority of them are more or less
oval or elliptical, without any distinct parts, were it not
that they usually retain traces of the segments which com-
posed the larva's body ^. Of this figure are the pupae of the
common cheese-maggot '*, and many other flies. Others

* Von Scheven in Naturf stk. xx. 64. t. n.f. 4.

" Plate XVII. Fig. 2. Lesser L. t. ii. /. 26.

•• Plate XVII. Fig. 1. Lesser L. U ii./ 24, 25.

'' Whether M, Meigen has separated this fly generically from

STATES OF IN'SECTS. 259

{Sepedon Latr.) have the pupa shaped Ukea boat. That
of Scccva Pi/raslri F. assumes the figure of a flask ; or,
according to Reaumur's more accurate comparison, of a
tear^. The tail of many of these pupae, particularly of
aquatic species, is clongatetl into a sort of beak, either
simple or forked, or is beset with spines variously ar-
ranged. The pupa of Stratijomis Chamcdeon, and other
allied species, differs from all the rest of this subdivision
in retaining the exact form of the larva''; and hence con-
stitutes an exception to the general character of our se-
cond great Division.

iii. There is much less variety in the colour of pupse
than in that of larvae. The majority of coleopterous and
hjnnenopterous pupae are white, or whitish ; of lepido-
pterous and dipterous, brown of various shades, often
verging on black in tiie former and on red in the latter.
The angular lepidopterous ones, however, are more
gaily decorated. Some, Pieris Brassica, are of a greenish
yellow, marked with spots of black ; others are of a uni-
form green, Apahira IriSi Pieris Cardamiiies ; others, red-
dish, f'atiessa C. albu?n; others again red with black
spots, Urania Leiliis '^. A still greater number shine as
though gilded with burnished gold — either applied in
partial streaks, Vanessa Cardui ; or covering the entire
surface, Vayiessa Urticce. It was from this gilded appear-
ance in some ohtected pupae that the terms Chrysalis and

others, I am not aware : in my catalogue it stands under the name of
Ti/rophaga.

^ Reaum. iii. 376. t. xxxi./. 7-

'' Ibid. iv. 318. t. xxiii./. 1—4. xxv./. 1,

*^ Ins, Surinam, t, xxix.

S 2

260 STATES OF INSECTS,

Aurclia were applied to the whole. The alchemists mis-
took this for real gold ; and referred to the case as an
argument in favour of the transmutation of metals. But
Reaumur lias satisfactorily shown, that in this instance
the old proverb is strictly applicable — " All is not gold
that glitters." He found that this appearance is owing
to the shining white membrane immediately below the
outer skin, which being of a transparent yellow gives a
o-olden tino-e to the former ; in the same way that tinfoil,
when covered with a yellow varnish, assumes the metallic
appearance which we see in gilt leather. He mentions,
too, that for the production of this effect — it is essential
that the inner membrane be moist : whence may be ex-
plained the disappearance of the gilding as soon as the
butterfly is ready to escape from the pupa. The shade
of colour in these gilded chrysalises is various : some are
of a rich yellow, like pure gold; others much paler; and
some nearly as white as silver. That of Hipjiarchia
Cassia F. is red with silver spots *.

Though by far the greater number of the chrysalises
of moths are of an uniform chestnut, brown, or black, —
a few are of other colours ; as that of Geometra alniaria,
which is of a glaucous blue; oi Noctua sponsa, lilac; and
of Nocfua pacta, of a lovely blue, caused by a kind of
bloom, like that of a plum, spread upon a brown ground.
A similar bloom is found on that of Parnassius Apollo,
and on the anterior part of that of Platypterix cultaria
and sicula ,- in which last, Kliemann observed it to the

^ Ins. Sunnam. t. xxxii. Lister imitated the gilding of Chiysa/ises
by putting a small piece of a black gall in a strong decoction of net-
tles : this produced a scum, which when left on cup-paper, he says,
will exquisitely gild it. — Ray's Letters, 87. 90.

STATES OF INSECTS. 261

be renewed wlien rubbed oll'^. Many j)upa> have the
sheaths of the wings of a different colour from that of the
rest of the body ; a lew are vai'iegated with j^aler streaks
or bands, as Clostera Anastomosis, wliich has two red
longitudinal stripes down its dark-brown back ; and that
of the common gooseberry and currant moth, which may
be found in every garden, has alternate rings of black
and yellow ''.

A few pupas vary in their colour, as the ]5ainted \B.(!iy~
hniiev^y [Vanessa Cardui), some of which are light-brown
with gray streaks and golden dots, others wholly of a
golden yellow or brown, others of a light green '^.

Almost all at their first assumption of the pupa state
have a different colour from that which they take a few
days afterwards. This last they retain until the disclo-
sure of the perfect insect ; except some that have trans-
parent skins, which a few days previously to this period
exhibit the colours of the included animal.

iv. There is as great variety in the length of the age
of Insects in their pupa as in their larva state. Some
species continue in it only tvco or three days {Alei/?'odes
Ckelidonii hatr., Ti?iea j^rolctella L..) ; others, as many
weeks, or months, or even years. Each, however, has in
general a stated period, which in oidinary circumstances
it neither much exceeds nor falls short of. The only
general rule that can be laid down is — that small pupae
continue in that state a shorter time than those oi larger
bulk. Thus, amongst coleopterous genera, the more mi-
nute species of Curculio L. ; amongst the Hymenopta-a^

» Beitiage, 181. '' Sepp.pt. ii. ^ii./. 1. '' Rosel. I. i. 61. ii.5.

262 STATES OF INSECTS.

the Ichneumones miniiti L. ; amongst the Lepidoptei-a, the
subcutaneous tribes ; and the majority of the Diptera^ —
remain as pupae only a few days or weeks : while the
larger species in all these orders commonly exist in the
same state several months — many even upwards of two
years. There are, however, numerous exceptions to
this rule ; for some large pupae are disclosed in a much
shorter time than some others not a twentieth part of
their bulk.

The reasons both of the rule and of the exceptions to
it are sufficiently obvious. And first, as to the rule : —
If you open a pupa soon after its assumption of that state,
you will find its interior filled with a milky fluid, in the
midst of which the rudiments of its future limbs and or-
gans, themselves almost as fluid, swim. Now the end to
be accomplished during the pupa's existence is, the gra-
dual evaporation of the watery parts of this fluid, and the
development of the organs of the inclosed animal by the
absorption and assimilation of the residuum. Reaumur,
by inclosing a pupa in a stopped glass tube, collected a
quantity of clear and apparently of pure water, equal to
eight or ten large drops, which had evaporated from it,
and was condensed against the sides of the tube, and it
was found to have lost an eighteenth part of its weight '.
It is plain, therefore, that this necessary transpiration,
other circumstances being alike, must take place sooner
in a small than in a la7'ge pupa. Next, as to the excep-
tions : — Since the more speedy or more tardy evaporation
of fluids depends u|)on their exposure to a greater or less
degree of heat, we might a priori conclude, that pupae

= Reau.m. i. 385.

S'I'ATEb or INSECTS. f;Q3

exposed to a high temperature would sooner attain ma-
turity, even though larger in bulk, than others exposed
to a low one : — and this is the fact. The pupa of a laro-e
motli, which has assumed tluit state in the early part of
summer, will often disclose the perfect insect in twelve or
fourteen days ; while that of an Ichneumon, not one hun-
dredth part of its size, diat did not enter this state till
late in autumn, w ill not appear as a fly for seven or ei'dit
months. But this is not the whole. The very same in-
sect, according as it has become a pupa at an earlier or
later period of the year, will at one time live but a few
w^eeks, at another several months, in that state. Thus,
if the caterpillar of Papilio Machaon, one of those which
has annually a double brood, becomes a pupa in July,
the butterfly will appear in t/iiriee?i days : if not until
September, it will not make its appearance until the June
following ; that is, not in less than lu'ne or ten months :
and the case is the same with the pupae of Noctua Psi,
and of a vast number of other insects. To put bevond
all doubt the dependence of these remarkable variations
on temperature merely, it was only necessary that they
should be effected, as Lister long ago advised '"', by arti-
ficial means. This Reaumur accomplished. In the
month of January he placed the chrysalises of several
moths and butterflies, which would not naturally have
been disclosed until the following May, in a hotliouse :
the result was, that the perfect insects made their a])pear-
ancein less than a fortnight, in the very depth of winter;
and by other numerous and varied experiments he ascer-
tained, that in this heated atmosphere five or six days

' Lister's (ivrtloit, ]2'.

261; STATES OF INSECTS.

hastened theii' maturity more than as many 'weeks woukl
have done in the open air. The disclosed insects Avere
in every respect perfect, and the females, after pairing,
laid their eggs, and then died, just as if they had not
been thus prematurely forced into existence. The con-
verse of this experiment equally succeeded: — by keeping
pupae the whole summer in an icehouse, Reaumur caused
them to produce the flv one full vear later than their or-
dinary period ^.

This extraordinary fact leads us to a very singular and
unexpected conclusion — that we have the pov.er of
lengthening or shortening the life of many insects at
pleasure ; that we can cause one individual to live more
than twice as long as another of the same species, and
vice versa. Had Paracelsus made this discovery, it would
have led him to pursue his researches after the elixir of
immortality with redoubled confidence, and v/ould have
supplied him with an argument for the possibility of pro-
longing the life of man beyond its usual term, which his
sceptical opponents would have found some difficulty in
rebutting. Even the logical Reaumur seems inclined to
infer from it, that this object of the alchemists was not so
chimerical as we are wont to conclude ^. He confesses,
however, if it were to be attained only by the same pro-
cess as effects the extension of an insect's life — by pro-
longing its state of torpor and insensibility, — that ^ew
would choose to enjoy it on such conditions. The man
of pleasure, blunted by excess of use to all modern sti-
muli, might perhaps not object to a sleep of a hundred
years, in the hope of finding something new under the

" Reaum. ii. 10—. >- Ibid. 21.

STATICS Ol- INSECTS. '265

sun when he waked ; and an ardent astronomer would
])robably connnit himself with scientific joy to a repose as
long and as sound as that of the seven sleepers, lor the
chance of viewing his predicted return of a comet, on
stepping out of liis cave: but ordinary mortals would
consign themselves to the jierils of so long a night with
reluctance, apprehending a fate no better than what be-
fel the magician, wlio ordered himself to be cut in small
])icces and put in pickle, with the expectation of becom-
ing young again *.

The duration, then, of an insect's existence in the
pupa state, depends upon its bulk, upon tlie temperature
to which it is exposed, and upon a combination of these
two circumstances. This experiment appears very sim-
ple. We seem to ourselves to have accomplished what is
so often undertaken in vain — to have found an entrance
into the cabinet of Nature, and to have made ourselves
masters of the contents of one of the pages of her sealed
and secret book. We deceive, ourselves, however : this
book, when it seems most legible, is often interlined with
si/mj>at/ielic inks, if I may so speak, which require tests
unknown to us for their detection. If you la}^ up a con-
siderable number of the pupae of a moth now called EriO'
gastcr lanestris, the larva of which is not uncommon in
June on the black-thorn, selected precisely of the same
size, and exposed to exactly the same temperature, the
greater number of them will disclose the perfect insect
in the February following ; s(mie not till the February of
the year ensuing, and the remainder not before the same

* This is a legend of Virgil, of which an account is given in The
J.ny of the Ln:t Minslrel, Note xv. 1 ,?mo ed. 1832j p. ^.i/.

266 STATES OF INSECTS.

month in the third year ^. Mr. Jones of Chelsea, a most
acute lepidopterist, in one of his excursions captured a
female of Arctia mendica, another moth, which laid a
number of eggs, thirty-six of which produced caterpil-
lars : all these fed, spun their cocoons, and went into the
pupa state in the usual manner, but at the proper season
only twelve produced the fly. As this was no uncommon
circumstance, he concluded that the rest were dead : to
his great astonishment, however, in the next season twelve
more made their appearance ; and the following year the
remainder burst into life, equally perfect with the fore-
going''. In this extraordinary result, which also occa-
sionally has been observed to take place in the emperor-
moth [Saturnia pavonia), the privet-hawkmoth [Sphinx
Ligustri), and that of the spurge (S. Eupho7-hice) ^, and
other species, — it is clear that something besides mere size
and temperature is concerned : for, these circumstances
being precisely alike, one pupa arrives at maturity in six
months, and another of the same brood requires between
two and three years. We can guess, that the end which
the All-wise Creator has in view, in causing this remark-
able difference, is the prevention of all possibility of the
destruction of the species. Eriogaster lanestris and Arc-
tia mendica, &c., for instance, are doomed, for some rea-

* Haworth Lepidoj)t. Britann. i. 125, An iirstance is recorded in
Scriba's Journal, in which a pupa was not disclosed until the fourth
year. B.i. st. iii. 222. Pezold. 170.

*> Marsham in Linn. Trans, x. 402.

* Meinecken found, that of several pupae of Saturnia pavonia,
some kept all winter in a room heated daily by a stove, and others
in a cold chamber, some of both parcels appeared in March (none
earlier), and some of both had not appeared in July, thougli evidently
healthy. Naturf. viii. 143.

STATES or INSECTS. 267

son unknown to us =, to be disclosed from the pupa in
the cold and stormy months of February and March,
almost every day of which in certain years is so ungenial
that few insects could then survive exposure, much less
deposit their eggs and ensure the succession of a progeny.
Now, were all these to make their appearance in the per-
fect state in the same year, it might happen that the
whole race in a particular district would be destroyed.
But this possibility is effectually guarded against by the
beautiful provision under consideration, it being very im-
probable that three successive seasons should be through-
out unfavourable ; and witliout such occurrence, it is clear
that some of the race of this moth will be preserved. In
the case of other moths, whose pupae though disclosed in
the summer are governed by the same rule, the prevention
of the extinction of the species, by any extraordinary in-
crease in a particular year of their natural enemies, seems
the object in view ^. But though the intention be thus
obvious, the means by which it is effected are impene-
trably concealed. What physiologist would not be puz-
zled with the eggs of a bird, of which one-third should
require for their hatching to be sat upon only a fortnight,
another third a month, and the remainder six weeks? Yet
this would be an anomaly exactly analogous to that ob-
served by Mr. Jones with respect to the pupse of A. men-
dica. Reaumur found that when the skin of pupae was
varnished, so as to prevent absorption, the appearance of

^ The exclusion of certain moths, &c. from the pupa is probably
regulated by the time their eggs require to be hatched, and the uj)-
pearance of the leaves that constitute their appropriate food.

•• Mr. Marsham makes a similar observation in Linn. Trnns., ubi
?upr.

268 STATES OF INSECTS.

the fly happened nearly two months later than in ordi-
nary circumstances. Are we to conjecture that those of
the moth just mentioned, or of E. lancstris, that are lat-
est matured, from a greater degree of viscidity in the
fluid that forms them ^, have thicker and more imper-
vious skins than those disclosed at an earlier period?
Or are we to refer the difference to some unknown pe-
culiarity of organization ? On any supposition, the fact
remains equally wonderful ; and I know of none the illus-
tration of which is more worthy of the patient investiga-
tion of the physiologist.

As the period of maturity of the perfect insect is thus
in some cases not fixed even to years, and as in many
it seems dependent upon such variable causes ; nothing-
appears more improbable than that it should ever be
so strictly determined, that even the week in which the
fly will leave its pupa-case can be pretty accurately pre-
dicted. Such, however, is the fact with regard to the
Ephemera so interestingly described by Reaumur, the
myriads of which that issue from the banks of the Seine
all appear in two or three days, somewhere between the
10th and 18th of the month of August^ in every -year;
at which time the fishermen regularly expect them. A
like regularity attends the appearance of those described
by Swammerdam, which every year, for thi'ee days about
the feast of St. John, issue in clouds from the Rhine ^ —
Not only is the week fixed, but in several instances even

' See above, p. 345.

'' The appearance of them sometimes continues to near the end
of the month : it began on the 19th, when Reaumur observed them,
vi. 480. 488.

' Bibl. Xal. E. Trans), i. 103—.

STATES OF INSECTS. 269

the hour. The Ephemerae observed by Reaunuir appear
at no other time than between ci'g/ii and teti o'clock in
the evening ; and so unalterably is their exclusion fixed,
that neither cold nor rain can retard it. Between these
hours, in the evenings on which they appear, you may
see them fill the air, but an hour before or after, you will
in vain look for one ^. So also the silkworm-moth and
the hawkmoth of the evening primrose {Sphinx (Eno~
thercc) constantly break forth from the pupa at sunrise :
and the hawkmoth of the lime [Smerinthus Tilia) as cer-
tainly at noon ^. Schroeter states, that of sixteen speci-
mens of the death's-head-hawkmoth [S. Afropos) which
he bred, every one was disclosed between ^o?/;;- and seven
o'clock in the afternoon ^.

Before I conclude this head, I must obsei've, that after
a caterpillar or gnat has spun its cocoon, it sometimes
remains for a considerable period before it incloses itself
in the pupa-case, and casts off the form of a larva. Thus
tlie little parasite [Ichneumon glomeratus L.) that destroys
the caterpillar of the common cabbage-butterfly, remains
a larva in its cocoon for many montlis, but it becomes a
perfect insect a few days after it has put on its pupa-
rium"*; and the caterpillars of the great goat-moth [Cos-
sus ligniperda), if they spin their cocoon in the autumn,
remain in it through the winter in the larva state;
whereas, if they inclose themselves in the month of June,
they assume the pupa, so as to appear as flies in three or
four weeks ^ It is not therefore easy to state precisely

- Rcaum. vi. 486. •> Brahm. 4:53. 421.

•^ Nahtrf. xxi. 75. ^ Reaiini. ii. 423.

* De Gecr ii. 370. It is not certain, however, that De Geer did
not, in this instance, mistake the winter luibitation of a larva for a

270 STATES OF INSECTS.

the age of those pupae which are produced from lai'vae
that spin cocoons.

V. I have not much to say with regard to the sex of
pupae. The male is probably to be distinguished from
the female by being smaller ; but in the first great divi-
sion of pupae, those which resemble the larvae, and are
locomotive, the female in numerous cases may be known
by the Ovipositor, or instrument for depositing her eggs
in their proper station : and the male also has his anal
instruments. Sometimes in this state the animal is so
matured, as to be capable of continuing its kind. I have
found the pupae both of a Grylliis L. and of a Cimex L.
in coitu.

vi. Though the pupae of the second great division are
usually not locomotive, yet I must not omit some notice
of their motions. As the legs of insects in this state are
folded within a common or partial integument, of course
none of the pupae now under consideration, with the ex-
ception of those of the Trichoptera order, can walk : co~
arctate ones are even incapable of the slightest motion,
and exhibit no symptom whatever of animation. Some
of those that are termed incomplete.^ however, and most
chrysalises, have the power of communicating to their
bodies a slight movement, extending more or less in di^
ferent species, which is effected by the abdominal seg-
ments solely. The latter, during the first twelve hours
of being pupae, when their skin is soft, frequently turn

cocoon intended to shelter the future chrysalis; since Lyonnet in-
forms us that they spin a habitation to pass the winter in. Trcnte
Anatomique, &c. 9.

STATES OF INSECTS. 271

themselves, that the side on which they He may not be
flattened ; afterwards by far the majority merely wriggle
or twist their abdomen when touched, or in any way in-
commoded or disturbed. We learn from De Geer, that
the pujia of the ghost-moth {Hepiolus Ilumidi), the co-
coon of w hich is more than twice the length of the chry-
salis, moves in it from one end to the other *. Bonnet
observed one of a moth (perliaps Lasiocampa Qiiercus)^
which alternately fixed itself at the top and bottom of its
spacious and obliquely-fixed cocoon ; descending slowly,
but ascending as quickly, and almost in the same manner,
as a chimney-sweeper in a chimney ^. The pupa of the
weevil of the water-hemlock [Lixus paraplecticiis) will
move from one end of the interior of a branch to another
by means of its adminicular aided by the motion of its
abdominal segments *^. But the most locomotive of pu-
pae of the second division ar©^ those of gnats, and many
Tipulidans, which pass this state in the water. These
will move from the bottom to the surface, and back again,
with great facility and velocity. I have before mentioned
several other motions of pupae '^, which I shall not repeat
liere, by which they extricate themselves from their seve-
ral places of intermediate repose, before they leave the
puparium : if the imago were to be disclosed in the in-
terior of a tree, or in the earth, its wings would be ma-
terially injured in forcing its way out. The object ot
several of the above motions may be to alarm insects^that
might attack these defenceless beings. The twirling mo-
tion m particular, formerly noticed *, in some species, by

n De Geer i. 490. /. vii./. 3, 4. •> CEuv. ii. 1.

•^ De Geer v. 229. "^ Vol. II. 300—.

^ Vol,. II. 298—.

272 STATES OF INSECTS.

causing a rustling against the sides of the cocoon, makes
a considerable noise — so singular in that of a red under-
wing-moth [Noctua pacta), that Rosel tells us, (who by
the by was more timid than becomes a philosopher,) that
the first time he heard it, he had nearly thrown away the
box that contained it, in his fright ^.

vii. We are next to consider The extrication of the per-
fect i?2sectfrom the pnparium^ or piipa-case, and from the
cocoon. The period when the pupa has attained matu-
rity, and the inclosed insect is ready to burst the walls of
its prison, may be often ascertained. Just at this time
the colour frequently undergoes an alteration, the golden
or silver tint of the gilded chrysalises vanishes ; and those
which are transparent, usually permit the form and co-
lours of the insect within and the motions of their li bs
to be distinctly seen through them. In the LibcUulina
the eyes become more brilliant ^. The mature pupaj of
the moth lately mentioned [Eriogaster lanestris) have a
particular swell of the abdominal segments, not apparent
in those that are to continue till another season, or
longer'^. Those of the case-worms {Trichoptera) push
off the grates from the cases which they have hitherto
inliabited, and swim about ^. Other signs and motions
doubtless predict the approach of this great change in
other species, which have not been recorded.

The mode in which insects make their way out of the
puparium differs in different orders. In ohtected pupae,
the struggles of the included butterfly or moth first effect
a longitudinal slit down the middle of the thorax, where

» T. iv. 101. ^ Reniim.vi. 40".

'^^ Haworth Lrpidnpt. Britnnn.S. 1-27. '' De Geer ii. oBG.

STATES OF INSECTS. 273

there is usually a sutui-e lor the purpose. The slit ra-
pidly extends along the head, and down the parts which
compose the breast, and the insect gradually withdraws
itself from its case. It is not, however, from the outer
skin merely that it has to disengage itself, but also from
a series of inner membranous cases, which separately in-
close the antenna^, proboscis, feet, &c., as a glove does
the fingers ; and similar cases inclose the parts of the
perfect insect in pupnc of all the other orders. This is
sometimes a work of difliculty, but ordinarily it is cffjcted
with ease.

Incomplete and semicomplete pupae undergo nearly the
same process, save that in them the body is not swathed
up in a common case ; and therefore they have only to
liberate themselves from the partial cases that envelop the
several parts of their body.

In coarctate pupae, as those of Mtiscida;, Sijrphidcey
CEstridce, &c., the process is different. Their outer-case
is ordinarily more rigid and destitute of the sutures,
which in the former tribes so easily yield to a slight effort.
Yet in these, at the anterior end under which the head of
the fly lies, and from which it always issues, there is
comm.only a sort of lid, joined by a very indistinct suture
to the rest, which can be pushed off, leaving a sufficient
opening for the egress of the insect. In the pupae of
many of this tribe this lid is composed of two semicir-
cular pieces, which can be separately removed. Many
species seem to*be able to force off the lid of their pupa-
rium, by merely pushmg against it with their heads :
but the conmion flesh-fly and many other Muscidce, which
are perhaps too feeble to effect this, or whose puparia
are stronger than ordinary, are furnished with a very re-

VOL. III. T

271' STATES OF INSECTS.

markable apparatus for this express and apparently sole
purpose. They are gifted with the power of introducing
air under the middle part of the head, to which the an-
tennas are fixed, and of inflating that part into a sort of
membranous vesicle as big as the head itself; by the action
of which against the end of the pupa-case, the lid is soon
forced off. So powerful is this singular lever, that it is
even sufficient to rupture the fibrous galls in Avhich the
pupoB of the gay- winged Tephritis Cardui^ are inclosed.
That it is designed by Creative Wisdom to answer this
sole purpose seems proved, from its disappearing soon
afler the disclosure of the fly, whose head shortly becomes
all alike hard. Reaumur suspects that it may also be
intended to promote the circulation of the insect's fluids;
but to me his reasons appear not conclusive*^. In one
instance a mode still more unexpected obtains. Tlie il-
lustrious naturalist just named found that the fly which
proceeded from one of the rat-tailed grubs [Elophilus
Latr.) had actually the power of completely reversing its
situation in its narrow case; and that it then employed its
tail in pushing off the lid, which other species remove by
means of their heads ^.

The extrication of insects whose pupse are above
ground, like those of butterflies, many beetles, flies, &c.,
is comparatively a simple operation. But what, you will
ask, becomes of those species whose pupse are concealed
deep in the earth, or in the heart of the trees on which
their larvae have fed ? Of this you shall be informed. —
Coleopterous insects disclosed from pupas thus circum-

» Reaum. iii.^xlv./. 12—14,

>> For this whole account, see Reaum. iv. Mem. viii.

^ Ibid. 472.

STATES OF INSECTS. 275

stanced, wait until their organs have acquired strength,
and their elytra are sufficiently hardened to protect their
fihny wings from damage in forcing their way through
the earth or wood wiiich covers them. Thus Orycies nasi-
cofiiiSi ^ rhinoceros beetle common on the Continent, is
a full mojith before it reaches the surface of the earth,
after quitting its puparium. But it is evident that no
delay would enable Icpidopterous or dipterous insects,
which are without elytra, to make their way out of such
situations, without irreparable injury to their delicate
wings. Many of these, therefore, while still within the
hard case of the pupa, have the precaution, a few days
previously to their exclusion, to force themselves up to
the surface of the earth, or, when they reside in the in-
terior of trees, to the entrance of their hole. This is ef-
fected by a successive wriggling of the abdominal seg-
ments, which in several species, of the Coleoptera, Lepi-
doptera, and Diptcra orders, for this purpose, as has
been more than once observed ^, are furnished with
sharp points {admininda), admitting a progressive, but
not a retrograde motion. The puparia of the great goat-
moth [Cossus ligniperda) may be often seen projecting
from orifices in willow-trees ; and those of the comjnon
crane-fly ( Tipula oleracea) from the surface of the earth,
to which they have thus made their way from a depth of
several inches.

In all the preceding instances the exclusion of the per-
fect insect is complete, as soon as it has withdrawn itself
from the puparium. But to a very large number, even
after diis is effected, the arduous task still remains of

' See above, p. 255 — . and Vol. II. [). 301 — .
T 2

276 STATES OF INSECTS.

piercing the cocoons of leaves, of thick silk, of tougli gum,
or even of wood, in which the pupae are incased. We
can readily conceive how the strong jaws of coleopterous
and hyynenopterous species may be employed to release
them from their confinement. But what instruments can
be used for this purpose by moths in a state of great de-
bility, whose mouth has nothing like jaws — merely a soft
membranous proboscis ? How shall the silkworm-moth
{B. Mori) force its way through the close texture of a silken
ball, through which the finger could not be easily pushed?
Or the puss-moth [Cerura Vinula) pierce the walls of
its house of glue and wood, which scarcely yield to the
knife? You will not doubt that these difficulties have been
foreseen by Infinite Wisdom, and provided against by
Infinite Power. The egress of moths from their co-
coons is secured in two ways; — either by some peculiarity
in the first construction of the cocoon by the caterpillar,
or by some process which the pupa or perfect insect is
instructed to perform. As examples of each, several cu-
rious instances may be cited.

The larva of the moth which about 1760 made such
havoc in the province of Angoumois in France, becomes
a pupa in the interior of the grain of wheat which it has
excavated ; but the opening by which it first entered is
not bigger than a pin's point, and is quite insufficient for
the egress of the moth. How, then, is the latter to force
its way through the tough skin which surrounds it ? The
larva, previously to assuming the pupa state, gnaws out a
little circular piece at that end of the grain where the head
of the future moth would lie, taking care not to detach it
entirely. At this little door, which is sufficient to pro-
tect it from intruders, the moth has but to push, when it

STATES OF INSECTS. 277

iliUs down, aiitl leaves a free passage for its exit. A
conti-ivance almost siniilax' is adopted by a caterpillar
which feeds hi the interior of the heads of a species of
teazel {Dipsacus L.), for a minute and interesting history
of which we are indebted to Bonnet. This caterpillar
previously to its metamorphosis actually cuts a cizcular
opening in the head, sufficiently large for the egress of the
future moth ; but to secure this sally-port during its long
sleep, it artfully closes it with fibres of the teazel, closely
but not strongly glued together ^. Another small cater-
jiillar described by the same author, resides in the leaf of
an ash curiously rolled up into a cone, and then assumes
the pupa, which is inclosed in a silken cocoon, ingeni-
ously suspended by two threads like a hammock in the
middle of its habitation, and of so slight a texture that
it presents no obstacle to the extrication of the moth.
It is the closely-joined sides of its leafy dwelling that form
a barrier, which, were it not for the precaution of the
larva, would be impeneti'able to so small and weak an
animal. The little provident creature, before its change
to a }nipa, gnaws in the leaf a round opening, taking
care not to cut through the exterior epidermis. This
door is to serve the moth for its exit, like that formed by
the wheat-caterpillar. But in proportion to its bulk its
verdant apartment is of considerable size. How then
shall the mothk now the exact place where its outlet has
been traced ? How, without a clue, shall it discover in
its dark abode the precise circle which requires only a
push to throw it down ? Even this is foreseen and pro-
vided against. Out of twenty positions in which its ham-

* Bonnetj (Ehv. ii. 163,

278 STATES OF INSECTS.

mock might have been slung, the caterpillar has been di-
rected so to place it, that the silken cord that suspends
the head is fastened close to the side of the door which it
has previously constructed ; and the moth, guided by this
Jihm ariadneum, at once makes its way out of an apart-
ment which, but for this contrivance, might have been to
it a labyrinth as inextricable as that of Minos ^.

The mode in which other catei'pillars provide for their
extrication, wdien become moths, from their silken co-
coons, is not less ingenious. Those o^Eriogaster lanestris
(of which I have lately said so much,) and others, form
oblong cocoons, which, viewed externally, you would at
the first glance assert were of one solid piece : but on
examhiing them more narrowly, you perceive one end of
them to be a distinct lid, of a size large enough to per-
mit the moth to issue out ; and that it is kept in its place
by a few slight threads, easily broken by pressure from
within^. A few pages back '^ I mentioned a cocoon formed
by the larva of Tortrix prasijiana, of the shape of a
boat reversed, composed of two inclined walls fastened
together at the top and ends. In constructing this cocoon,
it firmly glues to each other the top and one end, so as to
form an impermeable suture ; but the other end, at which
the moth is to issue, though externally it seems as strong
as the rest, is merely drawn close by a slender thread or
two fastened on the inside, and easily broken from within.
And, what is particularly singular in the construction of
this ingenious habitation, the sides forming the end last
mentioned, though originally requiring force to draw

a Bonnet, (Euvr. ii. 207. *" Ros. I. iv. .209. t. Ixiii. ccxii.

■" See above, p. 317.

STATES OF INSECTS. 279

llioiii into their required position, become so elastic as to
close again when the moth has passed between them and
made her escape ; the cocoon preserving its usual shape,
even when deprived of its inhabitant ^. A similar cocoon
is constructed by another leaf-rolling caterpillar, that of
Tortrix chlorana ^. Many similar proofs of contrivance
in the construction of silken cocoons might be adduced,
but I shall confine myself to one move only — I mean that
furnished by the flask-shaped brown one o^ Satw-nia Pu-
x^onia, and some other moths. If you examine one of
these cocoons, which are common enough in some places
on the pear-tree or the willow, you will perceive that it
is generally of a solid tissue of layers of silk almost of
the texture of parchment; but at the narrow end, or
that which may be compared to the neck of the flask,
that it is composed of a series of loosely-attached longi-
tudinal threads, converging, like so many bristles, to a
blunt point, in the middle of which is a circular opening^.
It is through this opening that the moth escapes. The
silk of its cocoon is of so strong a texture and so closely
gummed, that had both ends been similarly closed, its
egress would have been impracticable ; it finds, however,
no difficulty in forcing its way through the aperture of a
sort of reversed funnel, formed of converging threads
that readily yield to pressure from within. But an ob-
jection will here probably strike you. You will ask. Is
not this facility of egress purchased at too dear a rate?
Must not a chrysalis in an open cocoon be exposed to
the attacks of those ichneumons of which you have said
so much, and of numerous other enemies, which will find

'■" Bonnet, CEuvr. ii. 2^9. ^ De Geer ii. 477.

■^^ Sepp. iv. t. xi./. 8.

280

STATES OF I^■SECTS.

admittance through this vaunted door ? Our cateipiUar
■would seem to have foreseen your dilemma ; at least, un-
der heavenly guidance, she has guarded against the dan-
ger as effectually as if she had. If you cut open the co-
coon longitudinally, you will see that within the exterior
funnel-shaped end, at some distance she has framed a
second funnel, composed of a similar circular series of
stiff threads, which, proceeding from the sides of the co-
coon, converge also to a point, and form a sort of cone
exactly like the closed peristome of a moss ; or, to use a
more humble though not less apt illustration, like the
wires of certain mousetraps *. In this dome not the
slightest opening is left, and from its arched structure it
is impenetrable to the most violent efforts of any ma-
rauders from without; whilst it yields to the slightest
pressure from within, and allows the egress of the moth
with the utmost facility. When she has passed through
it, the elastic threads resume their former position, and
the empty cocoon presents just the same appearance as
one still inhabited. Riisel relates with amusing naivete
how this circumstance puzzled him the first time he wit-
nessed it: he could scarcely help thinking that there was
something supernatural in the appearance of one of these
fine moths in a box in which he had put a cocoon of
this kind, but in which he could not discover the slight-
est appearance of any insect having escaped fi'om it, until
he slit it longitudinally ''. But from an observation of
Meinecken, it appears that these converging threads serve

* Plate XVII. Fig. 5. N. B. Scpp's figure represents the exterior
funnel ; and this, which exhibits the cocoon divided longitudinally,
the inlcrior one, or dome.

^ Roi. I.iv. 31.

4iTATi:S or IN-BIiCTS. '2H\

a double purpose ; being necessary to compress the ab-
domen of the moth as it emerges from the cocoon, which
forces the fluids to enter the ncrvures of the wings, and
give them their pro}ier expansion. For he found, that
when the pupa is taken out of the cocoon, tlie moth is
disclosed at the proper time, but remains always crippled
in its wings ; which never expand properly, unless the
abdomen be compressed with the finger and thumb, so
us to imitate the natural operation ^.

I am next to give you some account of the second
mode in which the release of the perfect insect from
its cocoon is effected — that, namely, wherein its own
exertions chiefly accomplish the work. I shall from a
large number select only a few instances. The texture
of the cocoon of the silkworm-moth is uniform in every
part, and the layers of silk are equally thick at both
ends. The moth makes its way out by cutting or
breaking these threads at the end opposite to its head :
an operation which, as it destroys the continuity of
the silk, those who breed these insects are particularly
careful to guard against, by ex})osing the cocoon to
heat sufficient to destroy the included pupa. The ques-
tion is — What instruments does the moth employ to
effect this? And this we are not able to answer satis-
factorily. Malpighi asserts that the animal first wets the
silk with a liquid calculated to dissolve the gum that
connects the threads, and then employs its lengthened
head to push them aside and make an opening''. But, as
Reaumur has observed, besides that so obtuse a part as the
head of a moth is but ill fitted to act as a wedge, we find

' Xattdf. viii. 133. ^ De Bombyc, 39.

282 STATES OF INSECTS.

the threads not merely pushed to each side, but actually
cut asunder. He therefore infers that the ej'es, which are
the only hard organs of the head, are the instruments by
■which the threads are divided — their numerous minute
facets serving the purpose of a fine file *. It should be
observed, however, that Mr. Swayne confirms Malpighi's
asserdon, that the silkworm does not cut, but merely
pushes aside, the threads of its cocoon ; and he informs
us that he has proved the fact, by unwinding a pierced
cocoon, the thread of which was entire ''. Yet Reau-
mur's correctness cannot be suspected: and he affirms,
that from observation there can scarcely be a doubt that
most of the threads are broken "= ; which is further con-
firmed in an account of the breeding of silk-worms pub-
lished in the American Philosoj)hical Transactions : in
which it is expressly stated, that cocoons out of which
the fly has escaped, cannot be wound '^. Analogy, it
must be confessed, is against Reaumur's opinion ; since
other kinds of silkworms make their escape by means of
Vijluid. Thus we are informed by Dr. Roxburgh, that
Attacus PapJiia^ when prepared to assume the imago,
discharges from its mouth a large quantity of liquid, with
which the upper end of the case is so perfectly softened,
as to enable the moth to work its way out in a very short
space of time, — an operation which, he says, is always
performed in the night ^. Perhaps the two opinions may
be reconciled, by supposing the silkworm first to moisten
and then break the threads of its cocoon. In those
that are of a slighter texture, a mere push against the

2 Reaum. i. 654. ^ Trans, of the Socieh/ of Arts, vii. 131.

« Reaum. ubi siq^r. "* ii. 359.

* Linn. 2\mis. Tii. 35.

STATErJ OF INSECTS. 283

moistened end is probably sufficient : and hence we find
in so many newly disclosed moths the hair in that part
wet, and closely pressed down ". If it be apparently
diflicult for the silkworni-nioth to effect an opening in its
cocoon, how much hartler must seem the task of the
puss-moth {Cerura Vi?iula) to pierce the solid walls of its
wood- thickened case ? Here the eyes are clearly incom-
petent; nor could any ordinary fluid assist their opera-
tion, for the gum which unites the ligneous particles is
mdissoluble in aqueous menstrua. You begin to tremble
for the fate of the moth incarcerated in such an imper-
vious dungeon — but without cause : what an aqueous sol-
vent cannot effect, an acid is competent to : and with a
bag of such acid our moth is furnished. The contents of
this she pours out as soon as she has forced her head
through the skin of the chrysalis, and upon the opposite
end of the cocoon. The acid instantly acts upon the
gum, loosens the cohesion of the grains of wood, and a
very gentle effort suffices to push down what was a mi-
nute ago so stronjj a barrier. How admirable and effec-
tual a provision ! But there is yet another marvel con-
nected with it. Ask a chemist, of what materials a vessel
ought to be to contain so potent an acid : he will reply,
— of glass. Yet our moth has no glass recipient: her
bottle is a membranous bag ; but of so wonderful a fabric
as not to be acted upon by a menstruum which a gum,
apparently of a resinous nature, is unable to resist ! This
fact can only be explained by the analogous insensibi-
lity of the stomach to the gastric juice, which in some
animals can dissolve bone, — and it is equally worthy of

' Pezold. 171.

284' STATES or INSECTS.

admiration. In both cases, the vitahty of the membra-
nous or fleshy receptacle secures it from the action of
the included fluid ; but how — who shall explain ?

Ordinarily it is the moth that breaks the cocoon ; but
in the goat-moth and many Tortrices it is the pupa it-
self that performs the work, either wholly or partially.
The pupa of the former is for this purpose furnished
with sharp points upon the head, capable of effecting
this object *. The locust-moth, another species of Cossus
(C. Rohinice Peck), whose history has been admirably
detailed by Professor Peck, has a different process. " In
the silk-moth," says he, " and all others which I have
had opportunity to observe, the chrysalis bursts in the
cocoon, and the fluid which surrounded the new insect in
it escaping at the same time, so weakens or dissolves the
fibre and texture of the silk, that the moth is able to ex-<
tricate itself, leaving the chrysalis behind it; but this is
not the manner in the locust-moth. After remaining till
all its parts are fully grown and it is ready to quit its
prison, a certain quantity of exercise is necessary, to
break the lie-aments which attach the moth to the shell
of the chrysalis, and to loosen the folds of the abdomen.
In taking this exercise, it can only move the abdomen in
various directions : as one side of the rings is moved for-
ward, the hooks in the serrated lines above mentioned
(the adminicula) take hold of the silk, and prevent their
sliding back ; the next flexure brings forward the oppo-
site side of the rings, which are prevented by the points
on that side from slipping back in the same manner, and
the chrysalis is forced out of the slightly woven extremity

* Lyonnet 16.

STATES OF INSF.CTS. 285

of the cocoon, and tlirough the silk-lined cavity, till it is
protruded for about one-third of its length out of the
opening in the bark, and into the air ^."

An exception to the general rule — that the rupturing
of the cocoon is the business of the inclosed insect itself
— is met with amongst ants ; the workers of whicli not
only feed the young, but actually make an aperture in
their cocoons, cutting the threads with their mandibles
with admirable dexterity and patience, one by one, at
the time they are ready to emerge, the precise period for
which these indefatigable nurses are well aware of, that
they may meet with no obstacle. Without this aid, the
young ant would be unable to force its way through the
strong and dense coating of silk that infolds it''. And a
proceeding somewhat akin to this was observed by the
Hon. Captain Percy, R.N., who himself related it tome.
Being fond of the study of insects, he was in the habit of
attending to their motions ; and in the beginning of Sep-
tember 1821 noticed those of a number of female Tipnlce^
probably J", oleracea L., busily engaged in depositing
their eggs amongst the roots of grass. While observing
these proceedings, he at the same time saw one quitting-
its pupa-case, which had already by its own efforts got
its head, thorax, and anterior legs out of it. It was then
joined by two male flies ; which, with their anal forceps
and posterior legs taking hold of the pupa-case, appeared
with their mouths and anterior legs to push the little pri-
soner upwards, moving her backwards and forwards;
and as they kept raising her, shifting their hold of the

* Some Notice of the Insect which destroys the Locust-trees, 70.
This Memoir is in some American periodical work, of Nvhich I have
not tlie title. ^ Huber Foiirmis S2.

286 STATES OF INSECTS.

skill till she was entirely extricated, when they left her
to recover her strength by herself. Probably the extreme
length of the two pair of hind-legs of these animals may
render such assistance necessary for their extrication.

There remains yet to be explained under this head the
manner in which the perfect insect is excluded from cer-
tain aquatic pupa3 ; such as those of Phryganece^ gnats,
and one of those Tipulidce that resemble gnats. These
pupae (perhaps that they may be safe from the attack of
birds) are destined to remain during the greater part of
their existence in this state at the bottom of the water.
But it is obvious that if the perfect insects were there to
be disclosed, their wings would be wetted, and they would
be drowned. It is the provision by which this result is
obviated that now calls for your attention.

You have already been told that the larvae of Pliry-
ganece inclose themselves in cases of different materials,
open at each end *. You have also learned, that in be-
coming pupae, they secure each end of their cases with a
grating of silk ^. When that change has occurred, they
remain motionless at the bottom of the water. Now how
are these pupae, encased in tubes of a greater specific
gravity than the surrounding fluid, to make their way to
the surface when the time has arrived for their becoming
denizens of the air ? This they accomplish in the follow-
ing manner : — The pupa is furnished with two strong
exterior moveable mandibuliform processes, and has the
power of moving its four anterior legs and antennae while
in the pupa-case. With these temporary Jaws it makes
an opening in one of the silken doors of its case, forces its

» Vol.. I. p. 4G7. ^ Vol. II. p. 264.

STATES OF INSECTS. 287

way out at that end, and then by moving its legs, tlie
cases of which in some species are cihated for this very
purpose, swims to the surface, where its skin splits, and
discloses the included insect. That these jaws are given
for the express and exclusive purpose of being thus ap-
plied, seems undeniable. The pupa eats nothing — they
are therefore in every other point of view superfluous.
They arc given to it alone of all other similar pupa?, be-
cause unnecessary to all others ; and they are cast off
along with the rest of the puparium, the perfect insect
having no vestige of jaws ^.

The gyiat has to undergo its change on the surface of
the water — How is it to accomplish this without being
wetted ? In the pupa state they usually remain suspended
with the posterior end of the body turned downwards :
but when the period for its change is arrived, it stretches
it out upon the surface, above which its thorax is elevat-
ed. Scarcely has it been a moment in this position, than,
swelling out the interior and anterior parts of the thorax,
it causes it to split between the two respiratory horns.
Through this opening the anterior part of the gnat then
emerges. As soon as the head and trunk are disengaged,
it proceeds with its labour, and gets out more and more;
elevating itself so as to appear in the puparium like a
mast in a boat. As it proceeds, the mast is more and
more elevated and lengthened, till it becomes nearly per-
pendicular— just as the mast of a boat is gradually raised
from a nearly horizontal to a vertical position : at this
period a very small portion of the abdomen remains in
the puparium. Neither its legs nor wings are of any use

» De Geer ii. 519.

288 STATES OF INSECTS.

in maintaining it in this position. The latter are too soft,
and, as it were, folded ; and the former are stretched out
along the abdomen — the segments of this last part are the
only agents. The observer who sees how the little boat
gradually sinks, and how its margin approaches the wa-
ter, forgets the mischievous insect it contains, which at
another time he would crush without remorse, and be-
comes mterested for its fate ; especially should wind agi-
tate the water. A very little is sufficient to drive about
rapidly the little voyager, since it catches the wind in
some degree as a sail. If it should be upset, it would be
all over with it; — and numbers do thus perish. The gnat,
after having fixed itself thus perpendicularl}"^, draws first
its two anterior legs out of their case, and moves them
forward, and next the two intermediate ones ; then in-
clining itself towards the water, it rests its legs upon it,
for water is to them a soil sufficiently firm and solid to
support them, although surcharged with the weight of
the insect's body. As soon as it is thus upon the water,
it is in safety ; its wings unfold themselves and are dried,
and it flies away. All this is the work of an instant '.

The pupae of C/iiro?iomus plumostis proceed from tliose
red worm-like larvae so common throughout the summer
in tubs of rain-water, &c., described by Reaumur^.
They are not inclosed in cases, but are of a greater spe-
cific gravity than the water at the bottom of which they
reside, until within a few hours of the exclusion of the
fly. They have the power of swimming, however ; and
by moving the tail alternately backwards and forwards,
can slowly raise themselves to the top of the water. But

" Reaum. iv. CIO—.

^ Ibid. V. 30— . t. v./. 1—10. See above, p. 15.3—.

STATICS Ol' INSECTS. 289

here occurs :i ililliciilty. For the extricalion of ihe imago
it is necessary tliat they should renuiin quietly suspended
at the surface ; and moreover that the thorax, in which
the o}iening for its exit is to be made, should be at least
level with it: and this is precisely what takes })lace. If
yon watch one of these pupae when it ascends from the
bottom, you will see that as soon as it has reached the tt)p
it remains suspended there motionless ; and that its tho-
rax is the highest part of the body, and level with the
surface. Now the question is, in what^way this is accom-
plished ? How can a pupa of greater specific gravity than
water, remain suspended without motion at its surface ?
and how can its thorax, which is at its heaviest end, be
kept uppermost ?-r- By a most singular and beautiful con-
trivance, which I shall explain ; the more particularly
because it has escaped Reaumur, and, as far as I know,
all other entomological observers. The middle of the
back of the thorax has the property of repelling water —
apparently from being covered with some oily secretion.
Hence, as soon as the pupa has once forced this part of
its body above the surface, the water is seen to retreat
from it on all sides, leaving an oval space in the disk,
which is quite dry. Now though the specific gravity of
the pupa is greater than that of water, it is but so very
slightly greater, that the mere attraction of the air to the
dry part of the thorax, when once exposed to it, is sufli-
cient to retain it at the surface; just as a small dry needle
swims under similar circumstances. That this is a true
solution of the phaenomenon, I am convinced by the re-
sult of several experiments. If, when the pu2)a is sus-
pended at the surface, a drop of water be let fall upon
the dry })ortion of the thorax, it instantly sinks to the
VOL. 111. u

290 STATES OF INSECTS.

bottom, — the thorax, which belongs to the heaviest half,
being the lowest ; and if the pupa be again brought to the
surface, so that the fluid is repelled from its disk, it re-
mains suspended there without effort, as before. Just
previously to the exclusion of the fly, the dry part of the
thorax is seen to split in the middle. The air enters, and
forms a brilliant stratum resembling quicksilver, between
the body of the insect and its puparium ; and the former
pushing forth its head and forelegs, like the gnat, rests
the latter upon the water, and in a few seconds extricates
itself wholly from its envelope.

Before I close this letter, I must state a fact connected
with the subject of it that deserves to be recorded. It is
a general rule, that one pupa-case incloses only one insect;
but Kleesius, a German entomologist, asserts that he
had once two specimens of Gastropaclia quercifolia pro-
duced from one pupa; which was large, being full two
inches long, and one thick.

LETTER XXXII.

STATES OF INSECTS.

IMAGO STATE.

When the insect has Cjuitted the exuviae of the pupa, it
has attained the last stage of its existence. It is now
termed an Imago, or perfect insect ; and is capable of
propagation.

Just after its exclusion, it is weak, soft, and languid :
all its parts are covered with moisture ; and, if a winged
insect, its wings have so little the appearance, either in
shape, size, or colour, which they are about to assume,
that it might be taken for a mutilated abortion, rather
than an animal in the most vigorous stage of life. If it
be a beetle, its elytra, instead of covering the back of the
abdomen, are folded over the breast : their substance is
soft and leathery, and their white colour exhibits no
traces of the several tints which are to adorn them. If
the insect be a butterfly or a moth, the wings, instead
of being of their subsequent amplitude, and variegated
and painted with a variety of hues and markings, are in
large species scarcely bigger than the little finger nail,
falling over the sides of the trunk, and of a dull muddy
colour, in \Nhich no distinct characters can be traced.

u 2

292 STATES OF INSECTS.

If tlwi exclucletl insect be a bee or a fly, its whole skin is
white and looks fleshy, and quite unlike the coloured
hairy crust which it will turn to in an hour or two ; and
the wings, instead of being a thin, transparent, expand-
ed film, are contracted into a thick, opaque, wrinkled
mass.

These symptoms of debility and imperfection, how-
ever, in most cases speedily vanish. The insect, fixing
itself on the spoils of the pupa, or some other convenient
neighbouring support, first stretches out one organ, and
then another : the moisture of its skin evaporates, the
texture becomes firm, the colours come forth in all their
beauty; the hairs and scales assume their natural posi-
tion ; and the wings expanding, extend often to five or
six times their former size — exhibiting, as if by magic,
either the thin transparent membranes of the bee or ^y,
or the painted and scaly films of the butterfly or moth,
or the coloured shells of the beetle. The proceedings
here described I witnessed very recently with regard to
a very interesting and beautiful butterfly, the only one of
its description that Britain has yet been ascertained to
produce — I mean Pajnlio Machaojz. The pupa of this
being brought to me by a friend early in May this year
(1822), on the sixteenth of that month I had the pleasure
to see it leave its puparium. With great care I placed it
upon my arm, where it kept pacing about for the space of
more than an hour ; when all its parts appearing conso-
lidated and developed, and the animal perfect in beauty,
I secured it, though not without great reluctance, for my
cabinet — it being the only living specimen of this fine fly
I had ever seen. To observe how gradual, and yet how
rapid, was the development of the parts and organs, and

STATES OF INsr.CTS. 293

particularly of the winos, and ilio perfect coming forth of
the colonrs and spots, as the sun gave vigour to it, was a
most interesting spectacle. At first it was unable to ele-
vate or even move its wings; but in proportion as the
aerial or other fluid was forced by the motions of its trunk
into their nervures, their numerous corrugations and folds
gradually yielded to the action, till they had gained their
greatest extent, and the film between all the nervures be-
came tense. The ocelli, and spots and bars, which ap-
peared at first as but germes or rudiments of what they
were to be, grew with the growing wing, and shone forth
upon its complete expansion in full magnitude and
beauty.

To understand more clearly the cause of this rapid
expansion and development of the wings, I have before
explained to you that these organs, though often exceed-
ingly thin, are always composed of two membranes, hav-
ing most commonly a number of hollow vessels, miscalled
nerves, running between them *. These tubes, which,
after the French Entomologists, I would name nervm'eSf
contribute as well to the development of the wings, as to
their subsequent tension. In the pupa, and commonly
afterwards, the two membranes composing the organs in
(juestion do not touch each other's inner surface, as they
afterwards do: there is consequently a space between
them ; and being moist, and corrugated into a vast num-
ber of folds like those of a fan, but transverse as well as
longitudinal, and so minute as to be imperceptible to the
naked eye, the wings appear much thicker than in the
end. Now as soon as the insect is disclosed, a fluid enters

•* Hee above, Vol.. 11. \>. Md.

294 STATES OF INSECTS.

the tubes, and being impelled into their minutest ramifi-
cations, necessarily expands their folds ; for the nervures
themselves are folded, and as they gradually extend in
length with them, the moist membranes attached to them
are also unfolded and extended. In proportion as this^
takes place, the expanding membranes approach each
other, and at last, being dried by the action of the atmo-
sphei'e, become one. To promote this motion of the fluid,
seems the object of the agitations which the animal from
time to time gives to its unexpanded wings. That a kind
of circulation, or rather an injection of an aqueous fluid
into these organs, actually takes place, may be ascertained
by a very simple experiment. If you clip the wings of a
butterfly during the process of expansion, you will see
that the nervures are not only hollow, but that, however
dry and empty they may subsequently be found, they at
that time actually contain such a fluid *. Swammerdam,
who appears to have been the first physiologist that paid
attention to this subject, was of opinion that an aeriform
as well as an aquiform fluid contributes to produce the
effect we are considering. He had observed that, if a
small portion be cut off" from the wing of a bee, a fluid of
the latter kind exuded from its vessels in the form of
pellucid globules, becoming insensibly drops — which he
concluded proved the action of the latter ; and he no-
ticed, also, that the wings were furnished with tracheae,
which were at that time distended by the injected air ;
whence he justly surmised, that the action of the ai}- was
also of great importance to produce the expansion of the
wing ^. And Jurine found that every nervure contains

=* Reaum. i. Mem. nit. De Geer i. 73. Swamni, Bibl. Nat. i. 184.
'' Swamni. Ibid.

STATES OF INSECTS. 295

a tracliea, which, proceeding from the interior of the
trunk in a serpentine direction, follows all the ramifica-
tion of the nervure, though it does not fill it ^. Though
Reaumur attributes the expansion of the wings chiefly to
an aqueous fluid, yet he suspects that the air on some
occasions contributed to it''.

The wings of the other tribes of insects probably differ
from the Lcpidoptera in the manner in which they are
folded. It should seem from Reaumur's description, that
those of some flies, instead of the straight transverse folds
of the former, have angular or zigzag folds *= ; which
equally shorten the wing. Many Htjmenoptcra have
wings without any nervures except the marginal. We
may conjecture that these are more simply folded, so as
to render their expansion more easy ; but even in these
wings there are often tracheae, which appear as spurious
nervures, and help to effect the purpose we are consi-
dering:.

The operation of expanding their wings, in by far the
larger number of insects, takes place gradually as de-
scribed above ; and, according to their size, is ended in
five, ten, or fifteen minutes; in some butterflies half an

^ Jurinc Hymcnopt. IG.

'' iv. 342. Herold also attributes the rapid expansion of the wing
to the flow of an aqueous fluid, which he calls blood, into the ner-
vures, the orifices of which open into the breast. Entwickclukgs.
dcr Sclimetterl. 101. sect. 106. — M. Chabricr, in his admirable Esmi
sur le Vol des Insectcs {Mem. da Mus. 4icme, ann. 335), having ob-
served a fluid in the interior of the nervures of the wings of insects,
thinks it probable that they can introduce it into them and withdraw
it at their pleasure : the object of which, he conjectures, is either to
strengthen them and facilitate their unfolding, or to vary the centre
of gravity in flight, and increase the intensity of the centrifugal force.

^ W. .340.^

296 STATES OF INSECTS.

hour, in some even an hour. A few species, such as
Sphinx (Fmotliercc F., require several hours, or even a
day, for this operation ; and, from the distance to whicli
tliey creep before it has taken place, a considerable rle-
gree of motion seems requisite for causing the necessary
impulse of the expanding fluids^. In a few genera, how-
ever, as the gnat, the gnat-like Tipulidse, and die Ephe-
merae, this process is so rapid and instantaneous, that the
wings are scarcely disengaged from the wing-cases before
they are fully expanded and fit for flying. 1 hese genera
quit the pupa at the surface of th.e water, from which,
after resting upon it for a few moments, they talie flight:
but this would evidently be impracticable, and immersion
in the fluid, and consequent death, would result, were not
the a'eneral rule in their case deviated from.

Some species of the last of these genera, Ej)hcmcra,
are distinguished by another peculiarity, unparalleled, as
far as is known, in the rest of the insect world. After be-
ing released from the puparium, and making use of their
expanded wings for flight, often to a considerable di-
stance, they have yet to undergo another metamoi'phosis.
They fix themselves by their claws in a vertical position
upon some object, and withdraw every part of the body,
even the legs and wings, from a thin pellicle which has
inclosed them, as a glove does the fingers ; and so exactly
do the exuviae, which remain attached to the spot where
the Ephemera disrobed itself, retain their former figure,
that I have more than once at first siffht mistaken them
for the perfect insect. You can conceive without diffi-
culty how the body, and even legs, can be withdrawn

, a Brahm. Inselc ii. 423.

STATES OF INSECTS. 297

from llieir cases; but you must be puzzled to conjecture
how the wings, which seem as thin, as mucli expanded,
and as rigid as tliose of a fly, can admit of having any
sheath strij)pcd from them ; nuich less how they can be
withdrawn, as they are, through a small opening at the
base of the sheath. The fact seems to be, that though
the outer covering is rigid, the wing inclosed in it, not-
withstanding it is sometimes more tlian twenty-four hours
before the change ensues, is kept moist and pliable. In
proportion, therefore, as the insect disengages itself from
the anterior part of the skin, the interior or real wings
become contracted by a number of jilaits into a form
nearly cylindrical, which readily admits of their being-
pulled through the opening lately mentioned ; and as
soon as the insect is released from its envelope, the plaits
unfold, and the wing returns to its former shape and di-
mensions. Thus our little animal, having bid adieu to
its shirt and drawers, becomes, but in a very harmless
sense, a genuine descamisado and sansculotte. It does
not seem improbable, that the pellicle we have been
speaking of is analogous to that which, in addition to the
outer skin, incloses the limbs of Z/r/;/V/cy;/6';r/, &c. in the
pupa state, but which they cast at the same time with the
puparium, and leave adhering to it *.

The body of newly-disclosed insects commonly ap-
pears at first of its full size; but the aphidivorous flies
{Syrphus F. &c.), and some others, in about a quarter of
an hour after leaving the pupa become at least twice as
large as they were at their first appearance: this ajipa-
rent sudden growth, which is also noticed by Goedart,

* Reaum. vi. 505 — , /. xlvi./. 0. Coinp, Do Ciee; a 'o^r'H--

298 STATES OF INSECTS.

Reaumur found to depend upon the expansion of the
previously compressed segments of the animal by means
of the included air *. Both in this instance and in that
of insects whose wings only require expansion, the size
of the imago often so greatly exceeds that of the pupa,
that we can scarcely believe our eyes that it should have
been included in so contracted a space. The pupa of
one of the beautiful lace- winged flies {Hemerohius Perla)
is not so big as a small pea, yet the body of the fly is
nearly half an inch long, and covers, when its wings and
antennae are expanded, a surface of an inch square ^.

When the development of the perfect insect is com-
plete, and all its parts and organs have attained the re-
quisite firmness and solidity ■=, it immediately begins to
exercise them in their intended functions; it walks,
runs, or flies in search of food ; or of the other sex of its
own species, if it be a male, that it may fulfill the great
end of its existence in this state — the propagation of its
kind. Previously to thus launching into the wide world,
or at least immediately afterwards, almost all insects dis-
charge from their intestines some drops of an excremen-
titious fluid, often transparent, and sometimes red. I
have before related to you the alarm that this last cir-
cumstance has now and then produced on the minds of
the ignorant and superstitious ^. Whether this excre-

a Reaiim. iii. 378. ^ Ibid. 385,

*= Insects of the beetle tribe, especially such as undergo their me-
tamorphosis under ground, in the trunks of trees, &c., are often a
considerable time after quitting the puparium before their organs
acquire the requisite hardness to enable them to make their way
to the surface. Thus, the newly-disclosed imago of Cetonia auratn
remains a fortnight under the earth, and that of Litcanns Cervus, ac-
cording to Rcisel, not less than three weeks.

•' See above, Vol.. I. p. 34 — .

STATES OF INSECTS. 299

ment is produced indifferently both by males and females
I cannot positively assert; but a circumstance related
by Jurine affords some ground for a suspicion that it
is peculiar to the latter. A specimen of a female of
Lasiocampa Iludi, when killed emitted some of this
fluid, which dropped upon the floor: this appeared to
attract the males to the apartment in which it happened,
and to the very spot — from whence it may be conjectured,
that the scent of the fluid brought them there, and that
the use of it is to brincj the sexes together soon after ex-
elusion from the pupa *.

The colour, sculpture, and otiier peculiarities which
distintruish insects in this state I shall consider at lar^e
in another letter, when I treat of their external parts and
organs. Under the present head I shall confine myself
to pointing out the characters by which the sexes of many
species are distinguished from each other; as likewise
the (Jura/ ion of their life in their jierfect state ; together
with the circumstances on which this duration depends.

I. Sexual Distinctions. The first general rule that
may be laid down under this section is, — That among
insects, contrary to what mostly occurs in vertebrate
animals, the size of the female is almost constantly larger
than that of the male. Even in the larva and pupa states,
a practised eye can judge, from their greater size, which
individuals will become females. There are, however,
some exceptions to this rule. Thus amongst the Colco-
ptera^ the male DyjiastidcE, remarkable for their horns,

* Jurine Hymenopt. 9. Note 1.

300 STATES or INSECTS.

as you may see in D. Alocus, A/i/(Ci/s, Actceou, &c., as
likewise those of Lucanus^ are larger than the unarmed
females ^. In the Ncuroptcra the female Lihellulid(C are
sometimes sensibly smaller, and never larger, than their
males''. In the Hijmcnoptera the male of the hive-bee,
but more particularly that of Anthidium manicatum and
other bees of that genus, is much more robust than the
other sex *^. In the Diptcra, the same difference is ob-
servable in Sj/rpkus Rihesii, and some other aphidivorous
flies, and also in Scatophaga stcrcoraria ^. And amongst
the apt er Otis tribes, we are informed by De Geer that
the male of Argyroneta aquatica, which builds an aerial
palace in the bosom of the v/aters ^, usually exceeds the
female in bulk ^. The reason of this rule seems in some
deoree connected with the office of the female as a mo-
ther, that sufficient space may be allowed for the vast
number of eggs she is destined to produce; and it is
when impregnation has taken place, and the eggs are
ready for extrusion, that the difference is most sensible.
In the majority of cases this sexual disproportion is not
very considerable, but in some few it is enormous. Reau-
mur mentions a beetle, of which he intended to give the
history, the male of which is so small compared with the
female, that a bull not bigger than a sheep, or even a
hare, set by the side of the largest cow, would aptly con-
trast with them. This litde beetle, he says, has wings

» Oliv. N. i. t. If. \. c.f. N. 3. t. iii./. 22. a b c. t. v./. 33.
t. y'x.f. 5. t. xiii./. 124. a b. '' Reaum. vi. 423.

•^ Kirby Mon.Ap. Angl. ii. t, xvi./. 12, 13. /. xvii./. 10—12.
•^ Reaum. iv. 393. * See above, Vol. 1. 473—.

' De Geer vii. 304.

STATTS OK INSKCTS, 301

and dytia, while the gianl Icmalc has no vestige of either,
having the upper siutace of its body naked and membra-
nous ^. The species to which this illustrious Naturalist
lure alUides, does not appear to have been ascertained.
Tile female of many gall-insects {Cocci) is so hirge in
comparison with tlie male, that the latter traverses her
back as an ample area for a walk '\ But this is nothing
compared with the prodigious difference between the
sexes of Tcrmcsjatalc, and other species of white ants,
w i)ose males are often many thousand times less than the
females, when the latter are distended with eggs '^. Acci-
dental differences in the size of the sexes sometimes arise:
as when the It^male larva has, I'rom any cause, been de-
))rived of its proper supply of food, it will occasionally be
less than the male. De Geer has stated a circumstance
with respect to the Aphides that })roduce galls, that
should be mentioned under this head — the first, or mo-
i/ier female, is larger than any of her progeny ever be-
come ''.

The second observation that may be generally applied
to the sexes of insects is, that, size excepted, there is a
close resemblance between them in other respects. But
to this rule the exceptions are very numerous, and so im-
portant that it is necessary to specify examples of each
under distinct heads.

i. In some species the sexes are either partly or wholly
of a different colour. Thus, in the order ColcojHera, the
elvtra of the male of R/icuriian mcridiimnm F. are testa-
ceous, and those of the female black. Leplura nibra of

" Hcanin. iv. .30. ^ Ibid. /. iv./. 15.

•^ Sec above, Vol. II. 36. •' Dc Gcer iii. ^5,

302 STATES OF INSECTS.

Linne, with red elytra, is the female of liis L, testacea,
in which they are testaceous. Cantharis derniestoidcs of
the same author is the other sex of his Meloe Marci ;
one of which is chiefly testaceous, and the other black :
which seems to have so misled Linne, that he placed
them in different genera. One more instance in this
order, the female of Cicindela campesiris, as was first ob-
served to me by our friend Sheppard, has a black dot on
each elytrum, not far from its base near the suture, which
the male has not.

Amongst the Orthoptera, the male LoaistiS F., as Pro-
fessor Lichtenstein has informed us ^, have a fenestrated
ocellus, which is not to be found in the other sex. I was
once attending to the proceedings of a Hemipterous spe-
cies, Pentatoma oleracea Latr., which I found in union :
the paired insects had white spots, but another individual
was standing by them, in which the spots were of a san-
guine hue. I mention this by the way only — the spots
in the prolific sexes being of the same colour : but might
not the red spotted one be a neuter ?

The sexes of many Lepidoplera likewise differ in their
colour. I must single out a few from a great number of
instances. The males of JLyctcna Argus F. have the up-
per surface of their anterior wings of a dark blue, while
in the female it is wholly brown. The wings of the for-
mer sex of Hypogymna dispar are gray, clouded with
brown; but those of the latter are white, with black
spots. In the brimstone butterfly {Colias Rhamni), which
is one of the first that appear in the spring, the wings of
the male are yellow — of the female whitish. In the coni-

* Linn. Trans, iv. 54 — .

STATES or INSECTS. 303

mon ornngc-tip {Pier is Cardamincs F.), one sex has not
the orange tip to the upper wings: and, to name no more,
the male of Lycccna disj)m\ one of our rarest and most
beautiful butterflies, has only a single black spot in the
disk of its fulgid wings ; while in the other sex, the pri-
mary pair have nine, and the secondary are black, with
a transverse orange fascia near the posterior margin.
But the most remarkable difference in this respect ob-
servable in the insects of the order in question, takes
place in a tribe, of which only one species is certainly
known to inhabit Britain — I mean the Papilioncs Equites
of Linne : what he has called his Trqjani and Achivi in
some instances have proved only different sexes of the
same species. Mr. MacLeay's rich cabinet affords a sin-
gular instance confirming this assertion ; — a specimen of
a Papilio is divided longitudinally, the right hand side
being male, and the left hand female. The former be-
longs to P. Polycaon, a Grecian, the latter to P. Lao-
docusy a Trojan. An instance of two Grecians thus united
is recorded in the Encyclopcdie Methodique, as exhibited
in a specimen preserved in the Museum of Natural Hi-
story at Paris; which on the right hand side is P. Ulj/sscs,
on the left P. Diomedes ^.

In the Nairoptera^ the Libelhdidcc are remarkable for
the differences of colour in the sexes. In the common
Libcllida depressa, which you may see hawking over
every pool, the abdomen of the male is usually slate-
colour, while that of his partner is yellow, but with darker
side-spots. Reaumur, however, noticed some males that
were of the same colour with the females ''. Schelver

» ix. 65. n. 110. " vi. 423.

30 1< STATES OF INSECTS.

observed, when lie put the skins of Lihdlula depressa into
water, that the colours common to both sexes were in
the substance of the skin, and remained fixed; while
those that were peculiar to one could be taken ofl* with a
hair-pencil, and coloured the water: which therefore
were superficial, and, as it were, laid on ^. The yellow
males, therefore, that Reaumur observed, were probably
such as had the superficial blue colour which distinguishes
them washed off. In Calepteryx Virgo Leach, the for-
mer are of a lovely silky blue, and the latter green. In
Agrions. F. nature sports infinitely in the colours of the
sexes.

In the order Uymcnoptera there are often differences
equally great; the sexes of many of the Ichneumons and
Saw-flies are of quite different colours. The former tribe
Linne has divided into sections, from the white annulus
observable in the antennae of some, and from the colour
of their scutellura: but these are often merely sexual
characters ^. The male of AntJiopJiora rehisa Latr., a
kind of wild bee, is wholly black, the female wholly gray,
and of so very different an aspect that they were long
regarded as distinct species ; a mistake which has likewise
occurred with regard to the sexes of Osmia ccermlescens,
another bee, of which the male has a bronzed and the
female a violet abdomen '^. The nose of male A7idrcnce
Latr. is often yellow, or white, as in A. hcemorrhoidalis —
when that of the female is black ''. The lahriim also is often
of a different colour in the sexes, as in Ccraiina Latr.

^ Entomologiscke, &c. 224.

'^ De Geer ii. 847. 850. Jiirine Ilymcnopt. 100.

-^ Kirby Mon. Ap. AngL ii. 21)6. 264.

^1 lOici. ii. 142- . 144, 147, 148, e*tc.

STATES OF INSECTS. 305

In the Diptera, Aptera, AracJmida, &c., I am not aware
of any striking diflerence in the colours of the sexes.

ii. The sexes of insects vary (but more rarely than in
colour) in theii' sculpture also, and pubescence. Thus the
elytra of the females of many of the larger water-beetles
[Dytiscus) are deeply furrowed, while those of the males
are quite smooth and level ^. The thorax of the female
in several species of Colymbetes of the same tribe, as
C. Hi/bneri and transvcrsalis, on each side has several
tortuous impressed lines or scratches, like net-work,
which are not to be discovered in the male. Hyphydrus
gibbus Latr., which differs solely from //. ovalis [Dytis-
cus ovalis Illig.) in being thickly covered with minute
impressed puncta, is, from the observation of the Rev.
R. Sheppard, the other sex of this last, with which he
has taken it coupled ; and it is by no means improbable
XhatHydropoms picipes (Dytiscus pimctatus Marsh.) and
M. lifwatus, — between which, as Gyllenhal has justly ob-
served, the same difference only exists, — are in like man-
ner sexual varieties. With respect to j^ubescence, I have
not much to say. Another aquatic beetle, Acilius sidcatus
Leach, has not only its elytra sulcated, but the furrows
of these, and a transverse one of the thorax, are thickly
set with hair; while the male is smooth, and quite naked.
Particular care seems to have been taken by the Creator,
that when all the above inhabitants of the water are paired,
the male should be able to fix himself so firmly, by means

=* A remarkable anomalous exception to this rule sometimes oc-
curs in the female of D. margitialis, which has smooth elytra like the
male (Gyll. Im. Suec. i. 467 — ). I have this variety from the Rev.
Mr. Dalton, of Copgrove, Yorkshire.

VOL. III. X

306 STATES OF INSECTS.

of his remarkable anterior tarsi, (which I shall afterwards
describe,) and these asperities, &c. in the upper surface
of his mate, as not to be displaced by the fluctuations of
that element, the reluctance of the coy female, or any
other slighter cause.

In a moth called the ghost {Hepialus Hiimtdi), the
posterior tibia of the male is densely bearded, but not of
the female ^. — Some Hymenoptera, as AmmopJiila Kirb.
and Stigmus Jurine, have the upper lip of the male clothed
with silver pile, while that of the female is not so orna-
mented. The legs of some bees are distinguished in the
sexes by a difference in their clothing. That observable
in those of the hive-bee has been before noticed ^. In
Andrena of Latreille *= the posterior tibia of the female is
covered externally with a dense brush of hairs, for col-
lecting the pollen ; and the posterior legs at their base
have a curled lock of hair — which are not to be found in
the male '^. In Dasypoda, Melecta, Anthophora, Centris,
Epicharis^ &c. of the same author, the first joint of the
tarsus of the female, and in Xylocopa almost the whole
tarsus, is also similarly signalized from that of the other
sex. In Bombus, as in the hive-bee, the posterior tibiae
of the females and neuters are furnished with a basket of
hairs for carrying their pollen paste, which you will in
vain look for in the male ^. The latter, however, in some
species of this tribe are distinguished from the former by
the longer hairs of their legs, but not in the posterior
ones. Thus, in Anthophora retusa the first joints of the

* De Geer i. t. vii./. 1 1 .

•> See above. Vol.. II. 125, Note *•.

•^ Mclitta ** c, Kirby Mon. Ap. Angl. i. 140.

" Ibid. t. i\.f. 10. a. b.f. 14. ' Ibid. t. xiii./. 20. a.

STATES OF INSECTS. S07

intermediate tarsus are bearded internally with a thin
fringe of long hairs, and the first externally with a tri-
angular one of short ones at the apex : but what is most
remai-kable, the last or unguicular jomt, which in al-
most every other bee is naked, is on both sides fringed
with long hairs *. In that remarkable genus Acajithojnis
Illig., of which the male only is known, the first and last
joint of the intermediate tarsus have a dense external
brush of stiff hairs, which probably is also a sexual cha-
racter ''. Another sexual kind of clothing is exhibited
by the females of those bees that have their labrum or
upper-lip inflexed [Megachile Latr.) *=. Their abdomen
is covered underneath with a brush of stiff hairs, involved
in which they carry the pollen they collect. In the males
of some of this tribe, as of M. JVillugkbiella, the first four
joints of the anterior tarsus on their inner side have a
long dense fringe of incurved hairs ^ : a circumstance
also to be found in the same sex of Xylocopa laiipes, in
which the claw-joint also is bearded ^. In Andrena Latr.
the last dorsal segment of the abdomen of the same sex is
fringed, while that of the male is naked ^ In the humble-
bees {Bomhis\ the mandibles of the male are bearded
with curled hairs, while those of the females and neuters
are without them. Some bees, as Andrena and Halictus
Latr., have the anus of the female bearded, and that of the
male naked : in some Bombyces the reverse takes place.

* Kirby Mon. Ap. Angl. i. t. xi. Apis **. d. 2. et. (i.f. \% a. b. c. d.
^ Coquebert Illustr. Icon. i. t. vi./. 6.

<= Kirby Mon. Ap. Angl. i. Apis **. c. 1. «. **. c. 1. /3. **. c. 2. «.
**. c. 2. (5. **. c. 2. y. **. c. 2. S.

«• Ihid. t. viii./. 28,/. g. * Christ. Hj/mejiopt. t. \v.f. 3. b.

f Kirby Mon. Ap. Angl. i. /. iv. Melitta **. c./. 1, a.

X 2

SOS STATES OF INSECTS.

iii. With regard to the general shape of their body,
the male and female usually resemble each other : but
there are some exceptions to this rule. The male of the
hive-bee is much thicker and more clumsy than either
the female or the worker ; but in Halictiis Lfltr. the males
are nearly cylindrical in shape, and very narrow ; while
the other sex are oblong or ovate, especially their abdo-
men : and in Andre?ia Latr. the former are much slen-
derer than the females, and of a more lanceolate shape.
But a still more striking difference in this respect be-
tween the sexes is exhibited by some species of the genus
Ptinus F., in which the male is long and slender, and the
female short and thick. This, in more than one instance,
has occasioned them to be mistaken for distinct insects :
thus, P. Lichenum and P. similis, P. ovaius and P. tes-
taceiis, of Mr. Marsham, are mere sexual varieties. But
the most entire abalienation of shape at present known,
is that which distinguishes the male from the female
Coccus s these are so completely dissimilar as scarcely to
have any part in common. In Bombyx vestita F., and
others of the same family, while the males are of the or-
dinary conformation of the order, the females are without
even the slightest rudiments of wings ; they have no an-
tennae, the legs are extremely short, not longer than
those of the caterpillar ; and the body is entirely desti-
tute of scales, so that they altogether assume the exact
appearance of hexapod larvae ^. A conformation nearly
similar takes place in the female of Tinea Lichenella ; but
in this the feet are longer, and the anus is furnished with
a long retractile ovipositor ^.

a Scheven Naturfors. stk. xx. 65. t. ii./. 4. Compare Ih'uL x. 101,
^ Reaum, iii. t. xv./. IS, 19.

STATES OF INSECTS. 309

iv. Ill many cases, the structure of particular parts and
organs of the body differs in the sexes. As the facts con-
nected with this part of our present subject are extremely
numerous and various, it will be convenient to subdivide
it, and consider the sexual characters that distinguish —
the Head, Trunk, and Abdomen of insects, and their se-
veral appendages.

1. The Head. This part in some females is consider-
ably larger than it is in the male. This is the case with
the ants, and several other Hymenoj)tera ; while in some
Andrcncc, as A. hccmorrhoidalis, and StaphylinidcB, as
St. olens, that of the male is the largest. But in none is
the difference more conspicuous than in the stag-beetle
(Lucajius); in which genus the male not only exceeds the
female in the tength of his mandibles, but also greatly
in the size and dimensions of his head. In the Aj)ion
genus, the rostrum of the female is generally longer and
slenderer than that of her mate; and in Brefitus, the
rostrum of one sex (probably the male) is long and fili-
form, while in the other it is thick and short. This is
particularly visible in B. dispar and maxillosus ^, &c.

One of the most striking distinctions of the males in
this part of their body, arc those threatening horns, usu-
ally hollow, with which the heads of many of the male
lamellicorn insects and some others are armed, and which
give them some resemblance to many of the larger qua-
drupeds. Many are unicorns, and have their head armed
with only a single horn ; which in some, as in Oryctes
Illig., Dynastes Endymion^, &,c. is very short; in otiiers,

» Oliv. no. 84. Urcnltis, t. If. 1. h. c. t. ii./. I?, n. h.
^ Oliv. no. 3. HcarabcEus, I. xviii./. l(if>.

310 STATES OF INSECTS.

very long, as in Dynastes Enema, Pan, Elephas ^. In
one, again, it is thick and robust ; as in the clumsy Dy-
nastes Actaeon '° : in another very slender, as in Ontho-
phagtcs spinifer^. With respect to its direction in Ele-
phastomus proboscideus MacLeay, it is horizontal ^ and
straight ; in Phaleria cornuta horizontal and broken, or
the apex turning outwards and forming an angle with the
base ^ ; in Dynastes Hercules horizontal, and recui^ved
at the apex^; in D. Actceon, Elephas, and Typhon, re-
curving from the base. In Geotrupes dispar it is re-
curved, so that its point exactly coincides with that of
the porrected thoracic horn, with which it forms a kind of
forceps s. In Copt-is lunaris F. and Diaperis horrida, the
horn is nearly upright ^. In Ontliopliagus Xiphias it is di-
lated at the base, and reclining upon the ihorax ; and at
the apex attenuated, and bending forwards, or nodding.
In Passalus cor?iutus it rises a little, and then bends wholly
forwards. In Dynastes Milon, a most remarkable beetle,
it slopes backwards in a waving hne ' ; and in Onthophagus
spinifer it is recurved and reclining. — In speaking of the
direction of the horn, you must recollect that it will vary
in proportion as the head varies from a horizontal posi-
tion : so that an upright horn will become inclined or
reclined, as the head bends forwards or backwards ; but
I speak of it as it appears when the head is horizontal.

» Oliv. ScarabcBus, t.\\\.f. 114. t. xv./. 138. a.

»> Ibid. t. v./. 33. " Ibid. t. xu.f. 112.

'' Linn. Trans, vi. t. xix./, 12. t. xx.f. 2.

^ Oliv. no. 57. Tenebrio, t. If. 2.

f Oliv. tcbi supr. No. 3. t. i.f. 1.

i Oliv. no. 3. f. iii./.20.ff.

•* Ibid. no. 55. Diaperis, t. \.f. 3.

' Oliv. ScarabcBus, t. xx.f. 185.

STATES OF INSECTS. 311

Again, it varies in its teeth or branches. In Dynastcs
Hercules it is armed with several teeth. In D. Elcphas
and Actceon it has only one large one at its upper base '.
In D. Milan it is serrated above. In D. Alcidcs, TityuSi
jEgeon, Copris lunaris, &c. the horn is miarmed and sim-
ple at the apex. In D. Oromedon, Gedeon, Ene?na,
Actceon and congeners, it is bifid. In some the horn is
at first a broad lamina or ridge, which terminates in two
branches, as in Onthophagus Vacca. In this the branches
are straight; but in another undescribed species in my
cabinet (O. Aries Kirby, MS.) they are first bent in-
wards, and then at the apex a little recurved : and in
Z). dichotomus it is divided into two short branches, each
of which is bifid ''. Other males emulate the bull, the
he-goat, or the stag, in having a pair of horns on their
head. In OntJiophagus Taurus, these arms in their curva-
ture exactly resemble those of the first of these animals <^.
In Goliathus pulveindentus, the straight, robust, diverging,
sharp horns are not unlike those of some of the goat or
gazel tribe. I have a beautiful little specimen in my ca-
binet, (I believe collected by Mr. Abbott of GeorgjA,) in
which the horns have a lateral tooth, or short branch,
like those of a stag ; and which I have therefore named
O. cervicornis. In O. Vacca, Camelus, &c: the horns are
very short, and nearly perpendicular. In the male of

* As Dynastes Actaon, Elephas, Typhon, &c. differ from D. Her-
culcs, &c., not only in their general habits, horns, &c., but also in
their maxillae and labium, — the former in D. Actceon being simple,
and in D. Hercules toothed, and the labium of the first bilobed at
the apex, and in the last entire and acute, — according to the modern
fij'stem they ought, therefore, to be considered as distinct genera.
I would restrict the natne Dynastes to D. Hercules and its affinities:
D. Actceon, &c. I would call Megasoma.

*• Oliv. ScarabcEus, t. xvii./. 156. ' Ibid. t. viii./. 63.

312 STATES or INSECTS,

Copris Midas, the two longer perpendicular horns have a
deep cavity between them, which, together with its black
colour, give it a most demoniac aspect ; so that you would
think it more aptly representative of a Beelzebub or Beel-
zehul than a Midas ^, or than Phajiccus Beelzebul MacL.
A similar cavity is between the occipital horns of Dia-
peris JiccmotThoidalis Payk. Some species of Rynchcenus,
as R. Taurus, have a pair of long horns upon the rostrum
of the male, the rudiments only of which are to be traced
in the female''. Other species go beyond any known
quadrupeds in the number of horns that arm their heads.
ThusDiiomus c«Zj/(/owz«5 Bonelli, belonging to Ca?ribusl^.,
has t/iree equal horns '^. The same number distinguishes
Onthophagus Bo7iasus ; but the intermediate one is very
short. In Goliathus 'Polyphemus the middle horn, on the
contrary, is much longer and thicker than the lateral
ones, and forked at the apex ; so that it looks as if it had
four of these weapons ''. A little Diaperis (Z). viridipen-
nis F.), a native of Carolina, has four horns upon the
head of the male ; namely, two long ones on the occiput,
and two short dentiform ones on the nose. In a species
nearly related to this, sent me by Professor Peck from
New England, there is a cavity between the two occipi-
tal horns. The same number disthiguishes Ontliopliagus.
quadricornis [Copris F.). The situation also of the
horns varies : In some it is in the middle of the head,
as Ori/ctes nasicoryiis, Copris lunar is, Sec: in others, as
in Onthophagus nuchico?-nis, Xipihias, &c. it is a process

' This insect is beautifully figured in M. Latreille's Insecta sacres
des Egyptiens,/. 11. See Luke xi. 15. ]r{eb.l\1l\l'^'^ Dominus stercoris^
*• dliv. no. 83. 160. /. vi./. ^0. $ . t. v./, 45. $ ?
* Jbid, no. 36,. /, ii,/. 12. " Ibid, no. 6. /. vii./. 61.

STATES OF INSECTS. SIS

of the occiput or hind-head; and in O. Oryx F. tlie two
horns proceed iVoni the anterior part of the head. In
the other sex, in insects tlie head of whose males is armed
with horns, they are usually rejilaced by mere tubercles,
or very short elevations, as you may see in the female of
Copris lunaris; or by transverse ridges, as in the Ontho-
phagi: or else the head is without arms, and quite smooth,
as in Diapeiis^ Phaleria^ &c. What may be the use of
these extraordinary appendages, as well as those on the
tliorax, and in some cases on the abdomen, (which I shall
mention afterwards), to the males, has not yet been ascer-
tained. Whether the individuals of this sex are more
exposed to the attack of biixls and other enemies, in con-
sequence of being more on the wing than the females,
and are therefore thus provided with numerous project-
ing points for defence, is a question worth considering *.
It is the only probable conjecture on the cui bono of these
arms that I can at })resent make. Under this head I
ought to notice the remarkable membranous process of
an obovate shape, which like an umbrella covers the
head of Achetct umhraculata F. ^ Whether the sharp
curved horns which arm this part in another Acheta
figured by Stoll •=, in an incumbent posture, with their
point towards the mouth, are a sexual distinction, we are
not informed, — probably they are.

The organs of the head also present many sexual di-

« See above, Vol. II. 234—.

'' Coquebert Jlliistr. Icon. iii. t. xxi./. 2.

•^ Stoll Ciga/es, t. xviii./. a b c. Grillons t. iv. /. IG — 18. This sin-
gular animal, which svas found by Mr. Patterson at the Cape of
Good Hope, is stated to be an aquatic, and affords the only known
instance of an Orthnpteroiis insect inhabiting the waters. Tiie Gryl-
lolalpa loves the vicinity of water.

SI 4? STATES OF INSECTS.

stinctions. The upper lip (labrufn) in Halictus Latr., a
tribe of wild bees, in the female is furnished with an in-
flexed appendage, which is not discoverable in that of
the male ' ; and the shape of this lip in Sphecodes Latr.
differs in the sexes ^. Perhaps the horn or tubercle ob-
servable on this part of some female Nomadce F. '^ may
be wanting in the male.

The under-lip {labium) — taken in a restricted sense for
that central part from which emerge the labial palpi, and
which is often considered as the mentum, — does not offer
any striking variations in the sexes. One, however, is
of importance, as it helps to prove which are the true
female Lucani. In the male the labium is emarginate,
in the female it is intire. This may be seen both in
L. Cervus and Jemoratus, and probably in other species.
The sculpture also is different, the lip being smooth in
the former and covered with excavated pimct a in the lat-
ter. The tongue (lingua or ligula) of the sexes is usually
the same ; except in the hive-bee, in which that of the
neuters is longer than that of the male and female.

The upper-jaws {inandibulce), however, often afford
striking sexual characters. The enormous protended
ones of the common stag-beetle [Lucanus Cervus) attract
the attention of the most incurious observer ; and these
are now generally allowed to be of this description.
Geoffroy and Mr. Marsham, indeed, have asserted that
they have taken in coitu those with long mandibles : but
as these males are pugnacious, and attack each other with
great fury, as Mr. Sheppard informs me, it is not impro-
bable that these gentlemen may have mistaken a battle

^ Mon. Ap. Angl. i. Melitta **. b. 139. /. ii./. 4 — 6.

»> Ibid. **. a./. 4, 5. "= Ibid. Apis *. b. 190--. /. v./. 18 b.

STATES OF INSECTS. SI 5

for an amour : since not only have those with long man-
dibles been often taken united with those that have short
ones *, but the same difference obtains in the sexes of
other species. This is particularly observable m Lucmms
Jemoratns, of which I received from Brazil many speci-
mens agreeing in every respect except in this, that one
had short and the other very long mandibles. These
organs vary in diffeient specimens, as to the number of
their teeth and branches. They are singularly robust in
L. Alecs ''; but in none more threatening than in L. Ele-
phas'^, in which they curve outwards and downwards.
In Mr. W. INIacLeay's genus Pholidotus, they are almost
parallel to each other, and curve downwards ; in Lucanus
nebulosus Kirby, they assume a contrary direction''; as they
do likewise in Lamprima Latr.^ In Lucanus Capreolus
the points close over each other ^ In Lethnis F. in the
female, but not the male, the mandible is armed below with
a long incurved horn. In I/ucanus serricornis they form
a complete forceps s. In Siagonium quadric&rne Kirby ^
the mandible is furnished at its base with an exterior
horn, which is probably a sexual distinction. The male
of Synagris cornuta, a kind of wasp, is still more conspi-
cuous in this respect ; for from the upper side of the base
of its straight slender mandibles proceed a pair of crooked,
decurved, tortuous, sharp horns, not only longer than

* By Rosel, by a friend of De Geer's, and by M, Marechal. De
Geer iv. 331 — . Konv. Diet. d'Hist. Nat. xviii. 225.

*• Oliv, no. i. Lucanus, t. ii.f. 3, •" Ibid. t. iii./. 7.

<" Linn. Trans, xii. 410. /. xxi./. 12. * Ibid. vi. 185. /. xx./. 1.

f Oliv. ubi supr. t. ii.f. 4.

f Regne Animal, iii. t. xiii./. 3.

» See Vol. I. Plate I. Fig. 3.

316 STATES OF INSECTS.

the mandible, but than the head itself^. Many sexual
differences are observable in the mandibles of the va-
rious tribes of bees [Anthophila Latr.). Thus, in Colletes
Latr. the male mandible is more distinctly bidentate at
the apex than the female"^: in Sphecodes Latr. and others,
the reverse of this takes place '^. Where these organs in
both sexes are toothed at the apex, they often vary in the
number of teeth. Thus, the female of Megachile cenhm-
cularis Latr. has four teeth at the apex of its mandible,
while the male has only two''. In M. Willughhiella,
though the mandibles of both sexes have four teeth, yet
those of the male are sharp, and the two external ones
the longest; while those of his mate are obtuse, and all
nearly equal in length ^. In Anthidium manicatum Latr.,
the former has only three teeth, while the latter has five ^.
The differences in this respect in the hive-bee have been
before noticed = ; those of the humble-bees [Bombus Latr.)
are strikingly distinguished from each other ; the female
mandible being very stout and wide, constricted in the
middle, and furrowed on its outer surface ; and the male,
on the contrary, very slender at the apex, dilated at the
base, and without furrows ''.

Of all the organs of the head, none seem so little sub-
ject to sexual variation as the under-jaws {7naxillce) \ I

' Christ. Ilymenopt. t. xviii.y. 2.

*> Mon. Ap. Angl. i. Mel'dta *. a. i. If. 5. $ . 7. <? •

♦^ Ibid. Melitta **. a. t. ii./. 6. $ . 7. d' • and **. b. t. iii./. 3. $ . 4. <J .

«• Ibid.t.vm.f.W. 5 . 12. <?,

*■ Ibid.i. f.viii,/. 9. $ . 10. <?.

' Ibid. Apis **. c. 2. /3. f. ix.f. 6. $ , 7. <? .

^ See above. Vol. II. 135. Note ''.

^ Mon. Ap. Angl. ubi siipr. t. xiii./. KJ, 5 . 14. <?.

' MacLeay Hor. Entomolog. 4 — .

STATES OF INSECTS. SI 7

can bring forward only one striking instance of it, and
some degree of doubt rests even upon that. In the genus
Nemuguniha of IlHger, the niaxilhi? of the male are elon-
gated, narrow, setiform, and often involute or spiral, like
those of a bee or a butterfly. But that this is peculiar
to the males is at present only surmised *. I possess se-
veral species of the genus, all of which are distinguished
by long maxilla? ; though in some they are as long as
the body, and in others scarcely half that length. Gna-
thium Kirby is similarly characterized ^.

The rnoxillarj/ ]mlj)i occasionally differ in the sexes.
In Ccrocoma those of the female are filiform, while the
two intermediate joints of those of the other sex are mucii
thicker than the first and the last <=. In Hylccccius and
Lijmexijlon, those of the male are still more remarkable :
they are pendent, the last joint very large, and laciniated
so as to form a tuft ''. The female ones grow gradually
larger towards the end, but are not at all divided there •=.
The palpi of male spiders are of a very different struc-
ture from those of the other sex, terminating in a very
Complex incrassated piece, which has been supposed to
contain the organ of generation ; but this, according
to Treviranus, is a mistaken idea — that organ being, as
usual, to be found in the abdomen ^ In the common
gnat the palpi of the male are as long as the proboscis,
consist of five joints, and at the end are tufted with hairs;
while those of the female arc scarcely one-fourth of its

» K. Diet. Wllist. Kat. xxii. 488.

^ Lhin. Trans, xii. 425—. I. xxii./. G. <• Plate XXVI. Fig. 2,
•< Ibid. Fig. .3. ^ Oliv, no.xxv. Lymexylon, t. \.f. 1.

' De Geer vii.249— . /.xiv./. 20, 21. Treviranus Arachnid. 3fi— .

t. w.f. Kun h c. t. IV. f. .35— .';;.

318 STATES OF INSECTS.

length, have only three joints, and are not tufted. Whe-
ther the labial palpi in any genus differ in the sexes, I
cannot affirm with certainty : I have not, however, ob-
served any such variation in them.

I shall next mention some organs of the head, in which
the diiference between the sexes is often very striking
and peculiar. You will readily conjecture that I am
speaking of the antemicE. And here the advantage seems
wholly on the side of the males : since in them these
wonderful instruments of unknown sensations are not
only more complex, but usually more elegant, than
those of the other sex. You will pardon me, therefore,
if I enlarge a little more than ordinary upon a subject so
full of interest, and say something upon the differences
observable between the sexes — in the shape, magnitude,
and length, number of articulations, ramification and
plumage, and individual joints of their antennae.

With regard to their shape^ variations are sometimes
observable between the antennae of the sexes ; but this
principally occurs in the Hymenoptera order. For in-
stance, those of Chelostoma maxillosa, a small bee that
deposits its eggs in little holes in posts and rails, are cla-
vate in the female and filiform in the male ^ — a circum-
stance that distinguishes in some degree those of Sp/ie-
codes, Halictus, and Andrena of Latreille, three other
genera of wild-bees ''. In Dinetus Jur. the male antennee
are moniliform at the base, and filiform at the apex ; the
female, on the contrary, are entirely filiform*^.

' Mon. Ap. Angl. i. Apis **. c. 2. y. L ix.f. 7. $ . 9. <?.
^ Ibid. Melitta **. a. t. ii./. 8. $ . 9, <J . and **. b. t. iii./. 6. $ .
7. 3. **.c.i. iv./. 11. 5. 12. <J.
" Jurine Hymenopt. t.\\.f.2.

STATES OF INSECTS. SI 9

The antennae of the sexes also sometimes differ in
magnitude and length. This is the case in the three ge-
nera of wild bees just mentioned ; those of the female be-
ing thicker than those of the male, while these last are
longer than the former. But in this tribe the males of
the Fabrician genus Eucera are most remarkable for their
long antennae '. With regard to the different length of
these organs in the sexes, no insects are more distinguished
than some species of the capricorn-beetles {Cerambyx L.).
In Lamia Sutor the male antennae are twice the length of
the female ; and in another Brazilian species in my cabi-
net, related to L. aimulata {Stenocorus F.), they are thrice
their length. Some of the Anthribi F. approach the
Cei'amhycidce, not only in some other characters, but also
in this circumstance : — thus the antennae of A. albimis, a
native of Britain, are vastly longer in the male than in
the female; and in A. cinereus {Macrocephalus Oliv.)'',
which I suspect to be of the former sex, they ai'e as long
nearly as is usual in the tribe just named, called in France
capricorn-beetles.

I may here observe, that sometimes in the sexes a dif-
ference is also to be found in the direction or flexure of
their antennae. Thus in Scolia F., Pejjsis F. &c., in the
males the antennae are nearly straight, but in the females
convolute or subspiral. The reverse of this takes place
in Epipone spinipes, a kind of wasp, and its affinities; and
Systropha Illig., a kind of bee : for in these the male an-
tenna is convolute at the apex '^, and the female straight.
In the various tribes of bees {Anthophila Latr.), these

' Alon. Ap. Angl. i. Apis **. d. 1. ^. x./. 7.
'' Oliv. no. 80. Macj-ocephalus, t. i.f. 2.
" Latr. Gen. Crust, et Ins. iv. 156.

320 STATES OF INSECTS.

organs in the latter are what is denominated broken^ the
main body of the antenna forming an angle with the first
joints : but in the former this does not take place.

The antennae of the sexes do not always agree in the
number of joints. In the bees, and many other Hymeno-
■ptera^ the male has one more joint than the female; as is
the case also in CEdemera notata [CantJiaris ac?/to Marsh.).
In Pteronus Laricis, a kind of saw-fly, the latter has only
sixteen joints in its antennae, while the former has twenty-
four *. In Rhipicera marginata, a beetle, the beautiful
antennae of the male consist of thirty-two joints, while
the female has no more than eleven ! In Chelonus Jur.
the male, on the contrary, has the smallest number of
joints, namely sixteen; while the female has twenty-
five ^

In nothing do the sexes differ more materially than in
the ramificatio7i o{ \hQse oYgaxis, and \h&\t plumage. By
attending to this, you may often detect the sexes in an
instant ; since the antennae of the males in numerous in-
stances are much more complex than those of the females.
For what end the Creator has so distinguished them is not
quite clear ; but most probably this complex structure is
for the purpose of receiving from the atmosphere informa-
tion of the station of the female. A tendency to branching
will be found in the antennae of some males, in tribes where
these organs are usually perfectly simple in both sexes.
Thus, in the male of Chelostoma maxillosa, — mistaken for
another species by Linne, which he names Apisjlorisom-
niSf — the intermediate joints on their inner side project
into an angle *^ ; and those of the same sex of the common

» Jurine Hymenopt. 61. t. vi./. 8. ^ Ibid. 389.

^ Mon. Ap. Aiigl, i. t. ix. Apis **. c. 2. y.f. 9.

STATES Ol" INSIU I:». 321

hornet, by means of a central sinus, have two obtuse
teeth on each. M'ith regard to more direct ramifica-
tions, some male antenna? terminate in a fork, or two
branches. This is the case with Hylotoma J'urcata Latr.,
a saw-fly"; and the peacock-louse {Nirmus Pavonis
Herm.) ^\ Others, again, have three lateral branches,
as in Eulophus Geoft'r. a little parasite, the male anten-
nae of which send forth a hairy external and rather long
branch, from the base of the fourth, fifth, and sixth
joints'^. In Elatcrjlabellicorni^ L., the eight last joints
are flabellate, or elongated and flat, resembling the sticks
of a fan in the male '^; in the female they are shorter, and
more properly may take their denomination from the
teeth of a comb. In Lamj^yris LatrciUii Kirby, the an-
tennas of the former are flabellate on both sides, while
those of the latter are little more than serrate ^. These
organs are extremely beautiful in the males of the Rhi-
picera of Latreille. In R. margmata K. they consist of
thirty-two joints, from thirty of which issues a branch,
the first very short, but the rest gradually increasing in
length as they approach the middle of the antenna ; then
gradually decreasing to the end, so as to represent an
expanded fan ^ But in none are they altogether so re-
markable as in those moths that Linne denominates
Bomhyces Attaci, and some others. In these, in the males,
these organs in their contour are lanceolate, and every
joint is furnished with a couple of parallel equal branches
on each side s. In the females these branches are shorter

* Plate XI. Fig. 19. . " Platk V. Img. 3.

« Plate XI. Fig. 18. -< Ibid. Fig. 17-

" Plate XXV. Fig. 11. Linn. T'/wwxii. /. xxi./. 4. a.
' Ibid. f. 3. « Plate XXV. Fig. 22.

VOL. III. Y

322 STATES OF INSECTS.

on the whole, and alternately one long and one short; but
in some, as Satiirnia Pavonia, there is only one short
branch or tooth on each joint in this sex ^. In Bomhyx re-
galis &c. only the first part of the antenna is so branched ;
and those of the female are setaceous and witliout branches.
In B. versicolor, &c. there is only one branch from each
side on every joint ; those of the female being much
shorter than those of the male. The latter sex of Ptero-
nus Laricis Jur., a saw-fly, afford an example of a dif-
ferent structure, the antennae on one side sending forth
a branch from every joint but the two first; but on the
other side, the nine or ten last joints also are without a
branch. The female antenna is serrated ^. In another
of this tribe, Pterygoptenis cinctus Klug, the male an-
tenna resembles a single-toothed comb, being branched
only on one side : that of the female, like the former in-
stance, is serrated '^. Whether the remarkable antennae
that distinguish the known individuals of the genus Phen-
godcs [Lampyris plmnosa F.) is a sexual character has
not been ascertained ; but it is not improbable that it
may be, as in other LampyridcE. A pair of delicate
flexile and almost convolute plumose branches proceeds
from the apex of each joint except the basal ones, which
have something the air of cirri, and give a more than
usual degree of lightness and elegance to these organs ''.
Other antennae, especially in the Diptera order, assume
an appearance of plumes — not from the bi'anches that pro-
ceed from them, but from the fine long hairs that beset
and adorn them. These are universally indications of the

■•' De Geer i. t. xix /. 11, 12. '' Juriiie Htjmenopt. t. \i.f. 8.
' Plate XXY. Fig. 25, 20. •' Ihi.l. Fir.^ 4.

STATES OF INSECTS. .'j23

male sex, those of tlie females being generally compa-
ratively naked. If you take the common gnat, you will
find that the antenna; of one individual are thickly fringed
on each side, and tufted at the end with fine long hairs,
while in the other only four or five placed at intervals in
a whorl are to be perceived '. In CJiirononms Meig., a
kind of Tipnla L., resembling a gnat, the male antennae
are beset on all sides with the finest hairs, and resemble
a beautiful plume'', while the females to the unarmed
eye appear naked. Even in some HymcnojHera, the an-
tennas of the males are thus feathered, in a less desree :
for instance, in Hylotoma Latr. ^ Whether the tufts
and fiinges which ornament, in a remarkable manner,
the antenna; of many CeramhycidiC ^, are sexual charac-
ters, is not certainly known.

We are now to consider other sexual differences in
these organs, resulting from the size or configuration of
one or more individual joints. To begin with the first
joint, or scapus. In many of the Mymenopiera^ particu-
larly the Anthophila Latr., this is elongated, and the re-
maining joints form an angle with it in the females : while
in the other sex it is much shorter, and in the same line
with the rest of the antennas ; and in Hi/lccns dilatatus.
{Melitta dilatata Kirby) the first joint in the male is di-
lated and shaped something like a patella ^. In Mala-
c/iius bipustnlaius, &c. the sex just mentioned is pecu-
liarly distinguished by a white excrescence on the first

=> Reaum, iv. /. xl./.2. a a. S.t xxxix,/. 3. $ . In the last the
hairs arc too conspicuous.

•• Plate XII. Fig. 24. ■" iwr'me ilt/menopt.t.xx. f. 2

•' Plate XH. Fig. 2.0, 2(>. XXV. Fin. 17, ."2!
' Il.iil. Fic. 12.

Y 2

324 STATES OF INSFCTS.

four joints of the organs in question, most conspicuous
in the second and fourth. The antennae of male Cero-
comce are not very different ^. Mr. Marsham has de-
scribed a little Haltica under the name of Chrysomela
nodicornis, from a peculiarity of the same sex not to be
found in the other. The fourth joint is very large and
obtriangular ; in the female it is merely longer than the
rest. In U. BrassiccE and quadripushdata the fifth joint
is larger and longer than all but the first in the male, in
their females it is only longer. In some moths {Hermi-
nia Latr.j Cr ambus F.) there is also a knot in the middle
of the male antennae ''. In Noterus, a water-beetle, the
six intermediate joints are thicker than the rest, begin-
ning from the fourth, and the last but one ends internally
in a truncated tooth. The fifth and two following joints
in the male antennae of Meloe are larger than the rest,
which distinguishes them, as well as a remarkable bend
observable at that part '^.

Variations of the kind we are considering are also ob-
servable in the clava, or knob, in which antennae often
terminate. You have doubtless observed that the la-
mellated clava of the antennae of the common cockchafer
is much longer and more conspicuous in some uidividuals
than in others — the long clava belongs to the male ^. In
another species, M. Fullo^ that of this sex is nine or ten
times the length of that of the other. In Colymhetes
serricornis^ a water-beetle, the male has a serrated clava
of four joints. In Dorcatoma dresdcnsis ^, and also Eno-
plium damicoi'nei two beetles, it is nearly branched in the

' Plate XL Fig. 22. ^ N. Diet. d'Hist. Nat. xiv. 395.

- Plate XII. Fig. 7. '' Pi ate XXV. Fig. 1,

• Ibid. Fig. 21.

STATES OF INSLCTS. 32.5

male, but much less so in the female. In a little destruc-
tive beetle, common in our houses {Attagenus Pellio),
in the latter it is very short, but in the former it is very
long, and nearly formed by a single joint. In FAirhinus
Kirby, a New Holland genus of the weevil-tribe, in the
male the last joint, also, is much longer than it is in the
female ". These examples will give you some idea of the
principal variations that take place in the anteimae of the
sexes, and of the wonderful diversity of forms in this re-
spect to which mere sexuality gives rise amongst insects.
In theses, or slemmata, this diversity is less remarkable.
Latreille has described two ants, Formica contracta and
cueca^ in the neuter of which he could discover no eyes'*:
in the former, the female, however, had laz'ge ones. The
male he appears not to have known, but it probably was
not destitute of these organs ; of the latter he was ac-
quainted only with the workers. The neuter of M^yt-
mica rubra, another ant, has no ocelli or stemmata,
although the male and female are jirovided with them '^.
They are discoverable only in the former sex of that sinr
gular insect related to the ants, Mutilla europcea. Other
insects differ in the size of the eyes of their sexes. In
the hive-bee, and some JLplicmercc, the eyes of the drone
or male are much larger than those of the worker and
female, and also meet at the vertex, having their stemmata
below the conflux; whereas in these latter they are
widely distant ^. In Stratyomis, Tabanus, and many other

* Linn. Trans.xW. t. xxii./. 8. e. S ■/• + •
•• HUt. Kat.des Fournm, 195—. 270—.
'' De Geer ii. 1094.

^ Ibid. 650. Mon, Ap. Aug/, i. (. xi. Ajm xx. e. 1./. x\ ^ . t. xii.
/. 3. ? .

326 STATES OI' INSECTS.

two-winged flies, the male eyes meet at some point beloAV
the stemmata, and above the antennae. In the former
they touch more at an angle ; for the vertex forming a
narrow isosceles triangle, and for the anterior part of the
face one nearly equilateral : while those of the female are
separated by a considerable interval. In Heptatoma
and Hamatopota in that sex, a similar interval obtains ;
while in the other, after forming a minute short triangle,
they unite for a considerable space, and then diverging,
form the face. This is also the case in Tahanus ; but in
the female, the space that intervenes between the poste-
rior part of the eyes is much narrower than in these two
cognate genera of the horse-flies. In some others of
this order, as Musca Latr., the eyes of the male do not
touch, but approach posteriorly much nearer to each
other than those of the other sex. In a few instances
the sexes vary even in the number of their eyes, as well
as the size. This occurs in some species of EpJiemera L.
{E. diptera, &c.), in which the male, besides the com-
mon lateral ones, has two large and striking interme-
diate eyes, that sit upon vertical pillars or footstalks *.

2. The Trunk. The thorax of many coleopterous
males, especially of the Dijnastidcc and Copridce amongst
the petalocerous tribes, exhibits very striking differences
from that of the female. In many Lucani the lateral
angle is more prominent. In Anthia it is bilobed poste-
riorly, while in the last-mentioned sex it is entire ^. In
PhaiKEus carnifex MacLeay {Copris F.) it is elevated into
a plane triangular space, with the vertex of the triangle

■■' Plate XXVI. Fig, 39. Dc Gccr ii. 051. 659.
^ Voct Colcopt. i. /. xxxix./. 4/, 18. J . 46. <^ .

STATES Ol- INSECTS. 327

pointing to the head; but in the remiile it is convex, willi
an anterior abbreviated transverse ridoc ».

In a hjrpje proportion terrific Iionis, olten hollow, like
those of the head lately noticed, arm the thorax of the
male, of which you will usually only discover the rudi-
ments in the other sex. In the first place, some are iini-
C07HS, or armed only with a single thoracic horn, which
frequently, in conjunction with the thorax itself, not a little
resembles a tunnel reversed : of this description are Dy-
7iastes Hercules^ Tili/us, Gcdcoii, E7icma, &c. ^ In the
three first this horn is porrected, or nearly in the same line
with the body ; but in the last, and Z). Pan, it forms an
angle with it ; and in Z). JEgco7i it is nearly vertical *=.
In D. Hercules it is very long; in D. Alcides^ and Tityiis
very short ; in the two last, and in Oxi/telus tricornis
which is similarly armed, it is undivided at the apex;
but in D. Gedeon, Pan, bilohns, &c. ^ it is bifid or bilobed.
It is usually rather slender, but in D. ChorincEus ^ and
bilohus, it is very stout and wide. In D. claviger it is
hastate at the apex s. In D. hastahis it is short and
truncated ^. Others, again, have t'wo thoracic horns.
In Copn's iiemcstrinus these are discoidal, diverging, and
inclining forwards '. In Plumceusjloriger ^ they are late-
ral, triangular, and incline towards each other, with, as
it were, a deep basin between them. In P. sjjlcndididiis
they sink into two longitudinal ridges, most elevated

» Oliv. no. 3. t. \\.f. 4(). a. ^.b. ^.

" Ibid, t.'i.f. 1. iv. x./. 31. xi./. 102. xii./. 114.

« Ibid. /. xxvi./. 219, •» Ibid, t If. 2.

"= Ibid. t. xxiii./. 35. f Ibid. /. ii./. 7-

8 Ibid. /. v.f. 40. •• Ibid. xix./. ] 75.

' Ibid. ^ xii./. 115.

^ Copris Jloiiger Kirby in Iaiih. Trans, xii. 306.

328 STATES Ot INSECTS.

posteriorly, with an intervening valley *. In P. bellicosus
they are posterior, compressed, truncated, and emargi-
nate at the apex, and include a basin ^. In Copris Sahceus
they ai'e merely two acute prominences ^. — Three horns
distinguish the thorax of many. In Z). Aloeus^ and its
affinities, they are arranged in a triangle, whose vertex
is towards the head. In D. Antaiis ^ these horns are
nearly equal in length, and undivided at the apex. In
2). Titanus ^ the anterior horn is longer than the rest,
and bifid at the apex ; in Z). Atlas and Endymion s, both
of whicli have a horn on the head, it is much shorter.
In others, as in Megasoma Kirby, the vertex of the tri-
angle is towards the anus. In M. Typhon ^ it is longer
than the anterior ones, and bifid at the apex ; in M. la-
nigerum they are equal in length '. In M. ILlephas and
Actceon ^ it is merely an elevation of the thorax ; in the
last almost obsolete. In Geotrupes Typhceus, common
on our heaths, the anterior of this part is armed by three
horizontal horns, the intermediate one being the short-
est '. Copris lunar is also, another of our own beetles,
has three short posterior thoracic horns, two lateral and
triangular ones, and a transverse intermediate elevation,
with a notch in the middle ™. In Dynastes NepUmus the
horns are porrected, the middle one being very long, and
i;he lateral ones short ", In D. Gcryon the point of the la-

» Oliv. no. 3, /. ii./. 18. " Ibid, f.xxii./. 32.

-= Ibid. t. IX. f. 85. 'i Ibid. t. iii./. 22.

• Ibid. t. xiii./. 124. a. f Ibid. t. v./. 38.

« Ibid. L xxviii./. 242. t. xviii./. 169.

" Ibid. t. xvi./. 152. ' Ibid. /. xxviii./. 247,

t Ibid. /. XV. /. 138. a. t. v./. 33.

' Saiiiouelle's Compend, I, i,f. 1.

"' Oliv. no. 3, t. v./. 36. a. " Schoii. Si/iwn. i. /. 1.

!JTATi:S OF INSKCTS. 329

teral liorns is towards the anus, aiul llie base of the in-
termediate one covers the scutellum *. Otliers havejour
of these singular arms: this is the case with one of our
rarest beetles, Bolboccrns mohilicoinis K., which has four
dentiform horns, the intermediate })air being the short-
est, arranged in a transverse line on the anterior part of
the thorax ''. In B. quadridcns these are merely teeth.
In Phatucus Faumis *^ it has two lateral, elongated, com-
pressed, truncate, horizontal horns, and two intermediate
teeth. Dijnustcs Milon has a still greater number of
horns on the thorax of the male, there being two lateral
anterior ones and three posterior ones — the intermediate
being the longest **; and Copris Atitenor Fabricius and
Olivier describe as having a many-toothed thorax; and
from the figure of the latter ^^ the male apj)ears to have
seven prominences.

But the males of insects are not only occasionally di-
stinguished by these dorsal arms — in a lew instances they
are also furnished with pectoral ones. The illustrious
traveller Humboldt found in South America a species
of weevil [CiyptoyJiynchus Spiculator Humb.), the breast
of which was armed with a pair of long projecting horns;
and I possess both sexes of four species, three at least
from Brazil, that exhibit in one individual the same cha-
racter. One, concerning the country of which I am un-
certain, recedes somewhat from the type of form of the
rest, and comes very near that of RyncJuvnus Stvix F. ^
In the individual which I take to be C. Spiculator, the
pectoral horns are very long, curving upv.ards at the

» Oliv. no. 3. t. xxiv./. 208. " Ibid t. x /. 88.

« Ibid./. 87. ^ Ibid. /. xx./. 185.

' Ibid. I. vi. /'. l.\ n. ' Ibid. ii. ^o. Ciaculw t xxii.y.^JOo.

330 STATES OF INSECTS.

apex, and nearly in a horizontal position ; while in the
three others they are much shorter, and inclined towards
the horizon. The males of some species of liynchites, as
R. Bacchus and Populi *, are also armed with a pair of
lateral horns or spines, which jnay be termed pectoral
rather than dorsal.

I shall now advert to the sexual characters that are to
be found in the instruments of motion attached to the
trunk — beginning with those for Jlig/it. In the female of
the common glow-worm [Lampyris noctilucii) not the
slightest vestige of elytra or wings is visible, and it re-
sembles a larva rather than a perfect insect ; yet its mate
is a true beetle furnished with both. The same circum-
stance distinguishes the female cockroach [Blatta) and
is more universally prevalent in that genus than in Lam-
pijris, in which a large number of females have both ely-
tra and wings. The males of Bomhyx antiqtia and Gono-
stigma, and of many other moths, have wings of the usual
ample dunensions, while those of their females are merely
rudiments. This is the case, also, with some of the Ick-
7ieumonida; ^. In the tribes of Ants, Termites, &c. the
neuters or workers are without wings. Amongst the
plant-lice [Aphides) there are individuals of both sexes,
some of which have wings, and others not '^. Amongst
the Coleoptera, the female of Tenehrio Molitor, the com-
mon meal-worm, has elytra and no wings; while the
male has both ^. — Sometimes these organs vary in size
in the sexes : thus in Aradus Betidcc F., a kind of bug,
the hemelytra and wings are narrower and shorter in the

a Oliv. no. 81. Attclabus I. W.f. 27. b. 28.

'' Dc Gecr ii. t xxxi /. 18—22. <• Ibid, iii. 21.

'' Lesser L. i. 185.

STATKs or iNsiirrs. 331

Icnuilc llum in the male-'. In the gciuiti Blaps F., the
niucro that anus the apex of each clytrmn is longer in
the former sex than in the latter. In Jltcuc/ius sibbo-
sus F., a ilnng-beetle, the elytra have a basal gibbosity
near the suture in one sex that does not obtain in the
other. In the OrtJioptera order, the sexes are often to
be known, almost at first sight, by a diflerence in the
veining and areolets of the wings ; but upon this I en-
larged so fully when I treated of the sounds produced by
insects, that it is not necessary to repeat what I have
said ; which observation also applies to the drums which
distinguish the male Cicadcc ^. The wings of some but-
terflies, and of most moths and liawkmoths {Sj)/n/ix L.),
are furnished with a singular apparatus for keeping them
steady, and the under-wing from passing over the upper
in flight. This appears to have been first noticed by
Moses Harris, and was afterwards more fully explained
by M. Esjjrit Giorna ^. From the base of the under-wing
proceeds a strong bristle, received by an annulus or
socket, which springing between the two principal ner-
vures of the upper-wing terminates in the disk of the
wing : in this annulus the bristle moves to and fro, and
prevents the displacement of the under-wing. This ap-
paratus is perfect only in the males, which alone have
occasion for long flights ; the females, though they have
often several bristles, having no annulus '^.

The other instruments of motion, the legs, also differ in
the sexes. In some instances they are disproportionably
long. This is particularly the case with the anterior pair

« Dc Gcer iii. 308. ^ Sec above, Vol. II. 394—,

' Linn. Trans, i. 145. 135 — .
•i Ibid t. xiii./. 1. 2.,?. 3. ^ .

332 STATES 01-- INKECTS.

of some beetles, as Macropus longiiuamis, Scarabn'us longi-
mamts L., in which they are so long as to make the males
of these individuals rather inconvenient in a cabinet.
Amongst British beetles Clytra longimana and Curculio
longimanns Marsh, are also remarkable in this respect.
In some other males the middle pair are the longest; as in
AntJiophora retusa Latr., a kind of wild-bee ^. There are
two known instances of remarkably long ^os/e/7'o;' legs in
the Capricorn tribe, which I suspect belong to the present
head. One is Saperda hirtipes Oliv.^, in which the hind-legs
are longer than the whole bod}', and adorned with a sin-
gular tuft of hairs ; and the other a Chjtus, I think, which
Mr. MacLeay purchased from the late Mr. Marsham's
collection, in which the hind-legs are not only very long,
but have tarsi convolute, like some antennae. From ana-
logy I should affirm that these were the characters of
male insects.

To come to the parts of legs. Sometimes the coxce of
the last mentioned sex are distinguished from those of
the female by being armed by a mucro or spine. Thus
the male of Megachilc Willughbiella, and others of that
tribe, have such a spme on the inner sides of the anterior
coxa '^. The Trochanter also of some differs sexually;
and you will find that the posterior one of the male in
Anthidium manicatum is of a different shape from what
it is ill the female ^. In Sphodrus leucopiththalmus, one of
the beetles called black dors, in one sex the same tro-

» Mon. Ap. AngL i. /. xi. Apis **, a. S. u. (i.f. 18.

•> Oliv. no. 68. Saperda t. i.f. 8.

« Mon. Ap. Angl. i. t. viii./. 38. c.

*< Ibid. t. ix. Apis **. c. 2. "(i.f. Y2.

STATES OF INSECTS. 333

chanter terminates in a long nmcro or spine ^, and in the
other it is ronnclcd at tlie apex.

Peculiar characters in their f/ii^/is also often indicate
different sexes. In Prionus damicornis tliei'e is a short
spine at the apex of" the anterior ones in the female that
is not in the male ; while in Macropus longima7ius, at their
base externall}' the male is armed with a mucro, which I
cannot find in the female ''. In Scarabccua longimanm ly.
this thifjh is furnished with two teeth *=. — The intcrme-
diate thighs also sometimes differ. In an Onitis from
China, a vni'iety perhaps of O. Sphinx, those in the male
are dolabriform, and in the other sex of the ordinary
shape. In Odynetnis spinipes they have on their lower
side two sinuses, so as to give them the appearance of
being toothed. The posterior thighs are sometimes in-
crassated in the mule, and not in the female. This you
will see in a weevil, not imcommon, Apoderus Betulce,
and also in many species of Citnbex F., a kind of saw-fly ;
and the same circumstance distinguishes the latter sex in
many species of Li/g<rus F., a kind of bug : I discovered
this from JL. cruciger, of which I have both the sexes ; and
from Stoll's figure of L. Pharaonis ^. In some of these
the female thighs are enormously lai'ge. A remarkable
variation in this respect is observable in the coleopterous
genus (Edemera [Necydalis L.). In ffi. Podagraricc these
limbs are incrassated in one sex and not in the other *;
in (E. cccrulea they are so in both sexes; and in (E. ceram-

» Clairv. Ent. Helv. ii. t. xii./. B.

»> Oliv. Ins. no. 66. t. iii. iv./' 12. * Ibid. no. X t. iv./. 2".

«" Punaiscs, t. iii./. 20.

* Mr. Marsham has made two species of thi"* from thi-; circum-
stance, viz. Xcfydalit Podagrnri/v and simplex.

334 STATES OF INSECTS.

boidcs in neither. In Pelecinus Polycerator F., one of
the Iclineumon tribe, or an insect very near it from Bra-
zil, these thighs in the female are armed with two spines
underneath, which are not in the male.

The anterior tibia in Scarabceus longimanus L. differ
remarkably in the sexes. In the female they are of the
ordinary shape, and serrated externally ; but in the male
they are very long, incurved, and without teeth or serra-
tures ^. In the males of the genus Onitis F. they are bent
like a bow, and acute at the end ; but in the females they
are formed on the common tj'pe ''. In Hispa spinipes F.
they are armed internally with a crooked spine '^. But
the most extraordinary sexual variation of this joint of
the \q^ may be seen in the male of Crabro a-ibarius F.
and several other species of the same family, in which
these tibias are dilated externally into a concavo-convex
plate, or rather have one fixed to them and part of tlie
thigh, of an irregular and somewhat angular shape '^j
with numerous transparent dots, so as not badly to re-
semble a sieve : whence the trivial name of the species.
Rolander, who first described it, fancied that this plate
was really perforated, and that by means of it the animal
actually sifted the pollen ; but it is most probablj^ for
sexual purposes. In another species, the plate is orna-
mented with transparent converging streaks. In the
bee-tribes {Anthophila Latr.) the posterior tibia of the
working sex is generally bigger than the corresponding-
part in their more idle partners : this is particularly con-

« Oliv. n. 3. ;. xxvii./. 27- ? . and L iv.f. 27. S •
'■ Ibid. t. vii./. 58. (?./. 57. $ .
■= Ibid. n. 95. Hispa t. If. 4. Plate XXVII. Fig. 24.
-^ PrATr XV. Fig. 3.

STATES OF INSF.CTS. SS.**

spicuous in the genus Euglossa, in the females of which
this part is trianguhir, very broad towards tlie apex, and
filte<l for carrying a hirge mass of pollen paste. The
tibiiu of the mules of some Lcpidoptcra are remarkable in
this res})ect. That of Hepialus Hunmli is much more
hairy ; but in //. Hectus it is a dilated mis-shapen mass,
without a tarsus, anil with long scales pendent from the
tlisk *. Differences of this kind also occur in the calcaria
or spurs that arm the apex of the tibiae of a large num-
ber of insects. Thus in Acanthopus Klug, a singular
bee, in the male the spur of the intermediate leg is dilated
at the a})ex, and armed with six strong spines, the inner
one larijer than the rest''.

But the part of the leg in which the sexes most vary
is the tarsus ,- and this variation takes place both in the
number of the joints, and their form and circumstances.
The first case has been observed only with regard to cer-
tain species of Cnjptophagus Herbst, as C. ftimatus, &c.
in which the female \s pentamcrojis, or having^w joints
in all the tarsi ; and the male heteromerous^ or having /?rjc
joints in the two anterior pairs, and only four in tiie
posterior ^. With respect to the form of the tarsal joints,
the sexes more frequently differ ; and by inspecting this
part, especially in the predaceous and carnivorous Co-
Uoptera^ you may often, without further examination,
ascertain whether any individual is male or female.
Even in the slender-footed Cicindelidcc, the three first
joints of the anterior tarsus of the male are more dilated
than the two last, and covered imderneath with a brush

■» De Gceri. /. vii /. 14, 15.

•> Coquebert llhist. Icon. i. t vi /. G. Plati; XXVII, Fin. .'V2.

'• WWs.. Maf^.iw 214. Gyllcnlial. Iiiscrl. Sure. i. KiS.

336 STATES OF INSECTS.

of stiffisli hair ; in the female all are equally slender, and
not so hairy. In Carahus, Feronia^ &c. Latr. \\x^f(Mr first
joints of these tarsi in the males are dilated, and furnished
with a brush or cushion : in the Silphidce, also, the same
circumstance takes place. In Harpalus Latr., and Sil-
pha americana, the Jour anterior ones are similarly formed
in this respect. But one of the most remarkable sexual
characters, in this tribe of insects, that distinguish the
males, are those orbicular patellae, furnished below with
suckers of various sizes, and formed by the three first
joints of the tarsus, which are to be met with in the Z)j/-
tiscidcE, &c. ; but as I shall have occasion to treat of these
more fully in another Letter, I shall only allude to them
now. The second pair of tarsi have in these also the
three first joints dilated and cushioned ^. In Hydro-
jphilus piceus, another water-beetle, the fifth joint of the
tarsus is dilated externally, so as to form nearly an equi-
lateral triangle ^. Christian, a German writer on the Ui/-
menoptera^ has described some very singular appendages
which he observed on the first joint of the four posterior
tarsi of "Kylocopa latipes F. These were battledore-
shaped membranaceous laminae, with a reticulated sur-
face, of a pale colour ; which were fixed in pairs by the
intervention of a footstalk to the above joint, on which
they sometimes amounted to more than a hundred : the
use of which, he conjectures, is the collection of pollen ^
I possess two specimens of this bee; one has none of
these appendages, and on the other I can discover them
only in one of the tarsi — from which circumstance I am

» Plate XV. Fig. 9. ^ Ibid. Fig. 8.

« Christ. Hiimenopt. US. t. iv./. .3.

STATES OF INSECTS. 337

led to conjecture that, like the supposed Clavariee that
were imagined to grow on some humble-bees, but which
are now ascertained to be the anthers of flowers — these
also belong to the kingdom of Flora, and are spoils which
the bee in question has filched from the blossom of some
plant. The individuals that have been thus circum-
stanced are males ; whether the female is guilty of simi-
lar spoliations is not known. In my specimen there are
no traces of them. In many bees, the first joint of the
posterior tarsi is much larger in the females and workers
than in the males; but in the hive-bee this joint is larg-
est in the latter ^. In Beris clavipes and Emjns tiigra,
two flies, the joint in question is large and thick in the
male, but slender in the female. The penultimate tarsal
joint in the posterior legs is dilated internally, and termi-
nates in a mucro in one sex of Anoplog7iathus Dytiscoi-
des of Mr. W. MacLeay ''. In some insects the anterior
tarsus of the males has been supposed to be altogether
wanting : I allude to the petalocerous genus Ofiitis F. ;
but I have a specimen of Onitis A_pelles of this sex, or a
species nearly related to it, in which one of these tarsi
is to be found <= ; which, though very slender, consists of
five joints, and is armed with a double claw : from which
circumstance it may, I think, be concluded, that although,
as in Phana^us, these tarsi are very minute, they are not
wanting. What renders this more probable is, a circum-
stance which every collector of insects, who has many
specimens of Mr. W. MacLeay's ScarabmdcB in his ca-
binet, must have noticed : namely, that in all, except Co-

* Mon. Ap. Aug/, i. t. xi. Apis **. e. 1. <?./. 8. c. and t. xii, **.
e. 1. neut./. 19. c.

*> Hor. Entoiuolog. 144. " Pr.ATF. XXVII. Fro. 45. a.

VOL. III. Z

338 STATES OF INSECTS.

pris and OiitJwphagus, the anterior tarsi are usually broken
off. Out of seventeen individuals of Scarabaus MacLeay
in my own, not a single one has a relic of an anterior tar-
sus ; and scarcely one in a much greater number of Pha-
nai. The tarsus in question m the nobler sex in Crahro,
at least in C. cribraj-his and its affinities, is also very short,
especially the three intermediate joints ; but at the same
time very broad and flat. In the species just named, the
external claw forms a kind of hook ; and in the rest it is
considerably longer than the other ^. The claws, indeed,
occasionally vary in the sexes in other Hijmenoptera :
thus in Melecta Latr., a kind of bee, in the female they
are intire, but in the male they are furnished with an in-
ternal submembranaceous tooth or process ^. In Cceli-
oxys conica and others, those of the latter sex are bifid at
the apex, but those of the former acute <=. In MegacJiile,
the male claw is as in the instance just mentioned, while
the female has a lateral tooth '' ; and a similar character
distinguishes the sexes in the hive-bee ^.

3. The abdomen. This part affords many external
sexual characters, whether we consider its general shape;
the number of segments that compose it ; its base, mid-
dle, or extremity*

In general shape it often differs in the sexes. Thus,
the abdomen of female Tipulcs is lanceolate; that of the
male cylindrical, and thickest at the extremity ^. In

^ De Geer ii. t. xxviii./. 2.

^ Mon. Ap. Aiigl. i. t. v. Apis **. a./. 10. cj . 1 1. $ .
<^ Ibid. t. vii. Apis **. c. 1. o«. 17- ? • 18. <J.
d Ibid.t.vm.f.ZQ. <?. 31. $.

^ Ibid. t. xi. Apis **. e. 1. mas./. 9. t. xii. Apis *«. e. 1. fern. /. 9.
and neut / '2,2. ' De Geer vi. t. xviii./. \2, 13.

STATES OF INSECTS. fiii*)

MulurcJius F. it is convex above in the former, and flat
in the latter, — the female of this beetle not unaptly repre-
senting some female Ichneumons in this respect, and the
male their males *. In Andrena it is oblong in the one,
and lanceolate in the other. In the hive-bee the drones
have a thick, obtuse, and rather long abdomen ; in the
females it is long, and nearly represents an inverted cone;
and in the workers a three-sided figure, or prism.

The number of segments, also, is generally different in
the two sexes — the male having one more than the female;
but in Dijtisc7is marginalis, &c. the reverse of this takes
place : the female, if you reckon the bipartite half-con-
cealed anal segment as one, having seven ventral seg-
ments, and the male only six. She has also eight dorsal,
and the male seven. — In the ant tribes [Formica L.), the
little veitical scale, at the base of the abdomen in one
description of them, or the double knot in another, is
less in the male than in the female. In a very singular
male insect belonging to the Vespidce, and related to Sj/-
nagris, (which I purchased from the late Mr. Drury's ca-
binet,) the second ventral segment sends forth from its
disk two remarkable parallel very acute and rather long-
spines. The same sex of Chclostoma maxillosa has like-
wise on the same segment a concave elevation, opposite
to which on the fifth is a cavity which receives it, when
the animal rolls itself up to take its repose ''. In another
species, C. Camparmlarum, the segment in question has
only a tubercle ^.

On the second segment of the abdomen of some spe-

* De Gecr v. 151 — .

'" Mon. Ap. Angl. i. 17/. /. ix. Apis **. c 2. y./. \\.a,d.
«= md.f.U.a.

z 2

340 STATES OF INSECTS.

cimens, probably males, of the remarkable African ge-
nus Pneumora before alluded to ^, there are thirteen lit-
tle elevated ridges, placed rather obliquely in an oblique
series; and gradually, though slightly, diminishing in
size towards the belly : on their upper side they are flat,
formnig nearly a horizontal ledge, but on the lower they
slope to the abdomen. The posterior thigh in its natu-
ral position covers the three first of them, and, if moved
downwards, would strike them all ^. I conjecture, there-
fore, that these are the animal's instruments of sound,
imitating the harp or violin rather than the drum ; and
that the thigh acts the part of the hand or bow. The
abdomen of these insects being blown out like a bladder,
and almost empty •=, must emit a considerable sound when
the thigh of the animal passes briskly over these ridges ;
and their different length would produce a modulation
in the sound. When struck with a pin, they emit a gra-
ting noise.

In Staphylinus sple7ide}is, the penultimate ventral seg-
ment is very deeply cleft, and the antepenultimate emar-
ginate in one sex, and in tire in the other. In S. lamina-
tus, an allied species, the penultimate segment is cleft,
less deeply, however; but the antepenultimate is very
short and intire; while the fourth is extremely long, and
rounded at the margin, appearing as if it was only an
elevated part of the last-mentioned segment ; for which
it was mistaken by Gravenhorst '', while it is of the usual
form in the other sex.

^ See above. Vol. II. 395.

b Plate XXIX. Fig. 13. Stoll. Spectres, &c. t. xxv./. 99.

' Sparrm^n. Voi/age, i. 312 — .

^ Coleopt. Micropt. IG.

STATES OF IMSCCTR. .141

The exlicmilij ot" (he abdomen or its anal sc<>;nicnts
and organs 1 urnish a variety of sexual characters. Some-
times the last dorsal segment is emarginate in the male,
and not in the female ; as in MegacJdle ligniscca, one of
the leaf-cutter bees, Clmcx /ucmorrhoidalis, &c. * At
other times little lateral teeth are added to this notch, as
in another of the same tribe, M. Willughbiella ^. Again,
in other males, both the ventral and dorsal anal segment
are armed each with a pair of teeth or mucros, as in
Chelostoma maxillosa ^, In Anthidium manicatum, an^
other bee, the anus terminates in five spines ''. In Cceli-
oxys co7iica of the same tribe, in which this part in the
female is very acute, that of the male is armed with six
points ^. In that singular Neuropterous genus Paiiorpa,
while the abdomen of the female is of the ordinary form,
with a pair of biarticulate palpiform organs attached to the
last retractile joint, or ovipositor, that of the male termi-
nates in a jointed tail, not unlike a scorpion's, at the end
of which is an incrassated joint armed with a forceps ^. In
the common earwig [Torjicnla auricular ia) the two sexes
differ considerably in their anal forceps: in one it is armed
with internal teeth at the base, and suddenly dilated, above
which dilatation it is bent like a bow : in the other it is
smaller, without teeth, grows gradually narrower, is
very minutely crenulate from the base to the end, and is
straight, except at the very summit, where it curves in-
wards. Misled by these and similar differences, Mr. Mar-

» Mon. Ap. Aiigl. i. t. viii./. 25. De Geer iii. 253. /. xiv./. 8.

b Mon. A]}. Angl. i. t. viii./. 24. " Ibid. t. ix. Apis xx. c. 2. y.f. 12.

•* Ibkl. Apis**, c. 2./3./. 11.

« Ibid. t. vii. Apis**, c. 1. «./. 11, 12. ? . 13, 14. <?.

f Plate XV, Fig. 12. De Geer ii. t. xxiv./. 9, 10. ? . f. xxv.

34<2 STA'IKS OF INSECTS.

sham has considered them (the sexes both of F. auricu-
laria and T. minor) as distinct species.

The tail of some species of the genus Ephemera is fur-
nished witli three long, jointed, hairy bristles. We learn
from Reaumur with respect to one, that though in the
female these are all equal in length, yet in the male there
is only a rudiment of the third. On the belly near the
anus these males have four fleshy appendages, the poste-
rior ones setaceous and long, and the anterior pair fili-
form and shorter. They are supposed to represent the
anal forceps of other insects ^. In Ephemera wdgata,
described by De Geer, both sexes have three bristles,
but those of the male are the longest ; and he describes
the forceps as consisting of only a pair of jointed pieces,
forming a bow not unlike the forceps of an earwig ^.

V. All the differences I have hitherto noticed between
the sexes of insects occur in their bodily structure ; but
there are others of a somewhat higher description ob-
servable in their character. You may smile at the idea
of character in beings so minute; but if you recollect what
I formerly related to you when treating upon the socie-
ties of insects, you will allow that something of this kind
does take place amongst them. In general the males are
more fitted for locomotion and more locomotive; and
the females, on the contrary, are necessarily more sta-
tionary. And this for an obvious reason : — the law is,
that the male shall seek the female, and therefore he is
peculiarly gifted for this purpose, both in his organs of
sensation and motion : while his partner in many cases
has very simple antennae, he has very complex ones; and

-' Reaum. vi. 494. ^.xliv./. 3— 11. '^ Dc Gcer ii. /. xvii./. 5 — 7-

STATKS OF INSECTS. 313

wliile she has either no wings or only rudiments of them,
he is amply provitled with them. Again : amongst the
insects that suck the blood of man or beast, such as the
gnat {Culex) or horse-flies {Tahanidce), it is the female
alone that is bloodthirst}', the males contenting them-
selves with the nectar of flowers ^. But the difl'erence of
character in the sexes is most conspicuous, at least it has
been more noticed, in those that live in societies, and is
quite the reverse of what takes place in the human spe-
cies. While the females and workers (which are now
generally considered as sterile females, in which the ova-
ries are not developed) are laborious and active, diligent
and skilful, wise and prudent, courageous and warlike; —
the males, on the contrary, take no part in promoting the
common weal, except merely a sexual one. Though till
a certain period they are supported at the expense of the
community, they take no part in its labours, either in
collecting and forming the public stores, or in feeding
and attending the young. They are idle, cowardly, and
inactive; have neither art nor skill of any kind, and
are unprovided with the usual offensive weapons of theii
species. These observations in their full force apply par-
ticularly to the hive-bee, and partially to the other social
insects; amongst which, if you consult my former com-
munications, there are some exceptions to this slothful
character in the males ''.

II. Age. There is less diversity in the duration of the
lives of insects in their perfect than in their larva or pupa

•' N. Did. (VUhf. Xaf. xxxii. 44a.
" See above, Vol. 11. 110, 118.

31'4- STATES OF INSECTS.

State. Some, like several species of Ephemercc, live only
a few hours ; some never even see the sun * : others, as
flies, moths, and butterflies, and indeed the majority of
insects, a few days or weeks ; and a comparatively small
number, such as some of the larger Coleoptera, Ortho-
pier a, &c., six, nine, twelve, or fifteen months — a period
beyond which the life of perfect insects rarely extends.
Some, however, certainly enjoy a longer existence in the
perfect state. Mr. Baker kept one of the darkling beetles
{Blaps Mortisaga) alive under a glass upwards of three
years. The rose-beetle (Cetotiia aurata\ Rosel informs
us he fed with fruit and moist white bread for as long a
period''. Esper kept our most common water-beetle
[Dytisciis marginalis) in water in a large glass vessel,
feeding it with meat, for three years and a half "=. With
regard to the Arach?iida, from the very slow growth of
Scorpio europceus, Rosel suspects that it must live two
or three years ; and Audebert is stated to have kept a
spider for several ''. In this respect insects follow a law
very different from that which obtains amongst verte-
brate animals. In these the duration of their life is in
proportion to the term of their growth : those which at^
tain to maturity the latest, in almost every case living the
longest. In insects, on the contrary, we often meet with
the very reverse of this rule. Thus the larva of the great

^ Vol. 1. 283. ^ II. i. 6.

•= Clairville Eiit. Helvet. ii. 214 — . I have seen it asserted in some
popular work on Natural History, (the title of which I do not recol-
lect,) that Mantis religiosa has been known to live ten years ; and a
Jtea, when fed and taken care of, six. But this is so contrary to expe-
rience in other cases, that the statement seems quite incredible.

d Rosel III. 379. N. Did. d'Hid. Nal. ii. 2S5.

STATICS OF INSEC'IS. 34t5

i^oat-moth {Cossns ligtiipoda) is three years, that of tlio
cabbagc-butterlly {Pieris Brussiccc) not three months, in
attaming maturity ; yet the perfect insects Hve ecjually
lon<r. Melulontha vuliiaris. which in its first state Uves
four years, as a beetle hves only eight or ten days ^.
And some Ephcmcrcc, whose hu-va? have been two years
in acquiring their full size, live only an hour ; while the
flesh-fly, whose larva has attained to maturity in three or
four days, will exist several weeks.

There is yet another anomaly in the duration of the
life of perfect insects. This is not, as in larger animals,
a fixed period liable to be shortened only by accident or
disease, and incapable of being prolonged ; but an inde-
terminate one, whose duration is dependent on the ear-
lier or later fulfilment of a particular animal function —
that of propagation. The general law is, that a few days,
or at most weeks, after the union of the sexes, both pe-
rish, the female having first deposited her eggs. If,
therefore, this union takes place immediately after the
disclosure of the insect from the pupa, their existence in
the perfect state will not exceed a few daijs or weeks, or
in some cases hours, as in that of the Ephemera, and like-
wise of the PhalcencE Attaci L. &c., which fall down dead
immediately after oviposition ^. But if by any means it
be put off" or prevented, their life may be protracted to
three or four times that period. Gleditsch asserts, that
by keeping apart the sexes of a grasshopper, their lives
were prolonged to eight or nine weeks, instead of two or
three, their oi'dinary length; and under similar circum-
stances Ephema'a, which usually perish in a day, have

» Dumcril Trailc Elancnl. ii. 8?. u. Gbo. •' Dc CJccr ii. i288.

3i'6 STATES or INSECTS.

been kept alive seven oi* eight. It is in consequence of
this very curious fact, which has not received from phy-
siologists the attention that it merits, that many butter-
flies and other insects, which, when excluded from the
pupa in summer, perish in less than a month, live
through the winter, if excluded late in the autumn, and
the union of the sexes does not ensue. It is probable
that the great age to which Baker's Blaps^ Rosel's Ceto-
nia^ and Esper's Drjtiscus attained, was owing to their
being virgins when taken, and subsequently kept from
any sexual intercourse. A parallel case happens in the
vegetable kingdom : — if annual plants are kept from seed-
ing, they will become biennial ; as, likewise, if they are
sown too late in the year to produce seeds.

In the case, however, of the earlier or later exclusion
of the imago, another agent has probably some influ-
ence. Buflbn found that, other circumstances being alike,
the silkworm-moths placed in a northern,^ lived longer
than those exposed to a southern aspect : whence it ap-
pears that the stimulus of heat shortens the lives of in-
sects, and consequently that cold tends to lengthen
them.

It must be observed too, that as the death of the fe-
male insect does not take place until all the eggs are ex-
cluded, the term of her life, though usually short in the
majority of species, which lay their whole number at
once, is proportion ably long in those which, like the
queen-bee, have a longer period assigned them for this
important oflice. Huber affirms, that he had certain
proofs that she was engaged for two years in laying eggs,
all impregnated by a single sexual union " ; and in the
* Huber i. 106.

STATF.S OK INSECTS. 347

females of most insects that live in society, several months
are required to mature the last eggs that are in the
ovary. There is one tribe of insects, however, the fe-
males of which are affirmed to survive this operation :
I mean Dorthesia Bosc ; after which they even moult,
though not so often as before ".

I formerly related to you the singular fact, that the
drones in a beehive at a certain period are without mercy
slaughtered by the workers ^. A fact the reverse of this
is recorded by Morier with respect to the locusts : he
affirms that the female, when she has done layinf>- her
eggs, is surrounded and killed by the males. He says
that he never himself witnessed this extraordinary cir-
cumstance ; but that he heard it from such authority that
he gave full credit to it •=. It is a fact, however, that
seems to require further evidence to entitle it to such cre-
dit. These are instances in which, by a law of nature,
the life of these insects is shortened by violence. It does
not appear to have been ascertained how long those
drones live that, under particular circumstances, as stated
in a former letter ^, are exempted from the usual slaugh-
ter.

I am, &c.

» N. Diet. (VHisl. Nat. ix. 553. ^ Voi.. H. 173—.

«■ Morier's Second Journey through Persia, 100.
<» Vol. II. 175.

LETTER XXXIII.

EXTERNAL ANATOMY OF INSECTS.

TERMS, AND THEIR DEFINITION.

JhlAVING shown you our little animals in every state,
and traced their progress from the egg to the perfect
insect, I must next give you some account of their struc-
ture and anatomy. And under this head I shall intro-
duce you to a microcosm of wonders, in which the hand
of an. Almighty workman is singularly conspicuous.
One would at first think that the giant bulk of the ele-
phant, rhinoceros, or hippopotamus, must include a ma-
chine far more complicated, a skeleton more multifarious
in its composition — covered by muscles infinitely more
numerous — instinct with a nervous system infinitely more
ramified — with a greater variety of organs and vascular
systems in play, thap an animal that would scarcely coun-
terpoise a ten-millionth portion of it. Yet the reverse of
this is the fact ; for the Creator, the more to illustrate
his wisdom, power, and skill, has decreed that the mi-
nute animals whose history we are recording, shall be
much more complex in all the above respects than these
mighty monarchs of the forest and the flood. Of this
in the present and subsequent letters you will find re-

EXTERNAL ANATOMY OF INSECTS. 34'9

peated and scarcely credible instances, which in every
rightly constituted mind are calculated to excite, in an
extraordinary degree, those sensations of reverence and
love for the Invisible Author of these wonders, and
that faith and trust in his Power and Providence, which
an attentive survey of the works of Creation has a natu-
ral tendency to produce. And you will not only be
struck by this circumstance, but equally by the infinite
variations in the structure that will present themselves to
your notice ; and that not sudden and per salhis, but by
approaches made in the most gradual manner from one
form to another. And all along, where the uses of any
particular organ or part have been ascertained, if you
consider its structure with due attention, you will find in
it the nicest adaptation of means to an end : a circum-
stance this, which proves most triumphantly, that the
Power who immediately gave being to all the animal
forms, was neither a blind unconscious power, resulting
from a certain order of things, as some philosophists love
to speak'; nor a foi-mative appetency in the animals
themselves, produced by their wants, habits, and local
circumstances, and giving birth, in the lapse of ages, to
all the animal forms diat now people our globe ^; but a
Power altogether distinct from and above nature, and its
Almighty Author *=.

* Lamarck Hist. Nat. des Anim. sam Vertebr. \. 311, 214.

*" Ibid. 162. Compare the St/stcme des Anim. sans Vortcbr. of the
same author, p. 12 — .

« The doctrine of Epicurus — that tlie Deity concerns not himself
with the affairs of the world or its inhabitants, which, as Cicero lias
judiciously observed {De Nat. Deor. 1. 1. ad calcem), while it ac-
knowledges a God in words, denies him in reality / has furnished
the original stock upon which most of these bitter fruits of modern

350 EXTERNAL AXATOMY OF INSECTS.

I trust that what I have here advanced will excite your
attention to the subject I am now to enter upon ; and I
flatter myself, that although at first sight it may promise
nothing more than a dry and tedious detail of parts and
organs, you will find it not without its peculiar interest
and attraction.

This department of the science — the Anatomy of In-
sects— may still be regarded as in its infancy ; and consi-

infidelity are grafted. Nature, in the eyes of a large proportion of the
enemies of Revelation, occupies the place and does the work of its
Great Author. Thus Hume, when he writes against miracles, ap-
pears to think that the Deity has delegated some or all of his powers
to nature, and will not interfere with that trust. Essays, ii. 75 — .
And to name no more, Lamarck, treading in some measure in the
steps of Robinet (who supposes that all the links of the animal king-
dom, in which nature gradually ascends from low to high, were ex-
periments in her progress towards her great and ultimate aim — the
formation of man. Barclay On Organization, &c. 2G3), thus states his
opinion : " La nature, dans toutes ses operations, ne pouvant pro-
ceder que graduellement, n'a pu produire tons les animaux a-la-fois :
elle n'a d'abord forme que les plus simples ; et passant de ceux-ci
jusques aux plus composes, elle a etabli successivement en eux dif-
ferens systemes d'organes particuliers, les a multiplies, en a augmente
de plus en plus I'energie, et, les cumulant dans les plus parfaits, elle
a fait exister tons les animaux connus avec I'organisation et les fa-
cultes que nous leur observons." (Anim. sam Vertcbr.'i. 123.) Thus
denying to the Creator the glory of forming those works of cre-
ation, the animal and vegetable kingdom (for he assigns to both the
same origin, Ibid. 83), in which his glorious attributes are most con-
spicuously manifested ; and ascribing them to nature, or a certain
order of things, as he defines it (214) — a blind power, that operates
necessarily (311); which he admits, however, to be the product of
the will of the Supreme Being (216). It is remarkable, that in his
earlier works, in which he broaches a similar opinion, we find no
mention of a Supreme Being. (See his Sijstcme des Animaux sam Ver-
tebres, Discours d'Ouverture.) Thus we may say that, like his fore-
runner Epicurus, Re toUit, dum oratione relinquit Deum. But though
he ascribes all to nature; yet as tlie iynmcdiafe cause of all the ani-

EXTKUNAL ANATOMY OF INSECTS. 351

dering the almost insuperable difficulties which, from the
minuteness oftlie objects, oppose themselves to the skill
and instruments of the entomological anatomist, we can
scarcely hope that it will ever attain to that certainty and
perfection to which, as far as the larger animals are con-
cerned, anatomy has arrived. Yet infinitely more has
been accomplished than might have been expected, and
new accessions of light are daily thrown upon it. When

nial forms, he refers to the local circumstances, wants, and habits of
individual animals themselves ; these he regards as the modifiers of
their organization and structure (1(52). To show the absurd nonplus
to which this his favourite theory has reduced him, it will only be ne-
cessary to mention the individual instances which in different works
he adduces to exemplify it. In his Sj/steme, he supposes that the
web-footed birds {Ansercs) acquired their natatory feet by frequently
separating their toes as far as possible from each other in then- efforts
to swim. Thus the skin that unites these toes at their base con-
tracted a habit of stretching itself; and thus in time the web-foot of
the duck and the goose were produced. The waders {GrallcB),
which, in ortler to procure their food, must stand in the water, but
do not love to swim, from their constant efforts to keep theu' bodies
from submersion, were in the habit of alwaj's stretching their legs
with this view, till they grew long enough to save them the trou-
ble ! ! ! (13 — ). How the poor birds escaped drowning before they
had got their web feet and long legs, the author does not inform us.
In another work, which I have not now by me, I recollect he attri-
butes the long neck of the camelopard to its efforts to reach the
boughs of the mimosa, which, after the lapse of a few thousand years,
it at length accomplished ! ! ! In his last work, he selects as an ex-
ample one of the Molluscce, which, as it moved along, felt an incli-
nation to explore by means of touch the bodies in its path: for this
purpose it caused the nervous and other fluids to move in masses
successively to certain points of its head, and thus in process of
time it acquired its horns or tentacula I ! Anim. sans Vertcbr. i. 188.
It is grievous that this eminent zoologist, who in other respects
stands at the head of his science, should patronize notions so cou-
fessedlv absurd and childish.

352 EXTERNAL ANATOMY OF INSECTS.

we consider what has been done by Malpighi, Leeuwen-
hoeck, and especially Swammerdam, we admire the pa-
tience, assiduity, and love of science, that enabled them, in
spite of what seemed insurmountable obstacles, to ascer-
tain, the first with respect to the silk- worm, and the latter
in numerous instances, the internal organization of these
minute creatures, as well as their external structure.
Reaumur, and his disciple De Geer, extending their re-
searches, have also contributed copiously to our know-
ledge in this branch of our science.

But in this field no one has laboured so indefatigably
and with so much success as the celebrated Lyonnet ; and
thouo-h his attention was confined to one object — the ca-
terpillar of the goat-moth {CossJis ligniperda F.), — every
one who studies his immortal work must admire the
patient and skilful hand, the lyncean eye, and keen in-
tellect, that discovered, denuded, and traced every organ,
muscle, and fibre of that animal. Much is it to be re-
gretted that his proposed works on the pupa and imago
of the same insect, which, he informs us, were far ad-
vanced*, were never finished and given to the world.
Our regret, however, is in some degree diminished by
the elaborate work of M. Herold on the butterfly of the
cabbage [Pieris Brassicce), before eulogized ^ ; in which
he has done much to supply this desideratum.

In more modern times, besides Herold, M M. Latreille,
Illiger, Marcelle de Serres, Savigny, Ramdohr, Trevi-

* Lyonnet Traite, &c. Pref. xxii. Want of due encouragement,
it is to be feared, caused the abortion of these vaUiable treatises.
The MSS. are, I believe, still in existence. It would probably an-
swer now to publish them.

^ See above, p. 53 — .

EXTERNAL ANATOMY OF INSECTS. 353

ranus, Sprengel, Aiuloin, Chabrier, and, above all, M.
Ciivier in his celebrated Lectures on Comparative Ana-
iovii/f have considerably extended the boundaries of our
knowledge in this department : and much of what I have
to say to you in my letters on this subject, will be derived
from these respectable sources. In the exterior anatomy
of insects, I flatter myself that I shall be enabled to make
some material additions to the discoveries of my prede-
cessors ; though few have occurred to me with respect to
their internal orijanization.

In treating of the anatomy of the vertehratc animals,
it is usual, I believe, to consider, first, the skeleton and
its integuments, whether of skin or muscle, and their
accessories; and afterwards the organs of the different
vital functions and of the senses. But in considering
the anatomy of Insects, the difference before stated *, ob-
servable between them and the sub-kingdom just men-
tioned, as to their structure, renders it advisable to divide
this subject into two parts — the first treating of their
external anatomy, and the second of their internal. —
I shall begin by drawing up for you a Table of the No-
menclature of the parts of their external crust ; its ap-
pendages and processes '', external or internal, accompa-
nied by definitions of them; and followed by such obser-
vations respecting them as the subject may seem to re-
(juire for its more full elucidation.

Anatomists have divided the human skeleton into three

* See above, p. 43 — .

^ There are certain processes which are a continuation of tlie in-
ternal surface of the crust ; and serve, as well as the rest of it, for
points of attachment to the mjfscles : tiiese, though completely in-
ternal, must be considered as parts of the external skeleton.

VOL. III. 2 A

So'i' F.XTERXAL AVATOMY Ol' IXSECTS.

greater sections — the Head, tlie Trwik, and the Limbs.
That of insects, Hkewise, is resolvable into three primary
sections, but without inchiding the hmbs (which, as be-
ing appendages, and therefore secondary, had best be
considered under the section of which they form a part),
for the abdomen in insects, as well as the rest of the body,
being covered with a crust, and forming a distinct part,
may be properly regarded as a primary section. And in
fact these three parts may be received as primary under
another view — the head, as containing the principal or-
gans of sensation ,- the trunk, as containing those of mo-
tion ; and the abdomen, as containing those oi generation '.
Under each of these primary sections, I shall consider its
respective organs, members, and parts.

You are not to expect to find every part included in
the following Table in every insect; since it has been my
aim to introduce into it, the most remarkable of those
that are peculiar to particular tribes, genera, &c. With
respect to these, I shall generally refer you to the indivi-
duals in which they may be found.

DEFINITIONS.

Corpus (the Body). The whole crust of the insect;
consisting of the Exoderma or external covering, and
die Esoderma or internal cuticle tliat lines it"^. It is
divided into three primary parts, or sections — Caput,

Tr uncus. Abdomen.

^ See above, p. 28 — .

'' The crust which covers the body of insects is lined internally
with a kind of fibrous cuticle. Que-^, Whether in any degree ana-
logous to the Periosteum of Vertebrate animals ?

EXTERNAL ANATOMY OF INSECTS. 355

T. CAPUT (The Hf.ad).
Tlic Head is the anterior section of the body; con-
sisting of ti kind of box without suture or segment, which
receives the organs of sensation and manducation. It
includes the Os, Fades, Suhfacies, and Collum.

i. Os (the Month), niat part of the head wliich re-
ceives and prepares the food for passhig into the
stomach. It inchides the TropJii^.

1. Tropiii (the Trnphi). Tlie different instruments or
organs contained in tlie mouth, or closing it, and
employed in manducation or deglutition. They in-
clude the Labrum, Lnhium, Maiidibiihc. Maxillce,
IJngua, and Pluni/nx.

A Labrum (the Upper-lip). A usually moveable or-
gan ; which, terminating the face anteriorly, covers
the mouth from above, and is situate between the
MandihulcT^. It includes the Appendiada.

a \ppi:};nuvL.\ {the Apjyendkle). A small piece some-
times appended to the upper-lip '^. Ex. Halictiis ?
Walck. {Mclitta *-. b. K.)

B I^ABiuM (the Under-lip). A moveable organ, often
biarticulate, which terminating the surl'ace ante-
riorly, covers the mouth from beneath, and is situ-
ate between the Maxillce'^. It includes the Men-
turn, and Palpi Labiales.
a Mentum [\\\e Chin). The lower ]o\i\i o'i X\\e Labium,

' \\'o employ tiii*; term instead of Tnslrumenla Ciunria F., to avoid
circumlocution.

'' Pi.ATi;s VI. V[I. Sec. a', and XXVI. Fig. 30-;«.

' Ibid. Fig. .30. Mm. Ap. Angl. i. 130. MelMa **. b. t. ii./. 4, 5.

•^ Plaths VI. VII. &c. and XXVI. Fi6. 23—29. b'.

'J A 2

356 EXTERNAL ANATOMY OF INSECTS.

where it is jointed ; in other cases its base. It is
usually sealed between the base of the Maxil-
la''.

b Palpi Labiales (the Labial Feelers). Two jointed
sensiferous organs, the use of which is not clearly
ascertained, which emerge, one on each side, from
the Labium, mostly near its summit ''.

C Mandibul^ (the Upper-jaws). Two transverse late-
ral organs, in most insects used for manducation ;
generally corneous, moving horizontally, and clos-
ing the mouth above, under the Labium *^. They
include the Prostheca, Denies, and Mola.

a Prostheca (the Prostheca). A subcartilaginous pro-
cess attached to the inner side, near the base, of the
Ma7idibula; of some Staphi/linidcB'^. Ex. Ocypus
similis K., Creophilus maxillosus K., &c.

b Dentes (the Teeth). The terminating points of the
Mandibulce. They include the Incisores, Laniarii,
and Molares ^.

A Incisores (the Cutting-teeth). Teeth somewhat
wedge-shaped, externally convex and internally

" Plates VI. and VII. a ", and XXVI. Fig. 34, 35.

The part in this work regarded as the mentum, does not in all
cases accord with what MM. Latreille, Savigny, &c. have regarded
as entitled to that denomination. Thus in Hymenopiera, their
Mentum is what we term the Labium, while our Mentum is the
small piece upon which that part sits (Plate VII. Fig. 3. a"). This
is called the Fulcrum in Mon. Ap. Angl. (See i. Explan. of the
Plates.) Our Mentum may generally be known by its situation be-
tween the hinges and base of the Maxillcc.

b Plates VI., VII., and XXVI. b". <■- Ibid.

•» Plate XIII.F1G.7.C".

* Marcel de Serres Comparaison des Organes de la Masticalmi des
Orthopteres. 7. Ann. dn Mvs. 11.

EXTERNAL ANATOiMY OF INSECTS. 357

concave*. Ex. Gi-yllotalpa Latr., Grjlliis Latr.
{Acheta F.), &c. &c.

B Laniarii (the Canine-teeth). Very sharp and usu-
ally long conical teeth ''. Ex. Forjicnla L., Man-
tis L., Libcllula L.

C MoLAREs (the Grinding-teetJi). Teeth that terminate
in a broad uneven surface, fit for grinding the food'^,
Ex. the herbivorous Orthoptera.

c MoLA (the Mola). A broad, flat, subrotund space,
transversely grooved or furrowed, observable on the
inner side of some mandibles that have no grind-
ing-teeth at their apex '^. Ex. Euchlora MacLeay,
Anoplognat/ms Leach, Larva of Lnca?ius *=.

D Maxillje (the Under-Ja-iVs). Two organs moving
subhorizontally, fixed on each side at the base of
the Labiuniy and often parallel with it — which in
masticating insects seem primarily designed to hold
the food^ They include the Cardo, Stipes, Lobi,
and Palpi maxillares.

a Cardo (the Hinge). A small, transverse, usually
triangular, corneous piece, upon which the Maxilla
commonly sits ^.

b Stipes (the Stalk). The corneous base of the Max-
illa, below the Palpus ^.

c LoBi (the Lobes). The parts of the Maxilla above
the Palpus '. They include the Lobus superior, the
Lobiis iiiferior, and the Ungues.

» Plate VI. Fig. 6. c', a", and XIII. Fig. 5, a".

" Plate VI. Fig. 12. b ". and XIII. Fig. 5. b ".

= Plate XXVI. Fig. 1G. c". ■» Ibid. Fig. 20. d'".

• CiiV. Anat. Conip. iii. 322—.

f Plates VI. VII. d'. and XXVI. Fio. 9—15.

E Ibid. c". Mbid. f. Mbid. and XXVI. Fig. 13-15.

358 EXTER^•AL ANATOMY OF JN.SECTS.

A LoBUs Superior (the Upper-lube). The outer lobe
of the Maxilla, incumbent on the inner one. In
the Predaceous Beetles this lobe is biarticulate and
palpiform^; and in Staphylinus oleva, &c. it also
consists of two joints ^. It is called the Galea by
Fabricius, in Orfhopiera, &c. ^

B LoBUs Inferior (the Lower-lobe). The inner lobe
of the Maxilla, covered by the outer one''.

C Ungues (the Claivs). One or more corneous sharp
claws which arm the lobes of the Maxilla ^. In the
Predaceous Beetles there is only on.e terminating
the lower lobe, with which, in Ciciitdela, it articu-
lates ; in the Orilioptera and Libellidina there are
several.

d Palpi Maxileakes (the Maxillary Feelers), Two
jointed sensiferous organs, the use of which is not
clearly ascertained, emerging from an exterior la-
teral sinus of tlje Maxilla •".

E Lingua (the Tongue). The organ situated within
the Labium or emerging from it, bj'^ which insects
in many cases collect their food and pass it down
to the Pharynx, situated at its roots above. It va-
ries considerably in different orders and tribes. In
the Orthoptna, Libellulina, &c. it is linguifotm,
and quite distinct from the Labium^; it appears
also distinct in the lamellicorn beetles, &C.'' In many

> Plate VI. Fig. ?<. d . '■ Platk XXVI. Fig. 11. d ".

« Plate VI. Fig. 6,1,'. d".
■• Ibid. Fig. .-5, (5, 13. and XXVI. Fig. D, 10. e'".
' Ibid. VI. Fig. .•;, 12. f .

f Plates VI. VII. h '. XIII. Fig. 1 — 1, 8. 1. '. and XXVI.
,P^iG. \—^. ' Plate VI. ]-ig. (5, 12. c'.

h PLATr XXVI. Fig. 26, :9. e'.

EXTtRNAL ANATOMY OF INSFXTS. '359

Hymvnoptera it emerges from the Labium, and is
fitted to collect Hqiiids and pass them downwards =•.
In Formica it appears to be retractile **. In a con-
siderable proportion of insects it seems connate
with die Labium, and forming its inner surface?
According to circumstances it might perhaps be
denominated Lingua or Ligula. It includes the Pa-
raglosscc.

a PARAGLossiE (the Paraglossce). Lateral and often
membranous processes observable on each side of
the tongue in some Hymenoptcra, &c. "^

F Pharynx (the Pharynx). The opening into the gul-
let'^. It includes the Epipharynx and Hypopha-
tynx,

a Epipharynx (the JEj3//7/ian//?a'). A small valve under
the Labrum, that in many Hymenoptera closes the
Phaiynx^ and is an appendage of its upper mar-
gin'.

b Hypopharynx (the Hypopharynx). An appendage

* Plate VII, Fig. 2, 3, e'. — What is here called the Lingua in
Hymenoptera has been usually regarded as the Labium; but surely that
organ which collects, and as it were laps the honey, and passes it
down to the Pharynx, is properly to be considered as the tongue.
The Labium itself appears to be i-epresented by what has been called
the Mcntiim, and the true Mentum, as was lately observed, is at the
base of the part last mentioned, in the usual situation of that piece.
This, though long since noticed (Kirby Mon. Ap. Angl. i. 103 — ), has
not been much attended to by modern entomologists.

'' Huber Fourmis, 4 — .

' Plate VII. Fig. 2, 3. and XXVI. Fig. 28. i".

^ Plate VII. Fig. 14. f.

* Ibid. Fig. 2. k". This is M. Savigny's name for this part. It
has also been called Epiglossa. Latreille Organisation Exterieure des
Insectes. 185.

36Q EXTERNAL ANATOMY OF INSECTS.

of the lower margin of the Pharynx^ observable in
Eucera F. *

The seven organs of the mouth above defined, viz. the
Labrum, Labium, the two Mandibulse, the two Maxillae,
and the Lingua, constitute what maxj he denominated a
perfect mouthy pecidiar to those insects that masticate their
food^. In those that take it hy suction, the Trophi, to
adapt them for that purpose, assume a variety of forms,
and should he distinguished hy as many appellatio7is. In
almost every case, however, the rudiments err representa-
tives of the above organs have been detected by the elabo-
rate researches of that learned and able zoologist, M. Sa-
vigny •=. / shall next subjoin definitions of the principal
kitids of sudor ious mouths.

2. Promuscis (the Promuscis). The oral instrument of
Hemiptera, in which the ordinary Trophi are re-
placed '^ by a jointed sheath, covered above at the
base by the Labrum, without Lahella (Liplets) at
the end, and containing four long capillary lancets,
and a short tongue ^. It includes the Vagina, and
Scalpella.

" Vitle Savigny Mem. sur les Anim. sans Vertebr. I. i. 12 — .

•i The majority of Hymenopterous insects, though they have the
ordinary Trophi, are not masticators, using their mandibula only for
purposes connected with their economy.

•^ See his Memoircs sur les Animaux sans Vcrtcbres, I. i,

'' I have used this word here and on a former occasion (see above,
p. 29), perhaps not with strict propriety, in the sense of the French
word remplacer, for which we seem to have no single corresponding
word in our language.

' Plate VI. Fig. 7—9.

EXTERNAL ANATOMY OF INSFXTS. 361

A Vagina (the Vagina), The jointed sheath of the
PromusciSi representing the Labium in a jperfcct
mouth '.

B ScALPELLA (the Lanccis). Four pieces adapted for
perforating the food of the insect, which when
united form a tube for suction. The upper pair
represent the Mandibular ^ and the lower the Max-
nice ^

3. Proboscis (the Proboscis). The oral instrument of
Diptcra, in which the ordinary Trophi are replaced
by an exarticulate sheath, terminated by Labella,
and containing one or more lancets covered by a
valve '^. It includes the T/icca, and Haustellum.

A Theca (the Theca). The sheath or case of the Pro-
boscis, representing the Labium in a, perfect mouth •=.
It includes the Basis, and Labella.

a Basis (the Base). The whole lower part of the TJieca,
from the mouth of the insect as far as the Labella,
probably to be regarded as representing the Men-
turn P

b Labella (the Liplets). A pair of tumid lobes, often
corrugated and capable of tension and relaxation,
which terminate the Theca, and perhaps represent
the termination of the Labium, s ?

B Haustellum (the Haustellum). The instrument of
suction contained in the TJieca ^. It includes the
Valvula, Cultelli, and Scalpella.

=* Plate VI. Fig. 7, 9. b'. " Ibid. c'. = Ibid. d'.

d Ibid. VII. Fig. 5, 6. « Ibid. b'. f Ibid. Fig. G. b'.

« Ibid. a. The Labella have been usually thought confined, or
nearly so, to the genus Mhscu L. ; but they may be traced in all ge-
nuine Diplcia, i. e. excluding Hippobosca L.

" Platl VII. Fig. 5. a, c', d'.

362 EXTERNAL ANATOMY OF INSECTS.

a Valvula (the Valvule). A corneous piece which
covers the instruments of suction above, represent-
ing the Labrum in a perfect mouth ^.

b CuLTELLi (the Knives). Tlie upper pair of the in-
struments of suction, wliich probably make the first
incision in the food of the insect; they represent
the MandibulcE of the perfect mouth ^.

c ScALPELLA (the Laucets). A pair of instruments,
usually more slender than the CtiUelli, which pro-
bably enter the veins or sap-vessels, and together
with them form a tube for suction *=.

4. Antlia (the Antlia). The oral instrument of Lepi-
doptera, in which the ordinary Tropin are replaced
by a spiral, bipartite, tubular machine for suction,
with its appendages ''. It includes the Solenaria,
and Fisfnla.

A SoLENARiA (the Solcnaria). ' The two lateral subcy-
lipdrical air-tubes of the Ajitlia ^.

B Fistula (the Fistula). The intermediate subqua-
drangular pipe, formed by the union of the two
branches of the Antlia, which conveys the nectar
to the Pharynx ^. These two branches represent
the Maxilla; of the perfect mouth. — N. B. M. Sa-
vigny discovered the I'udiments of the remaining
Trophi in this kind of mouth s.

3. RosTRULUM (the Rostrulum). The oral instrument

=< Plate VII. Fig. 5, 6. a. '' Ibid. c'.

* Ibid, d'. It has not yet been satisfactorily ascertained, whether
nil the ordinary Trophi are represented in every Dipterous moulh,
the number of the lancets seeming in some cases to vary.

-i Plate VI. Fig. 13. ' Ihid. rr. f" Ibid, 6.

* Ibid. Labrum .V; Mandibul^ c'; Maxillary Piilpus h".

KXIT-RNAL ANATOMV OF INSIXTS. ."363

of Aphanipiera [Pulcx L.), in which the ordinary
Tropin are replaced by a bivalve beak, between the
valves of which there appear to be three lancets *.
It incluties the J„amincr, Scalpella, and Ligula.

A Lamin.e (theZ/fiw/y^Yc). Two corneous plates which
are laterally affixed to the mouth of a flea, proba-
bly representinjT the Mandibuke of the perfect
nioutli, which somewhat resemble the beak of a
bird ^

B ScALPELi.A (the Lancets). The two upper or outer
instruments, probably for making an incision in the
skin ; these are flat and acute, and seem to repre-
sent the Maxilla of the perfect mouth *=.

C Ligula (the Ligula). A capillary instrument between
the lancets; probably representing the tongue of
the perfect mouth ''.

6. RosTELLUM (the Rostellum). The oral instruments
of Pediculus and some other Aptera, in which the
ordinary Trophi are replaced by an exarticulate re-
tractile tube, which exerts a retractile siphuncle.
It includes the Tuhulus and Siphunculus.

A TuBULUS (the Tubnlel). The tube or retractile base
of the Rostellum.

B Siphunculus (the Siphwicle). The I'eal instrument
of suction, which when unemployed is retracted
within the tubulet.

Besides the above variations from the type of lichat I
call a Perfect Mouth, there are others in which the parts
of the Trunk appear to aid in the co?ivcrsion of the food,

» Pi.ATi: VII. Fig. 8. '^ Ibid. c'.

'• Ibid. d'. Maxillary Pali.i h". "* Ibid. e'.

564: EXTERNAL ANATOMY OF INSECTS.

and become a kind of accessor!/ Labium, Maxilla, ^c.
Jlkus in the Myriapods, the anterior pair of legs assume
a Maxillary yorw and office * ; the Prosternum those of a
Labium'': ifi ^/zc Arachnida, also, the anterior Coxae are
accessory Maxillae. In this Class, likewise, as has been
more than once observed •=, the representatives of the inte-
7'ior pair of Antennae of the Crustacea, are thought
to assume the form and the functions of suctorious Man-
dibles ^.

ii. Facies (the Face). The upper surface of the head ^
It includes all the parts that lie between its junction
with the Prothorax and the Labrum: viz. Nasus,
Postnasus, Frons, Vertex, Occiput, Genes, Tempora,
Oculi, Stemmata, and AnteniKB.

1. Nasus (the Nose). That portion of the face, often

elevated and remarkable, situated between the La~
brum, Postnasus, and Ge7icc, and with which the
Lahiim articulates; called by Fabricius the Cly-
peus ^. It includes the Rhinar'tum.
A RfiiNARiUM (the Nostril-piece). The space between
the anterior margin of the Nasus and the Labrum,
in which, in vertebrate animals, the nostrils are often
situated s. — N. B. This is remarkable in- some La-
mellicorn beetles, as Anoplognathus Leach. In Ne-
crophorus, and some others, it is viembranous.

2. PosTNAsus (the Postnasus). That part of the Face

immediately contiguous to the Aiitemicc, that lies

' Plate VII. Fig. 11, 13./'. *> Ibid. Fig. 11. d'.

« See above, p. 18, &c. " Plate VI. Fig. 10. c'.

« Plate VI. Fig. 1, 4, 10. a. f Ibid. a.
« Ibid. «'.

EXTERNAL ANATOMY OF INSECTS. 365

behind the Nasus, when disthictly marked out. —
Ex. Sagra, Prosopis.

3. Frons (the Front). That part of the Face which
hes behind the Posfnasus, and usually between the
posterior part of the eyes. This is sometimes the
region of the Stcmmata ,- or they are partly in this
or partly in the Vertex *.

k Vertex (the Fer/fj:). The horizontal part of the i^«-
cies, next the front, that lies behind the eyes and
between the temples ''. This also is often the region
of the Stemmata.

5. Occiput (the Occiput). The back part of the head
when it is vertical, or nearly so, to its point of junc-
tion with the trunks — Ex. Meloe, llipiphoiits,
Hymenoptcra, Diptera.

G. Gen.e (the Cheeks). Those parts which lie on the
outside of the anterior half of the eyes, and inter-
vene also between them and the Mandihulce ^.

7. Tempora (the Tetnples). Those parts which lie on

the outside of the posterior half of the eyes, between
which the Fi-ons and Vertex intervene '.

8. OcuLi (the Eyes). The principal organs of sight,

most commonly two in number, placed in the sides
of the head. In the majority they are compound,
consisting of hexagonal lenses. In the Arachnida
they are simple ^
A Canthus (the Canthis). A process of the face, which
enters the notch or sinus of the eye ^. — Ex. Scara-
bcEus'L.f Cerambyx L.

9. Steimmata (the Eyelets). Two, or more commonly

» Plate VI. c. " Ibid. d. <• Ibid. e. "^ Ibid, f,

* Ibid. g. f Pi.ATF.9 VI. VII. and XXVI. h.

« Platk VI. Fio. 1. and VII. Fig. ,'. h'.

366 EXTFRXAL ANATOMY OF INSKCTS.

three, convex, crystalline, simple eyes, observable-
in the Frons or Vertex, or common to both *. — Ex.
Orthopfera^ Hemiptera, J-Ii/menojJiera.

10. Antennae (the Antennce). Two moveable and joint-
ed sensiferous organs, situated in the space between
or before the eyes, but in no instance behind them^.
They include the Toruhis, Scojms^ Pedicellus, and
Clavola.

A ToRULUS (the Bed). The cavity or socket in which
the base of the Antenna is planted*^.

B ScAPUS (the Scape). The first and in many cases the
most conspicuous joint of the Antennce^. It in-
cludes the Bulbils.

a BuLBUS (the Bulb). The base of the Scapus, by which it
inosculates in the Toridus, often subglobose, and look-
ing like a distinct joint ^. It acts the part of a Rotuluy
being the pivot upon which the Antenna turns.

C Pedicellus (the Pedicel). The second joint of the
Antenna ^ : in some insects acting also the part of a
Rotula in the socket of the Scapus^ to give separate
motion to the Clavola.

D Clay oi. A {the Clavoler). The remaining joints of the
Antenna taken together^. It includes the Capituhmi.

a Capitulum (the Knob). The last joints of the Cla-
7'o/a when suddenly larger than the rest ''.

iii. SuBFACiEs (the Subface). The lower surface or under-
side of the head '. It includes the Lara and Jugidum.

» Plate VI. Fig. 4, 10. VII. Fig. \,2, 4. and XXVI. Fig. .39— 4 Li.

'' Plates XL XII. and XXV.

' Plate VI. Fig. 1, 2. and VII. Fig. 1. i'.

'' Ibid. XTI. Fig. (!, 9. k'. "= Ibid. 1". ' Ibid. 1.

2 Ibid. Fig. 6. nV. " Ibid. Fig. 6, 8-10. m".

i Pi.ATF. VI. Fig. 2, 8. e.

PXri'.nXAL AKATOMY OF INSECTS. ^67

1. LoRA (the Lnra). A corneous angular inacliine ol>-

servable in tlie mouth of some insects, upon the in-
termediate angle of which the Meiitum sits, and on
the lateral ones the Cardines of the Maxilla .- and
by means of which the Trophi are poshed forth or
retracted ^ — Ex. Hymcnoptera.

2. JuGULUM (the Throat). That part of the subface

that lies between the temples ^\

iv. CoLLUM (the Neck). The constricted posterior part
of a pedunculate Jiead, by which it inosculates in
the trunk '^. It includes the Nucha, Gnila, and
Myoglyph ides.

1. Nucha (the A^<7/»f). The upper part of the neck<*.

It includes the Myoglyphides.
A yiYOG\.\viuTHLii {the Mi(scle-notches). Notches in the
posterior margin of the neck, usually two in num-
ber, observable in Coleopterous insects, to which the
levator muscles are attached ^.

2. GuLA (the Gicia). The lower part of the neck *".

V. CEPnALOPiiRAtiMA(theCV;;/ir//oj!;//?-(707?z). A Y-shaped
partition that divides the head internally in Loctista
Leach, into two chambers, an anterior and posterior.

II. TRUNCUS (The Trunk).

The 2rnnk is the intermediate section of the body,
which lies between the Head and the Abdome7i ^. It in-
cludes the Matiifruncus, and the Alifrimcus i<.

* Plate VII. Vm. 2. 1. Moii. Ap. Angl. i. /. xiii./. \.a,c.

'■ Plate VI. Fig. 2. m. ' Ibid. i. '' Ibid. n.

•^ Plate XXVII. Fig. 1, ;}, 4. n'. f Plati; VI. Fig. 2. o.

e Plate IX. Fiu. 7, 10, J 1, &c. and XVI. Fir,. 4, 8. B.

■> M. C'haiu'icr, in liis admirable .Mcnioircs .tiir le Vol drs Insecles,

368 EXTERNAL ANATOMY OF INSECTS.

i. Manitruncus (the Manitrunk). The anterior seg-
ment of the trunk, in which the head inosculates, or
on which it turns '. It includes the Prothorax and
Antepectus.

1. Prothorax (the Prothwax). The upper part or

the shield of the manitrunk, in Coleoptera, Ortho-
ptera, &c. called by way of eminence the Tho-
rax ^. It includes the 0'«, Patagia, Umbones, and
Phragma.

A Ora (the Ora). The inflexed or inferior lateral mar-
gin of the Protliorax, separated in many genera
from the Antepecttts by a suture ^,

B Patagia (the Patagia). Two corneous scales ob-
servable in Lepidoptera^ fixed on each side of the
trunk, just behind the head, and covered with a
long tuft of hair ^.

C Umbones (the Bosses). Two moveable bosses sur-
mounted by a spine, with which the Prothorax of
the Coleopterous genus Macropus is armed.

D Phragma (the Phragm). The Septum that closes
the posterior orifice of the Prothorax in Gryllotalpa
Latr.

2. Antepectus (the Forebreast). The underside or

-breastplate of the manitrunk, and the bed of the
Arms ^. It includes the Spiracula Antepectoralia,
Prosterjium, Aiitefurca, and Brachia.
A Spiracula Antepectorali A (the Antepectoj'al Spira-
cles). A pair of breathing-pores fixed in the mem-
uses the term Tronc Alifere, which suggested the terms here em-
ployed.

■'^ Plate IX. Fig. 3, 12, 16, &c.,^ ^ Ibid. Fig. 1,2, 10, 11, &c.
' Ibid. Fig. 2. a'. * '' Ibid. IX. Fio. 4.

' Ibid. VIII. Fig. 3, 11.

EXTERNAL ANATOMY OF INSECTS. 3(59

brane that connects the Antepcctm with the Medi-

peel us ^.
B Prosternum (the Forcbrcast-boiic). A longitudinal

oi' other elevation of the AiUepeciJis between the

Braeliia ^.
C Antefurca (tlie Antefurea). An internal vertical

process of the Antcpeelm, consistin<y usually of two

branches, which afford a point of attachment to

muscles of the Brachia '^.
D Brachia (the Arms). The first pair of legs oi Hex-

apods, the direction of which is usually towards the

head ; when spoken of with the other legs, called

tlie Forelegs '*. They include the Claxnculaj Scaptda,

Huments, Cubitus, and Manns.
a Clavicula (the C/«t'/c/<:'). The /^V^/ joint of the ^rcr-

chium, answering to the Coxa in the legs.
b Scapula (the S'ca/;w/«'). T\\q second ]o\ni oi ihe Bra-

chiumj answering to the Trochanter in the legs.
c Humerus (the Humerus). The third and elongated

jouit of the Brachium, answering to the Femur in

the legs.
d Cubitus (the Cubitus). The Jhiirth and elongated

joint, answering to the Tibia in the legs. It includes

the Coronula and Calcaria,
A Coronula (the Corojiida). A coronet or semicoro-

net of spines, observable at the apex of the Cubitus

> Plate XXIX. Fig. 12. r. " Plate VIII. Fig. 2, 11. d'.

<• Plate XXII. Fig. 7. c.

"^ M. Latreille, in Iiis Organisation Exterieiire des Insectes {Mem.
du Mus. viii. 198.) proposes calling the fore-legs of Hexapods Pro-
pedes; but having long ago applied this term to the false legs of ca-
terpillars (see ahove. Vol.. II. p. 288. &c.), we shall not adopt it.

VOL. III. 2 B

370 EXTERNAL ANATOMY OF INSECTS.

or Tibia of some insects. — Ex. Dilophus Latr.,

Fulgora L.
B Calcaria (the Spurs). See the definition under Pedes

Postici. They include the Velum.
a Velum (the Velum). A membrane attached to tlie

inner side of the cubital spur in Apis L. ^
e Man us (the Hand). The terminal jointed portion of

the Brachiimi, answering to the Tarsus in the legs ''.

It includes the Pulvilli, Palma, and Digitus.
f Pulvilli (the Pulvilli). See definition under Pedes

Postici.
g Palma (the Palm). The first joint of the Majms,

when longer and broader than the subsequent ones,

or otherwise remai'kable ; answering to the Planta

in the legs ^.
A Digitus (the Finger). See definition under Pedes

Postici. It includes the Ungula.
a Ungula (the Claw-joi7it). See definition under Pedes

Postici. It includes the Pollex, Unguicidi, and

Palmula.
u PoLLEx (the Tliumh). A small accessory joint, at-
tached to the Ungida of the Manus in Mantis F.
/3 Unguiculi (the Claws). See definition under Pedes

Postici.
y Palmula (the Palmlet). A minute accessory joint

between the claws, answering to the Plantula in the

legs. It includes the Pseudoriychia.
* PsEUDONYCHiA (the Spurious Claxvs). See definition

under Pedes Postici.

^ Plate XXVII. Fig. .36. a: >> Pi.ati: XV. Fig. G— 9.

- Plate XXVII. Fig. 59. a.

EXTERNAL ANATOMY OF INSECTS. 371

ii. AUTRUNCus (the AUtrwik). The jws/en'or segment
of the trunk to which the abdomen is aflixed, and
which bears the legs and wings ^. It includes the
Mcsothorax and Mcdipedm^ and the Metathorax
and Postpcclus.

1. Mesothorax (the Mcsothorax)* That segment of
the alitrunk which bears the Elytra^ or the anterior
pair of wings, and the intermediate pair of legs ''.
It includes the Collare, Prophragma, Doisolum,
Sciiiellum, Frcenum, and Pnystega.

A Collare (the Collar). The J'rst or anterior piece of
the Mesothorax. In most insects that have a con-
spicuous ProthoraXi as the Coleoptera, lliis piece
appears scarcely to have a representative ; but in the
Libdhilina it co-exists with it, and is more con-
spicuous '^. It is particularly remarkable in Hi/me-
noptera and Diptera.

B Prophragma (the Prophragm). A partition of an
elastic substance, rather horny, connected posteriorly
with the Dorsolum, which passes down into the an-
terior cavity of the alitrunk, of which it forms the

^ Plate VIII. Fig. 3, 4, 12— 14, IG, 17- IX. Fig. 1, 3, 7, 8,
10—12, 15. i- Ibid. c.

«= Plate IX. Fig. 7, H, 12, 15, 19. g'. The Collare of Hymeno-
ptera and Diptera has usually been regarded as representing tlie
Prothorax of Colcoptera, Orthoptera, &c. But this difference obtains
between them — the latter evidently belongs to the Manitrimk, and
its muscles do not appertain at all to the Alilnmk ; whereas the Col-
lare as evidently is a part of the latter, its muscles belong to it, and
its functions in assisting in flight are important. These reasons, and
others we shall state hereafter, induced us long ago to consider thin
part as not representing the Prothorax ; and they seem to have in-
duced M.Chabricr almost to adopt a similar opinion. Siir le Vol dcs
Inxectes. Ann. du Mus. 3cnic Ann. 414. et 4eme Ann. 54 — .
2 li 2

372 EXTERNAL ANATOMY OF INSECTS.

upper separation from that of the manitrunk. It
affords a point of attachment to several muscles of
the wings, &c. ^

C DoRsoLUM (the Dorslet). The piece wliich lies be-
tween the Collare and Scutellum, to which the pro-
praghm is anteriorly attached, and which bears the
upper or anterior organs of flight ''. It includes
the Pteropega, Elytra, Tegmina, Hemelytra, Al(S
Superiores, and Tegulce.

a Pteropega (the Wmg-socket). The space in which
the organs for flight are planted. That for the se-
condary or under-wings is in the Metathorax'^.

b Elytra (the Elytra). The uj^per organs for flight,
when they are without nervures, and uniformly of
a thicker harder substance than membrane whether
corneous, or coriaceous ; lined by a fine membrane ;
and when closed, united by the longitudmal suture''.
They include the Axis, Suttira, Epipleura, Alula,
and Hypoderma, and are peculiar to the Coleoptera
and Dermaptcra.

A Axis (the Axis). A small, prominent, irregular pro-
cess of the base of the Elytrum, upon which it turns,
and by the intervention of which it is affixed to the
Dorsolum, in the anterior wing-socket ^.

B SuTURA {the Suture). The conflux of the sutural or
inner margins of the two Elytra, where when closed
they unite longitudinally ^.

" Plate XXII. Fig. 8, 11. //.

b Ibid. Fig. 8. Plate VIII. Fig. 3, 12, 14, 16. IX. Fig. 1, 7, 8,
10—12, 15, 19, 21. i'.
'^ Plate VIII. Fig. 14, 20. IX. Fig. 11, 12. and XXII. Fig. 8. i".
<» Plate X. Fig. 1.; and XXVIII. Fig. 1—8, 10.
*= Plate XX\1II. ¥ig. o— 3. b'" . ' Plate X. Fig. 1. c ".

EXTERNAL ANATOMY OF INSECTS. 373

C Epi PLEURA (the Ej)q>lcioa). Tlic inflexed accessory
margin observable luulerneatli in many E/j//ra,
wliich covers the sides of die ahtrunk and abdo-
men '.

D Alula (the IVhigld). A small, membranous, wing-
like appendage, attached to the Elijtnim on one side
and the Frcenmn on the other ; which probably
serves to prevent the dislocation of the former ^. —
Ex. Dylisciis. N. B. A similar organ for a similar
purpose is to he found in Blatta and the Diptera.

E HypoDERMA (the Hyjiodcrma). The skin, in some
species beautifully coloured, that lines the Elytra '^.
N. B. This skin is also found in some Hemelytra, but
not in Tefjmina.

c Tegmina (the Ti'o^;w/«a). The upper organs of flight,
when of a uniform coriaceous or pergameneous tex-
ture, veined with nervures, and lapping over each
other '^. Ex. Orihoptera^.

d He3IELYTra (the Hemelytra). The upper organs of
flight, when they are corneous or coriaceous at the
base and membranous at the apex^ — Ex. The
heteropterous Hemiptera. They include the Co-
rium and Membrana.

A CoRiU3i (the Corium). The corneous or coriaceous
part of the Hemelytntm s.

» Plate XXVIII. Fio. 6—8. rf". '' Plate XXIII. Fig. 6. e".

<= Plate XXVIII. Fig. 2. d" .

•^ Ibid. Fig. 19. and Plate X. Fig. 2.

* The upper organs of flight of many of the /wmoptcrous section
of the Hemiptera seem altogether membranous, and may ahnost be
included under the term Al<je Superiorcs.

f Plate X. Fig. 3. = Ibid./'".

374 EXTERNAL ANATOMY OF INSECTS.

B Membrana (the Membrane). The membranous part
of the same^.

e Al.^ Superiores vel Primari^e (the Upper or Pri-
mari) Wings). The upper or anterior organs of
flight when formed of membrane, or of the same
substance with the under-wings ^. They inchide
the Axes, Arece, Areola;, Neura, Stigma, Parastigma,
and Lobuli.

A Axes (the Axes), Several osseous or horny pieces,
by which the wing is connected with the Dorsolum'^.
One usually to each area.

B Are^ (the Areas). The larger longitudinal spaces
into which the wing may be divided '*. They in-
clude the Area Costalis, Intermedia, and Analis.

a Area Costalis (the Costal Area). That part of the
wing lying between the anterior margin and the
post-costal nervure ^. In Hymenoptera and Di-
ptera it includes all the space bounded by the ner-
vures that spring from the postcostal.

b Area Intermedia (the Intermediate Area). That
part of the wing lying between the costal area and
the interno-medial nervure, in Diptera ; or the
Anal in Orthoptera, Hemiptera, Hymcnoptera, &c. ^

c Area Analis (the A7ial Area). All that part of the
wing which iii Diptera lies between the interno-

" Plate X. Fig. 3. g".

b Ibid. Fig. 5—9, 11-15. and Plate XXVIII. Fig. 18.

«• Ibid. U".

'' N.B. In the Plate the Costal Area is red, the Intermediate while,
and the Anal yelloiv. When the i7£'/«e/?/<m are considered as divided
into Areas, the Membrana might be denominated the Apical Area.

• Plate X. Fig. 2, 3, b: ' Ibid.r'.

EXTERNAL ANATOMY OF INSECTS. 375

medial nervure; or in Orlhoptcra^ &c. between the
aiial nervure and the posterior margin ".

C Areol.'e (tlie Arcolds). The smaller spaces into
which the wing is divided by the nervures. They
include the Areolce Basilares, Medicc, and Apicales.

a AREoL.Ti Basilares (the Basal Areolets). The pa-
rallel arcolets of the base of the wing^.

b Areol/E Medi^ (the Middle Arcolets). The areolets
of tlie wing that lie between the basal areolets and
the apical '^.

c Areol.i; Apicales (the Apical Areolets). Those
areolets of the wing that terminate in or very near
the apex ''.

D Neur^. (the Nerwircs). Corneous tubes, for expand-
ing the wing and keeping it tense, and to afford
protection to the air-vessels — commonly called the
Nerves. They include the Ncura Costalis, Post-
costaliSi Mediastinal Externo-media, hiternO'incdiay
AncdiS) Axillaris^ and Spuria.

a Neura Costalis (the Costal No-vure). The first
principal nervure of the wing, close to or forming
the anterior margin in Lcpidoptera, Hymenojyteray
and Diptera ,• but sometimes remote from it in Teg-
mina ^. It includes the Phialum and Hamus.

a PiiiALUM (the Phial). A little bag to receive fluid at
the 'will of the insect, by which the weight of the
wing is increased. It is found also in the under-
wings in Coleoptera^.

=• Plate X. Fig. 2, 3. d-. ^ i^id. Fig. 7—15. r.

<■ Ibid./. " Ibid. g\ " Ibid. h\

' Ciiabricr Sur le Vol dcs Inscries, Ann. du Mns. 3enie ami. 4ii8,
4cme anil, 325 — . 3d Cahicr 78.

376 EXTERNAL ANATOMY OF INSECTS.

/3 Ham US (the Hook). A Hook fixed to the Costal
Nci'vure, near its base on the under-side, in the
wings of some Lepidoptera.) in which the tendon
runs *.
h Neura Postcostalis (the Fostcostal Nervure). The
second principal, and often strongest, nervure of
the wing ''. It includes the Neurce Subcostales.
u NEURiE Subcostales (the Subcostal Nervures). Ner-
vures springing from the under-side of the post-
costal nervure, or from each other; called thej^r^^,
second, third, &c. in the order of their occurrence '^.
c Neura Mediastina {Mediastinal Nervure). A usu-
ally slender nervure, springing from near the base
of the postcostal ; between which and the costal it
intervenes. In the Lepidoptera Diurna, however,
it is often a strong nervure ^.
d Neura Externo-media (the Externo-mcdial Ner-
vure). The third principal nervure of the wing ^.
It includes the Neura Suhexter no-media,
a Neura Subexterno-media (the Subextcr7io-medial
Nervure). A nervure that in some cases intervenes
between the externo-medial and interno-medial ^.
e Neura Interno-media (the Interno-medial Nervure).
The fourth principal nervure &. It includes the
Neura Subinter7io-media.
a Neura Subinterno-media (the Subinterno-medial
Nervure). A nervure that sometimes intervenes
between the externo-medial and the anal ^.

" Linn. Tram. i. t. xiii./. 2. 3. d. '' Plate X. Fig. 5 — 15. i\

^ Ibid, a *. ■' Ibid. Fig. 6. k: ^ Ibid. /•.

f Ibid. Fig. 5, G, 13.6*. * Ibid. Fig. i5— 15. nv.
" Ibid, Fig. 5, H, 13.c*.

EXTERNAL ANATOMY OF 1N8ECTS. 377

/' Neura Analis (the Anal Ncrvure). The principal
nervure nearest the interior or posterior inar<5in,
with which it hichules a space often siibtriangular,
traversed in most Diptera and many Hymenoiitcra
by another ncrvure; and in many Tcgmina and
Hcmelylra by several *. In these kinds of upper-
wing it is in many cases accompanied by a fold; and
the part between it and the interior margin seems
often capable of separate motion.

g 1SIevraAxill,au]s {the Axillarj/ Nervure). The short
nervure, where there is only one, intervening be-
tween the anal nervure and the interior margin ;
replaced in some Muscidcc by a spurious ner-
vure^.

h Neur^e SpuRiiE (the Spurious Ncrtmres). Very ob-
solete nervures, sometimes found in addition to
those usually occurring ; as in Syrphus '^.

E Stigma (the Stigma). A corneous spot or plate, sup-
posed to contain fluid, in the anterior margin of the
upper wings; often produced by the conflux of the
costal and postcostal nervures ''.

/•' Parastigma (the Parastigma). A corneous spot be-
tween the costal and postcostal nervures, distinct
from the Stigma observable in the Lihellulina.

G LoBULi [Lohuli). One or more rounded portions of
the base of the wing, separated from the rest by fis-
sures peculiar to the M^iscidcc, and the under-wings
of some Hymcnoptera ^.

f Tegul^e (the Tegulce). Small corneous concavo-con-

» Plate X. Fjg. 5—15. w. '' Ibid. o-.

' Ibid. Fig. 14. p-. •' Ibid. Fig. 11. nV .

' Ibid. Fig. 14,15. n".

378 EXTERNAL ANATOMY OF INSECTS.

vex scales, which in many Orders, particularly Hy-
vienojjtera, cover and defend the base of the Upper-
Wings '.

D ScuTELLUM (the Scutellwn). A piece, usually tri-
an<rular, which follows the Dor solum; and in Co-
leoptera is often only a continuation of it — placed
between the base of the JiXytra or upper-
wings ^.

E Froenum (the Frcenum). A piece that lies under the
lateral margin of the Sciitellum and Dorsolwn, or is
adjacent to it; and which in many cases connects
with the base of the upper organs of flight, so as to
prevent their dislocation, by being pushed too far
outwards^.

F Pnystega (the Pnystega). A corneous scale or plate,
which covers certain pneumatic vessels, usually
supported by the Scapularia, in LibelluLina, &c. be-
coming dorsal ^.

2. Medipectus (the MzV/-6r^as/). The underside of the
Jirst segment of the alitrunk ^. It includes the
Peristethium^ Scapular ia, Mesosternum, Medifurca,
and Pedes Interrnedii.

A Peristethium (the Peristethium). The anterior
piece of the Medipectus, which intervenes between
the Brachia and mid-legs ^

B ScAPULARiA (the Scapidars). Two pieces, one on
each side the Medipectus, which succeed the Peri-
stethium, and lie between the midlegs and the Pte-

» Plate IX. Fio. 5, 11. g". " Plates VIII. IX. XXVIII. k\

<• Ibid./'. '' Plate IX. Fig. 7. 'w'.

• Plate VHI. Fig. 4, 13, 1/.; and IX. Fig. 3, 8, 12. d.
' Ibid. n\

EXTERNAL ANA'IOMY OF INSECTS. 379

rupega or wing-socket *. It includes the Spiracula
Scapularia.

p.. Spiracula Scapularia (the Scajndar Spiracles).
Two spiracles observable, one in each scapular, in
Acrida laurifolia^ &c.

C Mesosternum (the Mid^breastone). The elevated
and central part of the Mcdipcctus, between the mid-
legs, often terminating anterioi'ly in amucro; some-
times, as in Elater, in a cavity, receiving the ma-
cro of the Prosternum ^.

D Medifurca (the Mcdifurca). A branching vertical
process of the Endostcrnum^ which serves as the
point of attachment to the muscles that move the
midlegs '^,

E Pedls Intermedii (the Mid-legs). The intermediate
pair of legs, consisting of the same parts as the
posterior legs ^.

3. Metathorax (the Metathorax). The posterior seg-
ment of the Alitnincus^. It includes the Meso-
2)hragma, Postdorsolum, Postscntellum, PostJ'rcenum,
Pleiircc, and Metaphragma.

a Mesophragma (the Mesophragm). A partition of a
firm consistence, connected by its posterior margin
with the Postdorsolunif and passing down vertically
into the mid-chest; serving as a point of attach-
ment to several of the muscles that move the
wings ^. This, with the prophragm, forms the an-

» Plates VIII. IX. o'. •> Plate VIIL Fig. 4, 8, 13, 1 /. / .

^ Plate XXII. Fig. 6. </'. << Plate XVI. Fig. 4—6. r.
= Plate Vlll. Fig. 3, 12.; and IX. Fig. 1, 7, 10, 11, 12,
I'j. e.
f Plate XXII. Fig. 9, 11..^'.

380 EXTERNAL ANATOMY OF INSECTS.

terior cavity of the alitrunk, and with the meta-
phragm it forms the posterior cavity.

b PosTDORsoLUM (the Postdorsoliim). The middle-
piece between the mesophragm and the Postscu-
telluni. In Coleoptera it consists of a tense elastic
membrane, which is quite covered by the Meso-
thorax *.

c PosTScuTELLUM (thePo5/s«^^cZ/««w). A narrow chan-
nel runnins from the Dorsoltim to the Abdomen in
Coleoptera, forming an isosceles triangle reversed.
In other orders it is either a triangular elevation of
the middle of the posterior part of the Postdorsolion,
or a distinct triangular piece ^.

d PosTFRCENUM (the Postfrcenum). In Coleoptera the
part of the Metathorax in which the Postsciitellum
lies, at first nearly horizontal, but posteriorly it takes
a vertical direction towards the abdomen. In ge-
neral it may be defined, the part that intervenes
between the Postsctitellum and the Abdomen ; and
which in many cases is connected with the posterior
basal margin of the under-wings, and prevents their
being pushed too far forwards •=.

e Pleura (the Pleura). The space behind the scapu-
lars, on which the lower organs of flight are fixed '^.
They include the Al^e Inferiores.

A Klm Inferiores (the Under-mngs). The lower or
secondary pair of organs for flight '^. They include
the Commissura, Tendo, Hamidi, Pterijgium, Alula,
and Halteres.

» Plate VIII. Fig. 3, 12, 20. and IX. Fig. 7, 10-12, 'io, 20. i .
b Ibid. u. ■■ Plates VIII. IX. XXVIII v.

" Plaxus VIII. and IX. iv . ' Plate X. Fig, 4, 10.

EXTERNAL ANATOMY OF INSECTS. 381

a CoMMissuRA (the C(y/«7M/5S^«'a). A joinl in the costal
nervure of the wings of Coleoptera^ where they bend
to take a transverse fold '.

b Tendo (the Tcjidoii). A strong bristle, or bristles
observable at the base miderneath in the under-
wings of many Lejndoptcra, which plays in the Ha-
mus of the upper-wings ''.

c Hamuli (the Hookicts). Very minute hooks in the
middle of the anterior margin, observable in some
Hymcnoptera, by which the under-wing is fixed to
the upper, to cause both to act as one organ in
flight "=.

d Pterygium (the Pterygium). In under-wings this is
a small wing-like apj^endage, fixed at the base of
the wing in some Lepidoptcra '^.

e Alula (the Winglct). A small concavo-convex sca-
rious appendage, fixed behind the wings at tiieir
base, in many Diptera ^.

f Halteres (the Poiscrs). Small capitate processes or
organs, observable under the wings of Diptera^ at-
tended by a spiracle ^ .

B Metapnystega (the Mciapnystega). A corneous
scale or lamina that covers the pneumatic organs
in the Mctathorax, situated sometimes in the Pleu-
rcBj as in the Coleoptera ; at others in the Posifrce-
num, as in Tenthrcdo L.; and sometimes, as in the
LihelMina, between that part and the abdomen ^.

'* Plate X. Fig. 4. d" . ^ Linn. Trans, i. t. xiii./. 1, b. ?,. a.

' Kirby Man. Ap. Angl. i. t. xiii./. 19.

•^ De Geer ii. t. ix.f. 9. d. '■ Ibid. vi. /. u.f. 23. a a.

f Plate IX. Fig. 1.9. p".

« Ibid. Fig. 7. and Platk XXII. Fu.. 14. k".

EXTERNAL ANATOMY OF INSECTS.

C Metaphragma (the Metaphragm). A nearly verti
cal septum or partition, attached behind to the
Postfrcemim, and usually deeply cleft at its apex in
Coleoptera^ of a rather horny consistence, which
forms the upper separation of the second cavity of
the Alitrunk from that of the Abdomen^. It affords
a point of attachment for many muscles of both
alitrunk and abdomen. It includes the Septula.

a Septula (the Septula). The lesser ridges and par-
titions raised on the surfaces of the metaphragm,
and on those of other parts of the cavities of the
trunk, serving as points of attachment to various
muscles ^.

4. Postpectus (the Postpectus). The underside of the
second segment of the alitrunk '^. It includes the
Mesostethium, Parapleurce, Metastei'num, Postfurca^
Opercular and Pedes Postici.

A Mesostehium (the Mesostethium). A central piece
between the intermediate and posterior legs, and
bounded laterally in Coleoptera by the Parapleurce:
— along the middle of which, where it exists, the
Metasternum runs '^.

B Parapleur^ (the Parapleures). Two pieces, one on
each side of the Postpectus, included between the
Scaptdaria, Mesostethium, and Pleurcs ^. They in-
clude the Spiracida Parapleuritica.

a Spiracula Parapleuritica (the Parapleyritic Spi^
racles). Two spiracles, one in each of the Para-'
pleuroe of Tetyra ^.

" Plate XXII. Fig. 10, 1 1, x. ^ Ibid. Fig. 9—1 1. /".

•^ Plates VIII. and IX./. ''Ibid.y. "^

« Ibid. 2. ' Plate XXIX. Fig. 15. w;".

EXTERNAL ANATOMY OF INSECTS. 383

C Metastehnum (the Mctastcrnum). The central and
often elevated part of the MesostetJiiiun. Its anterior
nuicro, in Colcoptera^ often meets the posterior one
of the Mcsoslcrnum^ and sometimes appears to form
one piece with it, as in Hydrophilm, and many
LamclUcom beetles. Sometimes, as in Cctotiia vit-
ticollis, it even passes between the arms, and covers
the Prostaiium, or supplies its place. Behind, it
often terminates in a bifid mucro. It is not present
in many Orders : as in the Hymenoptcra, Diptcia,
&c. ^ It includes the Pectincs.

a Pectines (the Pectincs). Two moveable processes,
fixed one on each side by its base below the posterior
\eg^ to XhiiMctastcrniimnx Scorpio: on the lower side
is fixed a series of parallel biarticulate processes, re-
sembling the teeth of a comb ^.

D PosTFURCA (the Postjurca). A process of the En-
dosternum, terminating in three subhorizontal acute
branches, resembling the letter Y, and forming an
acute angle wdth the Endostermwt, to which the
muscles that move the hind-legs, &c. are affixed *=,

E Opercula (the Opercida). Plates that cover the
vocal spiracles in humming insects; and likewise
two large cartilaginous plates fixed to the posterior
part of the Postpechis, which cover the Tympana
in male Tettigonia F. ^ I*erhaps these may be re-
garded as a kind of Metapnystega in a new situ-
ation.

F Pedes Postici (the Hind-legs). The pair of legs

=• Plates VIII. IX. a\. >> Plate XXVII. Fig. 50.

- Pr.ATF. XXII. Fig. .3. it.

'' Pi.ATi; VIII. Fig. 18; and XXII. Fig. 13. rf.

384 EXTERNAL ANATOMY OF INSECTS.

affixed to the postpectus ^. They incUide, the Ace-
tabulum. Coxa, Trochanter, Femur, Tibia, and
2^arsiis.

a Acetabulum (the Socket). The socket in the Post-
pectus in which the leg is planted ''. It includes the
Pessella.

A Pessella (the Pessella). Two little acute processes,
fixed one in each, in the socket of the hind-legs in
male TettigonicE, which appear designed to keep
down the Opercula'^.

b Coxa (the Hip). Thej'^rs/ joint of the leg which
plays in the socket '*.

c Trochanter (the Trochanter). The second joint of
the leg, by which the thigh inosculates in the Coxa.
It appears to have no motion separate from that of
the thiffh. It is sometimes biarticulate ^.

d Femur (the Thigh). The third }omt of the leg, long
and usually compressed ^. It includes the Gony-
theca.

A Gonytheca (the Knee-pan). A concavity at the apex
of the thigh, underneath, to receive the base of the
Tibia s.

e Tibia (the Shank). The Jburth joint of the leg, very
long, and usually tricjuetrous ^. It includes the
Epicnemis, Mohda, Talus, Ccdcaria, and Coi'o-
nula.

» Plate XIV. Fig. 5—8.

^ Plate VIII. Fig. 2, 4, U, 13, &c. o". / Ibid. Fig. IS. q'.

'• Plate XIV. Fig. 6—8; and XXVII. Fig. 12.?/'. ^ Ibid, q

' Plate XIV. Fig. 5-8; and XXVII. Fig. 6— 8. ;■".

« Plate XXVII. Fig. 7, 8, 15. /".

" Plate XIV. Fig. 5— 8.s".

EXTERNAL ANATOMY OF INSECTS. 385

A Epicnemis (the Epicncmis). An accessoiy joint at
the base of the Tibia in many Arachnida, wliich
does not appear to have separate motion ^.

B MoLULA [the Kncc-ball). Tlie convex and sometimes
bent head of the Tibiae armed with a horny pro-
cess on each side, by which it is attached to the
thigh ^.

C Talus (the Ankle). The apex of the Tibia, where it
is united to the Tarsus *^.

D Calcaria (the Sjnirs). One, two, or more moveable
spines, inserted usually at the apex of the Tibia;
and in many Carabi L., Lcpidoptera L., and TricJio-
ptera K., in the middle also. They may be regarded
as a kind of fingers auxiliary to the Tarsus, and fur-
nish often an important character in the disciimina-
tion of o-enera ''.

E Coronula (the Coronula). A coronet or semicoronet
o^Jixed spines observable at the apex of the poste-
rior Tibia in Fidgora candelaria, &c.

f Tarsus (the Tarsus). The ^/h principal portion
of the legs ; consisting in the majority of insects of
1 — 5 joints, but in the Phalangidcc of sometimes as
many as 50 ^. It includes the Plania, Digitus, and
Solea.

A Planta (the Instep). The first joint of the Tarsus is
so called when it is i-emarkably long and broad ^.
It includes the Calx.

=> Plate XXVII. Fig. 21 . s'" . '- Ibid. Fig. 9, 10, 1(5, 17. t'".
^ Ibid. Fig. 34—36. ti".

'' Plate XIV. Fig. Gj and XXVII. Fig. 29— 30. j;'".
« Plate XIV. Fig. 5—8 ; and XXVII. Fig. 44, 45, 63, 63. t".
f Plati; XXVII. Fig. 25, 26, 41. w".
VOL. III. 2 c

386 EXTERNAL ANATOMY OF INSECTS.

a Calx (the Heel), The curving part of the Planta, by

which it inosculates with the Tibia.
B Digitus (the Toe). The remaining joints of the 7«r-
sus taken together ^. It includes the Allux and Un-
gula.
a Allux (the Toe-ball). The last joint but one of the
Tarsus, when remarkable, as in Rhyncophorous
beetles [Curculio L.)^.
b Ungula (the Claw-joint). The last joint of the Tarsus,
which bears the claws ^. It includes the Arthrium,
TJnguiculi, and Plantula.
u Arthrium (the Arthrium). A very minute joint at
the base of the claw-joint, in most Tetramerous and
Trimerous beetles **.
/3 Unguiculi (the Claws). One or two pair of moveable
incurved claws, which usually arm the apex of the
Ungula ^.
y Plantula (the PZa«ifw/a). A minute accessory joint,
sometimes attached within the claws to the apex of
the Ungula ^. Ex. The Lucanidce. It includes the
Pseudo7iych ia.
* PsEUDONYCHiA (the Sj^urious Claws). Two stiff claw-
like bristles, that terminate the Plantida s.
C SoLEA (the Sole). The underside of the Tarsus '\ It

includes the Pulvilli.
a Pulvilli (the Pulvilli). Cushions of short hairs very
closely set; or of membrane, capable of being in-

» Plate XXVII. Fig. 25, 26. x'".

•> Plate XXVI. Fig. 47, 48 ; and XXVII. Fig. 43. r.

^ Ibid. s\ d Plate XXVI. Fig. 47, 48. d*.

" Plate XXVII. Fig. 37—67. e*. ^ Ibid. Fig. 56, 57./*.

s Ibid. Fig. 56. a ^. "" Ibid. Fig. 59. 3/".

EXTERNAL ANATOMY OF INSECTS. ^87

flatccl, or very soft ; or concave plates, which cover
the underside, or their apex, of the four first joints
of the Manus or Tarsus, and sometimes even of the
ends of the Calcaria, as in Cimhcx ; which act so as
to produce a vacuum, and enable the animal to sus-
pend itself, or walk against gravity ^. Ex. Timar-
cha, BuprestiSy Priocera K., the Gryllina, Musci-
d(C, &c.

III. ABDOMEN (the Abdomen).

The Abdomen is the third or posterior section of the
body which follows the Truncus ''. It includes the Ter-
gwn, Ve?itery Peiiolus, Cauda, and Arms.

i. Tergum (the Tergum). The upper or supine surface
of the abdomen <=. It includes the Scgmenta Dorsa-
lia, and Pulmonaria.

1. Segmenta DoRSALiA (thftZ)or5a/(S£g7wew^5). Trans-

verse segments of the back, the sides of which often
lap over and cover those of the ventral segments '*.

2. Pulmonaria (the Pulmonary Space). Two longitu-

dinal soft spaces, capable of tension and relaxation,
one on each side of the back of the abdomen, in
which, where they exist, the dorsal spiracles are
planted ^. They include the Spir acuta Dorsalia.
a Spiracula Dorsalia (the Dorsal Spiracles). Late-
ral breathing-pores observable in the dorsal seg-
ments, often covered by the preceding segment ^.

» Plate XV. Fig. 9 ; and XXVII. Fig. 35, 59—61. f.

^ Plate VIII. Fig. 5, 6, 9, 15, 18, 19.

' Ibid. Fig. 5, 15. A <) Ibid. ^'.

•= Ibid. Fig. 5, 9. E. ' Ibid. Fig. 5, 9, 15. A".

2c 2

388 EXTERNAL ANATOMY OF INSECTS.

ii. Venter (the Belly). The lower or prone part of the
abdomen *. It inckides the Hypochondria, Epiga-
strium ^, Segmetita Ventralia, and Elastes.

1. Hypochondria (the /j?i/poc/iow^r/a). Two portions

of segments, one on each side; which in some ge-
nera"^ {Carabus L., &c.) intervene between the first
intire ventral segment and the posterior part of the
Postpectus.

2. Epigastrium (the Epigastrium). The first intire ven-

tral sequent '^. It includes the Mucro and Tym~
pana.

A MucRO (the Mucro). The central posterior point of
the Epigastrium observable in many of the Orders,
which reposes between the posterior legs; and, ac-
cording to M. Chabrier, is useful to the insect du-
ring flight ^.

B Tympana (the Drums). Two deep cavities, contain-
ing a complex machinery on each side of the Epiga-
strium in male Tettigonice, which are the instruments
of sound ^

3. Segmenta Ventralia (the Ventral Segmefits). Trans-

verse sections of the belly ^. In Elytrophorous in-
sects they are usually of a firmer consistence than
those of the back. They include the Spiracula Ven-
tralia,
A Spiracula Ventralia (the Ventral Spiracles). —

''Plate VIII. Fig. 6, 9, \h.B.

^ The scientific reader miist recollect that these terms are em-
ployed, not because these parts are thought to be true representa-
tives of the Epigastrium and Hypochondria of vertebrate animals,
Jjiit merely on account of some analogy between them.

•= Plate VIII. Fig. 6. C. " Ibid. Z>'. ' Ibid. B' .

f .Ibid. Fig. 18, 19. C". « Ibid. Fig. 6, 9, 15. E'.

EXTERNAL ANATOMY OF INSECTS. 389

Breathing-pores observable in some genera in the
intermediate ventral segments, one on each side '.
Ex. Di/nastcs Aloeiis, &c.

•4<. Elastes (the Elastcs). The elastic organs on the
ventral segments of Machilis j)oli/poda which assist
this insect in leaping.

iii. Petiolus (the Footstalk). A slender part by which
the abdomen of many Hymmoptera is united to
the trunk, in some genera very long, in others very
short, and in others wanting ^. It includes the Fu-
niciihis, Foramen, Squama, and Nodus,

1. Funiculus (the Fimiculus). A small cartilaginous

cord, passing dirough a minute orifice of the Post-
frcenum, just above the point where the footstalk is
fixed, to an opposite hole above it, which enables the
animal the better to elevate or drop the abdomen *=.

2. Foramen (the Foramen). The orifice in the abdo-

men, through which the above cord passes ^.

3. Squama (the Scale). A vertical flat scale, observable

on the footstalk of the genus Formica, &c. ^

4. Nodi (the Knots). One or more subrotund protube-

rances of the footstalk in the genus Myrmica \
iv, Cauda (the Tail). Where the abdomen grows sud-
denly slenderer, and terminates in a long jointed
tail, as in Scorpio and Panorpa s. It includes the
Centris.
1. Centris (the Coitris). The last inflated joint of the
tail, terminating in the Sting.

" Plate VIII. Fig. 9. U. " Plate IX. Fig. 17, 18. C.

' Il)id. Fig. 13. F'. i Ibid. G'.

*■ Ibid. Fig. 17. //'. ' Ibid. Fig. 18. /'.

* Plate XV. Fig. 12. D.

390 EXTERNAL ANATOMY OF INSECTS.

V. Anus (the Anus). The termination of the abdomen,
consisting of the two last segments. It includes the
Podex, Hypopyghm, Cidits^ Ovipositor^ and Appeti-
dices.

1. PoDEx (the Podex). The last dorsal segment of the

abdomen ^.

2. Hypopygium (the Hypopygium). The last ventral

segment of the abdomen ^.

3. CuLUS (the Cuius). The orifice at the end of the

anus.

4. Ovipositor (the Ovipositor). The instrument of

oviposition, by which the insect conducts the eggs
to their appropriate nidus, and often bores a way to
it ; the same instrument is by some genera used as
a weapon of ofience, when it is called the Aculeus '^.
It includes the Unci^ Tubuhis, ValvcE, Vagimda, and
Terehellce.

A Unci (the Unci). Two pair of robust organs, the
upper incurved and the lower recurved, with which
the anus of Locusta Leach is furnished ^.

B TuBDLUS (the Tubulus). A tubular ovipositor, con-
sisting of several pieces often retractile within each
other, like the tubes of a telescope ^.

C Valv^s; (the Valves). Two lateral laminae, often coria-
ceous, by which the ovipositor when unemployed is
covered ^.

D Vaginula (the Sheath). A corneous case, with

» Plate VIII. Fig. 5, 15. K'. " Ibid. Fig. 6, 15, 18. L'.

<= Plate XV. Fig. 18-22; and XVI. Fig. 1—3.

>' Plate XV. Fig. 18. K.

' Plate XV. Fig. 22; and XVI. Fig. 2, 3.

f Ibid. Fig. 20, 21 ; and XVL Fig. 1. F".

EXTERNAL ANATOMY OF INSECTS. 391

two grooves, in which the Tercbclla or Spicula
play ».

E Terebell/E (tlie Terchellce). Instruments by which
the insect saws or bores a passage for its eggs to the
place in which her instinct directs her to deposit
them ''.

5. AcuLEUS (the Sting). The above instrument, when
fitted for an offensive weapon *=. It includes, besides
the Valvce and Vaginula before defined, the Spicula.

A Spicula {the Darts). The proper stings which inflict
the wound : retractile within the sheath, externally ser-
rulate at the apex ^. They include the Retinaculum.

a Retinaculum (the Retinaculum). A minute horny
moveable scale or plate with which the darts are fur-
nished, which prevents their dislocation by being
shot forth too far ^.

vi. Appendices (the Appendages). Other instruments
and organs, with which the anus of various insects
is furnished. They include — the Forceps, Forfex,
Furca, Sfi/li, Foliola, Flosculus, Caudulcv, Fila, Mam-
mulic, Papillce, and Siphofiuli.

1. Forceps {the Forceps). A pair of anal organs that

open and shut transversely, and meet at their inner
margin, or at the apex. Ex. Forficula.

2. Forfex (the Forfex), A pair of anal organs, which

open or shut transversely, and cross each other ^.
Ex. Male oiRaphidia Ophiopsis.

» Plate XV. Fig. 20. G' .
'> Ibid. Fig. 20, 21 j and XVI. Fig. 1. H" .

<= Kirby Mon. Ap. Angl. i. /. xii. Apis **. e. 1. nnil.f. 2.'? — 25; and
/, xiii./. 27, 28.

•I Ibid. t. xiii./. 30, 31. *= Ibid. a.

' Plate XV. Fig. 12. L" .

392 EXTERNAL ANATOMY OF INSECTS.

3. FuRCA (the Fork). An inflected elastic anal organ,

ending in a fork, by which the animal is enabled to
leap ^. Ex. Podura.

4. Styli (the Styles). Rigid, exarticulate, long and

narrow anal organs ^. Ex. Staphylinus.

5. FoLiOLA (the Leajiets). Rigid, exarticnlate, dilated,

leaf-like anal organs '^. Ex. Libellulina.

6. Flosculus (the Floret). A small, tubular, linuilate

anal organ, with a central style ''. Fulgora cande-
laria, &c.

7. Cerci (the Cerci). Two short, flattish, sublanceo-

late, jointed, lateral anal organs ^. Ex. Blatta. —
N.B. Analogous organs are obsei'vable in the Gryl-
lina, but usually conical and without joints ^. In
Gryllus Latr. they are setiibrm s.

8. Caudul^ (the Candida), Two or more slender, fili-

form or setaceous, jointed, flexile anal organs ^. Ex.
Lepisma, Machilis, Fphemera.

9. FiLA (the Threads). Two exarticulate, slender, fili-

form anal organs '. Ex. Machilis.

10. Mammul^ (the MammulcE). Anal protuberances,
containing instruments for spijining web ^. Ex.
Araneidce. They include the Fusi.

11. Fusi (the Spinners). Organs, consisting of two re-
tractile pieces, issuing from the Matmmdce, and ren-
dering the threads '.

* Plate XV. Fig. 14. M". •> Ibid. Fig. 17- ^".
^ Ibid. Fig. 15. O". " Ibid. Fig. 13. P".

* Ibid. Fig. 23. Q".

f De Geer iii. t. xxii./. 10. a a. « Ibid. i. xxiv./. 2. c; and/. 11.
" Plate XV. Fig. 16. R". ' Ibid. S". *

^ Ibid. Fig. 10; and Plate XXIII. Fig. 16, 17- ^".
1 Ibid. Fio. 12. B" . 15.

EXTERNAL ANATO.MY OF INSECTS. .393

12. SiPHONULi {the Siphonets). Truncated, fistular, seti-
form anal organs, emitting a saccharine fluid ". Ex.
Aphis.

You will observe, that when the wJiole Jipj)er-si(le of
the Truncus is spoken of, it is called the Tlimax ; and as
in Colcoptcra^ and some other Orders, the whole of the
Mcsothorax except the Sciitellnm is covered by the Tho-
rax, and the whole of the Mctaihorax by the Mcsothorax
and Elytra — the Thoracic shield may without danger of
mistake be denominated the Thorax, as it has always
been. When the 'H'holc underside of the Trunk is spo-
ken of, it is called the Pectus. When the three Sternums
are spoken of together, they may be called the Sternum ;
and the 'whole interior elevation of the Pectus may be
called the Endosternum.

^ De Geer ubi siipr. t. iii./. 5,20, 21. c.

LETTER XXXIV.

EXTERNAL ANATOMY OF INSECTS.

THE HEAD, AND ITS PARTS.

Before I confine my observations to the head of in-
sects, which I propose to consider separately in the pre-
sent letter, I must premise a few words upon their bod^
in general, or rather its crusi, or external integument.
In this we may notice its substatice, generaiyorm, sculp-
ture, pubescence, and composition.

i. I have already noticed the substance of this integu-
ment in the preparatory states of insects ^ ; I shall not,
therefore, here repeat what I then said, but restrict my-
self chiefly to the consideration of it as it is found in their
last state, in which it is usually firmer than in their pre-
vious stages of existence. In this respect, however, it
varies much in the different Orders, and even in the dif-
ferent genera of the same Order. In some Coleopterous
insects, for instance, it is very hard, and difficult to per-
forate ; while in others it is soft, flexible, and a pin easily
passes through it ^. And in general, from a substance

■^ See above, p. 86, 110,243—.

*> Many species of Hister, Ciirculio L-, Dor^phora Illig. are ex-

EXTERNAL ANATOMY OF INSECTS. SOr)

ill hardness resembling horn or shell, it passes through
the intermediate degrees of that of leatlier and parch-
ment, almost to a thin membrane. Yet in all cases there
is enougli of rigidity and hardness to answer the princi-
pal uses of a skeleton — to afford, namely, a sufficient
point of attachment for the muscles, and to support and
defend the interior organization; so that the play and
action of the vital and secretory systems may not be in-
terrupted or impeded.

With respect to the principles which enter into the
composition of this integument, very little seems to be
known at present; but few insects having been submitted
to a chemical analysis. The blister-beetle {Cantharis
vesicatoria), from its importance in medicine, has, how-
ever, been more than once analysed; and though the
products have not been very precisely stated, yet we find
amongst them phosphate of lime, albumen, and some
other usual components of the substance of vertebrate
animals ^. But which of these products belong to the
integument, and which to its contents, cannot be ascer-
tained, without a separate process for each ; which would
not, I conceive, be very feasible. The substance, how-
ever, of the integument of insects, though we know not
its precise contents, which probably vary in different ge-
nera, &c., appears not to be exactly of the nature of any
of those substances after which it has usually been deno-

tremely hard, while Cantharis GeofFr., Meloe F., and Telephorus
GeofFr., are very soft.

* Thenard Traite de Chimie Elementaire, iii. 637. n. 2005. The
other products he mentions are— a green oil, a yellow substance, a
black ditto, acetic acid, lyic acid, phosphate of magnesia. The vesi-
cant matter consists of little micaceous laminae soluble in boiling al-
cohol and oil, but insoluble in water.

396 EXTERNAL ANATOMY OF INSECTS.

minated : it is not properly analogous either to real horti,
shell, skm, or leather, &c. This seems to result from the
following circumstance : — Most of the excretions of ver-
tebrate animals, as horn, skin (at least when tanned),
feathers, wool, hair, &c. when exposed to the action of
fire liquify, more or less, before they incinerate; emitting
at the same time a peculiar and disagreeable scent : but
upon applying this test to the parts of insects of the dif-
ferent Orders, I found, in every instance, that incinera-
tion took place without liquefaction, and was unaccom-
panied by that peculiar scent which distinguishes the
others. Even the claws, which to the eye appear, as to
their substance, exactly like those of Mammalia, birds,
&c. burn without melting, and retain their form after
red heat. That the insect integument is not calcareous
like that of the Crustacea, and the shells of Molluscce,
you may easily satisfy yourself, by immersing them in an
acid test. I made this experiment upon portions of in-
sects of several of the Orders, in an equal mixture of mu-
riatic acid and water, and the result was, not only that
all hexapods, but octopods, Arachnida, and even Scolo-
pendridce, upon immersion only emitted a few air-bub-
bles; while, when the other myriapods, Polydesmiis, lu-
lus, Glomeris, &c. and the Oniscidce, were immersed, a
violent effervescence took place; proving the different
nature of their substance. It is remarkable that the two
great branches of the Myriapods, the Scolopendrid(E and
Iidida; [Chilopoda and Chilognatha Latr.), should in
this respect be so differently circumstanced — the latter
having a calcareous integument, and the former not. —
A further difference distinguishes these two tribes : old
specimens of the Iididcc usually lose their colour and turn

EXTERNAL ANATOMY OF INSECTS. 397

white, like Oniscidcc ,- while those of tiie Scolopcndridie
retaui it.

ii. T^heform of insects is so variable, that it can be
reducetl to no other general rules — than that, for the
most part, the length exceeds the breadth, and the
breadth the depth, and that the upper surface is usually
convex. But to these rules there are numerous excq>
tions. Thus many Tetyrce F. [Sciitellera Latr.), a kind
of bug, are as broad as they are long^; in the genus
Gonifleptes K. ^ amongst the Aptera, and Epeira cancri-
formiSf a crab-shaped spider, the breadth exceeds the
length ; in Ci/nips, and several other Hymenoptera, in
Acrida K. ^ [Locusta F.), and other Orthopterous in-
sects, the depth exceeds the breadth ; and in that singu-
lar beetle, Ewydiora ; the cockroach [Blatta), &c. the
upper surface is flat.

iii. The sadptitre of the integument of insects is often
very remarkable; but as this will call for attention here-
after, I shall only here observe in general, that ornament
and variety seem not to be the sole object of those eleva-
tions and depressions which form so prominent a feature
of many of the animals in question ; for by means of these,
many important purposes, that at first sight do not strike
the observer, may be served: such as giving firmness
to the crust in those places where it is most wanted ; di-

* Coquebert Ilbistr. Icon. ii. t. xviii./. 14, 15,

^ Linn. Trans. \n. t. xxii./. 16.

•^ This name I would give to Locusta F., reserving, with Dr. Leach,
the latter name to the true locust {Gri/llus ¥.). The name Conoce-
phalus, by which Locusta¥. has been distinguished, is better restricted
to those with a conical head.

398 EXTERNAL ANAT(>MY OF INSECTS.

minishing its powers of resistance in others, so that it
may yield somewhat to the action of the muscles; in-
creasing or deducting from the weight of the body, so as
to produce a proper equipoise during its motions, whe-
ther on the earth, in the air, or in the water. The de-
pressions of the outer surface of the crust, in many in-
stances, produce an elevation of it in the interior, and
so afford a useful point of attachment to certain muscles.
This observation seems more especially applicable to
those excavations that are common to particular tribes
or genera : thus the dorsal longitudinal channel to be
met with on the prothorax of most of the Carabi of Linne
on the inside of the crust have a corresponding ridge.
In Locusta Dux, also, (a Brazil locust,) the same part
\\2isfoiir transverse channels, corresponding with which
on the inside are as many septa, or ridges, to which mus-
cles are attached; and those larger impressed puncta
denominated puncta ordi7iaria, which distinguish the
same part in Geotrupes and many of the Scarab^eidcu,
within are elevated, so as to form a kind of ginglymous
articulation with the base of the anterior coxas. The
other impressed puncta so often to be seenon the diffe-
rent parts of various insects, which sometimes so intirely
cover the surface that scarcely any interval is discover-
able between them, though in many cases they appear to
be mere impressions that attenuate but do not perforate
the crust — yet in others, perhaps equally or more nu-
merous, they are real pores, which pass through the in-
tegument. If, for instance, you take the thoracic shield
of the cockchafer [Melolontha vulgaris), and after re-
moving the muscle &c., hold it against the light, with
the inner side towards the eye, you will see the light

EXTERNAL ANATOMY OF INSECTS. 399

through every puncture : or take the elytra of Geotrupes
stercorarius, or any common beetle in which these or-
gans have punctate striae, and examine them under a
lens on the inside, and you will see distinctly that the
punctures pass through the elytrum, and the membrane
that hues it ^. It is not improbable that in the case last
mentioned these pores may be of use, as the spiracles are
usually closely covered by the elytra, for the better trans-
mission of the air to those respiratory organs. Whe-
ther the pores in the other parts of the body are for
transpiration, is more than I shall venture to affirm ; but
as insects sometimes perspire, at least this has been ascer-
tained with respect to the hive-bee ^, this must be by the
means of some pores.

iv. The integument of insects is often clothed, either
partially or generally, with pubescence^ or hairs of vari-
ous kinds — a circumstance which seems to have more
than one object. In Paimus, Hetcrocerus, Gerris, Argy-
roneta aquatica, and some other aquatic insects, the end
in view seems to be to keep the water from wetting the
crust; and in this case the covering of hairs is dense,
silky, and decumbent. Another object is preventing
friction from being injurious : thus humble-bees, that
from their mode of nidification '^, are usually more par-
ticularly exposed to it, are well clothed with hair ; and
in those articulations of insects where much friction takes
place, we may often observe a dense fringe or coating of
the same substance. This you may see in the common

=> Plate XXVIII. Fig. 1, 2.

^ Huber Nouv. Obs. ii. 317. ' Vol,. I. p. 502—.

4-00 EXTEIINAL ANATOMY OF INSECTS.

Stag-beetle [Lucanus Cervus), where the thorax receives
the head ; and very remarkably at the same point in the
Hercules-beetle {Dynastes Hercules MacLeay) : but be-
sides these uses, there is probably one more universal,
which will apply as well to those thinly scattered bristles
and hairs, here and there one, to be noticed in many
insects : but concerning this I can only throw out a con-
jecture, as I do not recollect ever to have seen any ex-
periments with regard to this use of animal hairs. But
may they not act as conductors, either to introduce
some invisible fluid into the body in a positive state, or
to convey it out, when received by other means, in a ne-
gative state ? Every one knows that the fur of a cat has
electric properties, and there may be an important gene-
ral use of this kind attached to the fur and hairs of ani-
mals ^. But, as I said, I give this as a mere conjecture ;
and only wish it may excite your attention to the subject,
and put in exercise your natural tact for experiment.

M. Cuvier regards the hairs of insects as merely a
continuation of the epidermis, with which they fall when
the animal changes its skin''; but this will apply only to
the hairs of larvse: for the hairs of perfect insects in
many cases are implanted in a pore, and pass through
epidermis or crust to the membrane that lines it, in which
they terminate.

V. We are now to consider the composition of the in-
tegument; under which term I would include the diffe-
rent layers of which it consists, and its articulation.

^ Hair, in the Holy Scriptures, is used as the symbol of strength
or jjoioer. Judges xvi. 17 — . 1 Cor. xi. 10.
'' Anat. Compar. ii. 634.

EXTERNAL ANATOMY OF INSECTS. 401

1. With respect to the^rsf of these circumstances, the
lai/as of which the integument consists, it seems to ex-
hibit some, ahliough not an exact, analogy with the skin^
rather than the skeleton, of the vertebrate animals'". In
these last, the skin is stated to consist o^ four layers.
Of these the exterior one is the epidermis, or scarf-skin :
under this is the rete mucosicm, or nmcous tissue, which
gives its colour to the skin ; next follows the jnqnllary
tissue formed by the extremities of the nerves, and in
which the sense of tcnich principally resides ; the last and
innermost \i\yQ.Y \i ihc skin proper, or leather, called Der-
mis, Derma, or Corium ^. Thioo of these la^'ers M. Cu-
vier assigns to insects. They have, he observes, in every
state, a true epidermis'^; and in their state of larva he
finds that the infinite variety of colours that so adorn
many of them is produced by a nmcous substance ob-
servable between the epidermis and the muscles ^ : this
seems analogous to the }'ete mncosum. To this, dried
and mixed with their horny substance, he attributes also
the colours of the perfect insect : " for," says he, " w hen
the Lepidoptera are in the chrysalis, the little coloured
scales which are to ornament their wings, are then in a
state of mucosity similar to that which is found under the
skin of the caterpillar. The colours of the Arachnida,'
he goes on, " are also due to this mucosity : it is disco-
verable under the skin, and has the appearance of mi-
nute glandular points of which the shades vary consider-
ably. But in the Colcoptera, and many other Orders, the

a Anat. Comjiar. i. 119. " Ibid. ii. 540.

' Ibid. 547. '' Ibid. 553.

VOL. III. '2 \i

402 EXTERNAL ANATOMY OF INSECTS.

colours of the skin are mixed in its horny tissue, nearly as
those of the Testacea are in their calcareous shells ^. In
the perfect insects, therefore, in most cases, we may con-
sider the epidermis and rete imicostim as together form-
ing the exterior and coloured integument of insects —
that part which in the table, since it is not properly an
epidermis, I have distinguished by the name of Exo-
derma.

The learned author just quoted has observed nothing
under the skin of white-blooded animals that he regards as
analogous to nervous piapillce ^. In some parts of insects,
as in the lamellae of the antennae of the Pctalocera, and the
extremities of the joints, especially the last, of many palpi,
there is however an appearance of them ; and it seems
reasonable to suppose that M'here the sense of touch re-
sides, there must, even in insects, be something of a pa~
pillary tissue.

With regard to the innermost integument of the ver-
tebrate animals, — the leather, or real skin, — this learned
comparative anatomist finds nothing analogous to it in
the integuments of insects ^ ; but as he does not notice it,
he appears to have overlooked the substance that lines
the outer crust, or exoderma, in the Coleoptera and most
other orders. This is not always easily detected ; but it
may generally be discovered by breaking, or rather tear-
ing (not cutting), after having cleared away the muscles,
any part of the body of an insect. It is always very vi-
sible on the under side of elytra ^, but is not discoverable

» Amt. Compar. ii. 553. ^ Ibid. 557. ' Ibid. 560.

d Platk XXVIII. Fig. 3. «'".

EXTERNA!, ANATOMY OF INSECTS. 40;}

in tegmina. It appears to consist, in many cases, of se-
veral layers of a whitish membrand, and generally breaks
into fibres. In some elytra of the larger Dijnastidfc,
towards tiie sides the exterior layer is separated Irom the
rest by a kind of ccllnlar substance. The fibrous struc-
ture of this inner skin (which I call the Esodervia) seems
to give it some aflinity to the skin of vertebrate animals ^
In many })arts of the body, however, it appears to be
merely a thin pellicle. A medical friend, to whom I
showed specimens of it, thinks it a kind of cellular mem-
brane.

2. A few words are next necessary with regard to the
articulation of the integument, or the mode by which tlie
several pieces of which it and its members consist, are
united to each other. In some, as in several of the parts
of the head, the occiput, vertex, temples, cheeks, he. —
the line of distinction is merely imaginary ; in others an
impressed line separates a part from its neighbours, as is
the case with the nose in Vespa, &c. the head in the
Arachnida. But m the majority of instances the parts
are separated by a suture, or tbrm a real joint. The
kinds of articulation observed by anatomists in vertebrate
animals do not all occur in insects, and they seem to
have some peculiar to themselves. Thus, for instance,
they have no proper suture ; for though they exhibit the
appearance both of the harmonic and squamose {ecaiU
leuse Cuv.) sutures'^, yet these parts being all limited by

* Anat. Compar. ii. 55/.

'' A harmonic suture is when the margins of two flat bones simply
touch each other, without any intermediate substance; and a squa^
mose, when the thin margin of one covers that of the other. Auat.
Compar. i. 124. With regard to the flat portions of the integument of

2 D 2

404 EXTERNAL ANATO.'MY OF INSECTS.

the esoderma, or skin, above noticed as lining the inte-
gument, and all admitting a degree of motion more or
less intense, rather afford examples, as the case may be,
of other kinds of articulation =". Again, they have no
proper Enarthrosis, or ball and socket; though the an-
terior coxa? of the Capricorn-beetles {Ceramhyx L.) ap-
proach very near to this kind of articulation, as will be
shown more fully in another place. The inosculating
segments or rings, which distinguish the abdomen, and
sometimes other parts of insects, are an example of a
kind of articulation not to be met with in the Vertehrata.
The ginglymous articulation, in which the prominences
of the ends of two joints are mutually received by their
cavities, and which admits only of flexion and extension,
often prevails in the limbs, &c. of insects ; but in many
cases the joints are merely suspended to each other by a
ligament or membrane; and, in fact, the integument of
insects, with regard to its articulation, even where the
joints ginglymate, may be said in general to consist of
pieces connected by the internal ligament, membrane, or
skin that lines it; for even in the legs, where the gingly-
mous articulation is sometimes very remarkable and
complex, as will be shown to you hereafter, the joints
are also connected by this substance, as you may see if
you examine the legs of any Coleopterous insect.

insects, they have some motion; whereas a suture is an articulation
without movement. Ibid.

'' Their connexion by means of a ligament classes them under
Si/nneurosii! (Monro On the Bones, Dr. Kirby's edit. ;^1)), but even
this not strictly, since a common ligament connects them all. Those
of the trunk, as admitting a slight degree of motion, belong to A)):-
■phiarthrosis {Anat. Compar. i. 126), and those of the abdomen, wiiich
are capable of larger movements, to Diarthrosis {Ibid. 137).

EXTERNAL ANATOMY OF INSECTS. '105

TIk' number of arliculatioiis or pieces (li:it form (lie
integument anil its members in these animals, varies
greatly in different tribes, genera, &c. Thus, in the com-
mon louse {Pcdicuhis humafms) they scarcely reach fifty,
while in some cockroaches {Blaila) they amount to more
than eight times that number.

Having premised these observations on the external
anatomy of the body in general, in the remainder of the
present letter I shall confine myself to the consideration
of the head and its parts.

I. The Head of insects, as the princijial seat of the
organs of sensation, must be regarded in them, as well
as in the vertebrate animals, as the governing part of the
body. It may be considered with respect to its sub-
s/ance,JI'g7ire, composiliun, superficies, propo)-tion^ direc-
tion, articulation with the trunk, motions — and more par-
ticularly as to its parts and appendages.

i. With regard to its substance — the head may be said
in genei'al to be the hardest part of the crust : and it is
so for very good reasons. In the fii'st place, as it has to
make way for the rest of the body when the animal moves,
it is thereby best fitted to overcome such resistance as
may be opposed by the mediiun through which it has to
jiass ; in the next, as it bears the organs of mandueation,
it was requisite that it should be sufficiently firm and so-
lid to support their action, which is often upon very hai'd
substances ; and besides this, as no motion of its parts
iiiter se, as in the case of the trunk, is requisite to fa-
cilitate the play of its organs, a thin integument was
not wanted.

406 EXTERNAL ANATOMY OE INSECTS.

ii. The most general law relative to xhejigiwe or shape
of the head seems to be, that it should approach to that of
an equilateral triangle, with its angles rounded, and the
vertex being the mouth ; and that the vertical diameter
should be less than the horizontal, whether longitudinal
or transverse. But the infractions of this law are nume-
rous and various. Thus, in some insects an isosceles tri-
angle is represented by the head, the length being greater
than the breadth ; in others, instead of being flat it is
compressed, so that the horizontal diameter is less than
the vertical; in others, again, it is orbicular, or round and
depressed ; in others nearly spherical : occasionally it is
rather cylindrical. In many instances it is very long;
in others the width exceeds the length. Though often
narrowest before, in some cases the reverse takes place.
Its anterior end is often attenuated into a long or short
snout or rostrum, and its posterior into a long or short
neck. Its contour, though usually regular, is sometimes
either cut into lobes, or scooped out into sinuosities.
But to enumerate minutely all the variations of form
which take place in the head of insects would be end-
less; I shall therefore proceed to the next particular.

iii. The composition of the head is very simple ; for,
exclusive of its organs, it consists only of a single piece
or box, without suture or segment, with an aperture at
the end below to receive the instruments of manducation,
others for the eyes and stemmata when present, and also
for the antenna:. In the Arachnida, &c., in which the
head is not separated from the thorax, it is merely a
plate, the under-side or cavity of which is occupied and
filled bv the above instruments.

EXTERNAL ANATOMY Ol INSECTS. 107

iv. Willi regard to its supojicicsy the iieiul of insects
is geiieially more or less uneven, though in some cases it
jiresents no inequalities. In many of the Lamellicorn
tribes, and a few other individuals, in one sex at least,
as has been before observed ^, it is armed with long
Jiorns, or prominent tubercles ; it is often covered with
numerous puncta, or pores ; and some of its parts, as the
nose, after-nose, &c. in particular groups, marked out
by an impressed line ^. In many Hynicnoplcya^ Diptcra,
&c. its upper surface is convex, and the lower concave ;
in others both surfaces are convex.

V. It is the most general rule, as to its proportion, that
it shall be smaller than either trunk or abdomen ; but in
some instances, as in the S. American ant, Atta megace-
phala, it is much larger than either.

vi. By the direction of the heutl, I mean its inclina-
tion with respect to the prothorax. The most natural
direction, or that which obtains most generally, is for it
to form an angle more or less obtuse with the part just
mentioned. This seems to obtain particularly in Coleo-
ptera ; but in some, as Mi/labris, it is inflexed, forming
an acute angle with it. In the Heteropterous Hemiptera
{Cimex L. &c.) it is generally in the same line with the
body, or horizontal ; and in many Diptera it is vertical.

vii. We now come to a circumstance which will de-

•' Sec above, p. 309 — .

^ In the hornet and other wa<pb, this line on the inside of the
head furnishes a foundation for a septum, which in the sides of the
nose is very high, and connects also with the hind part of the head.

406 EXTERNAL ANATOiMY OF INSECTS.

tain us longer, namely, its articulation with the trunk,
or rather with its anterior segment, the prothorax. —
M. Cuvier makes t'voo principal kinds of articulation of
the head upon the prothorax, in one of which the points
of contact are solid, and the movement subordinate to
the configuration of the parts ; in the other, the articula-
tion is ligamentous, the head and the thorax being united
and kept together by membranes.

1. Thejirst of these kinds of articulation — that by the
contact of solid parts — takes place, he says, in Jour dif-
ferent ways. " In the most common conformation, in
the part that corresponds to the neck, the head bears
one or two smooth tubercles, which receive correspond-
ing cavities of the anterior part of the prothorax observ-
able in the Lamellicorn and Capricorn beetles. In this
case the head can move backwards, and the mouth for-
wards and downwards. The secojid mode of solid arti-
culation takes place when the posterior part of the head
is rounded, and turns upon its axis in a corresponding
caVity of the anterior part of the prothorax; as may be
seen in Curculio, Reduvius, &c. The axis of motion is
then at the centre of articulation, and the mouth of the
insect moves equally backwards and forwards, upwards
and downwards, to right and left. — The third, sort of ar-
ticulation, by solid surfaces, takes place when the head,
truncated posteriorly, and presenting a flat surface, is
articulated, sometimes upon a tubercle of the thorax,
and sometimes upon another flat and corresponding sur-
face, as in almost all the Hymenoptcra and the majority
of the Diptera. The disposition of the foiirih kind of
articulation allows tlie head only the movement of the
angular hinge (J,c seid mouvemcnt dc charniere angnlaire).

EXTERNAL ANATOMY OF INSECTS. 409

Tlie only examples at present known are in some species
of Attdabus F. The head of these insects terminates
behind in a round tubercle, received in a corresponding
cavity of the thorax : the lower margin of this cavity has
a notch, and permits the movement of the head only in
one direction "."

2. The second kind of articulation, the ligamentous,
he affirms takes place only in orthoptcrons and some
7icuroplcro7is insects : " The head in this kind of articula-
tion is only impeded in its movements towards the back,
because it is stopped there by the advance of the pro-
thorax ; but below it is quite free. The membranes or
ligaments extend from the circuit of the occipital cavity
to that of the anterior part of the prothorax, ^A'hich gives
a great extent to the movement ''."

When I consider the well-deserved celebrity of the
great author whose words I have here quoted, and the
great and useful light that the genius and learning which
conducted his patient labours and researches have thrown
over every department of comparative anatomy, — a sci-
ence he may be almost said to have foimded, — I feel the
most intire reluctance to differ in any thing from an au-
thority so justly venerable to all lovers of that interesting
study. But, however great my diffidence and hesitation
to express an opinion at all opposed to his, the interests
of truth and science require that I should state those
particulars in which my own observations, made upon a
careful examination of various insects of every Order,
liave led to results in some respects diffiirent from the

^ Annf. Cimpnr. t. 445 — . '' Ihul. 41/.

410 EXTERNAL ANATOMY OF INSECTS.

above. " Aliquando bonus donnitat Homcnis " and
if the Genius of Comparative Anatomy ever nodded, it
sometimes happened when he was examining the struc-
ture of insects. An instance of this with regard to the
mouth of the bee has been noticed by Mr. Savigny*;
and indeed it is not wonderful that in so extensive an
undertaking, in which the number of examples to be ex-
amined upon every branch of his subject must be im-
mense, that he did not always scrutinize minutely those
that seemed less important. Every writer on every de-
partment of Natural History, especially where the ob-
jects of research, as in the insect world, are so infinite in
number, will be liable to such mistakes ; but these will
meet with due allowance from every candid mind —
" Hanc veniam damus, petimusque vicissim :"

and I shall express my trust that you will overlook any
errors of mine ; and doubtless I shall not be free from

them —

" Quas aut incuria fudit,

Aut hiimana paruni cavit natura "

The two kinds of articulation of the head which our
learned author has stated as the principal ones, will, I
think, be found upon examination not so widely distant
as his expressions seem to indicate ; for in fact in all in-
sects, as well as the OrtJioptera, this part is suspended by
a membrane or ligament which unites the margins of the
occipital cavity with those of the anterior one of the pro-
thorax : thus forming all round some protection to the

» Mem.sur les Aiiim.sans Vertcbr. I. i. 11 — . Comp. Anal. Corn-
par, iii, 314 — .

EXTLUNAI, ANATOAIY OF INSECTS. 411

orgiuii) that iirc truiisniitted from the head throiigli the
latter part to the rest of the body. Tliough the head in
most Orlhoptcra is not partly received into the cavity
of the prothorax, as is the case in the Order Coleoptera,
but is rather suspended to it, yet in some instances, for
example in the mole-cricket {Grijllotalpa vulgaris), it is
partially inserted.

Again : when, in hisjirst mode of articulation by con-
tact of solid parts, he speaks of one or two smooth tu-
bercles of the neck, with their corresponding cavities in
the prothorax, as forming the most common conforma-
tion, you would expect to find examples of this in very
many insects ; yet upon a close examination, unless in
Orvctcs nasicomis ^, and perhaps in others of the D^-
nastidce MacLeay, you would scarcely meet with any
thing that could be called a tubercle and its correspond-
ing cavity in the neck or prothorax of any Lamellicorn
or Capricorn beetle that you might chance to examine.
You would find, indeed, that the occiput was usually
smooth and very slippery, as if lubricated ; that in its
margin were one or two notches {Myoglijphides\ with
nmscles attached to them ; that in the former of these
tribes, the Lamellicorns, it projected on each side so as to
form a more or less prominent angle ; and that the throat
[jugulum) was very convex, and lodged in a cavity of the
lower margin of the prothorax : but further appearances
of tubercles &c. you would in vain look for even in this

=• It is probable that M. Cuvier took his idea of this first kind of
tU'ticulalioi), by contact of solid parts, from this individual insect;
since, besides its very prominent throat, there is on each side of the
tower part of the occiput a small elevation, or approach to a tu-
bercle.

^12 EXTERNAL ANATOMY OF INSECTS.

tribe ; and in the Capricorns you would find that the ge-
neral conformation in this respect belonged to our learned *
author's seco?id mode of solid articulation, resembling
that of the majority of the weevils {CurciiUo L.), in which
the head has no projecting angles or tubercles, or other
elevation, but is received usually into the circular cavity
of the prothorax.

His third mode of this articulation, that of the Hymeno-
2)tera and Diptera, is so peculiar, that it ought to be con-
sidered as a primary kind ; since in this the head moves
upon the prothorax as upon a pivot, and has a kind of
versatile motion.

With regard to his fourth mode, which from his de-
scription appears to be that of Apoderus Oliv., he allows
motion to the head only in one direction, observing that
the lower margin of the prothoracic cavity has a notch.
But M. Latreille calls the articulation of the head in this
o-enus an Enarthrosis *, which admits motion in every di-
rection ; and if you examine the common species [A. Co-
ryli), you will find that the prothorax has a sinus taken
out of its upper margin, as well as out of its lower one —
which at any rate will allow a motion upwards.

I merely mention these little inaccuracies, with due
diffidence, as some apology for giving you a different and
at least a more popular and general view of this part of
my subject, which I shall now proceed to state to you.
It seems to me most convenient for the Entomologist, and
most consonant to nature, to divide insects, with respect
to the articulation of the head with the trunk, into three
primary sections, each admitting one or more subdivi-
sions.

' Gen. fits Cruslac. et Im. ii. 246. Rciinc Anim. iii. 325.

EXTERNAL ANATOMY OF INSECTS. 413

1. riu'//>.sY consists of those whose head inosculates
more or less in the anterior cavity of the chest; and
whose articulation, therefore, seems to partake in a greater
or less degree of the ball and socket [Enarthrosis). The
head, however, is often capable of being protruded from
this cavity. If you take into your hand any common Har-
palus that you may find under a stone, you will see, if
pressed, that it can shoot forth its head, so as to be en-
tirely disengaged from the prothorax : a neck of ligament
intervening between them*: of course this power of pro-
trudiuij the head enables the animal to diseno-ao-e it at its
will iVom the restriction imposed upon its motions by the
surrounding margin of the prothoracic cavity. To this
section belong all the Coleoptera, the Heteropterous Hr-
miptera (CiinexX^., &c.), and some of the Neiiroptera [Ra-
phidia, Semblisy &c.). — It may be further divided into t-joo
subsections — those, namely, whose head inosculates in
the prothorax by means of a neck : as for instance La-
treille's TracheluleSy Apoderus, and the Stuphi/lijiida;,
amongst the beetles ; the Reduviadce amongst the Hete-
ropterous insects, and Raphidla in the Neuroptera ,• and
those whose head inosculates in the prothorax without
the intervention of a neck ; as, the Pctalocera^ the aqua-
tic beetles {Dj/tiscus, Hj/drophilus, &c.), and m,ost of the
genus Curculio L. in the first of these orders, the great
body of the Cimicidcc in the second, and Semblis, Corij-
dalis, &c. in the third.

2. The second section consists of those insects whose
head does not inosculate in the chest, but is merely sus-

' This was written directly after the experiment recomniendcd iu
the text had liceii tried, witli the result there stated.

414' EXTERNAL ANATOMY OF INSECTS.

pended to it by llgtiment or membrane. To this belong
most of the tribes of the Orthoptera Order, with tiie ex-
ception of the Mcmfidce, the Dermaptcra, the Homo-
ptcrous Hemipteray and such of the Aptera as have the
head distinct fi'ora the prothorax. — This section admits
of a triple subdivision : those, namely, whose head is
\soliolly covered by the shield of the prothorax, as in
Blatta L.; those whose head \'s, partlxj covered by it, as
Gri/llotalpa, and other GryUina; and those whose head
is quite free, not being at all impeded in its motion by
the prothorax, as the Dermaptera, Ninnus, Pedicu-
his, &c.

3. The ihird section consists of those whose head is
truncated posteriorly, and flat or concave, with a very
small occipital aperture, and is attached to a neck of the
prothorax upon which it turns, or is merely suspended
to that part. This includes the Lepidoptera, Hymeno-
ptei'a, Diptera^ the Libelhdina, &c. in the New^ptera,
and the Mantidcc in the Oi~thoptera. Three subsections
at least, if not more, present themselves in this section :
the first is, of those whose head is united to the protho-
rax, without the latter forming any neck. To this belong
the Lepidoptera, Trichoptera ? The second is of those
the upper side of whose thoracic neck is ligamentous ;
and here you may range most of the Hymenoptera. The
third is of those in whom it is a continuation of the ordi-
nary integument. In this subsection the Diptera, Libel-
luli7ia and Mantidce will find their place. In this last
section the head appears to turn upon the thorax as upon
a pivot.

Before I finish v/hat I have to say on the articulation
of the head, I must direct your attention to the analo-'

EXTERNAL ANATOMY OF INSECTS. 415

gies that hold in tiiis respect between the different tribes.
Thus the Coleoptcra are analogous to the Heleroptcrotis
Hemiptera : the Orihopfcra, with the exception of the
Maiifi(hr, to the Horn opt eroiis Hemiptera ,- the Mantid(e
to the LibcUulina ,• the Lepiduptcra to the Trichoptera ;
the Hymenoptcra to the Diptera, with a slight variation,
and probably others might be traced.

viii. A word or two upon the motions of which the
liead of insects is capable. M. Cuvier, in the extracts
lately laid before you, speaks of different powers of move-
ment as the result of different configurations of the parts
of the head. This probably is correct with regard to
many cases ; but a great deal will depend upon the power
the insect has of protruding its head and disengaging
its base from the restriction of the prothorax ; for where,
like the Harpali^ StaphyUni, &c. it is able to do this, it
can probably move its head in every direction. It is
only where the ligaments are less elastic, or allow of lit-
tle tension, that its movements are confined; and few
living insects have been sufficiently examined to ascer-
tain how far this takes place. In those cases belonging
to the third section of articulations, in which the head
moves Kjion the thorax as upon a pivot, as is the case
with Hymenoptera and Diptera^ the movement is nearly
versatile. I have seen a fly turn its head completely
round, so that the mouth became supine and the vertex
prone; and from the form and fixing of the head, it
should seem that those of the MantidcE were endued
with the same faculty.

ix. The p«>/i and appendages of the head are now in

416 EXTERNAL ANATOMY OF INSECTS.

the last place to be considered. I shall begin with the
Mouth, or rather the orifice in which the trophi or organs
of mandiication are inserted. In some insects, as was be-
fore observed, they occupy all the under-side of the head,
as in the Arachnida, Myriapoda, Sec; but in the great
majority they fill an orifice in its antei'ior part, which in
some ■ instances, as in Lampyris, the Lepidoptera, Ci-
mex L., Truxalis, appears to be nearly under the head ;
but in general it terminates that part, though it extends
further below than above. In Chermes, a Homopterous
genus, the promuscis is stated to be in the Antejjcclus, and
consequently the mouth ; but, as I shall endeavour to prove
to you hereafter, this is ^ fallacy. In the males of the
species of Coccus there is no mouth at all. In that of the
elm (C Ulmi) in lieu there are ten little shining points,
arranged two before and tv/o behind in a line, and three
on each side in a triangle*. It is to be observed that the
orifice of which I am speaking is usually much smaller
in those insects which take their food by suction, the
Hemiptera, Lepidoptera, Diptera, &c., than in the mas-
ticating tribes. With regard to the real mouth, or that
through which the food enters, I have nothing at present
to observe, except that it lies between the upper-lip and
tongue, is sometimes covered by a valve, as in Apis,
Vespa^, &c., and is different in the masticators and
suckers.

I shall next offer a few observations seriatim, as they
stand in the Table, upon the organs of manducation ;
which, to avoid circumlocution, instead of Listrume7ita

' Reav.m. iv. 40. Latreille Founnis, 328—. '' Pi.atf. VII. Fig. 2. k".

EXTF.UNAL ANATOMY OF INSFXTS. 417

ciharia, the name Fabricius gave them, I shall call troplii
ovjeedeis. It is upon these parts, you are aware, tliat
the system of the celebrated Entomologist just mentioned
is founded ; and could they always, or even for the most
part, be inspected with ease, they would no doubt afifbrd
characters as various and discriminative as those of the
vertebrate animals. Differences in these parts indicate
a difference in the mode in which the animal takes its
food, and often in the kind of food, and sometimes in its
general economy and habits, — circumstances which are
powerful and weighty in supporting the claim of any set
of animals to be considered as forming a natural cenus
or group. Trifling variations, however, of these parts,
unless supported by other characters and qualities, ought
not to have much stress laid upon them, since, if we in-
sist upon these, in some tribes almost every species might
be made a genus.

With respect to their trophi in general, insects of late
have been divided into two great tribes *, masticators and
stickers; thejirst including those that are furnished with
instruments to separate and masticate their food; namely,
an upper- and under-lip [laLrum and labium\ upper- and
under-jaws {rnandibidcc and viaxillcc)^ labial and maxil-
lary palpi, and a tongue [lingua) : and the second those
in which these parts are replaced by an articulate or ex-
articulate machine, consisting of several parts and pieces
analogous to the above, which pierce the food of the ani-
mal, and form a tube by which it sucks its juices. If,
however, the mode in which insects take their food be

" Clairville (£'«/. He/vet. i. 44) appears to have been the first who
classed insects according to their mode of taking their food.
VOL. III. 2 E

418 EXTEHNAL ANATOMY OF INSECTS.

strictly considered, it will be found that in this view they
ought rather to be regarded as forming three tribes ; for
the great majority of the Hymeno-ptera order, and per-
haps some others, though furnished with mandibles and
maxillae, never use them for mastication, but really lap
their food with their tongue : these, therefore, might be
denominated lajjpers.

When a mouth is furnished with the seven ordinary
organs used in taking the food and preparing it for de-
glutition— I mean the upper-lip and the two upper-jaws ;
the under-lip and the two under-jaws, including the la-
bial and maxillary palpi ; and the tongue — I denominate
it z. 'perfect mouth ,- but when it is deficient in any of these
organs, or they exist merely as rudiments, or when their
place is supplied by others, (which, though they may be
analogous parts, have little or no connection with them
in their use or structure,) I denominate it an imperfect
mouth. This last I would further distinguish, according
to the nature of its trophi, by other and more distinctive
terms, as I shall presently explain to you.

1. Lahrum ^. — I shall first consider the organs pre-
sent in a perfect mouthy beginning with the upper-lip {la-
hrum). This part, which Fabricius sometimes confound-
ed with the nose, miscalling it clypeus, is usually a move-
able ^ piece, attached by its base to the anterior margin
of the part last named, and covering the mouth, and
sometimes the mandibles, from above. In insects in
their last state it is usually of a horny or shelly substance;
yet in some cases, as in Copris and Cetonia^ beetles that

» Plate VI. VII. XXVI. a'.

'' In Lucanm,La7nprina, &c. the labruin seems to form the under-
side of the nose, and to be connate with it.

EXTERNAL ANATOMY OF INSECTS. 419

imbibe juices, it is membranous. Inform and shape it
varies greatly, being sometimes nearly square, at others
almost round ; in some insects representing a parallelo-
gram, in others a triangle, and in many it is oblong. In
some instances it is long and narrow, but more generally
short and wide. It is often large, but occasionally very
minute. In the majority it has an intire margin, but it is
not seldom emarginate or bilobed, or even dentate. Its
surfoce is commonly even, but it is sometimes uneven,
sometimes flat, at others convex, and in a few species
armed with a short horn or tubercle ^. As to its pubesceiicef
it is often naked, but now and then fringed or clothed
with down or hairs, or sprinkled with bristles. It con-
sists in almost every instance of a single piece ; but an
exception to this occurs in Halic/us, a little bee, in the
females of which it is fiu'nished with a slender appen-
dage ^. — The (lircciion of the upper-lip is various. It is
rarely horizontal, or in the same line with the nose, often
vertical ; it sometimes forms an obtuse angle with tlie
anterior part of the head, and occasionaljy an acute one,
when it is more or less inflexed. The use -of this part is
ordinarily to close the mouth from above, to assist in re-
taining the food while undergoing the process of masti-
cation ; but in many Hymenopterous insects its principal
use seems to be, to keep the tropJil properly folded ; and
m some cases where it is inflexed, as in the leaf-cutter
bees {Megachile Latr.), to defend its base, while the man-
dibles are employed, from injury by their action <=.

=» Kirby Mon. Ap. Avgl. i. t. v. Apis *. h.f. 18. b.
"» Ibid. t. ii. Melitta **. h.f. 4, 5. Plate XXVI. Fig. 30.
" PtATE XXVI. Fic. 31. Mon. Ap. Angl.l t. x. Apis **. c. 2. 3.
/. 13. c.

2 E 2

420 EXTERNAL ANATOMY OF INSECTS.

2. Labium^. — On the under-side of the head, and op-
posed to the upper-lip, the mouth is closed by another
moveable organ, concerning the nomenclature and ana-
logies of which Entomologists have differed considerably.
At the first view of it, this organ seems a very com-
plex machine, since the under-jaws or maxilla; are at-
tached to it on each side, and the tongue is often seen to
emerge from it above, so as to appear merely a part of it;
but as the former answer to the upper-jaws, and the lat-
ter is the analogue of the part bearing the same name in
the vertebrate animals, I shall consider these as distinct
SinA primary organs, and treat of the under-lip {labium)
of which I am now speaking, by itself. Linne takes no
notice of this part, but his illustrious compatriot and co-
temporary, De Geer, did not so overlook it : he appears
to consider the whole apparatus, including the maxilla;,
as the labium^; but sometimes he distinguishes the mid-
dle piece by that name '^ ; and the tongue, in the case of
the stag-beetle, he denominates a proboscis [trompe) ^.
In the Hymenoptera he calls this part tongue.^ under-liy,
and proboscis: but seems to prefer the last term ^ Fa-
bricius originally regarded the whole middle piece as a
labium ^\ but afterwards (though his definition is not ac-
curate, since he assigns the palpi to the ligula, which he
affirms is covered by the labium — circumstances by no
means universal in Coleoptera) he considers this as con-
sisting of ligula and labium s. Latreille at first regarded

'^ Plates VI. VII. and XXVI. b.

»> De Geer iv. 124. t. iv.f. 12 iii. 415. /. xxi./. 4.

<= Ibid. iv. 281—. t. xi./. 7- "^ Ibid. 329. t. xii./. 3.

* Ibid. ii. 775— f. xxvi./. 10. b c, b c.

PMloH. EntomAS. ' ^ Syst. Eleuth.i.Vrsel'w.

EXTERNAL ANATOMY OF INSKriS. i'2l

tlie ligula of Fabricius as the labium^ and called the la-
bium of that author tlie metihwi * ; but afterwards he gave
the name of labium to the whole middle piece of the
lower apparatus of the mouth — calling the upper piece,
with Fabricius, the ligula, and retaining the denomina-
tion of mentum for the lower ''.

If the circumstances of the case are duly considered,
I think you will be convinced that the term under-lip,
or labium, should be confined to that part which the
learned Dane so named. For I would ask. Which is
the part on the under side of the head that is the anta-
gonist, if I may so speak, of the upper-lip or labrum ?
Is it not that organ which, when the mouth is closed,
meets that part, and in conjunction with it shuts all in ?
Now in numerous insects, particularly the Lamellicorn
beetles {Scarabceus and Lucanus L.), this is precisely the
case. In the Predaceous beetles, indeed, [Cicindela, Ca-
rabus, Dytiscus L. &c.) the under-lip does not meet the
upper, to close the mouth and shut in the tongue ; nei-
ther can the tongue be said so to do, but only, from some
circumstances connected with its manner of taking its
food, it is requisite that the last-mentioned organ should
not be retractile or covered ; but its miscalled meiiUim,
is still the analogue of that part which helps to close the
mouth in the former tribe. Should not this, therefore,
which so often performs the office, be distinguished by the
name, of a lip ? Again, is it not rather incongruous to
consider that organ which confessedly more or less per-
forms the office of a tongue, as a part of the lip P Though
it often wears that appearance, yet I believe, if the mat-

» Gen. Critslac. H Ins. i. 180. *• X Did. d'Hist. Nat. iv. 246.

4-22 EXTERNAL ANATOMY OF INSECTS.

ter is thorouglily and patiently investigated, it w ill be
found that on their upper side its roots are attached to the
interior of the upper side of the liead, as well as on their
lower side to the labium ; so that it may be regarded as
common to the two lips, and therefore not properly con-
sidered as an appendage of the under-lip alone.

Having assigned my reasons for preferring the name
given to the part in question by Fabricius, rather than
that of Latreille, I shall next make my observations on
the part itself In many cases the labium, or the middle
piece of the lower oral apparatus, appears to consist of
/wo joints : this you may see in the great water-beetle
{Hydrophiliis piceus), the burying-beetles {Necroj^horus),
the Orthopterous tribes ^, the Hymenoptera '', and others.
In this case the upper or terminal piece is to be regarded
as the labium, and the lower or basal one (which Mr.
MacLeay calls the stipes) as the mentum or chin — at
other times, as in some Lamellicorn beetles, the only se-
paration is a transverse elevated line, or an obtuse angle
formed by the meeting of the two parts, and very fre-
quently there is no separation at all, in which case the
whole piece, the mentum merging in it, may be denomi-
nated the labium.

With respect to its substance, the labium in most Co-
leopterous insects is hard and horny, in Necrophorus it
is membranous, and the mentum harder; in Prionus
coriarius, our largest Capricorn-beetle, both are mem-
branous ; in the bee-tribes, Apis L., the labium rather
resembles leather, while the mentum is hard. Its surface
is often convex, sometimes plane, and sometimes even

» PLATji VI. Fig, 6. b'. a". ^ PtAit \\l. Fig. 3. b'.a '.

EXTEllNAl. ANATOMY OF INSKCTS. 423

concave; as for instance in Mdolontha Fullo^ a rare
chafer occasionally found on the coast of Kent. In some
it is covered with excavated points ; in others it is quite
smooth. In numbers, as in the Predaceous beetles, both
labium and nicnlum are perfectly naked ; in others, as in
the common cockchafer, they are hairy ; in Geniates bat'
batus Kirby, another chafer in the male insect, the la-
bium is naked, while the mentiimn, which forms a piece
distinct from that part, is covered with a dense rigid
beard *. In shape tlie whole labium varies considerably,
much more than the labium ,• for in addition to most ot
tlie forms I enumerated when I described that organ,
which I shall not here repeat, you may meet with exam-
ples of many others. Thus, to instance in the Petalocerous
tribes {Scarabanis L.), in some, as in the Rutelidce, the
labium is urceolate, or representing in some degree the
shape of a pitcher '^; in others it is deeply concave, and
not a little resembles a basin or a bowl ^ ; this form is
pecidiar to the labium of Crema&toclieilus Knoch, a scarce
North American beetle ; in another related to this, but
of an African type [Genuchus Kirby MS. Cctonia cru-
enta F.), it is a trapezoid plate, which is elevated from
the head, and hangs over the throat like a chin ^. In the
Hijmcnoptera it is extremely narrow and long, and em-
braces the sides of the tongue, as well as covering it fi'om
below; so that it wears the appearance of a kind of tube ^.
Generally speaking, the length of the labium exceeds its
breadth ; but in the Predaceous beetles the reverse of

=* Kirby Z/iHH. Tram. xii. t. \\\.f,8.f.

h Ibid. /. xxi./. 10. d. MacLcay Ilor. EnlnmoL i. /. iii./. 2G, 27.

-^ Plate XXVI. Fir.. ;J5. " Ibid. Fu.. :J4.

' Plate \[\. Fio. ?>. b'.

i2'l- EXTERNAL ANATOMY OF INSECTS.

this takes place, it being very short and wide, and usu-
ally terminating towards the tongue in three lobes or
teeth which form two sinuses varying in depth *.

The mentmn taken by itself aiFords no very striking
characters to which I need call your attention : I shall
only observe, that in Hymenoptey^a it is generally of a
triangular shape'' ; but before I proceed to consider the
labial palpi, it will be proper to notice the remarkable
labium of Orthopteroiis insects, and of the Libellulina,
between which there is no little analogy. At first you
would imagine the terminal part of this organ in the for-
mer to be the analogue of the tongue, or ligula F. ; as it
is indeed generally regarded by modern Entomologists '^.
It seems, like the tongue of the Carahi L., Dytisci, &c., to
be a distinct piece, which has below it both labium and
mentian ; but when you look within the mouth, you will
find a linguiform organ '^, which evidently acts the part
of a tongue, and therefore ought to have the name ; and
the piece just alluded to must either be regarded as the
termination of the lip, or as an external accompaniment
of the tongue, analogous, it may be, to the paraglossce in
bees ^. In a specimen of Acrida viridissima [Lociista F.)
which I dissected, the tongue is as long as the appen-
dage of the under-lip, and by its upper surface seems
to apply closely to it. In the Libellidiyia a similar organ
is discoverable *^, which on its upper-side terminates in
the pharynx, like that of one of the Harpalidce before
mentioned. In the OrtJioptera, therefore, I regard the
labium as consisting of three articulations, the upper one

' Plate XXVI. Fig. 24. b'. ^ Plate VII. Fig. 3. a".

<" N. Diet. (VHist. Nat. xxiv. 171. '^ Plate VI. Fig. 6. e',
' Plate VII. P^ig. 3. i". f Plate VI. Fig. 13. e'.

EXTERNAI- ANATOMY OF INSICCTS. 425

divided into two, three, or more lobes*; the intermediate
one more directly answering to the labium of other in-
sects, and the basal one or mentum. This organ in the
LibcllttUna is of a different strncture : it has only two
articulations representing labium and mentum', but the
former consists of three parallel pieces, the two exterior
ones rising higher than the intermediate one, and at their
inner angle having an acute sinus from which the palpi
emerge; and the intermediate piece, which is longitudi-
nally channelled, lapping over the inner side of the lateral
pieces. From the angle of the covered part of these
pieces, a subulate short horizontal horn points inwards
towards the tongue, which it must keep from closing
with the labium^.

3. Palj)i Labiales *=. — The last-mentioned organs, the
labial palpi, next claim our attention ; but before I advert
particularly to them, it will be proper to premise a few
words upon palpi, or feelers, in general. These are usual-
ly jointed moveable organs, of a corneous or coriaceous
substance, attached by ligaments to the labium and
maxillce, and in the Cncstacea even to the mandibulce.
Their joints, which are usually more or less obconical,
articulate also in each other by ligaments, with perhaps
some httle mixture of the ball and socket. Their ends,
the last joint especially, seem furnished with nervous
pajnllcE which indicate some peculiar sense, of which they
are the instrument. What that sense is has not been
clearly ascertained, and concerning which I shall enter
more into detail in another place. Their motion seems

- Plate VI. Fig. G. b'. '■ Ibid. Fig. 13. b".

' Plat];5 VI. VII. XXVI. b' .

426 EXTERNAL ANATOMY OF INSECTS.

restrained, at least in some, to two directions, towards
and from the mouth. They were called j^cilpi or feelers,
because the insect has been supposed to use them in ex-
ploring substances. There seem to be no organs in the
vertebrate animals directly analogous to t\\epalj)i of in-
sects and Crustacea, unless, perhaps, the cirri that emerge
from the lips of some fishes, as the cod, red mullet, &c.
which Linne defines as used in exploring [prcetentantes).
Whether the vibrissa:, miscalled smellers, of some quadru-
peds and birds have any reference to them, I will not
venture to affirm ; but the feline tribe evidently use their
bristles as explorers, and they are planted chiefly in the
vicinity of the mouth.

Having made these general remarks, I shall now con-
fine myself to the labial paljpi. I call them labial palpi,
because that term is in general use, and because in many
cases they really do emerge from what I consider as the
labium, as in most of the chafers ; but they iflight with
equal propriety be denominated lingtial palpi, since they
sometimes appear to emerge from the tongue (as in the
stag-beetle (Lucanus Cervus). In some instances, as in
the Predaceous beetles, they seem to be common to both
labium and tongue, being attached at their base on the
upper side to the former, and on the under side to the
latter. As to their situation : they emerge from the base
of the labium in the locusts [Locusta Leach) ^ ; from its
middle in Hister maximus^; from its simimit in Amblyte-
rus MacLeay'^; and from its lateral margin in Dj/iias-
tes MacLeay, &c. They consist of from 07ie to four

* Plate VI. Fig. 6. b". '' Ho>: Enfomolog. i. /. If. l.g.

•^ Ibid. t. ii./. 18. g.

EXTERNAL ANATOMY OF INSECTS. 127

joints ; Avliich, I believe, they never exceed. Tlicy vary
in length ; though generally shorter than the maxillary
palpi, yet in the ferocious tiger-beetles {Cicindcla L.)
they equal them in length ; and in the hive-bee and hum-
ble-bees, and many other bees, they are considerably
longer ^. The two first joints of these palpi, however,
in these bees are different in their structure from the two
last, being compressed and flat, or concave; and the two
last joints, instead of articulating with the apex of the
second, emerge from it below the apex : so that these
two first joints seem rather elevators of the palpi than
really parts of them ^. With respect to the relative pro-
jwriions of their joints to each other : in some cases the
first joint is the longest and thickest, the rest growing
gradually shorter and smaller '= ; in others, the second is
the longest^; in others, again, the third % and sometimes
the last * ; and often all are nearly of the same size and
lengths. They are more commonly nakcd^ but some-
times either generally or partially hah-y. Thus in Cicin-
dela^ the last joint but one is usually planted with long
snow-white bristles in a double series, while the rest of
the joints have none ; and in Cupris Latr. all of them are
extremely hairy. In shajje they do not vary so much as
the maxillary palpi, being most frequently filiform or
subclavate, and sometimes setaceous; the last joint varies
more in shape than the rest, and is often remarkably

* KJrby Mon. Ap. Angl. i. t. xii. neut.f. \.g. c.

b Ibid. 93. 103—. t. vi Apjg **, b. /. 3. b c.

^ Ibid. t. i. » a./. 3. b ^ Ibid. t. ix. Apis «*. c. 2. -/./. 3. b.

" Clairv. Ent. Heluet. h /. xxiv/. 1. c.

i Plate XXVI. Fig. 24, 28. b".

' Mvn. Ap. Aiigf. i. (. ii, Mclitta **. h.f. 2. c.

428 EXTERNAL ANATOMY OF INSECTS.

large, triangular, and shaped like the head of a hatchet';
and at others it resembles the moon in her first quar-
ter''. In the great dragon-fly, or demoiselle if you pre-
fer the gentler French name {jEsJina F.) the labial palpi,
which are without any visible joints, are terminated by a
minute mucro or point *^. With regard to their direction
and flexure, they frequently, as in the instance just men-
tioned, turn towards each other, and lie horizontally upon
the end of the labium. Sometimes, as in the Cici7idelidce,
they appear to point towards the tail of the insect, the last
joint rising, and forming an angle with the rest of the
feeler. In other instances they diverge laterally from the
labium, the last joint turning again towards it at a very
obtuse angle.

4. MandihdcE^. — Having considered the analogues of
the lips in our little beings, I must next call your atten-
tion to the representatives of the jaws. The vertebrate
animals, you know, are mostly furnished with a single
pair of jaws, one above and the other below, in which the
teeth are planted and which have a vertical motion. But
insects are furnished with two pair of jaws, a pair of
upper-jaws and a pair of under-jaws, which have no
teeth planted in them, and the motion of which is hori-
zontal.— I shall begin with an account of the upper-jaws.
These by modern Entomologists, after Fabricius, are de-

" Plate XIII. P'ig. 2. Linn. Trans, xii. t. xxi./. 6. b.

'• This is the case with Oxyporus F. Plate XIII. Fig. 4.

« Plate VI. Fig. 12. b". Latreille, N. Diet. (THist. Nat. xvii.
545, seems not to regard these as palpi; but from their tubular form,
and insertion in the socket of the labium, it is clear that they ought
fo be so considered. ^ Plates VI. VII. XXVI. c'.

EXTERNAL ANATOMY OF INSECTS. 42i)

nominated mandibles [mandibulrv) : a term appropriated
l)y Linne to the beaks of birds. The upper-jaws of in-
sects this {^reat naturalist named maxilhc — and not im-
properly, since the ofhce of mastication is more pecu-
liarly their office than that of the under-jaws, which Fa-
bricius has distinguished by that name : as the term mari-
(lihlr, however, is generally adopted, I shall not attempt
to disturb it.

The ma7idibles close the mouth on each side under the
labrnm or upper-lij). They are generally powerful or-
gans, of a hard subsUnicc like horn; but in the Lamellicorn
beetles of Mr. MacLeay's families of ScarabcBidce and Ce-
toniadcB, they are soft, membranous, and unapt for masti-
cation. In Coleopterous insects they commonly articulate
with the head by means of certain apophyses or processes,
of which in many cases there ai-e three discoverable at
the exterior base of the mandibles ; one, namely, at each
anjile, and one in the middle. That on the lower side is
usually the most prominent, and wears the appearance
of the condyle of a bone : it is received by a correspond-
ing deep socket (or cotyloid cavity) of the cheek, in
which, being perfectly smooth and lubricous, it moves
readily, but without synovia, like a rotula in its aceta-
bulum. The upper one projects from the jaw, forms
the segment of a circle, and is concave also on its mner
face. A corresponding more shallow, or, as anatomists
speak, glenoid cavity of the cheek, where it meets the
upper-lip, receives it, and the concave part admits a lubri-
cous ball projecting from the cheek, upon which it turns".

» A corresponding articulation takes place between the tibia and
thigh of some of the Sc<trab(cid<^, which will be hereafter described.
See Plate XXVII. Fh;. S— 11.

430 EXTERNAL ANATOMY OF INSECTS.

This Structure you will find in the stag-beetle, and some
other timber-devourers. Other Coleoptera have only a
process of a similar structure at each of the dorsal angles
of the base of the mandible, the intermediate one being-
wanting ; and the articulation does not materially diifer,
as far as I have examined them, in the Hymenoptera and
Ncuroptera. In the Ortlioptera^ the structure approaches
more nearly to that of the stag-beetle, since there are
three prominences : it is thus well described by M. Mar-
cel de Serres : " This articulation," says he, " takes place
in txm ways. At first, in the upper surface of the man-
dible, and at its base, may be observed two small promi-
nences and a glenoid cavity ; these prominences are re-
ceived in two glenoid cavities excavated in the shell of
the front, as the cavity of the mandible receives a small
prominence of the same part. Below the mandible, and
at its base, there is a kind of condyle, which has its play
in a cotyloid cavity excavated in the shell of the temple,
far below the eye, and at the extremity of the coriaceous
integument of the head ^." Within the head m this or-
der, at least in Locusta Leach, is a vertical septum, which
divides the head into two chambers, as it were, an occi-
pital and a frontal, consisting of a concave triangular
stem, terminating in two narrower concave triangular
branches, so as to resemble the letter Y, and forming
three openings, an upper triangular one, and two latej'al
subquadrangular ones, which last are the cavities that re-
ceive the base of the mandibles. This partition, which I
would name Cephalophragma^ doubtless affords a point of
attachment to many of the muscles of the head. It does

» Comparaison des Organes de la Mastication des Orthopt^res, 2.

EXTERNAL ANATOMY OF INSECT?.. 431

not nppear to Imve been noticed, unless it be synonymous
with the intermaxillanj arcade of Marcel de Serres*.
Probably a corresjionding support to the nuiscles, &c.
may exist, as we have seen it does in Vcsjm L. ^, in many
other heads of the different Orders, which have not yet
fallen under examination. Many mandibles, as those of
the hornet &c., appear to be suspended to the cavity of
the head on the inside by a marginal ligament suffi-
ciently relaxed to admit of their play : those of the O;-
thoptera, M. Marcel de Serres informs us, are united to
the head bv means of two cartilages, the outermost beinof
much the shortest, to which their moving muscles are
attached. These he considers as prolongations of the
substance of the mandible ^. The bottom of mandibles,
when cleared of the muscles &c., inclines almost vmiver-
sally to a triangular form ; but in somd cases, as in the
stag-beetle, it is nearly a trapezium, I cannot conclude
this subject without noticing the motions of the mandi-
bles. What the author lately quoted has said with re-
gard to those of the Orthoptera, will, I believe, apply
equally well to all the mandibulate orders. " The arti-
culation of mandibles with the skull appears to take place
by two points solely ; and as these parts only execute
movements limited to a certain direction, they may be
referred to ginglymus '^. — The movements of mandibles
are limited to those from within outwards, and from
without inwards ^." Whether they are restricted from
any degree of vertical motion, has not yet been proved,
as the jaws of vertebrate animals move horizontally as

* Comparaison dcs Organcs de la Madical'um des Orthoptcrcs, 2.
•> See above, p. 40/. notch. '' Uhi supra, 4. "* Ibid. " Ibid. 5.

432 EXTERNAL ANATOMY OF INSECTS.

well as vertically — so those of insects may have some
motion vertically as well as horizontally ; and it seems
necessary for some of their operations that they should.
I am not anatomist enough to speak with confidence on
the subject, but the ball and socket articulation at the
lower part of the mandible, and the curving one at the
upper, though a kind of gingli/mus, seems to imply a de-
gree of rotatory movement, however slight.

I must next say something upon the general shape of
these organs. Almost universally they incline to a tri-
quetrous or three-sided figure, with their external sur-
face convex, sometimes partially so, and their internal
concave. Most frequently they are arched, curving in-
wards ; but sometimes, as in Prionus octcmgiilaris^, a Ca-
pricorn beetle, and others of that genus, they ai'e nearly
straight; and in Rhina barbirostris^, a most remarkable
Brazilian weevil, their curvature is outwards. In Pholi-
dotus lepidotus MacLeay, and Jjacanus Elephas, two in-
sects of the stag-beetle tribe, they ai'e bent downwards ;
and in Liicanus nebulosus K. [Ri/ssonotus MacLeay) they
turn upwards '^. They are usually widest at the base,
and grow gradually more slender to the apex, but in the
hornet ( Vespa Crabro) the reverse takes place, and they
increase in width from the base to the apex ; and in the
hive-bee, and others of that tribe, they are dilated both
at base and apex, being narrowest in the middle ; others
are nearly of the same width every where. In those
insects that use their mandibles principally for purposes
connected with their economy, the}^ are often more broad

^ Oliv. Ins. no. 66. Prionus. t.\m.f. 54.
'' Ibid. no. 83. Curcidio. t. iv.f. 37-
^ Linn. Trans, xii. t. xxi./. 12.

EXTERNAL ANATOMY OF INSECTS. 433

in proportion to their thickness, than they are in those
^vhich use them principally for mastication. In the lo-
cust tribes [Loctista Leach), they are extremely thick
and powerful organs, and fitted for their work of devas-
tation ; but in the glow-worm {Lampyris\ they are very
slender and minute. In those brilliant beetles, the Bu-
prestcs, they are very short ; but in the stag-beetles, and
those giants in the Capricorn tribe, the Pn'ojii, they are
often very long *. They cither meet at the summit, lap
over each other, cross each other, or are protended
straight from the head ; as j'ou have doubtless observed
in the stag-beetle, whose terrific horns are mandibles of
this description. These organs are usually sj/mmetrical,
but in some instances they are not : thus in Mister Iccinis^
a kind of dung-beetle, the left hand mandible is longer
than the right; in Creophilus maxillosns K. (Sfap/iy-
linus L.), a common rove-beetle, in the left liand man-
dible the tooth in the middle is bifid, and in the right
hand one intire; and in BolhoccriL K. the mandible of
one side, in some species the dexter, and in others the
sinister, has two teeth, and the other none.

The next circumstance with respect to these organs
which demands our attention, is the teeth with which
they are armed. These are merely processes of the sub-
stance of the mandible, and not planted in it by gompho-
sis ^, as anatomists speak, as they are in vertebrate ani-
mals. They have, however, in their interior, at the base

=' For Mandll)lcs of Lociista sec Platk Vf. Fig. G. c'. of Lampj/ru
Oliv. Ins. no 28. /. If. 1. of Buprcstix, Ibid. no. 1)2. t. iii./. 17. of
Lucaniis, Ibid. no. 1. /. i — v. and of Prionus, Ibid. no. Gfi. t. W.f. 8.

'' Gomphosis is, when one bone is imtnovealily fixed in another ns
a nail in ;i board.

VOL. III. 2 F

434 EXTERNAL ANATOMY OF INSECTS.

at least, in the Orthoptera, a coriaceous lamina that se-
parates them in some sort from the body of the mandi-
ble ^. Many insects, however, have mandibles without
teeth ; some merely tapering to a sharp point, others ob-
tuse at the end, and others truncated ''. Of those that
have teeth, some have them on the inside at the base, as
Manticora, an African tiger-beetle ^ ; others in the mid-
dle, as Staphylimis olens, a rove-beetle, Lethrus cejjha-
loteSf &C.''; others at the end, as many weevils {Curcu-
lio L.) *; others again on the back, as the Ruielidte, a tribe
of chafers *^, and Lethms, a beetle just named; others
once more on the lower side of the base, in the form
of a tooth or spine, as in Melitta spiniger-a, a species of
wild-bee, and some of its affinities s ; and lastly, others
on the upper side of the base in the form of a long tor-
tuous horn, as in that singular wasp Synagris cornuta F.
before noticed as a sexual character ''. In the stag-
beetle tribes (Lwc«?iMsL.) these teeth are often elongated
into short lateral branches, or a terminal fork '. They
are sometimes truncated, sometimes obtuse, and some-
times acute.

But with regard to their Mnd, it will be best to adopt
the ideas of M. Marcel de Serres ; for though his re-
marks are confined to the Orthoptera^ they may be ap-
plied with advantage to the teeth that arm the mandibles

" Marcel de Serres ubi supra. 7.

^ See Plate XIII. Fig. 7- Kirby Mon. Ap. Angl. i. t. xiii./. 13.
and /. xii. neut.f. 10. <^ Plate XXyi. Fig. 19.

'' Oliv. Ins. no. 42. t. If. 1. and no. 2. t. \.f. 1. b.
^ Plate XXVI. Fig. 16', 18. f Ibid. Fig. 21.

^ Mon. Aji. Angl. i. t. iv. Melitta. f. 5—8.
*" Drury Ins. ii. t. xlviii./. 3. See above, p. 315.
' Oiiv. no. 1. t. v./. 16. &c. t. m.f. 7.

EXTERNAL ANATOMY OF INSECTS. 4-35

of insects in general. He perceives an analogy between
those of this Order and the teeth of quadrupeds ; and
tlierefore divides thcni into incisive or cutting, laniary
or canine, and molari) or grinding teeth. He denomi-
nates those incisives that are broad, having in some de-
gree the shape of a wedge, their external surface being
convex, and their internal concave ; whence they are evi-
dently formed for cuttmg. The laniarics are those which
have a conical shape, are often very acute, and in gene-
ral the longest of any ; and in some insects, as the carni-
vorous Orthoptera (and the Libellulina\ they cross each
other. The molaries are the largest of all, and their
purpose is evidently to grind the food. There is never
only a single one to each mandible, while the number of
the incisives and laniaries is very variable. As the mo-
laries act the principal part in mastication, they are
nearer the inner base of the mandible or point of sup-
port : they serve to grind the food, which has been first
divided by the incisives or torn by the laniaries. The
carnivorous tribes are destitute of them ; in the omnivo-
rous ones they are very small, and in the herbivorous
ones they are very large ^. So that in some measure
you may conjecture the food of the animal from the teeth
that arm its mandibles. Of incisive teeth you may find
an example in those that arm the end of the mandibles
of most grasshoppers (Locusta), and of the leaf-cutter-
bees [Megachile Latr.)''; of the /aw/a;^/ or canine teeth,
you will find good examples in the mandibles of the
dragon- flies {Libellulina)', the two external teeth of the

' Comparaison des Organes, Sec. 7 — •

'■ Plate VI. Fig. 6. and XIII. Fig. 5. a ".

2 F 2

4/36 EXTERNAL ANATOMY OF INSECTS.

apex of those of the leaf-cutter bees may be regarded as
between the incisives and laniaries ; and the pointed man-
dibles without teeth may be deemed as terminating in a
laniary one ^. The lower part of the inner or concave
surface of the mandibles of grasshoppers will supply you
with instances of the molanj teeth, and the apex, also, of
those of some weevils, as Curadio Hancocki K.'' But
the most remarkable example of a molary organ is exhi-
bited by many of the Lamellicorn beetles, especially those
that feed upon vegetables, whether flower or leaf. —
Knoch, who indeed was the first who proposed calling
mandibles according to their teeth, incisive, laniary, or
molary, but who does not explain his system clearly,
observed that the mandibles of some MelolonthcE have a
projection with transverse, deep furrows, resembling a
file, for the purpose of bruising the leaves they feed upon •=:
and M. Cuvier, long after, observed that the larvae of
the stag-beetle have towards their base a flat, striated,
molary surface ; though he does not appear to have no-
ticed it in any perfect insect ^. This structure, with the
exception of the Scarahceidce and Cetoniadce, seems to
extend very generally through the above tribe; since it
may be traced even in Geotrupes, the common dung-

^ Plate VI. Fig. 12. and XIII. Fig. 5. b'".

b Plate XXVI. Fig. 16.

« I was not aware that Knoch had observed this part, till some
time after the publication of my paper On Mr. William MacLeay's
Doctrine of Affinity and Analogy (see Limi. Trans, xiv. 105 — ), when
I happened to meet with it in a letter from a friend, received more
than thirteen years ago ; but without any reference to the work of
Knoch, in which it was stated. It was doubtless taken from his
JBcitr'dge znr Insektengeschichte.

** Anal. Comj). iii. 3,21—.

EXTERNAL ANATOMY OF INSECTS. 4.37

chafer, iu which nt the base of one mandible is a con-
cave molary surface, and in the other a convex one, but
without any furrows : a circumstance that often distin-
guishes those that have furrows. — In the Dijnastidcc
the affinity of structure with the Melolonthidcc Sec. is
more pronounced, the furrows to which ridges in the
other mandible correspond being reduced to one or two
wide and deep ones; whereas in some of the latter tribe
they are very numerous. These mandibles, in many
cases, at their apex are furnished with incisive teeth to
cut off their food, and with miniature mill-stones to
grind it^*. The part here alluded to I call the Mola.

Were I to ask you what your idea is with regard to
the use of the organs we are considering, you would
perhaps reply without hesitation, " Of what possible use
can the Jaws of insects be but to masticate their food?'*
But in this you would in many instances be mucli mis-
taken ; as you will own directly if you only look at the
mandibles of the stag-beetle — these protended and for-
midable weapons, as well as those of several other bee-
tles, cannot be thus employed. " Of what other use,
then, can they be?" you will sa}'. In the particular in-
stance here named, their use, independent of mastica-
tion, has not been satisfactorily ascertained; but in many
other cases it has. Recollect, for instance, what I told
you in a former letter, of those larvae that use their un-
guiform mandibles as instruments of motion^. Again:
amongst the Hymenopterous tribes, whose industry and
varied economy have so often amused and interested you,

* One of these mandibles is represented in Plate XXVI. Fig.
20. a'", incisive teeth d'". molary plate. Comp. Linn. Trans, ubi
siipr. (. iii./. A.c ab. ^ Vol. II. p. 27-5 — .

438 EXTERNAL ANATOMY OF INSECTS.

many have no other tools to aid them in their various
labours and mechanical arts : to some they supply the
place of trowels, spades, and pick-axes ; to others that of
saws, scissors, and knives — with many other uses that
might be named. In fact, with the insects of this intire
Order mastication seems merely a secondary, if it is at
any time their use. Still comprehending in one view all
the mandibulate Orders, though some use their mandi-
bles especially for purposes connected with their economy,
yet their most general and primary use is the division,
laceration, and mastication of their food ; and this more
exclusively than can be affirmed of the under-jaws {rnax-
illce). This will appear evident to you, when you consi-
der that insects in their larva state, in which universally
their primary business \s feedings with very few excep-
tions use the organs in question for the purpose of masti-
cation, even in tribes, as the Lepidoptera, that have only
rudiments of them in their perfect state — while the max-
illce ordinarily are altogether unapt for such use. The
exceptions I have just alluded to are chiefly confined to
the instance of suctorious mandibles; or those which,
being furnished at the end with an orifice, the animal in-
serting them into its prey, imbibes their juices through
it. This is the case with the larvae of some Dytisci, He-
merobiuSy and Myrmeleon^i and spiders have a similar
opening in the claw of their mandibles, which is sup-
posed to instil venom into their prey ^.

Under this head I must not pass without notice an
appendage of the mandibles, to be found in some of the

'^ In the Myrmeleon, or ant-lion, the suction is promoted by the
action of a piston, that pumps up the juices. Reaum. vi. 369.
'' De Geer iv. 386 — . t, xv./. 10. See above, p. 121.

EXTERN AI- ANATOMY OF INSECTS. 43.0

rove-beellcs [Slaphijliniihc), as in Ocypiis, S/ap/ii/lmus,
and Creop/iilus Kirby. In the first of these it is a curved,
narrow, wliite, subiliaphanous, submenibranous, or rather
cartilaginous [)icce, proceeding from the ujjper side of
the base of the mandible ^ ; in the second it is broader,
straighter, and fringed internally and at the end with
hairs; and in this at first it wears the appearance of be-
ing attached laterally to the mandible under the tooth ^,
but if closely examined, you will find that it is separate :
in Creophilus maxillosus it is broader. This is the part
I have named prosthcca. It is perhaps useful in prevent-
ing the food from working out upwards during mastica-
tion.

5. Maxilla: <^. The antagonist organs to the mandible
in the lower side of the head, are the under-jaws, or max-
ilUc — so denominated by the illustrious Entomologist of
Kiel. Linne appears to have overlooked them, except
in the case of his genus Apis, in which he regards them,
and properly, as the sheath of the tongue. De Geer
looked upon them in general as part of the apparatus of
the under-lip or labium; and such in fact they are, as
will appear when we consider them more particularly.
Fabricius has founded his system for the most part upon
these organs, the principal diagnostic of ten out of his
thirteen Classes (properly Orders) being taken from them;
and in the modern, which may be termed the eclectic, sy-
stem, although the Orders are not founded upon them,
yet the characters of genera, and sometimes of large
tribes, are derived from them : and as they appear less

» Plate XIII. Fig. 1.c\

'' Oliv. Lis. no. 42. Slaphi/liniis. t. \. f. 1. b.

'• Plates VI. VII, XXVI. d.

i'M EXTERNAL Ax\ ATOMY OF INSECTS.

liable to variation than almost any other organ, as Mr.
W. S. MacLeay has judiciously observed, there seems
good reason for employing them — it is therefore of im-
portance that you should be well acquainted with them.
Their situation is usually below each mandible, on each
side of the labium; towards which they are often some-
what inclined, so that their tips meet when closed. In
some cases, as in the Predaceous beetles [Carahislu. &c.),
they exactly correspond with the mandibles; but in others
their direction with respect to the head is more longitu-
dinal, as in the Hymenoptera^ &c. In substance they
may be generally stated to be less hard than those or-
gans ; yet in some instances, as in the Libelluliiia, Ano-
plog7iathida;, &c. they vie with them, and in the Scara-
bccidcE and Cetoniadcc exceed them, in hardness. In the
bees, and many other Hymenoptera, they are soft and
leathery. Their articulation is usually by means of the
hinge on which they sit : it appears entirely ligamentous,
and they are probably attached to the labium at the
base, or mentum — at least this is evidently the case with
the Mymenoptera^ m which the opening of the maxillce
pushes forth the labium and its apparatus. In that re-
markable genus related to the glow-worms, now called
Phengodes [Lampyris plumosa F.), and in the case-worm
flies {Triclioptera K.), the maxillce appear to be connate
with the labium, or at least at their base. — As to their
compositioji, these organs consist of several pieces or por-
tions. At their base they articulate with a piece more
or less triangular, which I call the hinge (Cardo)^, This
on its inner side is often elongated towards the interior

' Platz VI. Fig. 3, G, 12. VII. Fig. 3. c".

EXTERNAL ANATOMY OF INSECTS. 4H

of the base of the labium, to which it is, as I have just
observed, probably attached. This elongate process of
the hinge in Apis, Bombus, &c. appears a separate arti-
culatit)n ; and the two together Ibrm an angle upon which
the mcntum sits *, and by this the maxilla acts upon the
labial apparatus.

The next piece is the stipes or stalk of the maxilla.
This is the part that articulates with the hinge, and may
be regarded in some cases, as in the Orthopicra &c., as
the whole of the viaxilla below the feeler; and in others,
as in the Geotrupidcc, Staj)hyli7iidce &c., as only the back
of it, the inside forming the lower lobe. This piece is
often harder and more corneous than the terminal part,
is linear, often longitudinally angular, and in the bee-
tribes [Apis L.) is remarkable on its inner side for a se-
ries of bristles parallel to each other like the teeth of a
comb ''. In Pogojiophorus Latr., a kind of dor or clock-
beetle, it is armed on the back w ith four jointed spines,
the intermediate one being forked '^. M. Latreille has
thus described the stipes of the maxilla: of Coleoptera :
*' Next comes the stalk," says he, " which consists of
three parts : one occupies the back and bears the feeler ;
the second forms the middle of the anterior face, and its
figuie is triangular; the third fills the posterior space
comprised between the two preceding ; and is that which
is of most consequence in the use of the maxilla,- the an-
terior feeler, where there are two, the galea, and the
other appendages that are of service in deglutition, are
part of that piece ^"

^ Plate VII. Fig. 3. a", e". Mon. Ap. Angl. i. t. xiii./. \.c.

•' Ilnd.f. 3. a. ^ Clairv. Ent. Ilvlcet. ii. 14G. t. xxiii./. super, i.

■^ X. Diet, d'llisi. Nat. iv. 243.

442 EXTERNAL ANATOMY OF INSECTS.

The third and terminal jiortion of the maxilla is formed
by the lobe, or lobes (Lobi). This may be called the
most important part of the organ, since it is that which
often acts upon the food, when preparing for degluti-
tion. When armed with teeth or spines at the end,
its substance is as hard as that of the mandibles ; but
when not so circumstanced, it is usually softer, re-
sembling leather, or even membrane ^ ; and sometimes
the middle part is coriaceous, and the margin membra-
nous. This part is either simple, consisting only of o?ie
lobe, as you will find to be the case with the Hymeno-
-ptera, Dynastidce, Nemognatha, and several other bee-
tles ; or it is compound, consisting of two lobes. In the
former case, the lobe is sometimes very long, as in the
bee tribes, and the singular genus of beetles mentioned
above'', Nemognatha; and at others very short, as in
Hister, &c. The bilobed majcilla: present several diffe-
rent types of form. Nearest to those with one lobe are
those whose lower lobe is attached longitudinally to the
inner side of the stalk of the organ, above which it
scarcely rises. Of this description is the maxilla in the
common dung-beetle {Geotrupes stercorarius), and rove-
beetle {StapJiylimis olens).^ Another kind of formation
is where the lower lobe is only a little shorter than the
upper : this occurs in a kind of chafer [Macraspis tetra-
dactyla MacLeay).'* A third is where the upper lobe
covers the lower as a shield ; as you will find in the Or-

^ In Anoplognathtis, however, though it has neither teeth nor
spines, it is as hard as the mandibles.
^ See above, p. 317-
<^ Plate XXVI. Fig. 10, U. d". c".
^> Ibid. Fig. 9. d". e".

EXTERNAL ANATOMY OF INSECTS. i'iS

thoptera order, and the Libcllulhia, and almost in Mtioe^.
A fourth form is where the upper lobe somewhat resem-
bles the galeate maxilla just named ; but consists of two
joints. This exists in Staphylinidcr, ^c.^ The last kind
I shall notice is when the upper lobe not only consists of
two joints, but is cylindrical, and assumes the aspect of
a feeler or palpus ^. This is the common character of
almost all the Predaceous beetles [Entomophagi Latr.).
This lobe, which has been regarded as an additional
feeler, is strictly analogous to the upper lobe in other in-
sects, and therefore should rather be denominated a pal-
piform lobe than a palpus. Where there are two lobes,
the upper one is most commonly the longest; but in
many species of the tribe last mentioned the lower one
equals or exceeds it in length '^.

The lobes vary in form, clothing, and appendages.
The upper palpiform lobe in those beetles just men-
tioned, in general varies scarcely at all mform ,• but the
genus Cychrus (which is remarkable for a retrocession
from the general type of form of the Carabi L. making an
approach towards that of those Heteromera which, from
their black body and revolting aspect, Latreille has named
Melosomes,) affords an exception, the upper joint being
rather flat, linear-lanceolate, incurved, and covering the
lower lobe % which it somewhat resembles. The lower

^ Plate VI. Fig. 6, 12. d'". e'". Oliv. Ins. no. 45. Meloe. t. i.
/. I.e. These ai'e what Fabricius CdXh galeate maxilla?, on which he
founded his class Ulonata.

h Plate XXVI. Fig. II. d'". e'".

<= Plate VI. Fig. 3. d".

•■ Clairv. Ent. Ilelvet. t. i. t. xviii./. super, b.

"" Ibid. /. xix. b. This genus may be the analogue of some hetcro-

411 EXTERNAL ANATOMY OF INSECTS.

lobe also in this tribe varies as little as the upper, being
shaped like the last joint of that lobe in Cychnis just de-
scribed, except that in Cicindela it is narrowest in the
middle *. In other tribes the upper valve is sometimes
linear and rounded at the apex, and the lower truncated,
as in Staphyli?ius olens^; sometimes the upper one is
truncated or obtuse, and the lower acute, as in Trogosita
and Pamus ^. In Pimus, another tribe of beetles, be-
fore noticed as injurious to our museums '', the reverse of
this takes place, the upper-lobe, which is the smallest
and shortest, being acute, and the lower truncated ^. In
Blaps both are acute ^. In Wiipiphorus and Scolijtus the
lobes are nearly obsolete. The lower lobe is bifid in
Languria, a North American genus of beetles, so as to
give the maxilla the appearance of three lobes S; and in
Erotyhis, a South American one, the upper is triangu-
lar **: it is often oblong, quadrangular, linear, &c. in
others. — In those that have only one lobe the shape also
varies. In Grjrinus, the beetle that whirls round and
round on the surface of every pool, which, though it be-
longs to the Predaceous tribe, has only one lobe, the lobe
represents a mandible in shape of the laniary kind, being

merous one yet undiscovered, as Calosoma is of Adelium (Kirby Linn.
Trans, xii. t. xxii./. 2.)

•^ Clairv. Ent. Helvet. ii. /. xxiv. f. super, b.

b Plate XXVI. Fig. 11.

<= Oliv. Ins. no. 19, Trogosita. t. 1./. d. no. 41 bis. Drj/ops. t.i.
/I.e. " See above, Vol. I. p. 238.

* Oliv. Lis. no. 1 7. Piinus. t. i.f. 1 . c.

f Ibid. no. 60. Blaps. t. \.f. 2. c.

t! Ibid. no. 88. Languria. t. i.f. 2. c.
. " Ibid, no, 89. Erotylu^. t. ii./. 12. c.

EXTERNAL ANATOMY OP INSECTS. id-.'J

ti'lgonal and acute * ; and in the Aiwplogjiathida:, a New
Holland tribe of chafers, in which it is, as it were,
broken, the lobe forming an angle with the stalk, it is
concavo-convex and obtuse, and somewhat figures a
molary tooth ''. In the first tribe into which the bees
{Apis L.) have been divided {Mditta Kirby), the lobe is
often linear or strap-shaped, and bifid at the apex ; and
in the second {Apis K.) lanceolate and intire *=. In Cero-
coma it is long and narrow ^. More variations in form
miglit be named, but these are sufficient to give you a
general idea of them in this respect. With regard to
their clothing, I have not much to observe — in examin-
ing the Predaceous beetles you will observe, that tlie in-
terior margin of the lower incurved lobe is fringed with
stiff bristles or slender spines, and in many other beetles
either one or both lobes have a thick coating or brush of
stiffish hairs ^; but in several cases only the apex of the
lobe is hairy. In the Orthoptera order, and many of the
Melolonthidce or chafers, the whole maxilla is without
hairs, or nearly so.

The appendages of the maxilla; are next to be noticed.
These are principally their claws, or laniary teeth ; for
they are seldom armed with incisive or molary teeth.
The whole tribe of Predaceous beetles, with few excep-
tions, have the inner lobe of their maxilla armed with a
terminal claw, which in the Cicindelidcc articulates with
the lobe, and is moveable, but in the rest of the tribe is

* OHv, Ins. no. 41. Gyrinus. t. \.f. 1. e.

" PtATE XXVI. Fig. 13. Hor. Entomolog.i. t. iii./. 29, 30. E.

<= Mon. Ap. Angl. i. t. ii. Mclitta. **. a./. 2. t. v. Ajris. *. b./. 4. 6ic.

"* Oliv. Ins. no. 48. Cerocoma. t. \.f. 1. c.

* Plate XXVI. Fio. 10—12.

446 EXTERNAL ANATOMY OF INSECTS.

fixed ^ In Phoberus MacLeay the lower lobe has two
spines ^. In Locusta this lobe has three or four spines
or laniary teeth, and in JEslma there are six, which, like
the claw of Cicindela^ are moveable *=. In others both
lobes terminate in a single spine or claw : this is the case
with Paxillus MacLeay ^. In Passalus, nearly related
to the last genus, the upper lobe is armed with a single
spine, and the lower one with two ^. Those maxilla; that
terminate in a single lobe are also often distinguished by
the spines or teeth with which it is armed ; thus in a
nondescript chafer belonging to the Dynastidce {Ar^
c/w7i K. MS.) it terminates in two short teeth ; in that re-
markable Petalocerous genus Hexodoji Oliv. in ^/ire^ trun-
cated incisive ones ^; in Dynastes Hercides in three acute
spmes s. Four similar ones arm the apex of the maxilla
in that tribe of Rutelidce which have striated elytra ; and
Jive that are stout and triquetrous those of Melolontha
Stigma F. Many others have six spines, sometimes ar-
ranged in a triple series '*. Besides teeth or spines, in
some cases the lobes of maxillce terminate in several long
and slender lacinice or lappets fringed with hairs. At
least those of a Leptura [L. quadrifasciata L.) described
by De Geer, appear to be thus circumstanced. He con-
jectures that this beetle uses its maxillce to collect the
honey from the flowers '.

* Clairv. Eni. Helvet. ii. Cicindela. t. xxiv./. super, b. for Carabi-
dee, Dytiscidce, his other plates.

^ Hor. Entomolog. i. t. ii./. 13. E. <^ Plate VI. Fig. 6, 12. f".

d Hor. Entomolog. t. If. 3. E. *= Ibid./. 4. E.

^ Oliv. Itis. no. 7- Hexodon. t. i.f. 1 . e.

s Ibid. no. 3. ScarabcBiis. t. I.f. 1 . f.

•• Kirbyin Lhm. Trails, xiv. 10!3. i. iii. /". 4. d.

' DeGeer V. 4\7.f.W.f.U.

EXTERNAL ANATOMY OF INSECTS. 447

As tlie principal use of the mandibles is cutting and
masticating, so that of the organs we arc considering
seems to be primarily that of holdhig the food and pre-
venting it from falling while the former are employed
upon it. I say this is their i)rimary use ; for I would by
no means deny that they assist occasionally in commi-
nuting or lacerating it. In fact, were there no organs
appropriated to this use, and if both mandibles and max-
ilhc were employed at the same time in comminuting the
footl, it seems to me that it must fall IVom the mouth.
In a large proportion of insects the lobes of the maxillcc
are not at all calculated for laceration or comminution ;
and in those tribes — as the Mtiolonthidce, Rutclidre, Z)j/-
nastidce — in which they seem most fitted for that pur-
pose, the mandibles have incisive teeth at their apex, and
at their base a powerful mola or grinder : circumstances
which prove, that even in this case the business of mas-
tication principally devolves upon them.

6. Palpi Maxillai-es ^. There is one circumstance that
particularly distinguishes the maxillce from the mandi-
bles— they are 2)^lpigc^'ous, as well as the under-lip. The
feelers, or palpi, emerge usually from a sinus observable
on the back of the maxilla where the upper lobe and
stalk meet. Their articulation does not materially difler
from that of the labial palpi. Each maxilla has properly
only ojie feeler ; but, as was lately observed ^,, in certain
tribes the upper lobe is jointed and palpiform, which
has occasioned it to be considered as a feeler, and these
tribes have been regarded as havinfj six feelers. The
most general rule with regard to the length of the palpi

' Pi AXES Vr.VII. h". " See above, p. 443.

448 EXTERNAL ANATOMY OF INSECTS.

is, that the maxillary shall be longer than the labial ; but
the reverse often takes place. In many hees the maxil-
lary consist only of a single joint, and are very short ;
while the labial consist oifour, and are very long^: and
in some insects (as in PogonopJioms Latr.) the four palpi
are of equal length ''. The antennae are most commonly
longer than the palpi ; but in several aquatic beetles, as
Elophorus, Hydrophilm, &c., whose antennae in the wa-
ter are not in use, the organs we are considering are the
lono-est. — As to the number of their articulations, it va-
ries from one to six ; which number they are not known
to exceed. In each of the Orders a kind of law seems
to have been observed as to the number of joints both
in the maxillary and labial palpi, but which admits of
several exceptions. Thus in the Coleoptera^ the natural
number may be set at ybza* joints for the maxillarij^ and
three for the labial palpi : yet sometimes, as in Stemis,
Notoxus^ &c., ihe former have only if /w^e joints, and the
latter, as in Stenus and Tillus, only tiioo. In the Ortho-
ptera the law enjoins /^t'e for the maxillary, and three for
the labial; and to this I have hitherto observed no ex-
ception. In the Hymenoptera, the rule is six va\dfour,
but with considerable exceptions, especially as to the
maxillary palpi, which vary from six joints to a si?igle
one : thus in the hive-bee and the humble-bee, the la-
bials, including the two flat joints or elevators, have four
joints, while the maxillaries are not jointed at all '^. In
Chrysis, in which the latter consist o^Jive, the former are
reduced to three. The Libelhdina may almost be re-

» Mon. Ap. Angl. i. t. ix. 2. c. 2. /3./. 2. d. g. 4. t. xii. Jieut.f. 6. d,
t. xiii./. 3. b. '' Clairv. Ent. Helv, ii. /. xxiii./. 1.

* Plate VII. Frc. 3. b". h".

EXTERNAL ANATOMY OF INSECTS. 44<J

garcled as having no maxillary palpi, since they exiiibit
no organ that is distinctly palpiforni. It seems to me
that the upper lobe of their maxilla, which articulates
with the stalk in the same manner as a feeler, may
be regarded as an instance in which that lobe and the
ieeler coalesce into one ; and the mucro that proceeds
from the lobe has the aspect of an emerging feeler, and
corresponds somewhat with the labiid one above no-
ticed ^. In the remainder of the Ncuropicra and the
Triclioptci-a^ the prevailing number is Jive and three.
In the latter there are exceptions, which will furnish
good characters for genera. In the Lcpidoptcra we find
twoy and sometimes thrcc^ the maxillary being very mi-
nute*'. The Diptcra Order presents two tribes in this
respect quite distinct from each other. The most natu-
ral number of joints in the maxillary palpi of the Tipu-
liJcc, Culicidcc, &c. \s four ov Jive : the last joint, how-
ever, in Tipula, Ctenocera, &c. like that of the antennoe
in Tabanus L., appears to consist of a number of very
minute joints'^; but in the Asilicltr and Muscida;^ &c., the
number tiuo seems to be most prevalent''. The labial pal-
pi in this order are obsolete. — As to shape, the maxillary
palpi, as well as the labial, are usually filiform ; but in
the weevil ti'ibes {Curculio L.) they are most commonly
very short and conical ^; in the chafers {Scarabceiis L.)
they usually ai*e thickest at the apex ^; in Megachile and
Euglossa, wikl bees, they are setaceous, growing gradu-

» Plate VI. Fig. 12. h".i"'.

*• Ibid. Fig. 1.3. h". Savigny Anhn. sans Vcrlebr. I. i. 29 — .
t. i.— iii. 6. c j)g Qggj. vj f xix./.4. d.

^ Ibid. /. ix./. 8. b b. t. xii./. 20. h. t. xiv./. 15. / i.
* Plate XXVI. Fig. fi. f Ibid. Fio. 5.

VOL. IJI. 2 G

450 EXTERNAL ANATOMY OF INSECTS.

ally more slender from the base to the summit ^ : a tribe
of small water-beetles [Haliplus), the saw-flies [Ten-
thredo L.), and several other Hymenoptera, have them
thickest in the middle ^. Their most important part,
however, and that which varies most in form, is the ^er-
7w/«aZ joint:-'— of this I have already related some singular
instances '^, and shall now describe a few more. This
joint is sometimes acute, at others blunt, at others trun-
cated : in figure it is ovate, oblong, obtriangular, hatchet-
shaped, lunate, transverse, conical, mammillate, subulate,
branched, chelate, laciniate, lamellate, &c. &c.*^: terms
which I shall more fully explam to you hereafter, and
which I only mention here to show the numerous varia-

* Kirby Mon. Ap. Angl. i. t, x. Apis. **. c. 2. o.f. 3. a. and **. d. 1.

/. 1. ^.

^ Clairv. Ent. Hdvet. ii. t. xxxi.jT. stqier. b. Mon. Ap. Angl. i. t. xiv.

/. 1. h. f. ?,, 5. c.

*= See above, p. 317.

"^ Plate XXVI. Fig. 1. As the very remarkable maxillary palpi
of that extraordinary Coleopterous genus Atractocenis seem not to
have been so fully described as they deserve, I shall give here a mi-
nute detail of their composition. They consist of yoztr joints: the
first is wide and short, and somewhat platter-shaped; the second is
much smaller and shorter : the third is concavo-convex, or shaped
like a shallow bowl : towards the breast this joint is elevated, and
on the elevated edge sits the last joint, which is longer than all the
rest taken together. In my specimen it points towards the breast ;
its under side is entire and slightly curVed, but in the upper side are
two rows of lamellae {b), placed alternately nine on eacii side, with an
odd one at the end : these lamellas are full of minute papilte, and
furrowed on the side next the mouth. From between the first pair
a slender exarticulate hairy branch or appendage emerges {a), which
forms nearly a right angle with the main stem. The labial palpi
appear to consist of three joints ; the two first very short, and the last
large, ovate, and acute. This description is not taken from A. necy-
daloides, but from a Brazilian species more than five times, its size,
which I have named A. Giga^.

EXTERNAL ANATOMY OF INSECTS. 451

tions as to figure, of which this joint exhibits examples.
Tlie palpi in general at their vertex are often rather con-
cave ; and this concavity is formed by a thin papillose
membrane, which it is supposed the animal has the
power of pushing out a little, so as to apply it to sur-
faces. The primanj use of the palpi of insects will be
considered when I treat of their senses; but they proba-
bly answer more puiposes than one. For instance, when
I was once examining, under a lens, the proceedings of
a species of Morddla^ which w^as busily employed in tlie
blossom of some umbelliferous plant, it appeared to me
to open the anthers with its maxillary palpi, and they
often held the anther between them : when not so em-
jiloyed, they were kept in intense vibration, more than
even its antennae ; and at the same time, as far as I could
judge, an Elater made the same use of them.

7. Lingua *. — This name was applied by Linne to the
part in insects representing the tongue in vertebrate ani-
mals ; and as it performs most of the common offices of
a tongue, and the pharijnx is situated with respect to it,
as we shall presently see, nearly as it is in those ani-
mals, there seems no more reason for giving it a new
name, than there is for giving a new name to the head
or legs of insects, because in some respects they differ
frftm those of the hijrher animals. I shall not therefore
call it Ligula, with Fabricius and Latreille, nor Labium^
with Cuvier and others, but adhere to the original term,
whicli every one understands.

The tongue lies between the two lip!^ — the labrum and
labium. On its upper side, at the base, it meets the pa-

- Pi.AiT VI. VII. XXVI. e'.

2 o 2

452 EXTERNAL ANATOMY OF INSECTS.

late or roof of the mouth, below which it is attached, it
may be presumed, by its roots to the crust of the head,
on each side the 'pharynx or swallow ; and on its lower
side, in many cases, it is attached to the lahium^ and that
very closely, so as to appear to be merely a part of it,
and to form its extremity: but in the Orthoptcra and
Libellulina, it is more free, and in form somewhat re-
sembling the tongue of the quadrupeds *. — In siibstatice
the tongue varies. In general it seems something be-
tween membrane and cartilage ; but in the Predaceous
beetles, in which it is not covered by the labium^ it ap-
proaches nearer to the substance of the general inte-
gument, and in Antliia F. it is quite hard and horny : —
that just mentioned of the Orthoptcra and Libellidina
is more fleshy ^. With regard to its station, in many
cases, as in the instance just named, in the Lamellicorn
tribe {ScarabcEus L.) and others, it is, when unemployed,
concealed Avithin the mouth ; the lips, mandibles, and
maxillae all closing over it. The tongue of some Hy-
menoptera also is retractile within the mouth. " When
ants are disposed to drink," says M. P. Huber, " there
comes out from between their lower jaws, which are
much shorter than the upper, a minute, conical, fleshy,
yellowish process, which performs the office of a tongue,
bemg pushed out and drawn in alternately: it appears
to proceed from the lower-lip.— This lip has the power
of moving itself forwards in conjunction with the lower
jaws : and when the insect wishes to lap, all this appa-
ratus moves forward ; so that the tongue, which is very
short, does not require to lengthen itself much to reach

•' Plate VI. Fic. 6, 12. e'. Cuvier Anat, Compar.va.. 347.
*' Cuvier Ibid.

EXTERNAL ANATOMY Ol' INSECTS. 4-53

the liquid =••" M. Lamarck thinks tiiat the labium of
insects has a vertical motion {de haul en has on de has
en haut)^. This it certainly has in some degree; Init it
has also, as in the above case, a more powerful horizon-
tal one, which is produced, in Hymenoptera at least,
by the opening of the maxillae — as I have already ob-
served '^.

I have little to say with respect to the structure of the
tongue : it generally seems to be without articulations ;
but in many bees it articulates with the labium where it
enters it, so as when unemployed to form a fold with it.
In the hive-bee it terminates in a kind of knob or button,
which has been falsely supposed to be perforated for im-
bibing the honey by suction. The upper part of this
tonffue is cartilaginous, and remarkable for a number
of transverse rincfs : below the middle, it consists of a
membrane, longitudinally folded in inaction, but capa-
ble of beinsT inflated to a considerable size : this mem-
branous bag receives the honey which the tongue, as it
were, laps from the flowers, and conveys it to the pha-
rynx •*. In Stenus this organ is retractile, and consists
of two joints ^

The shape of the tongue of insects probably varies as
much as any other part ; but as it is apt to shrink when
dried *^, and is not easy to come at, we know but little of
its various configurations : — in the bees it is very long,
in most other insects very short. Though frequently
simple and undivided, in many cases it presents a diffe-
rent conformation. Thus in the saw-flies {Tenthredo L.)

* Huber Fourmis, 4—. '' Anim. sans Vcrtebr. ui. 304.

•■ See above, p. 440. '' Reaum. v. 309—.

« Plate XXVI. Fig. 23. ' Clairv. Ent. Hclvel. ii. Prcf. xxii.

454- EXTERNAL ANATOMY OF INSECTS.

it terminates in three equal lobes ^ ; in Stomis and Geo-
trupes in three unequal ones, the intermediate being very
short ^ ; in Carabus, in three short teeth <= ; in PogonojjJio-
nis it represents a trident '^ ; in the wasp it is bifid, each
lobe being tipped with a callosity^; in Melolontha Stigma
it is bipartite ^; in Elaphrus, the analogue of the tiger-
beetles, it terminates in a single tooth or point; in the
aquatic beetles, Dytisais L., it is quath'angular and with-
out teeth ^; in some Ichneumonidce it is concavo-convex,
and forms a demitube; and in others it is nearly cylin-
drical ^.

In many insects it has no hairs^ but in the Predaceous
beetles it generally terminates in a couple of bristles '.
In the hive- humble- and other bees, it is extremely
hairy ''; a circumstance which probably enables it more
effectually to despoil the flowers of their nectar. In Geo-
trupes siercorarhis, the common dmigchafer, and Melo-
lontha Stigma lately mentioned, the lobes of the tongue
are fringed with incurved hairs '; and in jEshna it is
hairy on the upper side, each hair or bristle crowning a
minute tubercle. In many cases the tongue is attended,
and sometimes sheathed at the base, by two usually mem-
branous appendages: — these the learned Illiger has deno-

a Kirby Mon. Ap. Angl. i. t. xiv. (1) 3. i.

'' Plate XXVI. Fig. 24. e'. " Clairv. uhi siipr. t. xx. c.

•' Plate XXVI. Fig. 28. e.

• Kirby nbi siqjr. fig. (8) \. c c. The lateral pieces in the tongue
in Vesjm {Ibid, c c.) have been regarded as lobes of it, but they are
rather Paraglossce.

f Plate XXVI. Fig. 29. e'. ^ Clairv. iih'i supr. t. xxx. c.

" Kirby 7ibi supr. no. 2,/. 1, 3- ' Plate XXVI. Fig. 24. b.

^ Krby ubi supr. t. x. Apis. c. 2. o.f. 5. /. xii. neid.f. 2, 3. t, xiii,
f. \.h. ' Plate XXVI. Fig. 26, 29.

EXTERNAL ANATOMY OF INSECTS. iSS

m'mated paraglossiC ; and I shall adopt his term. You
will find them-fre(juently attached to the tongue of the
Prcdaceous beetles ^, and to that of many Hi/mctiojrhra.
In the hive-bee and humble-bee they are short, and take
their origin within the labial feelers '' : in Euglossa, an-
other bee, they are long, involute at the tips, and, Avhat
is not usual with them, very hairy ^ : in the wasp, like
the lobes of the tongue, they are tipped with a callosity.
Under this head I may observe to you, that the in-
sects whose oral organs we are considering besides a
/o;?^7^c appear likewise to be furnished with a j^alaic {Pa-
latum). This, though a part of the roof of the moutli,
is not precisely in the situation of the palate of vertebrate
animals, since it seems rather the internal lining of the
labrum. If you take the common dragon-fly [uEshna
viatica), you Avill find that the under side of this part
and of the rliinarium is lined with a quadrangular fleshy
cushion, beset, like the upper surface of the tongue, with
minute black tubercles, cro\Mied with a bristle. This
cushion is divided transversely into two parts by a de-
pression ; the anterior or outer piece being attached to
the labrum, and the other piece to the rliinarium. The
former has a central longitudinal cavity, black at the
bottom, on the sides of which the tubercles are flat and
without a bristle. From its base on each side a spini-
form process emerges, forming a right angle with it.
These processes seem the antagonists of those mentioned
above ^, that emerge from the labium. The posterior or

» Plate XXVI. Fig. 28. i".

•• Kirby Mon. Aj). Angl. i. f. xii. ncut.f. 1. /* h. t. xiii./. 1.//.

f Jbkl. Lk.**. d, l./.2.bb.

^ See above, p. 435.

456 EXTERNAL ANATOMY OF INSECTS.

inner piece has on each side a roundish space, attached
to the under surface of the two sides of the rhinarium,
beset also with bristle-bearing tubercles. You will find
something similar lining the lahrum and nasns of some
Colcoptera, — say Geotrupes, Nccrophorus, and Dytiscus.
The first piece I regard as the analogue of the palate, and
the second as connected with the sense of smelling. In
Necrophorus the circular pieces are covered with a finely
striated membrane, and in Dytisciis each has a little
nipple.

8. Pharynx ^. — On the upper side of the tongue, usu-
ally at its base or root, is the pliarynx\ or aperture by
which the food passes from the mouth to the oesophagus.
This orifice, which is situated with respect to the tongue
of the Orthoptera and Lihellulina nearly as in those in-
sects (at least as far as I have been able to examine them),
whose tongue is called a ligula or labium, — of course ex-
ists in all the mandibulate Orders whose mouth we are
now considering. In the Hijmenoptera it is covered by a
valve, \he Epiphari/nx oi Ssi\\gny ', and it appeared to me
to be so likewise in one of the HarpalidcB that I examined.
The formation seems different in Geotntpcs, as far as I
can get an idea of it; but it is so difficult to examine the
interior of the mouth without laceration of some of the
parts, that I can only tell you what the appearances were
in one instance, upon removing the lahrum from the man-
dibles; and in another, separating the whole apparatus
of the labium, including the maxillce, from the mandibles
and labrum. In the former case, the mandibles coincided

^ Plate VII. Fig. H. f .

EXTERNAL ANATOMY OF INSECTS. 457

at the base, the two molnry plates (mohr), which in this
genus are narrow, transverse and not furrowed, are so
applied as evidently to have an action upon each other,
as the mandible opens and shuts, proper for trituration.
Within these is the base of the tongue, under tlie form
of a ventricose sack. The upper part of this last organ,
which forms the internal covering of the labium, appears
to consist of three (in the recent insect Jhs/ij/) lobes, the
middle one being bent downwards internally, so as to
form a kind of sloping cover to an orifice in the part
I call the base. After two or three days, the tongue
shrinks and dries to a hard substance; — between the man-
dibles and the base of the tongue I could not discover
thejjharynx. The above apparent opening covered by the
tongue was the only one I could perceive. In the latter
case, the form and structure of the base of the tongue is
more visible: it is an oblong ventricose tubular sack,
projecting above anteriorly into an acute angle formed
by a fine white membrane, most beautifully and deli-
cately striated with oblique striae, to be seen only under
a powerful lens : on the anterior side of this sack are two
parallel cartilaginous ridges close to each other, fringed
with short hairs, which take their origin from the angle.
I could not be certain whether the orifice covered by
the intermediate lobe was only apparent, or real ; but I
did not succeed in my endeavour to find any other pha-
lyiuv, though from the molary structure of the base of
the mandibles one may conjecture that there must be one
situated at the base of this sack to receive the food they
render after trituration. The excrement of this animal
is not fluid. In the Libdlulina the jiharijnx seems
closed by two valves meeting. This part in Hijmcno^

458 EXTERNAL ANATOMY OF INSECTS.

j)tera, and probably in other Orders, has the aspect of
being cartilaginous and fitted to sustain the action of the
substances that have to pass through it ^.

The Epipharynx is a valve, called by M. Latreille
suhlahrum {sous labre^), attached by its base to the upper
margin of the pharynx^ or that next the lahrum. In
the bees it is said by Reaumur to be of a fleshy substance,
and capable of changing its figure. He seems to think
it the real tongue of the bee '^ ; but as it does not appear
to have any of the uses of a tongue, and merely closes
the orifice of the mouth, it surely does not merit that
name. M. Savigny calls it a membranous appendage
which exactly closes the phaty fix ^. De Geer has exa-
mined the epip)harynx of the wasp, which he describes as
of a scaly substance, and regards merely as the cover of
the part just named ^.

With regard to the Hypophaiynx, which Latreille con-
siders as a support and appendage of the epipharynx, I
have little to add to the definition I have given of it above.
In the Libcllulina the base of the tongue terminates
towards the pharynx in a fleshy cushion, armed at each
angle next to that part with a short hard horn or tooth
of a black colour. This cushion, I suppose, may be ana-
logous to the Jiypopharynx of M. Savigny ^. On the oppo-
site side the pharynx is closed by another fleshy cushion
[epipharynx ?), which appears to line the nose, behind
those two mammillag before described^, which form the
internal covermg of the rJmiarium.

^ Reaum. v. 317- ^ Organisatmi cxterieur des Ins. 184.

^ Ubisnpra. ^ Anim. sans VcrtcbrA. i. 12.

^ De Geer ii. 778 — . t. xxvi,/. 11. m. Plate VII. Fig. 2. k".

' Ubi siq^ra. « See above, p. 455.

EXTERNAL ANATOMY OF INSECTS. 159

Before I call your attention to what I woukl denomi-
nate an imperfect mouth, in which some one or more of
the seven organs above enumerated exist under another
form, or only as rudiments, — I nmst say something upon
the mouth of the Mijn'ajjods and Arachnidaf in which
there seem to be redundant organs of manducation. —
M. Latreille, in the Essay lately quoted, in which,
though some of his notions seem fanciful, he has shown
a vast depth and range of thought and research, has as-
serted,— from the admirable and curious observations of
M. Savigny, and those which since their publication he
has made himself, — that the masticating organs of a7i-
nulose annuals (called by him condylopes) are a kind of
legs '. And M. Savigny, whose indefatigable labours
and unparalleled acuteness have opened the door to a
new and vast field in what may be denominated analo-
gical anatomy, — has observed, that with certain Apirc-
pods ^ the organs that serve for manducation do not dif-
fer essentially from those which, with the other Apiro-
pods and the Hcxapods, serve for locomotion '^ : and the
unguiform mandibles of the larva3 of certain Diptera,
you have before been told, are used not only in mandu-
cation, but also as legs ^. These remarks will satisfac-
torily prove to you, that organs which at first sight pos-
sess no visible affinity or analogy — as for instance, jaws
and legs — may, if traced through a long series of beings,
exhibit a very great one ; — and will lessen your surprise

* Organisation &c. 182.

'' Under this name M. Savigny includes the Myriapoda, Arach-
nidoy and Crustacea. Anim. sans Vcrtcbr. I. i. 40.
<= Ihld. 4.3.
'^ Vol. II. p. 275 — . Also sec above, p. 131 — .

i60 EXTERNAL ANATOxMY OF INSECTS.

when you find, that in certain tribes such commutations
of organs and their use take place.

The following is the structure, as to its organs, of the
mouth of the myriapods, as exhibited by the centipedes
(Scolopendrid^). The part which appears to perform the
office of the upper lip (but which M. Savigny regards
as the nose, calling it the chaperon,) is a transverse piece
with a deep anterior sinus, in the centre of which is a
minute tooth *. This piece is separated from the fore-
part of the head by a suture; but it probably is not move-
able: however, it covers the mouth, and may be regarded
rather as analogous to the labrum. Below this are two
mandibles, armed at their end with five sharp triangular
teeth ^, under which are the maxillce, terminating in a
moveable concavo-convex lobe, resembling the valve of
a bivalve shell "^ ; and between them is the labium^ of a
rhomboidal shape, divisible into two lobes, attached la-
terally to the maxillae : these lobes M. Savigny terms the
second maxillcc, forming with the others, according to
him, the labium ^. Affixed to the base of this labium, or
covering it on the outside, are a pair of pediform palpi,
which he considers as the first auxiliary labium, and re-
presentative of the first pair of legs of hexapods and luli^.
I imagine them to be also the analogues, in some degree,
of the labial palpi of a perfect mouth. The last of the
organs in question is a large rhomboidal plate affixed to
the first apparent segment of the trunk, crowned at its
vertex with two truncated denticulated teeth, and from

=• Arum, sans Vertebr. I. i. t. n.f. 2. a. a',

b Plate VII. Fjg. 13. c'. <= Ibid. d'.

'' Anim. sans Vertebr. I. i. 100. Plate VII. Fig. 13. b'.

* Ubi supr. 45 — .

EXTERNAL ANATOMY OF INSECTS. 401

tlie iippei' sides of vvhicli emerge a pair of moveable or-
gans terminating in a powerful incurved claw, and which
entirely covers all the other parts of the mouth *. This,
M. Savigny deems as a 5t'co«r/ auxiliary labium^ and the la-
teral organs of prehension, — which may be regarded each
as a kind of maxillary hand, and as the only representa-
tives jn this tribe of the maxillary palpi, though widely
different, — he looks upon as really analogous to the second
pair of legs in lulus and the hexapods''. These two pairs
of pedipalpcs (to use an expressive French term) show
their relation to legs by their general structure, and their
analogy with palpi by their use as oral organs, though
belonjiino; to the tnink : so that here we see the Inis and
their appendages assume a material function in mandu-
catio?i, forming a singular contrast to what we had ob-
served before with regard to mmidiblcs becoming instru-
ments o{ locomotion. The mouth of the lulidce, with lit-
tle variation, is upon the same plan*^ with those here de-
scribed.

The next type of form with regard to the oral organs
is that of the Arachnida. In these, as you know, the
head is confounded with the trunk ; so that they are a
kind of Blemmyes in the insect world. Their organs of
manducation, amongst which there is no labrum or upper
lip, are, in the first place, a pair of mandibles planted
close and parallel to each other in the anterior part of
the head, which they terminate. In the s})iders they con-
sist of two tubular joints, of which the first is much the
largest, more or less conical or cylindrical, and armed

» Plate VII. Fro, 11./', a". ^ Ubi supra, 45.

' Ibid. 44—.

462 EXTERNAL ANATOMY OF INSECTS.

underneath with a double row of stout teeth ; and the
terminaJ one is more solid and harder, in the form of a
very sharp crooked claw, which in inaction is folded on
the first joint between the teeth. Under its extremity on
the outside is a minute orifice, destined to transmit a ve-
nomous fluid, which is conducted there by an internal
canal from the base of the first joint, where is the poison-
bag *. In the scorpion and harvest-man {Phalangiwn)
the mandible consists of two joints terminated by a chela
or double claw, the exterior one being moveable''. —
M. Latreille, as has been before observed, regards these
not as representatives of the mandibles of hexapods, but
as replacing the interior pair of antennae, in the situation
of which they are precisely placed, of the Crustacea ^ :
and M. Savigny is of opinion that the Arachnida may in
some sort be defined as Crustacea without a head, and
with twelve legs, of which the two first pair are converted
into mandibles and maxillcB'^. From the situation of the
organs in question, the first of these opinions seems pre-
ferable ; but the conversion of the legs in other cases, at
least the coocce, into organs of manducation, gives some
weight to the last. With regard to their use, it is said
to be to retain the insect which the animal has seized,
and to facilitate the compression which the maxillae exer-
cise upon it for the extraction of the nutritive matter ^.
If this be correct, in this respect the mandibles may be
said to represent the maxilla: of the mandibulate hexa-
pods ; and, vice versa, the sciatic maxillae, as they have

* N. Did. d'Hist. Nat. ii. 275—. Plate VII. Fig. 10. c'.

" De Geer t. xl./. 4. t. x.f. 7, 8. ' Sec above, p. 18, 30

'' Savigny Anim. smis Vertebr. I. i. G.2.

'■ X. Diet. d'Hkt. Nat. ii. 277.

EXTERNAL ANATOMY OF INSECTS. 4G3

been denominated ', of the Arachnida, tlielr mandibles.
The palpi are })edifoi'm, and the first joint of the coxa,
or hip, acts the part of a maxilla : — this is composed of
a single piece or plate, more or less oval or triangular,
sometimes straight and sometimes inclined to the labium,
with the interior extremity very hairy. The labium con-
sists also of a single piece, and is only an appendage of
the anterior extremity of the breast. The interior of
the mouth, or palate, presents a fleshy, hairy, linguiform
piece, which is usually applied to the internal face of the
labium. An opening is supposed to exist in its sides, for
the transmission of the alimentary juices''. If you ex-
amine the under side of the body of a scorpion, you will
find that not only the palpi, but the two anterior pair of
legs, by means of their coxa, are concerned in mandu-
cation : so that these insects have in fact three pairs of
maxillce — a circumstance that M. Savigny has observed
to take place also in the harvest-men {Phalangium L.) <=.
The palpi of the scorpion, which may be called its hands,
like the anterior legs of the lobster and crab, terminate
in a tremendous chela or forceps, consisting of a large
triangular joint, armed at the end with a double claw
internally toothed ; the exterior one of which, contrary
to what takes place in the animals just named, is move-
able, and not the ititerior '*.

Having given you this full account of the tropJii of
those animals that liave all the organs of manducation
developed, I must next advert to those in which one part

=» K. Diet. d'Hisf. Nat. ii. 27G. " Ibid.

• Ubi supr. 58. '' Pi.Axr XV. Fu.. /•

464- EXTERNAL ANATOMY OF INSECTS.

receives an increment at the expense of others, and the
whole oral machine is fitted for stiction ; or where some
parts appear to be deficient, so that this may be called
an imperfect mouth. At first sight one would regard the
trophi of a hee as of this description ; but this is not the
case, since it has all the ordinary organs, though the
tongue is unusually long, and looks as if it was made for
suction ; which, however, as you have been informed, is
not the case.

There qxg. Jive kinds of imperfect mouth to be met
with in insects that take their food by suction, each of
which I shall distinguish by a separate denomination.
The first is that of the Hemiptera Order : — this I term
the Promuscis ; the second is that of the Diptera, which
with Linne I call Probosci»; the third, peculiar to the
Lcpidoptera^ is with me an Antlia; the fourth, which I
name Rostruluyn, is confined to the Aphaniptera order,
or genus Pulex L. ; and the last is Rostellum, which I
employ to denote the suctory organs of the louse tribe
(Pediculid^).

1. Promuscis^. — The organ we are first to consider
has usually been denominated Rostrum : but since that
term is likewise in general use for the snout of insects of
the weevil tribes {Curcidio L.), I think you will concur
with me in adopting the one here proposed, for the very
different oral instruments of the Hemiptera. Illiger has
employed ^rom?«cz5 to denote those o^bees^: but since, as
I have just observed, they consist of all the ordinary or-
gans, they seem to require no separate denomination :

'^ Plate VI. Fig. 7-9. a', b', c', d'. " Maga%. 1806.

EXTERNAL ANATOMY OF INSECTS. 4G5

tTie term, therefore, may be applied to represent a diffe-
rent set of trophi, without any risk of producing confu-
sion. This part consists o^ five pieces : viz. a minute,
long, conical piece, conunonly very slender, which covers
the base of the promuscis, and represents the labrum * ; a
jointed sheath {vagina\ consisting of either three or four
joints, the analogue of the labium, and four slender rigid
lancets [scalpcUa)^ the two exterior ones, according to
M. Savigny, representing the mandibles, and the inter-
mediate pair the maxillcc ^. By the union of these four
pieces a suctorious tube is formed, which the animal in-
serts into the substance, whether animal or vegetable,
the juices of which form its nutriment. These pieces are
dilated at their base, and serrated at their apex ; and the
two central ones, though at their origin they are asun-
der, form one tube, which has often been mistaken for a
single piece. A phai-ynx and tongue have been disco-
vered by M. Savigny in this apparatus ; who thinks that
in Nepa there are also rudiments, but very indistinct, of
labial palpi : so that the maxillai'y palpi seem to be the
only part absolutely wanting *=.

The Promuscis when at rest is usually laid between
the legs; but when employed, in most cases its direction
is outward. In the genus Chermes L. [Psylla Latv.) the
origin of the promuscis has been supposed to be in the
breast; but if closely examined, this anomaly in nature
will be found not to exist. If you take one of these in-
sects, the first thing that strikes you upon inspecting the
head, is a pair of remarkable conical processes into which

' Plate VI. Fig. 7- a'.

'• Ibid. Labium b'. Mandibular c'. Maxillae d'.

'■ Savigny Aiiim. sans Vertcbr. I. i. ^"J.

VOL. III. 2 H

M)6 EXTERNAL ANATOMY OF INSECTS.

the front appears to be divided. Look below these, and
you will there discover the upper-lip : and from this you
may follow the promuscis till it gets beyond the forelegs,
when it takes a direction perpendicular to the body ^ ; a
circumstance which has given rise to the above false no-
tion. Though in Coccus^ Chei'mes^ &c. this instrument is
short, in some Aphides it is longer in proportion than in
any other insect. In A. Qiiercus it is three times the
length of the body ; so that when folded, it stretches out
beyond it, and looks like a long taiP; and in A. Abietis
it even exceeds that length "=.

ii. Proboscis ^. — Linne long since, and after him Fa-
bricius, has employed this term to designate the oral in-
struments, or rather their sheath, in the Mtiscidce and
some others, calling the same organ, when without fleshy,
lips, rostrum and haustellum: but as the parts of the
mouth in all true Diptera (for Hippohosca and its affinities
can scarcely be deemed as co-ordinate with the rest), are
analogous to each other ; although in some they are stiff
and rigid, in others flexile and soft, and in CEstrus (ex-
cept the palpi) mere rudiments, — the same appellation
ought to designate them all. I am happy to find that
M. Latreille agrees \y'\\h me in this opinion ; and to his
sensible observations on this head, if you wish for further
information, I refer you ^. The mouth of Dipterous in-
sects appears to vary in the number of pieces that it pre-

"^ De Geer iii. 137—. t. ix./. 4.
^ Reaum. iii. 335. t. xxviii./. 8—14.
•^ De Geer iii. 117. ^. viii./. 22. b.
^ Plate VII. Fig. 5, 6. a', b', c', d'.
« N. Diet. (THist. Nat. iv. 253.

EXTERNAL ANATOMY Ol JNSKCTs. IGT

sents; but in alJ, the theca or sheath is present, Avliich re-
presents tlie labium (including the mentum) of the nuin-
dibulate Orders *. It consists of three joints, the hist of
which is formed by the hplets [Lahclla). Those in the
Muscidcc are hirge, turgid, vesiculose, and capable of
dilatation ; in the Bomhylidcc and other tribes they are
small, slender, long and leathery, and sometimes re-
curved. The second joint or stalk, which may be said
to represent the mentnm, the liplets being properly in a
restricted sense the analogue of the labium , its sides being
turned up, forms a longitudinal cavity, which contains
the haustellinn. The upper piece of this, the valvula^ is
long, rigid, and very sharp, representing the labrum ^.
Beneath this cover, in the above cavity, are the lancets ;
which, as far as they are at present knowTi, vary in num-
ber and form: sometinies there arcjivc of them, some-
timesyowr, sometimes t'isoo, and sometimes, it should seem,
only 0716^. In the gnat (Culex) they are finer than a
hair, very sharp, and barbed occasionally on one side ^ ;
in the horse-fly ( Tabaims L.) they are flat and sharp like
the blade of a knife or lancet ^. In this tribe the upper
pair, or the knives [Cultelli\ represent the majidiblcs ;
the lower pair, or the lancets (Scaljjella), usually palpi-
gerous, the maxill(E ; and the central one the tongue. In
the horse-fly Reaumur has figured o\Ay four^ exclusive
of the labrum and labium ,- but in a specimen I have pre-

=> Plate VII. Fig. 5, 6. a'. ^ Ibid.

*• Reaum. iv. /. XVI. Fig. 13. z.

•^ Authors are not agreed as to the precise number of lancets con-
tained in a gnat's proboscis. Swammerdam affirms there are six, in-
cluding the labrum. i. 156. b. t. xxxii./. 3. Reaumur could find only
five. iv. 597 — . t- xlii./. 10. And Leeuwenhocck only/o;/r.

' Plate VII. Fig. 5.

2 H 2

IGR F.XTEnNAL AXATOMY OF INSF.CTS.

served there appear to hejire, one of which, as slender
as a hair, I regard as the analogue of the tongue ^.—
When the lancets are reduced to two, they probably re-
present the maxillce, the mandibles being absorbed in
the labrum ; and where there is only one, the maxillae
also are absorbed by the labium, which then bears the
palpi, the lancet representing the tongue ''. The lancets
are so constructed in many cases, as to be able by tlieir
union to form a tube proper for suction, or rather for
forcing the fluid by the pressure of the lower parts to the
'pharynx ■=. Labial palpi appear not usually present in
Xh^ proboscis ; but M. Savigny thinks he has discovered
vestiges of them in Tabanus ^. In this genus the maxil-
lary ones are large, and consist of ^wo joints ^. The pro-
boscis is often so folded, as to form two elbows; the base
forming an angle with the stalk, and the latter with the
lips, so as in shape to represent the letter Z, only that the
upper angle points to the breast, and the lower one to
the mouth : this is the case with the flesh-fly and many
others. In other flies, as Conops and Stomoxys, whose
punctures on our legs so torment us ^, there is only a
single fold, with its angle to the breast. The proboscis is
received in a large oblong cavity of the underside of the
anterior part of the head.

^ Plate VIT. Fig. 5. This figure is copied from Reaumur, and
was engraved before this discovery was made.

"> M, Savigny is of opinion that the central lancet or lancets re-
present the Epipharynx and Hypopharynx ; for which he does not
state his reasons : but as these are properly covers of the pharynx,
the idea seems incorrect. Uhi siipr. 15.

<= N. Diet. d'Hist. Nat. ix. 489. and iv. 253—.

" Ubi supr. 36. • Ibid. t. iv./. 1. o. o.

f Vol.. I. p. 48, 110—.

EXTEKNAL ANATOMY OF INSECTS. 469

It may here be observed, Unit In tlie jyromiiscis the
elongation ot" the organs seems to be made cliicfly at tlie
expense of all the ))alpi, but in ihe proboscis at that of
the labial only ; and in some cases at that also of the
mandibles or maxilla;, — the former merging in the lu-
bnun and the latter in the labium,

iii. Antlia ^. — The third kind of imperfect mouth is that
of the Lcpidoptcra, which I have called Antlia. Fabri-
cius denominates it lingua; but as this organ lias no ana-
logy Avith the real tongue of insects, this is confessedly
improper, and it appeared necessary therefore to exchange
it for another denomination : I have endeavoured to ap-
ply a term to it that indicates its use — to pump up, name-
ly, the nectar of the flowers into the mouth of the insect.
On a former occasion I described to you the structure of
this instrument''; but further discoveries with regard to
it having since been made by MM. Savigny and La-
treille, I shall here give you the result of their observa-
tions. The former of these able physiologists has de-
tected in the mouth of the Lepidoptera rudiments of al-
most all the parts of a perfect mouth. Of the correct-
ness of this assertion you may satisfy yourself, if you con-
sult his admirable elucidatory plates, and compare them
with the insects. Just above the origin of the spiral
tongue or pump, the head is a little prominent and
rounded ; and immediately below the middle of this pro-
minence there is a very minute, membranous, triangular
or semicircular piece ; which from its position, as cover-
ing the base of the antlia, ma}' lie regarded as the rudi-

» Plaxi; VI. Fig. 13. a', b', c, d'. " Vol. I. p. 31)4—.

470 EXTERNAL ANATOMY OF INSECTS.

meiit of the upper-lip (labrum) ^ On each side of the
outer base of the a7itlia is another small immoveable
piece, resembhng a flattened tubercle, the end of which
is internally hairy or scaly: these pieces appear to repre-
sent the mandibles ^. Near the base of each half of the
atitlia, just below a sinus, may be distinctly seen the mi-
nute, usually biarticulate rudiment of a maxillary pal-
pus *= ; demonstrating to a certainty that these spiral or-
gans, at least their lateral tubes or Soletiaria, are real
maxillae''. The rudiment o{ the 7inder-lip (Labium) is
the almost horny triangular piece united by membrane
to the two stalks of the maxillae, and supporting at its
base the recurved labial palpi ; which are so well known
that I need not enlarge upon them ^. Amongst these
parts there seems at first sight no representative of the
tongue; but M. Latreille has advanced some very inge-
nious, and I think satisfactory arguments ^, which go to
prove that this part, at least the tongue of Hymenoptera,
has its analogue in the intermediate tube or Fistula
formed by the union of the two maxillae, and which con-
veys the fluid aliment of this Order to the pharynx. As
in Diptera the maxillce sometimes merge in the labium^
so here the tongue (as it were divided longitudinally)
merges in the maxilla:. He further observes, that in a
transverse section of the maxilla of the death's-head
hawk-moth {Sphinx Atropos), the lateral tube appeared

' Plate VI. Fig. 13. a'. Savigny Anim. sans Vcrtcbr. I. i. 3 — .
t. i. — iii. a, '' Ibid. i. Plate VI. Fig. 13. c'.

■■ Ibid. Fig. 13. h". Savigny ubi siipi: o.
^ Plate VI. Fig. 13. d'. Savigny ubi siipr.i. 1 — 3. o.
<= Ibid. o. Plate VI. Fig. 13. b'.
f N. Did. d'llisl. Xat. xvii. 467.

EXTERNAL ANATOMY OF INSKCTS. 171

to be divided into two by a membranous partition, and
to contain in the upper cavity a small cylindrical tube,
vliich seemed to be a trachea '. To animals that are
without lungs, and breathe by trachece^ suction must be
performed in a very dilFerent way from what it is by
those that breathe by the mouth : and as in the very ex-
tended organs in question the fluid has a long space to
pass before it reaches the i^harynx, in some way or other
these lateral tubes may have the power of producing a
vacuum in the middle tube, and so facilitate its passage
thither. We see, in the antlia, that the maxillae receive
their vast elongation at the expense of all the other or-
gans, except the labial palpi.

iv. Most rul urn ^, — An animal very annoying to us af-
fords the type of the next kind of imperfect mouth — I
mean the ^ea. Its oral apparatus, which I would name
rustrulian, appears to consist of seven pieces. First are a
pair of triangular organs, the lainifue, which together
somewhat resemble the beak of a bird, and are aflixed,
one on each side of the niouth, under the antennae : these
represent the mandibles of a perfect mouth '^. Next, a
pair of long sharp lancets (Scaljjella), which emerge from
the head below the laminae: these are analogous to ynax-
illcE'^: a pair of palpi, consisting of four joints, are at-
tached to these near their base % which of course are
viaxillary palpi. And lastly, in the midst of all is a
slender setiform organ [lignla), which is the counterpart
of the tongue *. Riisel, and after him Latreille, seem to

•' N. Diet. (rHixl. Nat. iv. 253.

*• Pi.ATt Vir. Fig. 8. c', d', c', li". ' Il)icl. c'.

•' Ibid. d'. ' Ibid, h' . ' Ibid. e'.

4<72 EXTERNAL ANATOMY OF INSECTS.

have overlooked this last piece, since they reckon only
six pieces in the flea's mouth * : but the hand and eye of
our friend Curtis have detected a seventh, as you see in
his figure. From this account it appears, that the elon-
gation of the organs of the Aphaniptera Order is at the
expense of the labium and its palpi.

V. Rostellum. — So little is known of the composition
of the next kind of imperfect mouth, that I need not en-
large upon it. It is peculiar to the louse tribe {Pedicu-
lidce), and it consists of the tubulet ( Tubuhis), and si-
phuncle (Siphimadus). The former is slenderer in the
middle than at the base and apex, the latter being tur-
gid, rather spherical, and armed with claws which pro-
bably lay hold of the skin while the animal is engaged in
suction. When not used, the whole machine is with-
drawn within the head ; the siphuncle, which is the suc-
torious part, being first retracted within the tubulet, in
the same way as a snail retracts its tentacula ^. This ap-
paratus seems formed at the expense of all the other
organs.

There are some other kinds of imperfect mouth,
which, though they seem not to merit each a distinct
(denomination, should not be passed altogether without
notice. The first I shall mention is that of the family of
Pupipara Latr. [Hippobosca L.). It consists of a pair
of hairy coriaceous valves, which include a very slender
rigid tube or siphuncle, the instrument of suction, which
Latreille describes as formed by the union of two seti-

"^ Rosel. ii. t. iii./. 15. Latreille Gen. Crust, et Ins. iv. 365.
^ )Swaniraerdam Bibl. Xat. t. ii./. 4.

EXTERNAL ANATOMY Ol' INSECTS. 178

loiin pieces* . In Mdophagiis^ the sheep-louse, the union
of the valves of the sheath is so short, that they appear
like a tube ; but if cut off they will separate, and show
the siphuncle, as fuie as a hair, between them. This or-
gan is of a type so dissimilar, as was before observed, to
that of the Diptera in general, and approaclies so near to
that of the dog-tick (Ixodes), that they may be deemed ra-
ther apterous insects with two wings, than to belong to that
Order ; and the circumstance that some of the family are
apterous confn-ms this idea. In fact they are a trajisitw7i
family that connects the two Orders, but ai*e nearest to
tlie Apfera. In Ni/deribia the oral organs differ from
those of the other Piipipara in having palpi. This also
is the case with those of the genus Ixodes, the palpi of
which are placed upon the same base with the instru-
ment of suction, than which they are longer : they ap-
pear to consist of t-iSoo joints, the last very long and flat.
The instrument of suction itself is formed by three hard
rigid laminae ; two shorter parallel ones above, that co-
ver the third, which is longer and broader, and armed
on each side with several teeth like a saw, having their
points towards the base ^. Many of the other Acari L.
have mandibles, and several have not : but their oral or-
gans have not yet been sufficiently examined ; and from
the extreme minuteness of most of them, this is no easy
task; nor to ascertain in what points they differ or
agree.

If you consider the general plan of the organs of man-
ducation in the vertebrate animals, how few are the va-

* X. Diet. (I'Hist. Xal. xxviii. 2fiG.

•• Idid. xvi. 432. De Gecr vii. L \ij'. 4, Not quite accurate.

471j external ana'io.aiy oe insects.

nations that it admits ! An upper and a lower jaw
planted with teeth, or a beak consisting of an upper or
a lower mandible with a central tongue, form its princi-
pal features. But in the little world of insects, how won-
derful and infinite is the diversity which, as j^ou see, in
this respect they exhibit ! Consider the number of the
oro-ans, the varyino- forms of each in the different tribes,
adjusted for nice variations in their uses : — how gradual,
too, the transition from one to another ! how one set
of instruments is adapted to prepare the food for deglu-
tition by mastication ; another merely to lacerate it, so
that its juices can be expressed ; a third to lap a fluid
aliment; a fourth to imbibe it by suction — and you will
see and acknowledge in all the hand of an almighty and
all-bountiful Creator, and glorify his wisdom, power,
and goodness, so conspicuously manifested in the struc-
ture of the meanest of his creatures. You will see also,
that all things are created after a pre-conceived plan ; in
which there is a regular and measured transition from
one form to another, not only with respect to beings them-
selves, but also to their organs — no new organ being pro-
duced without a gradual appi'oach to it; so that scarcely
any change takes place that is violent and unexpected,
and for which the wa}^ is not prepared by intermediate
gradations. And when you further consider, that every
being, with its every organ, is exactly fitted for its func-
tions; and that every being has an office assigned, upon
the due execution of which the welfare, in certain re-
spects, of this whole system depends, you will clearly
perceive that this whole plan, intire in all its parts, must
have been coeval with the Creation ; and that all the
species, — subject to those variations only that chniate

EXTERNAL ANATOMY OF INSECTS. 4 75

and (.lifFerent Ibod produce, — have remained essentially
the same, or they would not have answered the end for
which they wore made, from that time to this.

Havmg given you this particular account o^ the trop/n
or organs of the mouth of insects, I must now make some
observations upon the o/her parts of the head. I have
divided it, as you sec in the Tabic, into Jhcc and suhjacc;
the former including its upper and the latter its lower
surface. Strictly speaking, some parts of the face, as the
temples and cheeks, are common to both surfaces ; but
I do not therefore reckon them as belonging to the sub-
face, which, exclusive of the mouth and its organs, con-
sists only of the throaty and where there is a neck, the
gula.

i. Nasiis^. — 1 shall consider the parts of the face in the
order in which they stand in the Table, beginning with
the ?iasns or nose. Fabricius has denominated this part
the cLiipeuSi in which he has been followed by most mo-
dern Entomologists. You may therefore think, perhaps,
that I have here unnecessarily altered a term so gene-
rally adopted, and expect that I assign some sufficient
reasons for such a change. I have before hinted that
there is good ground for thinking that the sense of smell
in insects resides somewhere in the vicinity of this part;
and when I come to treat of their senses, I shall produce
at large those arguments that have induced me to adopt
this opinion : and if I can make out this satisfactorily,
you will readily allow the pi'opriety of the denomination.
I shall here only state those secondary reasons for the

' PLAILS VI. VII. XXVII. a.

476 EXTERNAL ANATOMY OF INSECTS.

term, which, in my idea, prove that it is much more to
the purpose than clypeiis. This last word was originally
applied by Linne in a metaphorical sense to the ample
covering of the head of the Scarabcsidce, and the thoracic
shield of Silj)ha, Cassida, Lampyrisy and Blatta : in all
which cases there was a propriety in the figurative use
of it, because of the resemblance of the parts so illustrated
to a shield. But when Fahricius (though he sometimes
employs the term, as Linne did, merely for illustration,)
admitted it into his orismological table, as a term to re-
present universally the anterior part of the face of insects
to which the labrum is attached {though in some cases
he designates the labrum itself by this name), it became
extremely inappropriate ; since in every case, except that
of the ScarabcEidce, the part has no pretension to be
called a. shield; — so that the term is rather calculated to
mislead than illustrate. This impropriety seems at length
to have struck M. Latrellle, since in a late essay * he has
changed the name of tliis part to Epistomis, a term signi-
fying the part above the mouth. But there are reasons,
exclusive of those hereafter to be produced concerning
the sense of smell, which seem to me to prove that iiasus
is a preferable term; not to mention its claim of priority,
as having been used to signify this part a century ago ^.
When we come to consider the terms for the other parts
of the head, as lips, jaws, tongue, eyes, temples, cheeks,
forehead, &c. the concinnity, if I maj^ so speak, and har-
mony of our technical language, seem to require that the
part analogous in point of situation to the nose of verte-

^ Orgmmnt. Exter. dcs Ins. 1 96.

'' In the Transactions of the Rot/al Society, this part in Anobium
tesscllatum is so called- xxxiii. 159 — .

EXTERNAL ANATOMY OF IXSF.CTS- i7T

brate animals should bear the same name. Ami any per-
son who had never examined an insect before, if asked
to point out the iiose of the animal, would immediately
cost his eye upon this part: so that one of the principal
uses of imposing names uj)on parts — that they might be
more readily known — would be attained. If it is object-
ed, that calling a part a nose that has not the sense of
smell, supposing it to be so, might lead to mistakes — I
would answer, that this objection is not regarded as va-
lid in other cases : for instance, the maxillce are not ge-
nerally used asjaivs, and yet no one objects to the term ;
because, from their situation, they evidently have an ana-
logy to the organs whose name they bear. But enough
on this subject — we will now consider the part itself.

To enable you to distinguish the nose of insects when
it is not separated from the rest of the face by an impressed
line, you must observe that it is the terminal middle part
that sometimes overhangs the upper-lip, and at others
is neai'ly in the same line with it ; that on each side of it
are the cheeks, which run from the anterior half of the
eyes to the base of the mandibles. Just below the an-
tennae is sometimes another part distinct from the nose,
which I shall soon have to mention ; so that the nose
must not be regarded as reaching always nearly to the
base or insertion of the antenna?, since it sometimes oc-
cupies only half the space between them and the upper-
lip, which space is marked out by an impressed line.
But you will not always be left at such uncertainty when
you want to ascertain the limits of the nose ; for it is in
many cases a distinct piece, separated by an elevated or
impressed line from the rest of the face. This separa-
tion is either partial or universal. Take any species of

478 EXTERNAL ANATOMY OF INSECTS.

the genera Copris, Onitis, or Ateuchus, and you will see
the nose marked out in the centre of the anterior part of
the face by two elevated lines, forming nearly a triangle
and bounded by the horn *. Or take a common wasp or
hornet, and you will find a similar space, though ap-
proacliing to a quadrangular figure, marked out by im-
pressed lines ''. In Rhagio and Sciara, two Dipterous ge-
nera, this impression is so deep as to look like a suture.
Between these lines, in those cases, is included what I
call the nose. As to substance, in general it does not dif-
fer from the rest of the head ; but in the Cleridce it is
almost membranous. You must observe, that in all these,
what at first sight appears to be the termination of the
front, is not the nose, but the narrow depressed piece
that intervenes between it and the lip. With regard to
its clotJmig, it is most commonly naked, but in some ge-
nera it is covered with hair; in Crahro F. often with
golden or silver pile, which imparts a singular brilliance
to the mouth of the insects of that genus : M. Latreille
supposes that the brilliant colours of the golden-wasp
[Ckrysis L.) may dazzle their enemies, and so promote
their escape ^ ; the brilliance of the mouth of the C7-a'-
bro may on the contrary at first dazzle their prey for a
moment, so as to prevent their escape. The form of the
nose, where distinct from the rest of the face, admits of
several variations : thus in the Staphylinidce and Cleridce
it is transverse and linear; in Copris it is triangular, with
the vertex of the triangle truncated ; in Vespa Crabro it
is subquadrate and sinuated. In many Heteromerous

=« Plate XXVII. Fig. 4. a. ^ Plate VII. Fig. 2. a.

•^ Observ, Nouv. snr les Ht/menopleres {Ann- du Mus.) 5.

EXTKUNAL ANATOMY OK INSECTS. i^JU

beetles ' it is rounded posteriorly : in Pelecolma, a new
genus in this tribe, related to Asida^ there is a deep an-
terior sinus ; in Blaps the anterior margin is concave;
in Ctionia^ Broivnii^ and atrojninctata (forming a distinct
subgenus), it is bifid: it varies in the Scarabceida;, in
some being bidentate, in others quadridentate, and in
others again sexdentate, including the cheeks : in Myla-
bris, a kind of blister-beetle, it is transverse and nearly
oval; in La mi tty a capricorn-beetle, it I'epresents a paral-
lelogram; and in most Orthopte'ra it is orbicular : in Tet-
tigonia F. it is prominent, transversely furrowed, and di-
vided by a longitudinal channel : in Otiocenis K. it pre-
sents the longitudinal section of a cone *^ : in the Diplera
Order, with the exception of the Tipididxe and some
others, in which it unites with the cheeks, &c. to form a
rostrum, the nose in general, as to form, answers to its
name, resembling that of many of the Mammalia: in
some of the Asilidcc it is very tumid at the end, and ter-
minates in a sinus, to permit the passage of the proboscis
to and fro : in many of the Sj/rphidce, &c. it is first flat
and depressed, and then is suddenly elevated, so as to
give the animal's head the air of that of a monkey : in
some tribes, as RJiingia, Nemofelus, Eristalis, &c., in
conjunction with the cheeks it forms a conical rostrum :
in Tabanus bovinus, and other horse-flies, it terminates
in three angles or teeth. Many more forms might be
mentioned, but these will suffice to give you a general
idea of them. In size and jJroportions the nose also va-

* Those beetles whose posterior pair of tarsi have only /owr joints,
and the two anterior_/?rr, are so called.

•> Kirhy in Linn. Trnns. xii. 464. t. xxiii./. G.
<■ Ibid, xm.i.lf. \.b.

480 EXTERNAI, AXATOMY OF INSECTS.

ries. It is frequently, as in Tcttigojiia, the most conspi-
cuous part of tiie face, both for size and characters ; but
in the Staphylinidce it is very small, and often scarcely
discernible, being overshadowed by its ample front : and
it may be observed in general, that when the antennae
approximate the mouth, as in this genus and many others,
the front becomes ample, and the nose is reduced to its
minimum : but when they are distant from the mouth, the
reverse takes place; and the nose is at its maximum and
the front at its minimum. Mutilla, Myrmecodes, Scolia, &c.
in the Hymenopte7-a, are an example of the former; and
the Pompilidce, Sphecidie, Vespidce, &c. of the latter. In
Myopa buccata, &c. its length exceeds its width; but more
commonly the reverse takes place. The circumscription of
the nose also deserves attention. It is usually terminated
behind by the front [frons), or, where it exists, by the^os^-
nasus, in the sides by the cheeks, and anteriorly by the la-
brum. But this is not invariably the case; for in the Cimi-
cidiT, in which the cheeks form the bed of the Promuscis,
the front embraces it on each side by means of two lateral
processes, that sometimes meet or lap over each other
anteriorly, which gives the nose the appearance of being
insulated ; but it really dips below these lobes to join the
lahrum. This structure you may see in Edessa F., and
many other bugs. This part sometimes has its arms.
Thus in Copris, and many Dynastidcs, the horns of the
head seem, in part at least, to belong to this portion of
it; in Tipida oleracea (the crane-fly), &c. it terminates
before in a horizontal mucro. In Osmia cornuta, a kind
of wild-bee, each side of the nose is armed with a ver-
tical horn. The margin of the nose in most Lamellicorn
insects, thougli mostly level, curves upwards.

EXTERNAL ANATOMY OF INSECTS. 481

I am next to mention a part of the nose wlilcli me-
rits a distinct name and notice, whicli I conceive in some
sort to be analogous to the nostrils of quadrupeds, and
wliich I have therefore named the JRhinarium or nostril-
piece. I had originally distinguished it by the plural term
narcs, nostrils; but as it is usually a single piece, I thought
it best to denote it by one in the singular. When I
treat of the senses of insects, I shall give you my reasons,
as I have before said, for considering this part as the
organ of scent, or connected with it, which you will then
be able to appreciate. I shall only here observe, that the
piece in question is in the usual situation of the nostrils
— between the nose and the lip. In a large number of
insects this part may be regarded as nearly obsolete;
or at least it is merely represented by the very narrow
membranous line that intervenes between the nose and
the lip and connects them ; which, as in the case of the
head of Harpali before noticed, may be capable of ten-
sion and relaxation, and so present a greater surface to
the action of the atmosphere. But I offer this as mere
conjecture. In the lady-bird (Coccijiella) this line is a
little wider, and becomes a distinct Rhinarhim ; as it
does also in Geotnipes. With respect to its insc7-tio?i,
the I'htJiarhmi is a piece that either entirely separates
the nose from the lip, or only partially : the former is
the most conmion structure. It is particularly remaik-
able in a New Holland genus of chafers [AnoplognaiJms
Leach). In A. viridiccnciis it is very ample, and forms
the under side of the recurved nose, so that a large space
intervenes between the margin of the latter and the base
of the labnim. In Macropus Thunb., of the Capricorn
tribe {Ceramhyx L.), the nostril-piece, which forms a

VOL. III. 2 1

482 EXTERNAL ANATOMY OF INSECTS.

distinct sesment, is narrower than the nose, and the
uppe?-lip than the nostril-piece, forming as it were a
triple gradation from the front to the mouth. Again, in
others the part in question is received into a sinus of the
nose. This is the case with the dragon-flies {Lihellulina),
in which this sinus is very wide ; in the burying-beetle
[Necrophorus) *, in some species of which it is deep but
narrow ; and in a species of Tenehrio from New Holland,
which perhaps would make a subgenus. If you examine
with a common glass any of the larger rove-beetles [Sta-
])hylinid(E\ you will find that the nose itself seems lost in
the nostril-piece, both together forming a very narrow
line across the head above the labrum^ without any ap-
parent distinction between them ; but if you have recourse
to a higher magnifier, you will find this divided into an
upper and lower part, the former of the hard substance
of the rest of the head, and the latter membranous. I
once was of opinion that the prominent transversely fur-
rowed part, so conspicuous in the face of Tettigonia F.'',
was lihQ front: but upon considering the situation of this,
chiefly below the eyes and antennae, and comparmg it
with the analogous piece in Fulgora laternaria and other
msects of the Homopterous section of the Hemiptera^ I
incline to think that it represents the nose, and that the
longitudinal ridge below it is the nostril-piece *^. In the
Heteropterous section it is merely the vertical termina-
tion of their narrow nose. In other insects again, this
part approaches in some measure to the common idea of
nostrils; there being tvoo, either one on each side the
nose, or two approximated ones. If you catch the first
humble-bee that you see busy upon a flower, you will
"" Plate VI. Fig. 10. g'. ^ Ibid. Fig. 7- a. ^ Ibid. g'.

EXTERNAL ANAIO.MY OK INSECTS. 4&3

discover a minute membranous protuberance under each
ani»le of the nose. Somctiiing similar may be observed
in some species of Asiltis L. In the Orthojyfera^ esjie-
cialiy in Blatta, Phasma, and some Locustce, tw'o roundish
or square pieces, close to each other on the lower part
of the nose, represent the nostrils *. — With regard to
subsia7ice, in the chafer-tribes, at least those that feed
on leaves or living vegetable matter, as the Mclolon-
thiiJ(C, Anoplogiiathidaj and in many other insects, the
rhinarium is of the same substance with the rest of the
head; but in Macropus Thunb., StaphijUnus, NccropJwriis,
Ike, it consists of membrane.

ii. Postnasus ^. — This is a part that appears to have
been confounded by Entomologists with the front of in-
sects; in general, indeed, it maybe regarded as included
in the nose, and does not require separate notice :' but
there are many cases in which it is distinctly marked out
and set by itself, and in which it forms a useful diagno-
stic of genera or subgenera. There is a very splendid
and beautiful Chinese beetle, to be seen in most collec-
tions o^ foreign insects {Sag}-a purpurea), in which this
part forms a striking feature, and helps to distinguish the
genus from its near neighbour Donacia. If you examine
its face, you will discover a triangular piece, below the
antennae and above the fiasus, separated from the latter
and from the front by a deeply-impressed line : this is the
postnasus or after-7iose. Again : if you examine any spe-
cimens of a Hymenopterous genus called by Fabricius
Prosopis {Hyl(cus Latr.), remarkable for its scent of
baum, you will find a similar triangle markeil out in a

^ Plate Vf. Fig. 4. g'. '• PiATis VI. VII. b.

484 EXTETINAL ANATOMY OF INSECTS.

similar situation '. In many Coleopterous insects, besides
Sagra, you will discover traces of the part we are consi-
dering: as in Anthia, Dytisais, and several others of the
Predaceous beetles. In Cistela it is larger than the nose
itself; but it is more conspicuous in the OrtJioptera, par-
ticularly in Locusta {Gtyllus F.), in which it is the space
below the antennae, distinguished by two or four rather
diverging ridges''. In the Libellulina, Myrmeleo7iina,
&c. it is a distinct transverse piece. In Dasyga Latr.,
a kind of bee, it is armed with a transverse ridge or horn
— But enough has been said to render you acquainted
with it ; I shall therefore proceed to the next piece.

iii. Fro7is *^. — The Front of insects may be denomi-
nated the middle part of the face between the eyes,
bounded anteriorly by the nose, or after-nose, where it
exists, and the cheeks ; laterally by the eyes ; and poste-
riorly by the vertex. Speaking properly, it is the region
of the antennts ; though when these organs are placed
before the eyes, under the margin of the nose, as in many
Lamellicorn and Heteromerous beetles, they seem to be
rather na&al than Jt'ontal. This part is often elevated,
as in the elastic beetles (Elater), whose faculty of jump-
ing, by means of a pectoral spring, has been related to
you ^. In A?it/iia, a Predaceous beetle, it has often three
longitudinal ridges. In many of the Capricorn beetles
{Cerambi/x L.), it is nearly in the shape of a Calvary
cross, with the arms forming an obtuse angle, and then
terminating at the sinus of the eyes in an elevation for
the site of the antennae. In the ants also [Formicidce\

^ Kirby Mon. Ap. Angl. i. /. i. Melitia. *. h.f. 3.

^ Plate VI. Fig. 4. b. '^ Plates VI. VII. c.

■i Vol. II. p. 317—,

EXTERNAL ANATOMY OF INSECTS. 485

the front is often elevated between those omans. In
Ponaa, one tribe of them, this elevation is bilobed,
and receives between its lobes the vertex of the posl-
Jiasus. In tlie hornet {Vespa Crabro) the elevation is a
triangle, with its vertex towards the mouth. In Sagra
it is marked out into three triangles, the post/iasus mak-
ing a fourth, with the vertexes meeting in the centre.
In the Dijnastidcc and Scarabcci(I<r the horns are often
frunlal api)endages, as is that of Einpusa Latr., a leaf-
insect, and probably those o^ Sphinx la/rop/iccT., which
affords a singular instance of a horned Lepidopterous one.
Sometimes it is an ample space, reducing the nose to a
very narrow line, as in the Slaphylinidcc, or sending
forth a lobe on each side, as before mentioned, which
embraces the nose. In a species of bug from Brazil, re-
lated to Aradus F., these lobes are dilated, foliaceous,
and meet before the nose, so as to form a remarkable
extended frontlet to the head. In others this part is ex-
tremely minute : thus in many male flies and other in-
sects, as the Libellidina, where the eyes touch each other,
the front is cut off from the vertex and reduced to a small
angle. In the female flies the communication with the ver-
tex is kept open, and the front consequently longer. In
the horse-flies (Tabanida), in Hatnatopota, and Hepta-
toma, the frontal space is wider than in the rest of that
tribe. Many of these are distinguished by a levigated
area behind the antennae in the part we are treating of.
In the Libelhdina, and in the drone-bee, whose eyes are
confluent, the stemmata are in the front. In many Or-
thoptcra also, as Lociista Leach, one of them is below
the antennae ; and in the ianthorn-fly tribe {Fulgoridce),
both these organs, which are situate between (hem and

486 KXTERNAL ANATOMY OF INSECTS.

the eyes, as they do also in Truxalis, appear to be in
it ^. In this tribe the rostrum is an elongation of the
part in question ; and perhaps you would think at first
that what I have considered as the nose in Tettigonia F.
was also a tendency to this kind of rostrum ; but if you
examine the great lanthorn-fly [Fulgora laternaria), you
will find besides, at the lower base of the lanthorn, a tri-
angular piece analogous to the nose of Tettigonia, and
below it another representing its nostril- piece: — the hori-
zontal part of the nose in that genus may perhaps be re-
garded as part of the front. In Truccalis F. the face
consists of a supine and prone surface, and the latter is
composed of the front, after-nose, nose, and organs of the
mouth. I may notice here a most remarkable and singu-
lar tribe of bugs, of which two species have been figured
by StolP : in these the head, or rather those parts of it that
we have now been describing, the nose, namely, the after-
nose, and front, are absolutely divided longitudinally in
two, each half having an eye and antenna planted in it ;
or perhaps, as it is stated to be divided in one instance to
the commencement of the protmiscis, the nose is left in-
tire, and dips down, as in cases before alluded to : so that
in this the nose appears to leave the lobes of the front,
which in others embrace its sides.

iv. Vertex ^. — We now come to the vertex, or crown
of the head ; which is situated behind the front, and,
except where the communication is intercepted by con-
fluent eyes, adjoins it. It is laterally bounded by the
hind part of the eyes and the temples ; and 'posteriorly,

' Plate XXVI. Fig. 41. i.

'' Stoll Pxina'iscs, t. xxxix. /. 279, 280.

' Plates VI. VII. XXVI. d.

EXTERNAL ANATOMY OF INSECTS. 4-87

where that part exists, by the occiput. The vertex may
be denominated the ordinary region of the stemmata :
for thoii<vh in several cases, as we have just seen, one or
more of them are planted in the front; yet tiiis in the great
majority, especially in the Hj/fuenoptera, is their natural
station. In Blatfa and some other Orthoptera the poste-
rior angle of the head is the vertex. In many dung-
chafers of Latreille's genus Onthophagiis, which are said
to have occipital horns, as O. 7iutans, nuchicornis, Xi-
ji/iias, &c., the horn really arms the part I regard as the
vertex. In Locusta Leach, this part is very ample, and
in Tnixalis very long ; but more generally it is small,
and not requiring particular notice.

V. Occiput^. — The occiput, or hind-head, is that part
of the face that either forms an angle with the vertex
posteriorly, or slopes downwards from it. It has for its
lateral boundaries the temples, and behind it is either
terminated by the orifice of the head, or in many cases
by the neck. In those beetles that have no neck, as the
Lamellicorn and Capricorn, the hind-head is merely a de-
clivity from the vertex, usually concealed by the shield of
the thorax, very lubricous, to facilitate its motion in the
cavity of that part, and at its posterior margin distin-
guished by one or two notches, which I shall notice
hereafter, for the attachment of the levator muscles : but
in those beetles or other insects that have a neck, or a
versatile head, the occiput forms an angle with the vertex,
often rounded, and sometimes acute. This structure may
be seen in Latreille's Ti-achelides, and several other bee-
tles. In the Hymenoptera, Diptera, and others with a

•' Platks VJ. VII. c

488 EXTERNAL ANATOMY OF INSECTS.

versatile head, the part now under consideration curves
inwards from the vertical line, so as with the temples and
mider parts of the head to form a concavity adapted to
its movement upon the trunk.

vi. Ge7icc ^. — The cheeks of insects {Genai) usually sur-
round the anterior part of the eyes, and lie between them
and the mandibles or their representatives. Where they
approach the latter, as in the Predaceous beetles {Cicin-
dcla, Carabiislu. &c.), they are very short, and of course
longer where the eyes are further removed from the
mouth; as in the Rhyncophorous beetles (CmcwZ/o L.),
where they form the sides of the rostrum, and often con-
tain a channel which receives the first joint of the anten-
nae, when they are unemployed. In the Scarabaidce and
many other Lamellicorn beetles, their separation on each
side from the nose is marked by a ridge ^ ; and in the
wasps {Vespa) by an impressed line or channel. In an
African tribe at present arranged with Cetonia F., to
which C. bicornis Latr.*^ and another, which he has named,
I believe, C. vitticollis, belong, the cheeks are porrected
on each side of the mouth into a horizontal horn. These
horns have at first the aspect of a pair of open mandibles.
In the magnificent Goliathi Lam., the horns of the male
are rather a process of the cheek than of the nose. In
Alurnus, Hispa, and other beetles, these parts, by their
elevation and conjunction with the lower side of the
head, form a kind of fence which surrounds and protects
the oral organs ; in many Chnicida, by a similar eleva-
tion of the cheeks, the bed of the promuscis is formed.

' PLATiis VI. VII. f. b Plate XXVII. Fig. 4. f.

' Cuv. JRegne Animal iii. f xiii /. 4.

EXTERNAL ANATOMY OF INSECTS. 189

In ilic I loinopterous Hcmiptcra they run parallel nearly
with the rJiinariwn or nostril-[)iece. In the Hijmenoptcia
they are almost always ample, but they are confined to
the lower side of the eye. In Sirex Gigas^ and others of
that genus, the cheek at the base of the mandible is di-
lated so as to ibrm a rounded tooth below it. In the
Capricorn-beetles it is considerable, and sometimes ter-
minates, at the base of the mandible, in two or three
notches. In Scauriis and Eurjjc/iofa, darkling-beetles,
the cheek below projects into a lobe that covers the base
of the maxiUa. But the animal distinguished by the
most remarkable cheeks is a species of Phiyganca L.
[Phri/ganea personata Spence) ; for from this part pro-
jects a spoon-shaped process, which curves upwards, and
luiiting with that of the other cheek, forms an ample mask
before the face, the anterior and upper margin of which,
in the insect's natural state, are closely united ; and the
posterior part being applied to the anterior part of the
eye, causes the face to appear much swoln. It looks as
if it was a single piece; but upon pressing the thorax it
opens, both above and in front, into two parts, each con-
vex without and hollow within, and each having attached
to its inside a yellow tuft of hair resembling a feather.
The use of this machinery at present remains a my-
stery *.

vii. Tempore ^. — The temples ( Tempora) are merely
a continuation of the cheeks to the posterior limit of the

=• This insect was taken both at Matlock and Exmouth. The body
and thighs arc of a hght-brown, wings testaceous, legs pale ; anteniiEe
between setaceous and lilitorni, two-thirds ihe lciij;th of the body;
fast joint not nuich thicker than thercji.

• PLAliS VI. Vll ti.

4-90 EXTERNAL ANATOMY OF INSECTS.

liead, forming its sides and posterior angles, and includ-
ing the hinder part of the eyes, the vertex, and the occi-
put. They seldom exhibit any tangible character, ex-
cept in certain ants {Atta Latr.), in which their angle
terminates in one or two strong spines, giving the ani-
mal a most ferocious aspect ; and in that remarkable ge-
nus Corydalis they are armed below with a tooth or point,
which was not overlooked by De Geer ^.

viii. Oculi ^. — I must now call your attention to organs
of more importance and interest, and which indeed in-
clude a world of wonders : I mean the eyes ( Oculi) of
insects. These differ widely from those of vertebrate
animals, being incapable of motion. They may be re-
garded as of three descriptions — simple, conglomerate,
and compound.

1. Simple Eyes ^. We will consider them as to their
number, structure, shape, colour, magnitude, situation, and
arrangement.

As to their numher, they vary fi'om two to sixteen.
In the flea, the louse, the harvest-man {Phalangiuni),
there are only a pair ; in the bird-louse of the goose
[Nirmus Anseris), and probably in others of the same
genus, there are Jour ^; in some spiders (Scytodes, Dys-
dera, and Segestria Latr. ^), and some scorpions ^, there
are six. In the majority of spiders and Scolopendra mor-

^ De Geer iii. 561. t. xxvii./. 1. i> Plates VI. VII. XXVI. h.

<= Plate VII. Fig. 8, 9. XXVI. Fic. 43. h.

<• Viz. one on each side above, and one below.

"= Walckenaer Araneides, t. v./. 50, 52. t. viii /. 82.

f Treviranus {Arachnid. 4.) says that Scorpio Europisus has only
two eyes. He appears to have overlooked the two on the anterior
side of a tubercle at each angle of the head, where they are large,
but not conspicuous, at least in my specimen.

EXTERNAL ANATOMY OF INSFX'TS. 4-91

sitans, Scorji/o manrus, &c. there are eight ,- aiul in Po-
dura and Smmfhurus Latr. there are sixteen *.

As to their sfrucfiirc, nothing seems to have been ascer-
tahied ; probably their organization does not materially
differ from that of one of the lenses of a compound eye ;
which I shall soon exjilain to you.

Their colour in the many is black and shining, but in
the bird-louse of the goose they are quite white and
transparent. In spiders they are often of a sapphirine
colour, and clear as crystal. In Scolopendra morsitans
and many spiders, scorpions, and -phalangia '', they ap-
pear to consist of iris and pupil, which gives them a
fierce glare, the centre of the eye being dark and the
circumference paler. In the celebrated Tarantula {Ly-
cosa Tarantula)^ the pupil is transparent, and red as a
ruby ; and the iris more opaque, paler, and nearly the
colour of amber.

Where there are more than two, they vary in magni-
tude. In the enormous bird-spider (Mygale aviadaria)
the four external eyes are larger than the four internal '^;
but in the Tarantula and Spkastis, the two or Jour inter-
nal are the largest. In Cluhiona and Drassus they are all
nearly of the same size**; and in the Micrommata family
they are very small ^.

They vary also in shape. In Scolopendra morsitans the
three anterior ones are round, and the posterior one
transverse, and somewhat triangular. In Mi/gale cal-
peiana, a spider, the two smallest are round and the rest

» DeGeervii. /. iii. /. 8,9, 12.

>- Platf. XXVI. Fig. 43. h. ^ Walck. Aran. t. If. 3.

" Ibid. t. v./. 45— 4«. *= Ibid. t. iv./. 41.

4<92 EXTERNAL ANATOMY OF INSECTS.

oval ^. In the trapdoor or mason spider [Mygale ccc-
mentaria), the four small internal ones are romid, and
the large external ones ovaP; and those that are cir-
cumscribed posteriorly with an impressed semicircle, are
shaped like the moon when gibbous '=■.

The situation and arrangement of simple eyes are also
various. In many they are imbedded, as usual, in the
head ; but in the little scarlet mite, formerly noticed '',
( Trombidium holosericeum), they stand upon a small foot-
stalk ^ : the hairiness of this animal might otherwise have
impeded its sight. In spiders they are planted on the
back of the part that represents the head, sometimes four
on a central elevation or tubercle, and the remaining
four below it — as in Lycosa; sometimes the whole eight
are on a tubercle, as in Mygale ; and sometimes, as in
the common garden-spider [Epeira Diadema), upon
three tubercles, four on the central one and two on each
of the lateral ones. Other variations in this respect might
be named in this tribe. In the scorpions a pair are placed
one on each side, on a dorsal tubercle, and the other four
or six on two lateral ones of the anterior part of the
head ^. In the Phalangidce the Jrontal eyes of the scor-
pion cease, and only a pair of dorsal ones are inserted
vertically in the sides of a horn or tubercle, either bifid
or simple, often itself standing upon an elevation which
emerges from the back of the animal s. If their eyes
were not in a vertical and elevated position, the sight of

^ Walck. Aran. t. If. 2. •> Ibid. t. i.f. 7.

- Ibid. 1. 11. f. 18, 20. " Vol. I. p. 323.

^ DeGeer vii. 138. t.y'ni.f. \b.yy. ' Ibid. ^. xl,/. 3. ow, ?/»/.

= Plate XXVI. Fig. 43. h.

EXTERNAL ANATOMY OF INSECTS. 493

tliese insects would be very limited ; but by means of the
structure just stated, they "^et a considerable range of sur-
rounding objects, as well as of those above them. With
regard to the arrangement of tlie eyes we are consider-
ing, it varies much. Sometimes they are placed nearly
in the segment of a circle, as in those spiders that have
six eyes only, before noticed ^ ; sometimes in two straight
lines''; at others in two segments of a circle •=; at others,
in three lines'*, and at others in four ^. Again, in some
instances they form a cross, or two triangles ^; in others,
two squares s ; in others, a smaller square included in a
large one ^ ; in others, a posterior square and two anterior
triangles ' ; sometimes a square and two lines. Though
generally separate from each other, in several cases two
of the eyes touch ''; and in one instance three coalesce
into a triangle '. But it would be endless to mention all
the variations, as to arrangement, in the eyes of spi-
ders.

2. Conglomerate Eyes "* differ in nothing from simple
eyes, except that instead of being dispersed they are col-
lected into a body, so as at first sight to exhibit the ap-
pearance of a compound eye : — they are, however, not
hexagonal, and are generally convex. They occur in

' Segcstria pcrfula, Walck. Aran. t. v.f. 52. &c.

'' Tetragiiatha and Lntrodectts, Ibid. t. vii./. G4. and /. ix./. 84.

^ Nyssus coloripes. Ibid. t. vi./. 5S.

•^ IMomeda, Ibid. t. u.f. 18, 20.

* Sphasus, Ibid. t. Hi./. 24.

^ My gale aviciilaria. Ibid. t.\.f. 3.

c Sparasiis, Ibid. t. iv. /. 41. Platk XXVI. Fig. 37.

" Eresus, Ibid. t. iii./. 26. ' Siurena, Ibid. t. ix./. 80.

k Argynmefa, Ibid.f. 88. ' Pholcus, Ibid. t. viii./. 80.

" Plate XIII. Fig. 11.

4i94! EXTERNAL ANATOMY OF INSECTS.

Lepisma^ the Iididcei and several of the ScolopendridcE.
In Scolopendra forjicata the eye consists of about twenty-
contiguous, circular, pellucid lenses, arranged in five
lines, with another larger behind them, as a sentinel or
scout, placed at some little distance from the main body.
In the common millepede [Iidus terrestris) there are
twenty-eight of these eyes, placed in seven rows, and
forming a triangle, thus ^^ — the posterior row con-
taining seven lenses, the next six, and so on, gradually
losing one, till the last terminates in unity. Each of
these lenses is umbilicated, or marked with a central de-
pression. In Craspedosoma Leach, you will find a similar
formation. In Glomeris zonata, a kind of wood-louse
that rolls itself into a ball, the lenses are arranged in a
line curved at the lower end, with a single one by itself
at the posterior end on the outside ; they are oblong and
set transversely, and their white hue and transparency
give them the appearance of so many minute gems, espe-
cially as contrasted with the black colour of the animal*.
Between these eyes and the antennae is another trans-
verse linear white body, but opaque, seemingly set in a
socket, and surrounded by a white elevated line, like the
bezel of a ring. Whether it is an eye, or what organ, I
cannot conjecture ''. Its aspect is that of a spiracle.

3. Compound Eyes "=. — These are the most common kind
of eye in hexapod insects, when arrived at their perfect
state; in their larva state, as we have seen, their eyes
being usually simple '' ; except, indeed, those whose me-
tamorphosis is semicomplete, which have compound eyes

" Plate XXIX. Fig. 1 1. h. •• Ibid. a.

•-■ Plate XTII. Fig. 10. " See above, p. 117 — •

F.XTEUNAl, ANATOMY OF INSKCTS. 495

in every state. — In considering coni})oinid eyes, 1 shall
advert to their slntciiirc, number,, situction,Jigurc^ cloth-
ing, colour, and size.

As to their structure^ — when seen under the microscope
they appem* to consist usually of an infinite number of con-
vex hexagonal pieces. If you examine with a good glass
the eye of any fly, you will find it traversed by numberless
parallel lines, with others equally numerous cutting them
at right angles, so as apparently to form myriads of little
squares, with each a lens of the above figure set in it. The
same structure, though often not so easily seen, obtains in
the eyes of Colcoptcra and other insects. When the eye
is separated and made clean, these hexagons are as clear
as crystal. Reaumur fitted one eye to a lens, and could
see tlirough it well, but objects were greatly multiplied^.
In Coleopterous insects they are of a hard and horny
substance ; but in Diptera, &c. more soft and membra-
nous. The number of lenses in an eye varies in different
insects. Hooke computed those in the eye of a horse-
fly to amount to nearly 7,000''; Leeuwenhoeck found
more than 12,000 in that of a dragon-fly <^; and 17,325
have been counted iii that of a butterfly <^. But of all in-
sects they seem to be most numerous in the beetles of
Mr. W. S. MacLeay's genus Dynastes. In the eyes of
these the lenses are so small as not to be easily discover-
able even under a pocket microscope, except the eye has
turned white ^: it is not, therefore, wonderful, that Fabri-

" Reaum. iv. 245. ^ Microgr. 176.

<■ Episf. Mar. 6. 1717. '' Amoon. Acadcm. vii. 141,

* I possess a specimen in which the eye is partly black and partly

white : the lenses arc invisible in the black part, but very visible in

the white.

"496 EXTERNAL ANATOMY OF INSECTS.

cius should call these eyes simple *. In some insects, how-
ever, as in the Strepsiptera Kirby, the lenses are not nu-
merous : in Xenos they do not exceed fifty, and are di-
stinctly visible to the naked eye ^. These lenses vary in
magnitude, not only in different, but sometimes in the
same eyes. This is the case in those of male horse-flies
and flies, those of the upper part of the eye being much
larger than those of the lower '^. The partitions that
separate the lenses, or rather bezels, in which they are set,
are very visible in the eyes just mentioned, and those of
Xenos ; but in many insects they are only discernible at
the intersecting lines of separation between the lenses.
In hairy eyes, such as those of the hive-bee, the hairs
emerge from these septa. Every single lens of a com-
pound eye may be considered as a cornea^ or a crystal-
line humour^ it being convex without and concave within,
but thicker in the middle than at the margin : it is the
only transparent part to be found in these most remark-
able eyes. Immediately under the cornea is an opaque
varnish, varying according to the species, which pro-
duces sometimes in one and the same eye spots or bands
of different colours. These spots and bands form a di-
stinguishing ornament of many of the Tahani and other
flies. And to this varnish the lace- winged flies [Heme-
rohius, &c.) are indebted for the beautiful metallic hues
that often adorn them. When insects are dead, this
vai'nish frequently loses its colour, and the eye turns
white : hence many species are described as having lahite
eyes which when alive had hlacJc ones. The consistence

" Philos. Entomolog. 19. ^ Plate XXVI. Fig. 38,

* Hookc Microsr. schem. xxiv.

EXTERNAL ANATOMY OV INSECTS. 197

of this covering is the same witli tliat of the varnish ot"
the choroid in the eyes of vertebrate animals ; but it en-
tirely covers the underside of the lens, without leaving
any passage for the light. Below this varnish there are
numbers of short white hexagonal prisms ', every one of
which enters the concavity of one of the lenses of the
cornea, and is only separated from it by the varnish just
described : this may be considered as the retina of the
lens to which it is attached ; but at present it has not been
clearly explained how the light can act upon a retina of
this description through an opacjue varnish. Below this
multitude of threads (for such the bodies appear), per-
pendicular to the cornea^ is a membrane which serves
them all for a base, and which consequently is nearly pa-
rallel with that part. It is very thin, of a black colour,
not produced by a varnish ; and in it may be seen very
fine white trachece, which send forth branches still finer,
that penetrate between the prisms of the cornea : this
membrane may be called the choroid. Behind this is a
thin expansion of the optic nerve, which is a true nerv-
ous membrane, precisely similar to the retina of red-
blooded animals. It appears that the white pyramidal
threads which form the retina of each lens are sent forth
by this general retina, and pierce the choroid by a num-
ber of almost imperceptible holes ^. Fi om this descrip-
tion it appears that the eyes of insects have nothing cor-
responding with the xivea or humours of those of verte-
brate animals, but are of a type peculiar to themselves.
Having explained to you the wonderful and complex

" Plate XXIII. Fig. 3.

^ Cuvier Anat. Compar. ii. 442—. Compare Swanimerclaiu Bill.
Xat i. 211. t. xx./ 45.

VOL. III. 2 K

^SS EXTERNAL ANATOMY OF INSECTS.

Structure with which it has pleased the Creator to di-
stinguish the organs of vision of these minute beings,
proving, what I have so often asserted, that when ani-
mals seem approaching to nonentity, where one would
expect them to be most simple, we find them in many
cases most complex, I shall now call your attention to the
next thing I am to consider — the number of the eyes in
question. Most insects have only fwo; but there are se-
veral exceptions to this rule. Those that have occasion
to see both above and below the head, the eyes of all
being immovable, must have them so placed as to enable
them to do this. This end is accomplished in many
beetles, for instance Scarabatis L., Helceus Latr., &c., by
having these organs fixed in the side of the head, so that
part looks upward and part downward ; but in others
four are given for this purpose. If you examine the
common whirlwig ( Gyri?ius Natator) that I have so often
mentioned ^, which has occasion, at the same time, to
observe objects in the air and in the water, you will find
it is gifted with this number of eyes. Lamia Tornator
{Ceramhyx tetrophihalmus Forst.) and some others, of
which I make a genus, under the appellation of 2V-
trops, are also so distinguished. In these insects, one
eye is above and the other below the base of tlie anten-
nas ; in fact, in these the canthus, instead of dividing the
eye partially, as in the other Capricorn-beetles, runs quite
through it at considerable width ^. In Ryssonotus Mac-

■^ Vol. II. p. 4, 364, &c.

^ Plate XXVI. Fig. 36. h. Fiibriciiis, and after him Olivier,
though both quote Forster, regard one of these eyes in Lamia Tor-
nator as a spot ; but they could not have examined it attentively.
Saperda jir<^usta F. has also four eves.

EXTERNAL ANATOMY OF INSECTS. 199

Leay {Lucaniis nebulosns K.) the eye appears also to be
divided in two by the canthiis. In the Ncii7-oj)tcra Order
there is more than one instance of the same kind. In
Ascalap/im there are two considerable eyes on each side
of the head, wliich, though clearly distinct, meet like
those of many male flies and the drone. The male, like-
wise, of more than one species of Ephemera, besides the
common lateral eyes and the stemmata on the back of
the head, have a pair of compound eyes on the top of a
short columnar jirocess ^. In the Hemiptera Order, also,
an instance occurs of four eyes in the genus Aleyrodes ^.
Amongst the vertebrate animals, there is an example of
ej'es witli two pupils in Anahleps, a genus of fishes'^, but
no vertebrate animal has four of these organs. That
many insects should have more than tvoo eyes, will not
seem to you so extraordinary as that any should be found
that, like the Cyclops of old, have only one. There is,
liowever, an insect, before celebrated for its agility''
(Machilis polypoda Latr.), which has a single eye in its
forehead; or we may say, its eyes are confluent, without
any line of distinction between them except a small notch
behind. Now that I am treating of the number of eyes,
I must not forget to observe to you, that in some insects
no eyes at all have been discovered. In Polydesmus com-
planatus, on each side of the head there is an eye-shaped
portion separated by a suture, in which under a power-
ful lens I cannot satisfy myself that I can discern any
thing like the facets that usually distinguish compound
eyes. In Geophilus electricus, another myriapod, they

» Plate XXVI. Fig. 39. h.

«> Latreille Gen. Cnist. et Ins. iii. 7.3, ' A^. Diet, d' Hid. Nat. i. 47.0.

«" Vol.. II. 320.

2 K 2

500 EXTERNAL ANATOMY OF INSECTS.

certainly do not exist *. Whence we may conclude, as
was before observed ^, that the faculty of emitting light
is rather given it as a means of defence than to guide it
in its path.

The situation of compound eyes differs in different
tribes. In some, as in the Staphylinidce, they are planted
laterally in the anterior part of the head ; in others, the
Carabi &c., in the middle ; in others again, Locusta
Leach &c., in the posterior part. In some, their station
is more in the upper surface, either before or behind ; so
that a very narrow space separates them, or perhaps none
at all. Instances of this position of the eyes occur in a
minute weevil [Ramphus Clairv.*^), and many Diptera,
&c. Of those that form an union on the top of the head,
some are placed obliquely, so as to leave a diverging
space below them, as in many Lihellulina '^, the drone *,
&c. Others, as Atractocerus, in which the eyes occupy
nearly the whole head, and unite anteriorly, have this
diverging space above their conflux. In RJmia barbiro-
stris Latr., another kind of weevil, they are confluent
below the head, at the base of the rostrum, and a very
narrow interval separates them above. In a large num-
ber of the Heteromerous beetles, they are set transversely,
in the Capricor?i ones longitudinally. Their surface,
when they are lateral, has usually two aspects, one prone
to see below, the other supine to see above. In general
the eyes are situated behind the antennae, so that their
position, whether it shall be anterior or posterior, de-
pends upon that of those organs. Often, indeed, as in

» De Geer vii. 562. ^ Voi,. II. p. 228.

•= Ent. Hehet. i. t. xii. '' Plate VI. Fig. 10.

*■ IGrby Mon. Ap. Angl. i. t. xi. Apis. **. e. 1./. 2.

EXTERNAL ANATOMY OF INSECTS. 501

the last-named beetles, part of the eye is behind and part
before the antennae ; but except where there are four
eyes, as in Tetr-ops, they are never placed before or below
them.

Though the eyes of insects are generally sessile, yet to
give them a wider range they are sometimes, but it rarely
occurs, placed, like those of many Crustacea, on 2i foot-
stalk, but not a moveable one. An instance of this in cer-
tain male Ephemera; has already been mentioned. In the
Hemiptera De Geer has figured two species of bugs
[Cimicida) that are so circumstanced^; as are also all
the known Strepsiptera K., though in these the footstalk
is very short '' : but the most remarkable example of co-
lumnar eyes is afforded by that curious Dipterous genus
Diojisis, in which both eyes and antennae stand upon a
pair of branches, vastly longer than the head, which di-
verge at a very obtuse angle from its posterior part •=.

In their fgU7e eyes vary much. Sometimes they are so
prominent as to be nearly spherical: this is the case with
some aquatic bugs, as Raiiatra, Hydrometra, and several
male Ephemera '*. Very often they are hemispherical, as
in the tiger-beetles [Cicindela L.), and the clocks or dors
{Carahus L.); but in a large number of insects they are
flat, and do not rise above the surface of the head. —
With regard to their outline, they are often perfectly
round, as in many weevils ; oval, as in various bees ;

■•' De Geer iii. f.xxxiv. /. 17, 18, 24, oo.

*" Mon. Ap. Angl. i. t. xiv. no. 11./. 1./. Linn. Trans, xi. ^. ix.
/.lO.d.

•^ Plate XIII. Fig. 9. Fuessly Archiv. t. vi.

** Schellenberg Cimices t. xiii. ix. /. 1. a. De Geer ii. /. xviii.
/.lO.

502 EXTERNAL ANATOMY OF INSECTS.

ovate^ as in other bees [Andrena F.); triangular^ as in the
water-boatman [Notonccta). They are also often oblong,
and occasionally narrow and linear; as in that singu-
lar beetle Helceus. In many of the Muscidce they form
nearly a semicircle, or rather, perhaps, the quadrant of a
sphere. The eyes of the Capricorn-beetles {Ceramhyx L.)
have a sinus on their inner side, as it were, taken out of
them ; so that they more than half surround the anten-
nae, before which is the longest portion of them. An
approach to this shape is move or less observed in the
darkling-beetles {Tenehrio L.); but in these the sinus is
not so deep. I may under this head observe, that in
those Manf idee that represent dry leaves, and some others,
these organs usually terminate in a spine ^.

Though not distinguished by the beauty and anima-
tion that give such interest to the eye of vertebrate ani-
mals, and exhibiting no trace of iris or pupil, yet from
the variety of their colours the compound eyes of insects,
though most commonly black or brown, are often very
strikino-. Look at those of one of the lace-win^ed flies
that commit such havoc amongst the Aphides ^, and it
will dazzle you with the splendour of the purest gold,
sometimes softened with a lovely green. The lenses of
those of Xenos blaze like diamonds set in jet*^. You
have often noticed the fiery eyes of many horse-flies
(Tabanus L,.) with vivid bands of purple and green ^.
Others are spotted^; and Schellenberg has figured one
( TJiereva kemiptera) ^, that exhibits the figure of a flower

•^ StoU Spectres, &c. t. iv.f. 14. f. x.f. 38, &c.

*• Vol,. I. p. 2()1 — . <■ Linn. Trans, ithi supr.

■^ Stiiellenbert; Mouchis, t. xxvii./. 1, 2.a,d.

«■ Ihid. I. ix./. 3. n. ' Unci. t. \\.f. 2. n.

EXTERNAL ANATOMY OF INSFXTS. .50.'}

painted in red on a black ground. These colours and
markinfjs are all most vivid and brilliant in the livhw
insect, and often impart that fire and animation to tlie
eyes for which those of the higher animals are remark-
able. Take one of the large dragon-flies that you see
hawking about the hedges in search of prey, examine its
eyes under a lens, and you will be astonished at the bril-
liance and crystalline transparency which its large eyes
exhibit, and by the remarkable vision of larger hexagons
which appear in motion under the comea, being reflect-
ed b}' the retina — all which give it the appearance of a
living eye. This moving reflexion of the hexagonal
lenses in living insects was noticed long since in some
bees {Nomada F., Coelioxys Latr.)*

Compound eyes differ greatly in their size. In some
insects, as Atractocerus, the drone-bee, many male Mas-
cidce, &c., they occupy nearly the whole of the head ;
while in others, as numerous Staphyliiiidce, Locusta
Leach, &c., they are so small as to be scarcely larger
than some simple eyes of spiders : and they exhibit
every intermediate difference of magnitude in different
tribes, genera, and species.

Under this head I must say something of the Canthiis
of the eye ; by which I mean an elevated process of the
cheek, which in almost all the genera of the Lamelhcorn
beetles enters the eye more or less, dividing the upper
portion from the lower. Though usually only ?i process of
the cheek, yet in the Scarahaeida; the whole of that part
forms the canthus ^. It only enters the eye in the Ru-
telidiS, Cetonida, &c. ; it extends through half of it in

» Mon. Aj). Aug/, i. 148. ^ Plate XXVII. Fig. 4. h'.

504' EXTEllNAL ANATOMY OF INSECTS.

Copris; it goes beyond the half in Ateuchus; and in JRi/s-
sonotus MacLeay (Luca?iiis nehulosus K.) it quite divides
the eye into two ^, as I before observed. In Lucayius,
Passalus &c. it projects before the eye into an angle ; in
Lucanus femoralis nearly into a spine ; but in Lamprima
and (Esalus it does not exist. The part, also, that enters
the eye in the Capricorn-beetles may be regarded as a
kind of cantkus, though it is merely a dilatation of the
Jiwif.

4. Stemmata ^. — Having given so full an account of
the kinds and structure of the ordinary eyes of insects,
you may perhaps expect that I should now dismiss the
subject : you would, however, have great cause to blame
me, did I not make you acquainted with a kind of auxi-
liary eyes with which a large portion of them are gifted ;
I mean those pellucid spots often to be found on the poste-
rior part of the front of these animals, or upon the vertex,
frequently arranged in a triangle. These, Linne, from
his regarding them as a kind of coronet, called Stem-
mata. They have been of late denominated Ocelli ; but
as this latter term is also in general use for the eyelets on
the wings of Lepidoptera, I have adhered to that of the
illustrious Swede. Neither he nor Fabricius has ex-
pressed any opinion as to the Use of these organs ; but
Swammerdam and Reaumur were aware that they were
real eyes. The former found that there are nerves that
diverge to them though not easily traced, and that they

'^ This circumstance proves that Mr. W. S. MacLeay is correct in
considering this as a subgenus; but it militates against its being
connected with Lamprima.

^ Plate VI. Fig. 4, 10. VII. Fig. 1, 2, 4. XXVI. Fig. 39-42. i.

EXTERNAL ANATOMY OF INSECTS. 505

Iiave a cornea^ and what he takes for the uvea * ; and the
latter has supposed that the compound eyes and these
simple ones have, the one the power of magnifying ob-
jects much, and the other but little, so that the former
are for surveying those that are distant, and the latter
those that are near ^. The same author relates some ex-
periments that he tried with the common hive bee, by
which he ascertained that the stemmata, as well as the
com})ound eyes, were organs of vision. He first smeared
the lattcf over with paint, and the animals, instead of
making for their hive, rose in the air till he lost sight of
them. He next did the same with \\\e former, and placing
the bees whose stemmata he had painted within a few
paces of their hive, they flew about on all sides among
the neighbouring plants, but never far : he did not ob-
serve that these ever rose in the air like the others '^.
From this experiment it seems as if the compound eyes
were for horizontal sight, and the stemmata for vertical.

The definition of them by Linne and Fabricius as
smooth, shining, elevated or hemispheric puncta, con-
veys a very inadequate idea of them ; for, except in a
very few instances, they are perfectly clear and transpa-
rent, and their appearance is precisely the same as that
of the simple eyes of Arachnida &c., under which head
they might very well have been arranged ; but as the last
are primary eyes, and the stemmata secondary, it seemed
to me best that they should stand by themselves. The
structure of both is probably the same, and their inter-
nal organization that of one of the lenses of a compound
eye, and both are set in a socket of the head.

« Bihl. Nat. i. 214. ^ Reaum. iv. 245.

^- Ibid. V. 287—.

506 EXTERNAL ANATOMY OF INSECTS.

Though a large number of insects have them, they are
by no means universal, since some Orders, as the Stre-
psiptera, Dermaptera, and Aptera, are altogether without
them. The Coleoptera, also, have been supposed to af-
ford no instance of species furnished with them; but in the
last number of Germar and Zincken Sommer's Magasm^
it is affirmed that they are discoverable in Gravenhorst's
genus Omalium, but not in the kindred genera Micro-
peplus and Anthophagus ^. Upon examining the former
genus, I find, that although Omalium planum and affi-
nities, O. striafulum, and some others, appear not to have
them, yet with the aid of a good magnifier they may be
discovered in most species of that genus ; as likewise in
Evcesthetus Grav. I find them also very conspicuous in
A. Cai^aboides and other AntJwphagi, but some species
appear to want them. In these insects they are two in
number, situated in the vertex a little behind the eyes but
within them, and either at each end of a transverse furrow,
or at the posterior termination of two longitudinal ones.
Nor are they found in all the genera of the other Orders.
In the Orthoptera^ the Blattidtx, unless a white smooth
spot on the inner and upper side of the eyes may be re-
garded as representing them, have them not ; but in all
the other genera of that Order they are to be found ''.
In the Hemiptera all the Cicadiadcs are gifted with them;
as are likewise Tetyra, Pentatoma, with many other Ci-

* Magas. der Entomolog. iv. 410.

^ Latreille speaks of Phasma as having no stemniata; but it should
seem that he examined only the apterous ones, all the winged indi-
viduals, at least so far as I have examined them, having three very
visible ones. It may, I think, be laid down as a rule, that the larvae
and pupae of Orthoptcra have not these organs. Probably their use
is principally in flying?

EXTKKNAL ANATOMY OK INSECTS. 507

jiiiciiiie, and the lieduviadce very remarkably ; but many
others in both sections of this order, as Thrips, Coccus,
Aphisy Capsus, Miris, Naucoris, Nepa, and Notonecta, &c.
are deprived of them ". Of tlie Neuroptera the Libcllu-
Ihm add stcmmata to their hirge eyes, in the anterior
angle of which they are stationed''; but many other ge-
nera of that Order are without them ; as Mpincleo^i, As-
calap/ius, Hemcrobius, &c. The Trichoptcra and Lcpi-
duptera universally have them ; though in the latter,
except in Cast?iia and tlie Sphingida, they are not ea-
sily seen. In the Hymenoptera they are usuaUy very
conspicuous, but in Larra and Lyrops, two genera of this
order, the posterior pair are scarcely discernible ; and in
the neuter ants they are quite obsolete. In the Dipteral
though many genera are furnished with them, yet many
also want them ; amongst the rest Latreille's Tipularia;,
and all the horse-flies [Tahanus L.). Tlie Pupiparce
[Hippobosca L.) usually have none; but in Ornithomyia
avicularia, one of that tribe, though extremely minute
they are visible, arranged in a triangle, in the })olished
space of their vertex.

As to the Number of the stemmata, three appears to
be most universal. Reaumur mentions an instance in
which he counted four in a fly with two threads at its
tail ; but great doubt rests upon this statement '^. Some
Orthopterous genera, as Gryllotalpa, and many Hemi-

* Flatn phaleenoidcs F. antl affinities have no stemmata, while
Flata rcticulaia and affinities have them : a proof that tlicse tribes
are distinct genera.

b Plate VI. Fig. 10. i.

•^ Reamn. iv. 2A^. He refers for this insect to phite xiv, without
adding any number for the figure j but no such is in that phitc.

508 EXTERNAL ANATOMY OF INSECTS.

pterous, as Tetyra, Pentatoma, JReduvius^, Cercopis,
Fulgora^, &c., have no more than ttsoo; and in Larra
and its affinities, as just observed, the posterior ones are
obsolete, so as to leave only ojie discernible.

Where there are three of these organs, they are usu-
ally arranged in an obverse triangle in the space behind
the antennae, at a greater or less distance from them.
In those male flies (Muscidce) whose eyes are confluent,
the stemmata are in a little area hehind their conflux ;
but, as before observed, in the drone-bee and the Libel-
lulina they are before it. This triangle is in some cases
nearly equilateral, as in Perla related to the may-flies,
and many Hymetioptera ; in others it is aaitangular, as
in Locusta &c., in which the stemma forming the vertex
of the triangle is before the antenna *= : in others, again,
it is ohtusangular, as you will see in Pepsis and vari-
ous Hymenoptera. In the humble-bees {Bombus\ a line
drawn through them would form a slight curve. Their
situation also varies. In insects that have only two,
they are sometimes placed a little behind the eyes, or in
the back part of the space between them : this is the case
with most of the bugs {Cimex L.) that have them. —
They are often distant, as in Tetyra F., JEdessa F.; and
sometimes approximated, as in Rediwius F.'^ In many
of the Homopterous Hemiptera, as Cercopis, Ledra, &c.
they are planted in the upper part of the head ^, but in
lassus their situation is on the imder part ; and in a North
American subgenus, as yet without a name, they are ex-

« Plate XXVI. Fig. 40. i.

'' Cercopis, Ibid. Fig. 42 j and Fulgora, Fig. 41. i.

' Plate VI. Fig. 4. i.

d Plate XXVI. Fig. 40. i. " Ibid. Fig. 42. i

EXTERNAL ANATOMY OF INSECTS. 509

actly between the two, being placed in the frontal angle.
In Fidgora their station is between the eyes and antennae*.
They are most commonly sessile, and as it were set in
the head ; but in some, as Fulgora catidelaria, they stand
on a footstalk. The stemmata are set in the side of a
frontal tubercle in that four-winged fly of threatening-
aspect, Corydalis, which in its perfect state has mandi-
bles, but longer and more tremendous, like those that
distinguish the larva only of the kindred genus Hemero-
bins ^. These organs differ little in shape, being usually
perfectly round and somewhat convex ; but occasionally
they vary in this respect. In Fulgora serrata they are
oblong, with a longitudinal depression ; in F. Diadema
they are also umbilicated, but the umbilicus is circular ;
in Corydalis they are oval; in other insects they are
ovate: in some semicircidar, and in a few triansidar.
They vary much in size: in some of these animals being
so minute as to be scarcely visible, while in others, as
Coi-ydalis, Dorylus, Vespa pallida F., Reduvius, &c. ^,
they are as large as some compound eyes. They difler
also in colour, though often black : in Fulgora laternaria
they are of a beautiful j/eZ/oto,- in F. candelaria they are
'white; in many Hymenoptera they are crystalline, in
others red : the fierce look of Reduvius personatus is ren-
dered more hateful by its stemmata having a pale iris
round a dark pupil '^.

Let us here stop and adore the goodness of a benefi-
cent Creator, who, though he has deprived these little
beings of the moveable eyes with which he has gifted the

» PlateXXVI. Fig. 41.i.

•* De Geer iii. /. xxvii./. 1. Reaum. iii. t. xxxii./. 3, 9.

•^ Plate XXVI. Fig. 40. i.

510 EXTERNAL ANATOMY OF INSECTS.

higher animals, has made it up to them by the variety
and complex structure of their organs of vision, where
we have only two points of sight, giving them more than
as many myriads.

5. Antenna. — But of all the organs of insects, none
appear to be of more importance to them than their An-
tennce, and none certainly are more wonderful and more
various in their structure, and probably uses. Upon
this last particular I shall enlarge hereafter. Their
structure, as far as it differs in the sexes, I fully dis-
cussed in a former letter^; and the most remarkable
kinds of them will be included in a set of definitions
which I shall draw up for you before our correspondence
on this part of my subject closes : I shall therefore now
confine myself to the following particulars — namely, their
number^ insertion^ substance, situation, pi'oportion, general
form and structure, clothing, expansion, motions, and sta-
tion of repose.

As to their Number, in the majority of crnstaceous ani-
mals the antennae amount to four, but no insect has more
than two. A genus recently established ( Otiocertis Kir-
by**) seems to afford an exception to this rule, since the
species composing it at first sight appear to have four,
and in some instances even six antennae ; but as only two
of them terminate in a bristle, the other, though pro-
ceeding from the same bed of membrane, may perhaps
be regarded as merely appendages. Germar, who has de-
scribed a species of this genus '^ under the name of Co-
bax Wintheri, considers these appendages as analogous

•^ See above, p. 318 — . '' lAnn. Trans.xni.

*•' Man. der Entomolos. iv. 5.

EXTERNAL ANATOMY OF INSECTS. 511

to j^ulpi : but as they do not proceed from the oral or-
gans, but from the bed of the antenna at the base of the
nose ', tliey ought certainly to be regarded rather as ac-
cessories to the hitter, than as representing the former.
In the Apt era order the mites {Acaais L.) appear to be
without these organs. In the pupiparous tribe Hippo-
bosca they seem about to disappear ; and in the Arach-
nida &c., as has been more than once observed '', the
mandibula: have been tliought to represent, not indeed
tlie antennae of insects, but the innei' pair of those of the
Cnistacca.

In considering the insertion of antennae, by which I
mean their articulation with the head, we must advert
first to the orifice ( Torulus) that receives them ^. This
is a perforation of the crust of the head; commonly,
though not invariably, circular : in Coleopterous insects
oflen with concave lubricous sides, forming an acetabu-
lum, with processes usual in ginglymous articulations,
larger than the bulb or root of the antennae; and which is
commonly covered, except the central space occupied by
the bulb, with a tense membrane. Though not in gene-
ral remarkable, in some cases it merits attention. In the
genus Rhipicera Latr., the elegant antennae of whose
males I have described in a former letter "*, particularly
the Brazilian species, it is a long process on each side of
the nose, and might be mistaken for the first joint : in
another Coleopterous genus, Priocera K. % it has some-
what of the shape of a trumpet : in Cupes a tubercle rises

* Palpi quatuor, subaequales, cylindrici, ad basin clypci. Germ.

^ See above, p. 18, &c. ''■ Plate VI. Fig. 1, 4. i'.

^ See above, p. 321. Linn. Trans, xii. t. xxi./. 3.

' Ibid./;.

512 EXTERNAL ANATOMY OF INSECTS.

just above the base of the antenna : a circular process
forms the torulus in Fulgoj-a and others. It is also often
placed in a cavity of the front, as in several wild-bees,
Melitta K., and in Locusta Leach on the sides of an ele-
vation of that part *. In a large majority of insects the
bulb [Bidbus) or ball which is received by the bed, wears
the appearance, especially in the Hymenoptera, of a di-
stinct joint; but if you carefully examine it, you will
clearly see that it is merely the base of the scape swelled
out mto a spherical or other kindred form ^ ; and often
marked, as in the Cicindelidcey with impressed points :
as it is the piece by which the antenna moves in its soc-
ket, this form of a rotula was doubtless given for its more
ready motion in all directions. This structure is princi-
pally conspicuous in the Coleoptera and Hymenoptera
Orders : in the others the base is not so distinguished
from the rest of the scape. If you carefully extract the
antennae of a beetle, say a Copris or Lamia, and examine
its base or bottom, you will find that it is open for
the transmission of muscles and nerves ; that in its up-
per margin it has a deep notch or sinus, on each side of
which is a smaller notch ; and that all round the margin,
which is very lubricous, a membranous ligament is at-
tached, by which it was affixed in the torulus. Its arti-
culation, therefore, seems of a mixed kind, like that of
most other organs and parts of insects, partaking of the
ligamentous, ginglymous, and ball and socket. In the

* Plate VI. Fig. 4. c. i'.

'' Plate XII. Fig. 9. 1". This circumstance was very recently
discovered ; which will account for this plate not being quite correct
in this respect, the bulb being represented as a distinct joint in
Fig. 6, 10,20.

EXTERNAL ANATOMY OF INSECTS. 513

Orthoptera, Haniptcray &c. the articulation seems more
purely ligamentous.

With regard to their substance — these organs are re-
gulated, in some degree, by the nature of the integu-
ment of tiie animal of which they arc appendages; in the
softer insects being of a softer substance than they are in
hard ones. The vertex of the joints, where they receive
the succeeding one, appears in many cases to be softer
than the rest of it, and especially towards the apex, oiten
papillose. The antennas are generally opaque ; but in
Ncbria compla?mta, a beetle common on the sea-coast in
Wales and Lincolnshire, they are semitransparent.

The situation of antennaj must next be considered.
In this respect it seems necessary that they should be
so situated as to be under the direction of the eyes : for
if you examine ten thousand insects (except, as was be-
fore observed =*, where there are four eyes), you will not
find one in which these organs are situated either above
or immediately behind them ; their station being always
either somewhere in the space between the eyes or that
below them. In Ptinus F. they are placed near the
vertex; but in Gibhiicm, which is so nearly related to
that destructive genus ^, they are beneath them. In
many Melittce K. they are in the middle of the space
between the eyes ; and in many other Hymenoptera and
Colcoptera [Staphijlinus Sec), in the anterior part of it.
In many Lamellicorn genera, as Melolontha^ Cetonia,
LucanuSi &c. they may be regarded as planted in the
lower surface of the cheek before the eyes ; but in Co-
pris &c., in which they are inserted further under the

•» See above, p. 498, '' Vor.. I. p. 231, 238,

vol. I If, 2 L

fyl-i EXTF.RNAl. AN^ArOMV OF INSECTS.

shield of the head, diey are properly in Uie ^rwi^' surface
of theJ'ro7iL In die Capricorn-beedes {Ceramln/x L.) and
Ciiodalon F. diey may be termed hiocular, or placed in
a sinus of the eye ; in the former tribe in its interior^ and
in the latter its anterior side. In the Rhynchophorous or
rostrum- bearing beetles [Curculio L.) they vary in their
situation. Thus in Macroccphalns Oliv. they are inserted
at its apex ; in Anthribus in its middle, and in Calandra
at its base ^. In the water-scorpions [Nepa, Belostoma,
&c.) they may be called extraocular^ being placed under
the head in its prone part, outside the eyes ''. In A7r-
miis FringiUce, a kind of bird-louse, the}^ appear to be
oral, being situated, according to De Geer, under the
head near the mouth, at a great distance from the
eyes ■=.

In their i^ropoi-tions, both as to length and thickness,
antennae vary extremely. Thus sometimes they are very
short — much shorter than the head; as in the aquatic
beetles Gyrmus, Parnus, and the vi'ater-scorpion ; and
some land-beetles, as Anthrenus^ &c. At other times they
far exceed the length of the insect : the males of many
Capricorn-beetles are so distinguished. In that of Lainia
iedilis they are more than four times as long as the
body ; and every intermediate length between these two
may be found amongst them. They vary also greatly in
thicJcness : in PaussuSi whose antennae emit light in the
night '', and Cerapterus, they are nearly as thick, — at
least their knob, which forms the chief part of them, — as

" Oliv. Ins. no. 80. Macrocephalus t. i./.l — 4.; AMribiisf.5 — 12 ;
and no. 63. Curculio t.iu Calandra f. 16.
^ Schellenberg C/»«V« t. xiv./. 1. h.
' De Geer vii. /. iv./. 7- a a. -' Vor.. II. p. 421,

EXTEUNAL ANATOMY OF INSECTS. 51.5

the body of tlie insect * ; while in MaJitis, Acn'da K. and
Psoais, they are as slender as a hair. The antennas in
many of the Piioni, especially in P. imbi'icornis, are thick
from base to tip; while in other Capricorn-beetles they
are quite the reverse.

It will not be necessary to enlarge here upon the ge-
neral yo;7« of these organs : I shall therefore only notice
the two principal divisions of them in this respect. —
Antenna), regard being had to one of their uses, may be
divided into two sections, distinguished by forms ex-
tremely different: those, namely, that are employed by
insects as factors to exj)lore their way, and those that
cannot be so employe<l. The great majority are of the
former kind ; but those that may be denominated setige-
rons, — as the antennae of the LiheUtilina, Ephemcrina, of
the I lomopterous Hemiptera, and of many Dipiaa, the
last joint of which terminates in a bristle, or is furnished
with a lateral one, and of some gnats that have short
feathered antenna?, — appear not fitted to be used as tac-
tors to explore by touch, and form the latter description.
This difference in these organs, as I shall have occasion
to prove more at large hereafter, furnishes a strong pre-
sumption that their jji-imarij function is not touch. Were
this the case, it would be common to them all.

As to their structure, antennae consist in general of a
number of tubular joints ; each of which having separate
motion, the animal is thereby enabled to give them every
flexure necessary for its purposes. The scape, or first
joint, by means of the bulb inosculates in the torulus, or
is suspended to it; and the others, sometimes by a simi-

» Pi.atj:s Xn. Fio. 28; and XX.V. Fig, !), 24.
2 L 2

516 EXTERNAL ANATOMY OF INSECTS.

lar, though less pronounced knob at their base, inoscu-
late in the preceding one; but in some cases the inoscu-
lation seems not so perfect, the joints being simply sus-
pended by ligament. In pectinated or lamellated an-
tennae, the branch is usually a lateral process of the joint
from which it issues; but in Phengodes [Lampyris plu-
mosa L.) its involute plumose branches appear to articu-
late with the apex of each joint *. I have a specimen
of one of the Cleridce^ of a genus undescribed, in which
each branch is forked. In some tribes of the Capricorn-
beetles {Sie?iocorus, &c.) the antennae are often armed at
their apex with spines, sometimes on the upper side and
sometimes below. In some aquatic beetles [Gyrinus,
Paimus) they are furnished with an auricle at their base,
which, like the lid of a box, shuts them in when unem-
ployed, and protects them from the water ^,

The portions into which antennae may in general be
considered as divided, have been sufficiently explained
to you above ; but it may not be amiss to add here a few
words on the principal variations in their structure that
I have had an opportunity of observing. The scapus '^
or first joint, which includes the hnlhiSy is usually the
most conspicuous joint in the antenna (exclusive, I mean,
of the capitulum, in those in which that organ terminates
in a knob), it being thicker and often longer than the suc-
ceeding ones. In the Capricorn and Darkling beetles,
indeed {Ceramhyx and Tcnebrio L.), the third joint is tlie
longest, but the scape is still the thickest ; and in the
stag-beetles {Lucanus L.), many of the weevil tribes

a Plate XXV. Fig. 4.

" Plates XII. Fig. 29; and XXV. Fig. 28. a.

^ Plates XI. XII. XXV. k .

EXTERNAL AN ATOM V Or INSECTS. 517

(Curciilio L.), and those of tlic bees {Aph L.), except in
the males, it is as long nearly as the remainder of the
antenna?, wliicli forms an angle with it. In shape it is
generally somewhat curved and subclavate, or increasing
in size from the base to the summit; but it is sometimes
straight and filiform, at others oblong or square, at
others again triangular, in several instances three-sided :
in one {Ccfonia crucnta F. Genuchns K.) it is, as it were,
broken, the upper part forming nearly a right angle with
tlie lower ; in Ccrocoma Schccffcri it is foliaceous ; and it
is occasionally suborbicular : and probably many other
forms might be enumerated.

The Pcdicdlus * is the second, and may be deemed the
least €07ispiaions joint of the antennae. Though more
slender than the scape, it is generally thicker than that
which immediately follows it. In broken antenna; it is
the hinge or pivot on which the clavola or upper mem-
ber turns : it is usually very short, campanulate or bell-
shaped, or obconical ; but in a species of bug ( Tetyra,
from New Holland — T. pediccllata Kirb. MS.) it is
nearly as long as all the rest of the joints taken togetlier.
In those species of Lycus, a genus of beetles related to
the glow-worm, that have flattened antennae (as L. reti-
adatus, fasciatiiS) &c.), this joint is almost received into
the socket of the scape, so that their antenna; appear at
first to have only ten joints, but in those which have
those organs filiform (as L. minutus, Amora, &c.) it is
more conspicuous.

The Clavola^, or remaining joints of the antennae
taken together, constitutes the principal part of the or-
gan, which, especially at its extremity, exercises its func-

' Plaifs XI. XII. XXV. r. •■ Ibid, in' .

518 EXTERNAL ANATOMY OF INSECTS.

tions of touch, or any other sense. Tlie principal varia-
tions, as to form and structure, that occur in this part
will be mentioned in another place. I shall only here
observe, that in many instances the first joint of this part
is longer than the rest ; but in Tetijra pcdiccllata just
mentioned, it is by far the shortest, and shaped like the
pedicel of most insects. In the Libellulina^ the Homo-
pterous HemijJtera, and those Hies whose antennas ter-
minate in a bristle, the clavolet is represented by the
bristle. But in the flies which have a lateral bristle, on
the last joint, and those with triarticulate antennae that
have no bristle, the terminal joint represents it. The
clavolet often terminates in a knob, or in several joints
thicker than that which precedes them. This varies
greatly, not only in its form, but also in the number of
joints of which it is composed. Thus in Panssns, Plcitij-
pus, and many Calandnc, it consists of only a single
joint ^ ; in Anlhrenus, Ditoma, &c. of iiioo j in Nitichda,
Geotriipc's, &c. of three ^ ; in Teiratoma, the SilpJiidcc, of
four^\ oi Jive in Scapkidium^; of six in one species of
Languria , of scvcri in the common cockchafer [Melo-
lontha vrdgaris^); of eight in Diapcris Boleti, in which
the whole clavolet forms the club ''; of nine in Ooias; and
te7i in Cerapterus ^. All the above, you will observe, are
beetles. In the other orders there are eleveti joints in the
knob of some butterflies ; twelve in that of Ascalaphus •'
and Mijr77iel eon ; and histly, fourteen in TrachclusK

' PtATKs XII. Fig. 28; and XXV. Fig. 13. m".

" Plate XXV. Fig. 2, 5,21. ni".

<• Plati; XII. Fig. 10. ni". •' Ibid. Fig. 4.m".

■^ Plate XXV. Fig. 1. m". f Plate XI. Fig, 23.

s Plate XXV. Fig. 21. " Ibid. Fig. 30.

' Jurinc Ht^mcnopl. t. \u f. 3.

EXTl-.lfNAI, ANATOMY Ol INSLCT.S. f)\0

Uiuler striuturc also, tlie number of joints ol which
nnteniuc in general consist, should be considered. If
you examine the insects belonging to the difi'erent or-
ders, you will find remarkable variations in this respect,
lyct us run through them : — In the Colcoptcra the na-
tural number of joints is dcvcn ; but this rule is not
without many exceptions. Thus, many havej'tiocr than
the prescribed number : Paussus has only ixvo ", Clavi-
ger and Platypus five, Dorcatoma and Calandra eight *",
Gciiiates K. and Phanecus MacLeay nine ^, and lastly
Mclolonilia ten '*. Others, again, have more than eleven
joints : Cebrio Gigas, Chrijsomela stolido, some Sapcrdec,
and several others, have tioelve. In Prio)ius imbricornis
the female has nineteen^ and the male tweiifi/ '^. lihipi-
ccra marginata has t/rirtj/-ixsjo ,- and in a New Holland
species of this genus I counted ihirlij-eigJit. In the Or-
ihoptcra I can trace no general law in this respect. In
Locusla Leach in some species you may count fourteen
joints, in others sixteen, and in others tiventj/-fx^e. In
one, which appears to be a pupa, I found only thirteen.
In Mantis they exceed thirtj/; but in Blatta, from between
ihirti/ and fort ij, they reach nearly one hundred and^fifty ;
often varying in number in difierent individuals of the
same species. The order Hemiptcra exhibits two pecu-
liar types of antennae, which, with some exceptions, di-
stinguish the two natural sections into which M. Latreille
lias judiciously divided it. In the Heteropterons section
they are xinthout a bristle at their end ; and in the Homo-
ptero2is one, with the exception of Aphis, Thrips, &c.

" Plati: XXV. Fig. 28. •• Il)i«l. Fig. 1.3.

•■ Ibiil. Fig. .">. -i !!ml. Fig. 1.

"■ I'l.ATi: XI. Fig. 13. ' Linn. Tram. xii. /. xxi /". .3.

520 EXTERNAL ANATOMY OF INSECTS.

they have one. In the genera of both these tribes, the
number of joints varies in these organs. Thus, exclu-
sive of the seta, in Fkita and Cixiiis there are only tiao
joints; in Galgulus, Fulgora, and Cercojyis, there are
three; in LygcBxis, Coreus, &c. there are Jour ; in Tctijra,
Pentatoma, Tettigonia, there are^w*; in Aleyrodes there
are six ; in Aphis seven ,- in Thrips eight ; in Psylla ten,
the last of which is terminated by two bristles''; and in
Coccus eleven. The Neuroptera order, as it stands at
present, is regulated by no general rule with regard to
the number of joints in the antennas of the insects that
compose it. Several types of form in these organs distin-
guish its discordant tribes. The^;-^^ is that of the Ephe-
mercB, in which the antennas consist of two short joints,
crowned by a short, tapering, u?ijoi7ited bristle. The second
is that of the Libellidina^ similar to the above, but with a
jointed bristle. The third is that of Psocus, in which the
antenna has two short thick joints at the base, terminated
by a long filiform bristle, consisting of seven or eight
joints, and finer than a hair. Perhaps these three may
be regarded as belonging to a common type. The fourth
type is presented by the short filiform antenna? of Ter-
mes; theJiflh by the setaceous ones of Corydalis, Heme-
robius, &c.; and the sixth and last by the clavate and
capitate ones of Myrmeleon and Ascalaphus. In the
Licpidoptera and Trichoptera orders the antennae, though
varying in their general form in the three tribes of which
Linne formed his genera Papilio^ Sphinx, and Phalana,
with the exception of Hepialusy in which the joints are

'' Latreillc says six, but onXy Jive arc discernible ; the three last
form a kind of bristle.
^ '' I'Str. Fourmis, 323o

EXTERNAL ANATOMY Ol" INSECTS. 521

lew, arc always miiUiarticulatc : — wc will therefore, with-
out further delay, proceed to the Ilijmeiioptcra. In La-
treille's tribe Aculeata the general rule is, that the fe-
males shall have fivche joints and the males thirteen.
In his Ichncumoiiides the law seems to be, that the an-
tennae shall be multiarticulate and setaceous; but in most
of the other tribes of the order, even those that in other
res[)ects are most nearly related, — as in his Tcnthredinc-
tcv, — the number of joints of these organs varies without
end. Thus in Hijlotoma there are only thi'ec joints * ;
in Cimhcx Iceta^Jivc; in C axillcais and Pcrga Leach "=,
six : and so on to twenty-five or more ''. The same fluc-
tuation in this respect runs throughout the rest of the
order. In the Diptcra there are two general types of
antenna2 : — those of the Tijmla7icc Latr., consisting usu-
ally of h'om Jhurtee7i to sixteen joints, in the males often
resembling beautiful plumes ; and those of the remainder
of the order, in which they do not exceed ///r<7^ joints*:
though the last, or patella, is often further divided into
obsolete or indistinct ones ^. These antenna? may be
further subdivided into Jilatce and aristata^ or those
without and those with a bristle, either lateral or ter-
minal.

The clothing of antennae also merits attention, since it
is often not a little remarkable. By clothing I under-
stand the do'-jon or hairs of every kind with which they
are either generally or partially covered. A grsat number
of filiform aud setaceous antennas of Predaceous beetles
{Cicijidcla L., Carabus L.) have the first two, three, or

* Jurine Hymcnopt. I. v'l.f. 3. '' Ibid.f. 2.

- Ihid.f. 1. Plate XXV. Fig. 7- ' Plate XXV. Fig. 25,26.

' Plate XII. Fig. 1G— 22. ' Ibid. Fio. 19. a.

522 EXTERNAL ANAT031Y OF INSECTS.

four joints naked, and die rest covered wiUi a fine down.
In insects that have a knob at the end of these organs,
whether lamellated or perfohate, this down is often con-
fined to it, or to its intermediate joints, and seems inter-
mixed with nervous papillae. These are particularly vi-
sible in the flabellate antennae of RJiipicera, Lampyris
Latrejllii ^, Elater Jlabellicornis ^, &c. covering both sur-
faces of the processes of the joints. In some male bees
these papillae are inclosed in hexagonal spaces into which
the antennae are marked out*=. It is to be observed,
that in many antennae the jouits of the clavolet have one
or two bristles or more at their apex, one above per-
haps, and one below ; the lower angle in those of the
serrated antennae of Elater is usually so furnished, and
sometimes the upper. In many Capricorn-beetles and
various insects the antennae are clothed, instead of down,
with stiffish hairs or short bristles. Other insects have
these organs, at least the clavolet, beset with longer hairs
standing out from them on all sides: of this kind are
those of a singular beetle [Sarrotrium mutictim) some-
times found in tliis country'*. Again, there are some
that have only their underside bearded with longer hairs;
as Lamia cwculionoides, spcculifera K., and other Ca-
pricorns ^. In another of this tribe, Sapcrda Jtirsutkor-
nis, the three intermediate joints are ornamented with
branches of long black hairs, which give them an elegant
and feathiJry appearance *. In Callichroma alpina the

" Linn. Trans, xii. {. xxi./. 3, 4. Plate XXV. Fig. 11.

" Plate XI. Fig. 17.

•• Kirbv Mon. Ap. Angl. i, M6\. i. x. **. d. 1. f. 8.

•' pLATr, XXV. Fig. 2;. ' Plate XII. Fig. ;:(i.

» Pi.AXL XXV. Fig. 32.

EXTEUNAI. ANATOMY OT IN.SCCTS. 5'2:i

apex oi the slute-coloiucd joints ot its antennae is bearded
witli black hairs. In Lamia reliadata, and Sapcrda
fasciadata and plumi<icra, all also Capricorns, a single
bnnch of hnirs, reseniblinj!; the brush of a bottle-cleaner,
signalizes the middle of the antenna*: in Sapcrda sco-
pulicornis K. this is star-shaped ^. Sonietiines the scape
is externally bearded, as in Trox, a beetle found in horns
and bones ; and in many other Lamellicorns '^. In this
last tribe the two exterior leaves of the knob of the an-
tennae are often set with short bristles '^ ; and in a minute
beetle called by De Geer Dermcstcs atoma?-ius, the hairs
of this part are said to form a brush ^.

When insects, I mean more particulai'ly Colcoptcra^
are about to move from any station where they have
been at rest, the first thing they usually do, before they
set a step, is to bring forward and crpatid their antenna.',
which have either been carefully laid up in a cavity fitted
to receive them, or back upon, the body : if they termi-
nate in a lamellated knob, tliey separate the lamellae as
far as possible from each other; or if it is perfoliate, the
joints of it mutually recede. The object of this is evi-
dently to collect notices from the atmosphere, since the
papillose part of these joints cannot be applied to sur-
iiices. When the animal begins to move, in many cases
the antennae do the same, and continue their motion till
it stops and returns to a state of repose. In the parasitic
tribes of the Hymenoptcra [Ichneumon L.) they are kept
in an almost constant vibration. Many other insects
move them in all directions without any order or regu-

" Platk XII. Fig. 25. '• Plate XXV. Vh.. 17.

' Linn. Trans, xii. I. xxiii./. .'»./. ' Ibid. t. xxi /. 8 ,g. 9, 10. c.

' Dc Gter iv. 21[). /. viii./. 20.

524- EXTERNAL ANATOMY OF INSECTS.

larity ; and otherS; when they elevate one depress the
other, and so proceed as if balancing themselves by
means of these organs like a rope-dancer. I have before
stated to you how by motions of their antennae, ants and
bees communicate their wants or discoveries to each
other, or make inquiry concerning any thing they vv^ish
to know ^. But as I shall have occasion to make some
further remarks upon tliis subject, when the senses of
insects are under discussion, I shall for the pi'esent take
my leave of it.

I shall conclude what I have to communicate to you
relative to the organs of which we are treating, with a
few observations with respect to their station when the
insect reposes. In the Capricorn-beetles, JLucera and
other insects with long antennae, they are merely turned
back or on one side with no particular cavity for their re-
ception when unemployed, but probably the apex passes
under the body. In the Predaceous and Darkling bee-
tles {Carabush. Tenebrio L.) their station is usually un-
der the sides of the prothorax^ and in the Tortoise bee-
tles {Cassida), under its anterior margin. In the Elastic
beetles (Elater) they are received into a groove between
the under margin of that part and the fore-breast {ante-
pectus). In Anthrenus, when the animal reposes or
counterfeits death, the antennae are concealed in a ca-
vity of the underside of the prothorax^ at right angles
with the throat''. In the kindred genus Byrrhiis, another
simulator of death, a large cavity is excavated under the
same part, to receive both the forelegs and antennae, a
narrow space being left between the angle of the pro-

» See Vol.. II. p. 65, 201— " De Gcer iv. i.yW.f. 22.

EXTERNAL ANATOMY OF INSECTS. 52.'i

thorax and i'ore-brcast exactly a<linilting tlie base of the
latter, which are quite concealed under the former. In
Crypt occphalus and Chlamys^ kindred beetles, when at
rest they are withdrawn, except their scape and pedicel,
with the head within the cavity oi \\\q. protliorax. In
others they are turned under the head, without any par-
ticular cavity for their reception; as in many moths,
Ayion^ &c. In most of the Lamellicorn beetles their sta-
tion is in the cavity formed by the eye and the throat,
the knob forming an angle with the rest of the antenna.
In Heteiocerus they follow the contour of the eye *. In
B7-cnt7is, a genus of weevils remarkably long and slen-
der, they arc turned back and received by a slight longi-
tudinal cavity of the rostrum ; but in those of this tribe
{Curailio L.) in which the clavolet forms an angle with
the long scape, this latter part, bending back, is laid up
in an oblique channel of that part; and the former,
pointing in the contrary direction, is folded upon it. In
many flies [Muscidcc) a vertical frontal cavity receives
the antenna}, which point downwards during repose^.
Cryptocei'tcSj a very remarkable ant, has on its head a
singular square plate, the sides of which form a deep
longitudinal cavit}': in this cavity the antennas, quite
concealed, repose in safety. A cavity equally remark-
able is exhibited by the water-scorpions, particularly
Belostoma, in which is a very deep kidney-shaped box,
between the eye and throat, to receive and defend its
singular antennae "^ ; which, when they are reposing, is
closed by the exterior harder joints, and from which it
seems as if they turned out, like a sentinel out of his box,

• Plate XXV. Fig. .'J5. " Dc Goer vi. /. \.f. 5.

" PiAxr. XI. Fig. 21.

526 EXTERNAL ANATOMY OF INSECTS.

In some aquatic genera of beetles, as Gijrimis, Parnus,
&c. they are withdrawn within a lateral cavity of the
same part, and are defended from the water externally
by the auricle at their base ^. The flabellated and la-
mellated antennae, previous to their being folded for re-
pose, close all their plates; which in action are as widely
expanded as possible, so as to form a knob; and in some
the middle piece is entirely concealed, as if in a box.
In broken antennae, or those in which the clavolet forms
an angle vv'ith the scape, the former is folded upon the
latter, with its point downwards.

II. Subfacics. — Having dispatched the Fades, or up-
per side of the head, I am next to consider the Sub-
facies, or iinder side : but as the principal parts that oc-
cupy this side have been already considered, I shall have
no occasion to detain you long.

i. Jiigulum ^. — This part, which may be regarded as
analogous to the throat in vertebrate animals, lies between
the cheeks ; from which it may usually be distinguished
by being more lubricous and tumid, and often separated
by an impressed line. It is particularly conspicuous and
elevated in the Lamellicorn beetles, and calculated by its
lubricity for easy motion in the lower side of the cavity
of the chest. Its apex is the base in which the mentum
sits. It is not necessary to enlarge further upon it, as it
seldom exhibits striking characters.

III. Collum '=. — In a large proportion of insects the
head inosculates in the trunk without the intervention

' Plate XII. Fift. 29. a. ^ Plate VI. m. • Ibid.

EXTERNAL ANATOMY OF INSECTS. 527

of a neck, or a constriction of the head behind. In tlie
Orders Ortltoptera, Trichoptcra^ Lejndoptcra, HymeiiO'
ptcra, and Dipfcra, no instance of it that I recollect oc-
curs : in the Colcoptera there are many. In the Preda-
ceous beetles, though several have no distinct neck, yet
others, as Anfhia, &c. liave a short and thick one ; and
some few, as Colliuris, Agra, &c. one more pronounced.
Latreille has named a tribe in this Order TrachcUdcs,
from the circumstance of their havhig a neck: in this
tribe you will find the blister-beetles {Cantharis and M}j~
lahris) both of the moderns and the ancients. In the
Haniptcra order the water-scorpions Nepa, &c. Iiavc a
thick short neck; and Zelus, (a kind of bug,) one longer
and more slender; and, like RapJiidia, the snake's-head
fly, which is similarly circumstanced, has the air of a
serpent. Other Ncuroptera, likewise, have a neck; as
Hcmciohius, Corydalis, &c. This part presents no other
features tliat merit notice.

IV. Myoglyphidcs *. — The Myoglyphidcs, or muscle-
notches, are sinuses, some shallow and some deeper, in
the posterior margin of the upper side of the head, to
which the levator muscles are affixed. They seem prin-
cipally confined to the Colcoptera; though, in some
cases at least, they may be traced in the Heteropterous
Hemiptera. These notches vary in number and depth
in different insects. Thus in Buprcstis there is only 07ie
deep one'': in Copn's there are two shallow ones, in a
deep sinus separated by a small prominence ^ : in Elater
and Lamia there are also two not in a sinus ; and in Ca~

•' Platk XXVII. Fir,. 1, H— 5. n'. " Ibid. Vio. 3.

'■• Ibid. Fig. 4.

528 EXTERNAL ANATOMY OF INSECTS.

landra Palmarwin there are four, two on each side, with
a prominent lobe between them ^. To each of these
notches, at its under margin, below the ligament that
unites the occiput to the trunk, a muscle to raise the
head is usually attached.

» Plate XXVII. Fig. 1.

LETTER XXXV.

EXTERNAL ANATOMY OF INSECTS,

CONTINUED.
THE TRUNK, AND ITS PARTS AND ORGANS.

xTLS the head of insects is the principal seat of the organs
of sensatio?ii so is the 17-U7ik of those of niotion ,- and in it
are contained the muscles by which they are moved : it
may therefore be regarded as the great centre of motion,
and as the main support and prop of the two other pri-
mary sections of the body — the head and abdomen, be-
tween which it is situated — it may be deemed the most
important part of the insect, the key-stone of the whole
structure. In treating upon it, for the greater clearness,
I shall consider its subsiafice, general form, proportio7is,
composition, internal processes, and members. It will first,
however, be necessary to assign my reasons for the no-
menclature of its parts that I have adopted.

Had the entomological world been universally agreed
upon this subject, and there was an established system
of Orismology ^, I should have proposed no alteration
without great reluctance, and the fullest conviction of the
absolute necessity of some change; but as the standard

'^ For the reason which induced the autliors to use this word in-
stead of Terminologi/, before employed, see Vol. I. Pre/, p. xii — .
They are gratified to see tliat M. Latreille has adopted this term in
the work quoted on the other side, p. 194.

vor,. nr. 2 m

530 EXTERNAL ANATOMY OF INSECTS.

of language in our science is still unsettled, and different
terms are used by different writers, tliere seems full li-
berty left to me to select those that appear upon the
whole most appropriate ; and where proper and signifi-
cant terms seem wanting, to invent new ones. M. La-
treille, in a late Essay *, has proposed many changes of
this kind, and seems to hesitate concerning the adoption
of some of those recently coined in France for the parts
of the trunk ^ ; it may therefore, I think, be permitted
me to labour a little in this hitherto imperfectly cultured
field, and to suggest such improvements as the subject
may seem to require or admit.

Linne called the part we are now considering the
trunks its upper-side he usually denominated the thorax,
and its under-side the breast : he notices also the sciitel-
liim and sternum ^. As the ])rotkorax and scutellum are
the only apparent parts of the back of the trunk in his
first Orders [Coleoptera, Hemiptcra L.), the rest being
covered, in noticing these he puts the part for the whole,
calling the prothorax the thorax, but which strictly was
not synonymous with what he called by the same name
in the other Orders. Linne's phraseology with regard to
the trunk of insects was adopted by Fabricius and other
Entomologists, till Illiger employed the term thorax to
designate the whole of the trunk'', calling the upper part
thorax superior and the lower thorax inferior. M. De
Blainville, M. Latreille, and other French writers, im-

" Organisation Exterieure dcs Insectes, Mem. clu Mas. t. viii,

^ Ibid. 199 — . I have never been able to procure M. Audoin's
Memoire on this subject.

■^ Fundament. Entomolog. in Amoen. Acad. vii. 14.'i.

'' Terminologie, \b7'r^, &c. He afterwards called the trunk ^/f-////-
diian: Ternmiofogie der In.ieAfen Ma<iaz. 1800, 14.

EXTEU.VAL ANATO.WV OV IN.SF.( Ts. 531

proved upon this, naming the upper part the l)ack {</ur-
siifti), and the h)wer the breast {pectus); and dividing the
trunk, or accorthng to them thorax^ into tliree sections,
each bearing a pair oi' legs. But I see no sufficient reason
for this aheration — the terms triinh^ thorax, and breast^
in the common acceptation are well understood, and lead
to no confusion or glaring impropriety ; I shall therefore
adhere to the old phraseology, especially as PVench En-
tomologists in popular language still do the same.

As to the division of the trunk into segments by M. La-
treille and others, it has been regarded as consisting of
three primary ones, which have been called in the order
of their occurrence, reckoning from the head — prothorax,
mesothorax, metathorax. The first of these segments,
however — and the learned Entomologist just named seems
to hint as much* — is usually more distinct from the other
two, than they are from each other. If this idea be cor-
rect, the trunk is properly resolvable into two primary
segments, the first bearing the arms or fore-legs, and the
other the proper legs and the organs of flight. M. Cha-
brier calls the latter tronc alifere, or wing-trunk; — a
happy term, which I have adopted and latinized, call-
ing it the alitrunk [alitriincus): the first segment, because
it bears the fore-legs, I have named manitrunk {mani-
tnincus). I adopt likewise the terms above mentioned,
prothoi'ax, mesothorax, metathwax, to signify the three
segments into which the thorax of Linne, or the upper
side of the trunk, is resolvable ; and those of the breast
I denominate antepectus, mrdipectus, and postpectus. If
terms be thought necessary to designate the two intire

' O/oyiinsnfioi/, -Sf. 1 1)8.
2 M 2

532 EXTERNAL ANATOMY OF INSECTS.

segments into which the alitrunk is resolvable, the first
may be the meditrunk {rneditruncus)^ and the other the
potrunk (potruncus).

I. Substance. — With regard to its substance, the trunk
in general is softer than the head, and harder than the
abdomen, especially as to its upper surface ; but in some
cases, where it is not protected by the elytra, as in the
rove- beetles [Staphylinus L.), the abdomen appears as
hard as the trunk. Though usually not very different
from the elytra in this respect, in Meloe, Lytta, and other
vesicatory beetles, it is of a firmer consistence.

II. General Form. — In the Coleoptera Order the only
part of the trunk that is visible on its upper-side is the
prothorax : the mesothorax, with the exception of the scur-
tellwn, and the metathorax, being entirely concealed by
it and the elytra; so that, with regard to shape, it may
nearly be considered as merging in the prothorax. Be-
low it is more visible, and may be stated as more or less
quadrangular ; in oblong beetles inclining to a parallel-
ogram, and in shorter or hemispherical ones to a square.
In the majority it is more convex below than above, except
in the case of the hemispherical or gibbous beetles [Coc-
cinella, Erotylus, &c.), in which the under-side is flat and
the upper-side very convex. In the T>iurnal Lepido-
ptera the trunk approaches to a cubical shape, in the
Nocturnal it is more spherical. A similar difference ob-
tains in the Hymenoptera and Diptera : in the bees,
wasps and flies, the trunk appi'oaching to the figure of
a sphere; in the ants, Scolice, crane-flies, &c. to that of
a cube. The upper part of it in many Ichneumonidcef

LXJKIINAI. ANAIO.MY Ot INSECTS. .553^

female ants, &c. is very elevated, t'orming an arch, and
sloping towards the abdomen. In general it may be ob-
served with respect to the remaining Orders, that the
form of the trunk merges in that of the whole body, the
tendency of which is often to a tlnee-sided figure.

III. Proportions. — The trunk is usually longer and
larger than the head and longer than the abdomen, but
not wider : but there are exceptions to both these rules.
In ColliuriSi Mantis^ &c., it is more dender ; and in Atta
viegacephala and some neuter ants, it is shorter than the
head; in Atractocerus, many Staphj/linida, Phasnia, the
Libelhdina^ the Lepidoptera, and various Hymenoptera,
it is shortei', and in the Mantida; more slender than the
abdomen. The greatest disproportion between it and the
last part is exhibited by the genus Evania^ parasitic
upon the Blattce, in which the abdomen appears merely
as a minute and insignificant appendage of the trunk.
The vertical diameter of this part, almost without ex-
ception, is greater than that of either head or abdomen.
When we consider that it contains the muscles that move
both the organs of flight and the legs, we see clearly the
reason why the Creator gave it greater volume.

IV. Composition. — I lately intimated to you that the
trunk, though resolvable into three segments, in most
cases properly consists of only two primary ones. Who-
ever examines the perfect insects of every Order, except
the Aptera ^, will find this distinction strongly pointed

* In Xirmiis Aiisens,&:v, however, in this Order, the same distinc-
tion is obscrviible.

T»3i! EXTERNAL ANAIOMY Ol' INiSECT^.

out, not only by the diflerent direction of the first pair of
legs from that of the two last, but also in a large pro-
portion by a deep incisure ; and in all it is further mani-
fested by the anterior segment having a motion distinct
from that of the rest of the trunk, and separating readily
from it ; and this not only where it is large, as in insects
that have a thoracic shield, but also in those in which
the prot/iorax is less apparent : whereas the other two
pedigerous segments have little or no distinct motion,
will not readily separate from each other, and in some
cases exhibit no pectoral suture between them. Some-
times, however, these two last segments are more promi-
nently distinguished : in Lytta, Mylahris^ and other ve-
sicatory beetles, they are separated below by an incisure,
or rather the first or mid-leg segment, is not nearly so
elevated as that of the hind-legs. In some ants {Atta
Latr.), in the neuters, there is no distinction of segments
in the trunk; but in others {Formica Latr.) it follows the
general law, and consists of three. In the AracJmida,
widi the exception of Galcodes, in which the head is di-
stinct, and the three segments of the trunk may be traced,
these parts together form only a single segment. In-
duced by these reasons, I consider the trunk as consist-
ing in general of two jirimary segments, the manitrunk
and alit'nmk .- the latter resolvable into two secondary
ones.

* ManitrtmcHs ^. — The manitrunk, then, is the ante-
rior section of the trunk, which bears the arms and con-
tains the muscles that move them. This part has free
motion, or a motion independent oi" that of the rest of the

' Plau-s VIII. & IX. ff.

KXTEUNAL ANATOMY OT INSICCIS. 535

trunk. This indeed seems a necessary result of tlic di-
rection and uses of the arms. It consists of an upper
and lower part — the proihorax and aiUcpectns.

i. Prothonix^. — The upper part of" the manitrunk in
the Coleoptera^ Orthoptera^ and Hemiptera, is by far tlie
most conspicuous part of the trunk, but in the other Or-
ders it is less so. With respect to it, insects may be di-
vided into two classes — those that have and those that
have not a, p)rothorux. In the Coleopteia Order it is re-
markable both for size and variations in its shape and
sculpture. In the Otihoptera^ though less various, it
is almost equally conspicuous, especially in Blatta. In
the Homopterous section of the Hemiptcra, in many ge-
nera it has become extremely short ; while in the Hcte-
ropterous section its dimensions are not much reduced.
Ill the majority of the Neuroptcra, likewise, it is compa-
ratively large; in the Libellulina much shorter, and in
the Trichoptcra and Lepidoptera nearly evanescent ''. —
In the Hymcnoptcra and Diptcra, with very tew excep-
tions, the thoracic shield altogether disappears, at least
if I am correct in an idea, which I shall hereafter explain,
that the collar usually regarded as the analogue of the
prothorax, is really a part of the alitrunk. In these last
Orders, though there is no true protlimax^ the mani-
trunk still remains under the form of an antepectus,
bearing the fore-legs, and containing the muscles that
move them.

The prothorax of insects may in general be considered

• Platf. VIII. a.

'' If the head of aiij' iiKlividual of these two Orclcrs be carefully
taken oH', it will be found that above tiicre is a very short piece rcprc-
sentinjz \\\q prothorax, and quite unlike the collar of Hymen(yplcrn.

536 EXTERNAL ANATOMY 01' INSECTS.

with respect to its parts^ margin, appendages, shape,
sculpture, clothiiig, and proportions.

1. The prothoraa; regarded as a whole, distinct from
the antepectus or fore-breast, consists commonly of ^wo
pieces — the shield, or upper part *, and the 07'a, or under
part ''. In the shield you are to observe its apex^, hase^,
sides ^, limb^, and disk^. The apex is the part next the
head; the base that next the abdomen; the limb the cir-
cumference, and the disk the central part. In many Oi-
thoptera and Heteropterous Hemiptera, the shield ap-
pears further to consist of two pieces, an anterior and
posterior one. The ora is a continuation of the shield
below the lateral margin, turned downwards and in-
wards towards the fore-breast, and the legs, but separated
from the former in most cases by a suture, as in Cara-
bus L. ; and in others merely by an impressed line, as in
Blaps F. ; but in Curculio and Cerambyx L., &c. there is
no ora, the shield being without a lateral margin, and
forming one piece with the antepectus. The part we are
now considering varies in different genera. Sometimes
it is very narro^w, as in Scarites ; at others very broad, as
in Buprestis, Nepa, &c. In Lampyris, except L. italica,
and affinities, it projects posteriorly into a lobe or tooth,
which forms a right angle with the rest of the ora, and
becomes the lower part of the cavity that receives the
head ; and in Dermestes this part is excavated into an
anterior and posterior one which admits the antennae and
arms when folded for repose.

2. The margin of the prothorax is a ridge, either de-

» Plate VIIL Fig. 1. ^ Ibid. Fig.^. a.

^ Ibid. Fig. 1, 10, a. •' Ibid. b.

* Ibid. c. f Ibid. b. ' Ibid. n.

EXTERNAL ANATOMY OF INSECTS. 537

filling iti sides or wliole circumference. In many cases
this margin is broad and dilateil, but in others it is merely
a thread or bead that separates the shield from the ora.
Though generally terminating the upper surface, it some-
times, as in Staphxjlinns.) dips below it. In many insects,
however, as I just observed, the thoracic shield has no
lateral margin whatever.

3. Various and singular are the appendages with which
the prothorax of numerous insects is furnished. Many of
these are sexual distinctions, and have been before de-
scribed to you * ; but there are others common to both
sexes, the most remarkable of which I shall notice. —
Some are distinguished by a long horn which overhangs
the head, as Membi'acis cultrata, ensata, &c. ''; in others
it stands upright, as in Centrotus spinosm^i C Tau-
rus has a pair of thoracic horns like those of a bull,
only dorsal '^ ; in Ledra aurita they are flat, and repre-
sent ears *; in some species of Tingis ( T. Echii, Pyri, &c.)
a kind of reticulated hood, resembling lace, is elevated
from the anterior part of the prothorax^ which receives
and shelters the head ^. In Centrotus globularis and cla-
vatus F., especially the former, the part in question is armed
by a most singular and wonderful apparatus of balls and
spines, — in one case standing erect s, and in the other be-
ing horizontal '', — which gives these animals a most extra-
ordinary appearance. In many of the species here quoted

* Seeabove, p. .327— .

•» Coquebert Illustr. /c. 2, <. xviii./. 2, 4.

-■ Stoll Cigales t. xxi./. 116. " Ibid. t. \\.f, 5.3.

* Plate II. Fig. 4. f Plate XIII. Fig. 18. a.
■? Stoll Cigales t. xxviii./. 1G3.

•" Ibid, I. xxi./. llo. CoqiieberL Illiut. Ic. ii. /. xviii./. 5.

538 EXTERNAL ANATOMY OF INSECT.S.

the prothorax is producted posteriorly into a long scu-
telliform horizontal horn, which more or less covers the
wings and abdomen ; a circumstance which also distin-
guishes the genus Acrj^dhitn F. [Tetrix Latr.). This
horn seems to have been sometimes regarded by Linne
and Fabricius as a real scutelluni, and sometimes only as
a process of the prothorax : but that it is merely the
latter will be evident to you, if you examine carefully
any insect furnished with this appendage ; for if you re-
move that part, you will discover the true scutellum and
other parts of the trunk concealed beneath it. A very re-
markable prothoracic appendage is exhibited by some
species of Mantis. In genei'al the part we are treating
of in this tribe is very slender ; but in M. strumaria, gon-
gyloides, &c., it appears dilated to a vast width, and as-
sumes, either partially or generally, a subrhomboidal
form ; but if it is more closely examined, it will be found
that the form of the prothorax is really similar to that of
the rest of the tribe, but that this part is furnished on
each side, either on its whole length or anteriorly, with a
large membranous flat subtriangular appendage resem-
bling parchment ^. Perhaps this kind of sail may be useful
to the animal in flight. In PrioJius coriarius &c. its sides
are armed with teeth, and in maxiy LamicE^ Cerambyces, and
other Capricorn beetles, and ofl;en in various bugs {Pen-
tatoma Latr.) with sharp fixed spines. But the protho-
rax has moveable as well as fixed appendages ; of this
kind are those spines {umbones\ whose base is a spheri-
cal boss moving in an acetabidum of the thoracic shield
of the Capricorn subgenus Macropiis Thunb. If I might

•' StoU Spectres I. \\.f. 42. I. xii./. 45. /. xvi./. 58, 55).

EXTERNAL ANATOMY Ol- INSECTS. 539

hazard a conjecture, I should say tluit dicse organs were
given to this animal by an all-provident Creator, to en-
able it to push itself forward, when in the heart of some
tree it emerges from the pujia, that it may escape from
its confinement. Another kind of moveable appendages
are attached to the thorax of Lepidoptcra, usually in the
form of a pair of concavo-convex scales covered exter-
nally with a tuft of hairs ". M. Chabrier, who examined
these scales in recent insects, describes them as vesicles,
which appeared to him full of a liquid and of air, and ca-
pable of being alternately inflated and rendered flaccid ;
he regards them as accessories to a pair of spiracles,
which he looks upon as vocal '', opening into the mani-
trunk just above the insertion of the amis. These or-
gans are quite distinct from the tegulic that cover the
base of the primary wings of insects of this Order '^, and
are what, borrowing a term from Mouffet '^, I have called
in the table patagia, or tipjiets. Under this head I may
include the caruncles at the anterior angles of the p70-
thorax of a genus of beetles with soft elytra, named by
Fabricius Malachius. When pressed, says De Geer
of these insects, a red inflated soft vesicle, of an irregu-
lar shape, and consisting of three lobes, emerges from
the thorax and from each side of the anterior part of the
abdomen, which re-enters the body when the pressure is
removed *^. M. Latreille seems to think that these vesi-
cles have some analogy with the poisers of Diptera and

' Plate IX. Fig. 4.

'' Sur Ic Vol dcs Ins. c. vii. 371. /. xviii./. 1). i i.

'■ Plate IX. Fig. 5. "* T/uvtlr. Ins. 1)8.

' Dc GetT iv. 74.

SAfO EXTERNAL ANATOMY OF INSECTS.

the pectens of scorpions ; and that they are connected
with the respiration ^.

4t. We are next to say something upon the shape of
the prothm-ax. The forms of the thoracic shield, espe-
cially in the Coleoptera, are so various, that it would be
endless to aim at particularizing all ; but it may be use-
ful to notice a few of the most remarkable. The pro-
thorax of Moluris, a darkling-beetle, approaches the
nearest of that of any insect to a spherical form, from its
remarkable convexity ; in the vfhe.Q\-h\i^ [Reduvius ser-
ratus) it is compressed, and longitudinally elevated into
a semicircular serrated crest : it is crested, also, in many
LocustcB and Acridce, in some having two parallel ridges;
but, generally speaking, its surface is more depressed.
In Necrodes it is nearly circular, in Blatta petiveriana
semicircular, in Nilion and some Coccmellidce crescent-
shaped, in Carabus obcordate, in Cantharis and Sagra
approaching to a square, in La7ig7iria to a parallelogram ;
in many Cimicidce, Belostoma, &c., it is triangular, with
the vertex truncated; it is trapezoidal in Elater, in Ateu-
chus rather pentagonal, and exhibiting an approach to
six angles in some other beetles ^ : but the prothorax
most singular in form is that of some species of M. La-
treille's genus Helceus '^, as H. perforatus^ Brownii, &c. :
in these its anterior angles are producted, and curving
inwards, lap at the end one over the other, so as to form
a circular orifice for the head, which otherwise would be

■■' Organisation Exterieure des Ins. 177-

•> A subgenus, related to Lebia {Hexagonia K. MS.) and some Ci-
mic-idce, are so circumstanced.
'\Regne Animal iW. i. xiii./. 6.

EXTERNAL ANATOMY OK INSKC'I'S. 541

quite covered by the shield. Tlius the upper portion ot"
the eyes can see objects above, as well as their lower por-
tion those below. I might enumerate many other forms,
but these are sufficient to give you some notion ot" the
variations of this part.

5. The -prothorcux is equally various in its sculpture ;
but since in the Orismological table almost every instance
of it has its place, I shall here only notice it as far as it
is common to the whole tribes, genera, or subgenera.
The ScarabdeidcB of Mr. W. S. MacLeay are distin-
guished by a small excavation on each side of this part,
which, as has been before remarked ^, furnishes an ele-
vated base for an internal process with which the ante-
rior coxcc ginglymate. In Onitis and PhancEus, to these
excavations are superadded a pair impressed in the base
of the prothorax, just above the scutellum ; in Carahiis L.
a longitudinal channel divides the thoracic shield into
two equal portions ; and many genera of that great tribe
have in addition, at the base on each side, one or two
excavations or short furrows. Elophorus F. has on this
part several longitudinal channels, alternately straight
and undulated. Generally' speaking, in Carahus L. the
prothorax has no impressed points ; but in one or two sub-
genera o{ Harpalida: {Chldcnia &c.) it is thickly covered
with them. In numbers of Locusta Leach, the part we
are considering is what Linne terms cruciate^ being di-
vided into four longitudinal portions by three elevated
lines, the intermediate one being straight, and the late-
ral ones diverging from it both at their base and apex, so
as to form a sinus or angle ''. In certain Acridce K.

* See above, p. 398. ^ Pi.atf. XIII. Fig. 17.

542 EXTERNAL ANATOMY OF INSECTS.

[Locust a F.) there are only two of these lines or ridges,
but notched or toothed ; and in some of the genus first
named only one *; in Lomsta Dux and affinities \heprn-
thorax has several transverse channels or rather folds ^,
with corresponding ridges on its internal surface.

6. With respect to the clothing oHhe prothoraXf I have
not much to say : in Coleopterous insects this part is com-
monly naked; but in some genera, as Bi/rrhus, Anthrenusy
DermesteSf and many weevils [Curcidio L.) it is partially
or totally covered with hairs or scales. In the other tho-
racic Orders it is usually naked, but in some Ncuroptera^
the Mi/nneleo7iina, &c., it is hairy; and in the Libellulina

" it is fringed posteriorly with hairs.

7. As to its relative proportions^ theprothorax is some-
times rather wider than the rest of the trunk and the
head, as in Onitis^PasimacJms, &c.; it is considerably nar-
rower in Collyuris and Odaca?itka; and of the same width
in those Scaj-itidce with striated elytra *=. Again, it is
sometimes of the same width with the elytra, but wider
than the head, as in Hydrophilus, Dytiscus, &c. ; in some
instances it is of the same width with the head, and nar-
rower than the elytra, for instance in Anthia and Bra-
chinus. In most Coleoptera it is longer than the head
and shorter than the elytra ; but in Mmiticora, the vesi-
catory beetles, &c., it is shorter than either. In G?ionia
lofigicollis'^, it is nearly as long as the elytra; in many
Staphylinida, Atractocertis, &c., longer ; in Phancrus car-
nifex, bellicosus, &c., it is longer than the elytra and the
rest of the body. With regard to itself, it is sometimes

' Pi.ATF. VUI. Fig. 10. " Ibid.

■-' Limi. IVans. \']. L x\\.f. 10. ' Ilnd. /'. H.

EXTERNAL ANATOMY OK INSECTS. St.'}

very wide in proportion to its length — Dj/tisms, Helceus;
at others very long in proportion to its width — Collinrisy
BretitiiSf Mantis, &c. In Plata, and many other Ho-
mopterous Hcmiptera, it is extremely short ; extremely
long in Gnojua ,- in Sagra and Donacia its width about
equals its length ; in Elater, Dj/tisacs, and many Hete-
ropterous Hemiptera, it is narrowest before ; in Langu-
7'ia it is every where of equal width; in Anthia, Carabns,
&c., it is widest before ; and, lastly, in the Scarahceidce
MacLeay it is usually widest in the middle.

ii. Antepectus ^. — The antepcctus, as was before ob-
served '', in some tribes forms one piece, without any
kind of separation, with the prolhmax ,- but very often
this is not the case. In Carabiis L. it occupies almost
the whole under-side of the manitrunk ; but in Elafer,
in which the ora is very wide, the antepectus is merely
the middle portion of that part. In Carahns F. &c. be-
tween the ora and the base of the arms is a convex tri-
angular piece, distinguished from the rest of the a'nte-
pectus by a spurious suture ; and in Pentatoma and other
Heteropterous Hemiptera a similar piece is observable,
which terminates in a convex bilobed subtriancrular
sheath, receiving the base of the clavicle '^. This piece
seems a prop to that part, and analogous to the scapvla
of the mcdipectus and parapleiira of the postpectus. I
shall say no more upon tiie antepcctus, as it is seldom
remarkable. In the mole-cricket, however, one peculia-
rity distinguishes it: it is in this of an elastic leathery

" Pi.ATi. VIII. /;. '• See above, p. iiWQ,.

' Something of the kind is observable at the base of tlie other
less in this tribe.

54-4- EXTERNAL ANATOMY OF IS'SECTS.

substance, while the prustenium is hard, resemblijig a
bone. In other instances these parts are both of the
same substance.

1. The ste7-num or breast-bone of insects consists
mostly of thi-ee distinct pieces ; in this resembling the
human sternum, which is described by anatomists as
composed originally of three bones ^. Each of these
pieces is appropriated to a pair of legs, and each of them
at times has been called the sternum : thus in Elater the
prosternum, in the Cetofiiadce the 77iesosternum, and in Ui/-
drophihis the metasternum, have been distinguished by this
name. Our business is now with the first of these pieces,
the sternum of the antepectus or prosternum ^ : this is the
middle longitudinal ridge of the Jb7-e-breast, which passes
between the arms, when elevated, extended, or otherwise
remarkable. It is most important in the Coleopte7-a Or-
der, to which my remarks upon it will be chiefly con-
fined. In these it is sometimes an elevation, and some-
times a ho7-izontal process of the fore-breast. If you
examine the great Hydrophilus {H. piceus), at first you
will think that there is only a single sternum common to
all the legs; but if you look more closely, you will per-
ceive between the head and the arms a triangular vertical
process, with a longitudinal cavity on its posterior face,
which receives the point of the 7nesosternu7n that passes
between the arms ^ : this vertical piece is the real p7-o-
sternum, and not the other, which really belongs to the
alitrunk. In this case the elevation of the prostei'uum is
before the arms; in others it is bet'iioee7i them, as you

•' Monro On the Bones, 160. '' Plate VIII. d'.

<• Ibid. Fig. 7. d". '

EXTERNAL ANATOMY OF INSECTS. 515

may see in a Chinese chafer [Mimela K.), which imi-
tates the external appearance of a (juite different tribe* ;
in others again it is behind them, as in most of the Lamel-
licorn beetles. In the common dung-chafer [Gcotrupex
stercorariiis), it is a hairy process, which, when the head
is bent downwards, is received by a deep cavity of the
mesosternum. The Di/nasti(he MacLeay may always
be known by a columnar prostcrnum rising vertically be-
tween the arms and the medipcchis. Lastly, in other
tribes there is a prosternal elevation both before and be-
hind the arms, as in Cerambyx thoracicus, dimidiatus^ and
affinities. Of the second description, those that have a
less elevated horizontal p-osternum, the point in most is
to the anuSf but in some to the /lead : thus in Carabus L.
it is generally a subspathulate flat piece, the point of
which slides over the mesostcrmim, or covers it ; but in
Harpalus megacephalus Latr. ^, one of this tribe, though
similarly shaped, its point is to the head. These hori-
zontal prostcrna vary in their termination. In that of
Carabus L. the apex is obtuse ; in that of Elater, above
described *=, and Di/tiscus it is acute ; in Prionus lineattis^
Spencii K., &c., it is bilobed; and in Biiprestis variabilis^
attenuata, &c., obsoletely trilobed. With regard to the
other Orders no striking features of this part are observ-
able, except in some Orthoptera. In Acrida viridissivia
K. {Locusta F.) it is represented by two long filiform ver-
tical processes ; and in Locusta Leach by a single coni-
cal horn '*, mistaken by Lichtenstein for a process of the

« Kirby in Linn. Trans, xiv. t. iii./. 4. i.

" It is iloiibtful whether M. Latreillo's Harpahis mei^r/cep/iahts is
synonymous with Carabus megacephalus Fab. (,'omp. Gen. trust, el
ins. i. 20(1. with Si/st. Eleutk. i. 187. 95.

'• Vol.. II. p. .317—. '' ri.ATE VIII. Fig. 11. b.

VOL. III. 2 N

i546 EXTERNAL ANATOMY OF INSECTS.

throat ". In one instance, Gryllotalpa, this part is a long
piece between the arms, shaped like the human thigh-
bone or tibia, being more slender in the middle and
widest at the ends, and which is of a much harder sub-
stance than the rest of the antcpectus, and forms the
lower termination of a singular machine which will be-
fore long be noticed. In many bugs {Cimicida;\ instead
of being elevated, the three portions of the sternum are
hollowed out into a longitudinal gi'oove, in which the
promuscis when unemployed reposes.

The most conspicuous and remarkable appendages of
the manitrunk, are the brachia or arms. I shall not,
however, enter into the full consideration of these, as they
consist numerically of the same parts, till I treat of the
legs in general. Here it will only be necessary to assign
my reasons for calling them by a distinct denomination.
In this I think I am authorized, not only by the example
of Linne, who occasionally found it necessary to do this'',
and more particularly by the ancient notion that this
pair of organs in insects were not to be reckoned as legs"^,
but likewise from their different position and functions.
They are so inserted in the antepectus as to point towards
the head, whereas the other two pair point to the anus.
With regard to their functions, besides being ambtda-
tory, and supporting the manitrunk in walking, they are
applied to many other purposes independent of that of-
fice,— thus they are eminently the scansoiy or climbing
legs in almost all insects ; in most Carabi L., by means

* liinn. Trans, iv. 53. '' Syst. Knt. i. Cancer. Scorpio.

«' Moses, when he describe sinsects as going upon four legs, evi-
dently considers the anterior pair as armx ; Bochart docs the same.
Levii. xi. 20—. Hiej'ozoie. ii. 497-

KXTF.RNAL ANATOMY OF JNSECTl^. .517

of the notch aiul caJ<?ar *, they arc ^;i?W/^«,w;v/ legs; in
Scan'k's belonging to that tribe, the Lamellicorn beetles,
and the mole-cricket, they ^ve fossorious legs, or proper
for digging ''; in Mantis, Nepa^ and some Diptera^ they
are raptoriotis, or fitted to seize and dispatch their prey "= :
they are used also by many insects to clean their head,
eyes, and antennae, &c. For many of these purposes
they cannot be fit -without a structure dififerent from that
x>f the other legs, which renders it a matter of as great
convenience in descriptions to speak of them and their
parts under difierent names from tliose of the legs, as it
is of the ai'ms of man ; on this account it is that I propose
to give to the fore-leg and its part the names by which
the analogous parts, or what are so esteemed, in the hu-
man species ai'e distinguished; — when spoken of in qom-
mon with the other legs, they may still be called the fore-
legs.

*■ * Alitrimcus. TJje alitrunk is the posterior segment
of the ti'unk, which below bears the four true legs, and
above the organs for flight or their representatives. In
treating of this part we may consider its insertioti or ar-
ticulation, its shap£, composition, substance, motions, and
organs.

i. With regard to its insertion, or aiticulation with the
manitrunk and abdomen, it inay be observed that it is
attached to both by its whole circumference by means of
ligament ; in the Coleoptera, OrtJioptera, and Heteropte-
rous Hemiptcra being received by the posterior cavity of
the prothorax, the shield of which in these Orders, espe-

» Pr-ATF, XXVir. Fic. 31 . '■ Plati- XV. Frc. 5, G.

•^^ Samoiiclle /. v. /. 4.

2 N 2

54f8 EXTERNAL ANATOMY OF INSECTS.

cially the last, almost covers and conceals it ; but in the
remaining ones it is merely suspended to it. In the
former also, especially in the Coleoptera, it seems more
separate and distinct from the manitrunk than from
the abdomen, and more independent of its motions
than of those of the latter part : but in the Hymeno-
ptera and Diptera its greatest separation is from the
abdomen in both respects. In many insects, as in the
Lamellicorn beetles, the mole-cricket, &c., the mani-
trunk terminates posteriorly, drawing a line from the
base of the prothorax to the antepectus, in an oblique
section ; in other tribes, as in the Ceramhyx L., the
Predaceous beetles, &c., the section here is often vertical,
but in the alitrunk the anterior one is always verti-
cal, while the posterior, by which it articulates with the
abdomen, in the Orders with an ample thoracic shield, is
oblique, so that the pectoral portion is more ample than
the dorsal.

ii. As to its composition^ the alitrunk is usually much
more complex than the manitrunk ; for, besides the in-
struments of motion, it consists of numerous pieces. It
may be regarded as formed of two greater segments, the
first bearing " he elytra, or the primary wings, and the
intermediate legs ; and the second, the secondary wings
and the hind legs.

]. Collare *. The first segment of the alitrunk is the
middle piece of the whole trunk, and therefore, when
spoken of per se, may be called the meditruncus. It
consists primarily of an upper and lower part, which
in the table are denominated the mesotliorax and the

* Plate IX. g ,

EXTERNAL ANATOMY OF INSECTS. 549 .

medipectus. The first piece in the former that requires
notice is the collar. I formerly regarded this piece,
which is pecuhar to the Hijmenoptera^ Diptera, and one
tribe of the Neuropfera, as the representative of the p7-o-
thorax in the other Orders, and this opinion seems at this
time very generally adopted, but subsequent observa-
tions have caused me to entertain considerable doubts
of its correctness. Many other Entomologists have
thought it improper to distinguish these parts by the
same name*. Much, however, may be said on both
sides of this question, and I shall now lay before you the
principal arguments that may be adduced in defence of
each opinion, beginning with those that seem to prove
that the collar is the analogue of the prothorax. First,
then, the collar, like the prothorax^ is placed precisely
over the antepectus^ and being placed in the same situa-
tion, on that account seems entitled to the same denomina-
tion ; especially as in some genera, for instance Chlofion
F., it assumes the very semblance and magnitude of a
thoracic shield, and is separated from the mesothorax by
a considerable incisure. Again, in some cases that have
fallen under my own observation, the collar is endued
with some degree of motion distinct from that of the
alitrunk, since in Pompilus and Chrysis the animal can
make the former slide over the latter in a small degree.
A third and last argument is, that no prophragm is
formed from the collar : insects that have a thoracic shield
are generally distinguished by having the anterior margin
of the dorsohim deflexed so as to form a septum^ called in

* Latreille Organization &c., 199. Chabricr Sur le Vol des Im.
c. i. 412. c. iv. 54, &c.

556 EJttERNAL ANATOIMY OF INSECtS.

the table tlie j^rophragm, which enters the chest find se-
parates the cavity of the mesothorax from that of the pro^
thorax; now in Hymenoptera this septum is a process
of the piece behind the collar, and excludes it from
havino- any share in that cavity. These arguments at
first siofht seem to prove satisfactorily the identity of the
collar and prothorax. But audi alteram partefn^ and t
think you will allow that the stale containing ths claims
of the collar to be cdnsidered as a piece sui generis, dips
much the lowest. And, first, I must observe, that
thoitgh in Hi/kienoptera the collar seems to replace thd
prothorax by its situation, yet it is in fact a fiart of the
alitrunk ; for, if the manitrunh be separated from the lat-
terj ihe collar remains, in most cases, attached to it ^j
whilfe the antepectns and arm, with the ligament that covers
its cavity above^ the real representative of the prothorax,
are easily removed, and this in recent individuals: as a
further proof of this, I must request yoii will exatnine d.
neuter Miitilla; you will see that in tliis the collar is
not separated from the alitrunk in any respect, but forms
one piece with it, while the antepectns is distinct and
capable of sepiarate motion : further, the fiction of tlie
collar is upon the alitrunk, it being of essential import^
linee in flighty whereas the prothorax is of no other im-
portance than as a counterpoise to that part ''. A furthet
argument to prove thd distinction of these pa^ts mtiy be
drawn from the case of Xi/locopa, a kind of bee. In this
genus the collar forms a complete annidus or segmeiit of

" In Clilurion, Am»io2j//ila, &c.j this pai"t separates more readily
from the alitrunk.

'' Chabricr Sia- It- Vol dcs Ins. c. i. 413—. c. iv. 54. This author
seems to regard the collar as something peculiar to Hijmcnoptcra.

EXTERNAL ANATOMY OF INbLCTS. 551

the body : now, if it really represented tlie })rothorax,
the under side of the segment, as in those Coleoptera in
which no suture separates the upper from the lower part
of the manitrunk^*, should represent the antepcctus^ and
have the arms inserted in it; but in the case before
us there is a distinct antepeciits bearing the arms received
by the socket formed by this annulus. But the most
powerful argument is the fact that some insects have
both the 2>''o//io)ax and collar, a circumstance that com-
pletely does away every idea of their identity. If you
ejcaraine the common hornet [Vcspa Crabro), or any
saw-fly [Tcnthredo L.), you will find, as was before inti-
mated, tliat the real covering of the cavity of the mani-
trunk is a ligamentous membrane, which properly re-
presents the prothorax. In another genus of the same
order [Xiphijdria Latr.), the sides of the antepectus turn
upwards and nearly form a horny covering distinct from
the collar*', the ligamentous part being reduced to a
very narrow line, and in Fcemis the dorsal fissure is quite
filled up, so that in this the manitrunk is perfectly di-
stinct, and exhibits ho\\\ prothorax and antepecttis of the
usual substance. In Nomada likewise, N, Goodeniana K.
was the species I examined, there is a short minute ^;ro-
thorax besides the collar. Next let us turn our attention
to the Diptcra ; if you examine the common crane-fly
[Tipida oleracea\ you will find, first, a regular short
prothorax, to which the antepectus, with the arms, is at-
tached ; and behind this also is a short collar embracing
the alitrunk anteriorly. The next insects that I shall
mention, as exhibiting both prothorax and collar, are the

•■ See above, p. 536. '' Pj.ah IX. Fig. 1 i.

55^ EXTERNAL ANATOMY OF INSECTS.

Libellulina. These are generally admitted to have the
former of these parts *, but besides this they have also
the latter, which is the most ample and conspicuous
piece in the whole trunk ^; intervening, as the collar
should do, between the prothorax and those parts of the
trunk to which the wings are attached. There is one
circumstance connected with the subject which should
not be overlooked. In the Hymcnoptera, usually under
a lateral process of the posterior part of the collar, is a
spiracle or respiratory apparatus; in the Diptera there
is also one, though not covered by the part in question,
in the same situation ; now this you will find precisely so
situated with respect to the second piece in the thorax
of Tipula oleracea, proving that this piece is the real re-
])resentative of the collar. Enough, I think, has been
said to satisfy you that I have not changed my senti-
ments on this subject upon slight grounds. Probably
traces of the part in question might be detected in the
thoracic Orders in general, in connexion with some
vocal or respiratory oigan <^ ; but having had no oppor-

» Plate IX. Fig. 6. a. •> Ibid. Fig. 7- g.

■= M. Chabrier ( Vol. des Ins.) supposes that the liumming of insects
IS produced by the exit of the superfluous air from their thoracic
spiracles, &c. ; in Mdolontha he thinks they are in the metathorax un-
der the wings (c. i. 457 — . Plate XXII. Fig. 1 3. c. f . represents the
operculum of one of those of Uytiscus mai-ginalis) : in the Hymeno-
ptera, in the mesotkorax, near the posterior lobes of the collar (Ibid.
459. c. iv. 50.); and in the Diptera, in the metathorax, near the
poiser (c. i 457 )• I observed myself lately, that Elophilus tenax,
\i he'd by the anterior part of the body, when it hummed, alter-
nately opened and shut this spiracle. The wings during the sound
vibrated intensely. The hum ceased and was renewed, as they were
restrained from this motion or released from restraint ; when the
wing was moved towards the head, a different sound was emitted from
that ()roduced when it merely vibrated.

EXTERNAL ANATOMY OF INSECTS. 553

tunity, by an extended examination of living subjects, to
verify or disprove this suspicion, I shall merely mention
it, and conclude this head by observing, that the collar
varies most in the Hymcnoptcra order, and that its most
remarkable form is in Vespa, Cinibcx, Dorj/lus, &,c., in
which it bends into an ample sinus that receives the
dorsolum-''.

2. Dorsolum^. Where there is no apparent collar,
the (lorsolnm (dorslet) is \hejirst piece of the mesothoraoc,
and where there is one, the second; it bears the elytra
or other primary organs of flight. It varies in the dif-
ferent Orders, particularly with respect to its exposure.
In Coleopterous insects it is most commonly, but not
invariably *=, covered entirely by the shield of ihe protJio-
rax, the scntcUum alone being visible; as it is also
in the Orthopteia (with the exception of Mantis and
Phasma, in the first of which it is partially, and in the
latter intirely exposed), and the Heteropterous, and
most of the Homopterous section of the Hemiptera.
The scutellum is likewise covered in Gem's, Hydrome-
tra, and Velia, and the whole of the back of the alitrunk
by a process of the prothorax in Acrydium F., Centra-
tus, &c. But in the remaining Orders, and the tribe
of Tettigofiia in the Homoj)terous Hemiptera, the do7--
solum is not hidden by the thoracic shield. It is usually
less elevated than the scutellum; in Necrophorus, and
some other beetles, however, the latter is most depressed.
\\'ith regard to its substance, it is generally not so hard

» Plate IX. Fig. 11. g'. ^ Plates VIII. IX. i.

"^ When the prothorax is separated from the elytra by a kind of
isthmus, as in Scaritcs, Passa/us, Sec, tlie dorsolum is more or less
uncovered.

554 EXTER^fAL ANATOMY OF INSECTS.

and rigid as the scutellum, but in most Coleoptera harder
than in the other Orders in which it is covered ; in
the Hc'mij)te7-ay except in Tettigonia^ it approaches to
membrane. As to shape and other circumstances, it
varies in the different Orders. In the beetle tribes it
has generally a sinus taken out of its anterior margin,
and it approaches more or less to a trapezium ; in Blatta
it is transverse and somewhat arched ; in Gryllotalpa it
is nearly square, and distinguished besides on each side
by a minute aperture, fitted with a tense membrane,
which perhaps covers a respiratory apparatus. In the
locusts it is more or less triangular, and in Mantis and
Phasma long and slender. In the Hemiptcra the doiso-
lum appears to consist of several pieces, variously cir-
cumstanced, separated by sutures, corresponding with
which are as many ridges on the inside of the crust *.
In the Libcllidina it is rhomboidaP; in Panorpa nearly
liexagonal ; in the Epkemerina it is ample and oblong ;
in Sialis and the Trichoptera this pai't is represented by
three subtriangular pieces, the scutelliim constituting a
fourth, with the vertices of the triangles meeting in the
centre '^ ; in the Lepidoptera the part in question is large,
and receives the scutelhim into its posterior sinus ^. The
Hi/menoptera usually exhibit a very ample dorsohiniy
mostly subtriangular with the vertex rounded or trun-
cated, and pointing in some {Vespa L.) to the head%
and in others {Apis) to the anus ; in the Diptera, except in
I'ipula, the parts of the mcsothorax are not separated by
any suture, but only indicated by impressed lines or chan-

« Plate VIII. Fig. 16. 20. i'. ^ Plate IX. Fig. 7. »'.

'■ Ibid. Fig. 10. i. Ic . -^ Ibid. Fig. 1. i. k'.

• Ibid. Fig. 11. i'.

EXTERNAL ANATOMY OV INSECTS. 555

nels ; m the genus last mentioned, however, tlie dorso-
lum h distinct, subrhomboidal, and received by an angu-
lar sirtus of the sdhtellmn, which last, I think, is not the
part that has Usually been regarded as entitled to that
denomination ; tor this opinion I shall soon assign my
reasons.

3. Scutc'llum *. Some writers on the anatomy of in-
sects, lookino-, it should seem, only at the Colcojytera and
Orthoptcra^ have regarded the dorsolum and saitellum as
forming only on6 piece **, and others have affirmed that
the Lepidoptera and subsequent Orders have no scutel-
lum'^. But as we proceed in considering the scittclhim
in all the Orders, we shall see that both these opinions
are founded on partial views of the subject, and that all
winged insects have a scutellum, more or less distinctly
marked out or separated from the dorsolunt. In the Co-
leoptera the sciitellum is usually the visible, mostly trian-
gular, piece that intervenes between the elytra at their
base*^, and which terminates the dor solum. Some Lamel-
licorn beetles, &c. [Scarabccidde MacLeay) are stated not
to have the part in question [exscutellati) : but this is not
strictly correct, for in these cases the scutellum exists as the
point of the dorsolum covered by the prothorax, though
it does not intervene between the elytra: in others of
this it'\\yc, as Cetonia ckiriensis, bajula, Scc., it separates
these organs at their base, though it is covered by the
posterior lobe of the prothorax : in Meloe F., the elytra

- PlatksVHI. IX. XXVIII. k'. ^ Aiidoin, Chabi-ier, &c.

'■ Olivier, lie seems also to have thought that neither the Or-
ihoplcra nor Iloinopterous Hcwijilcra have this part. X. Diet.
itfTist. Xal. X. 112.

•' Plate VIII. Fig. 3. /.'.

556 EXTERNAL ANATOMY OF INSECTS.

of which are immoveable, there seems really to be no
scutellum. Generally speaking, as was lately observed,
but not always, it is distinguished from the dorsolum by
being more elevated : this is particularly conspicuous in
the genus Elater, in which it is a flat plate elevated
from the dorsolum by a pedicle; in Sagra the latter part
is horizontal, while the scutellum is vertical : and even in
cases where the distinction is not so striking, these parts
are separated either by a line, or some difference in their
sculpture and substance. In this Order this part varies
greatly, and often in the same tribe or genus, both
in size and shape ; being sometimes very large *, and
sometimes very minute; sometimes very long, and some-
times very short; sometimes nearly round, at others
square; now oval or ovate, heart-shaped, triangular,
acuminate, intire, bifid, &c. In the Orthoptera, though
less conspicuous, it still is present as a triangular eleva-
tion of the middle of the posterior part of the dorsolum,
with the vertex either pointing towards the head, as in
Blatta, or towards the tail, as in Locusta Leach ''. In
the Heteropterous section of the Hemiptera (which, in
columns of Mandibulata and Haustellata, appear to bear
the same reference to the Coleoptera, that the Hymeno-
ptera do to the Diptera, and the Homopterous Hemi-
ptera to the Orthoptera'^) the part we are considering is
mostly very large and conspicuous, quite distinct from the

' In Macraspis MacLeay it is often half as big as an elytrum.

b Plate VIII. Fig. 12. ^'.

<^ Mr. W. S. MacLeay opposes the Hemiptera to the Orthoptera,
the Homoj)tera to the Neuroptera, and the Aptera to the Coleoptera:
but if analogous structure be made the guide, I think my arrange-
ment will be found most correct. Hor. Entomolos. 367.

EXTERNAL ANATOMY OF INSECTS. 557

dorsolum, and in some {Tetyra F.) covering the whole
abdomen, as well as the Heinelytra and the wings ; it is
most conmionl}', as in the Coleoptera^ obtriangular*, but
in the last-mentioned genus it often approaches to a pen-
tagonal shape. Though usually so striking a feature in
this tribe, in the aquatic bugs {Gerris &c.) it is covered
by the prothorax. In some species oi' liediivhis F. (/?.
bigutfahis, mntillarhis^ lugens, &c.) it is armed with one
or more dorsal or terminal spines. In the Homopterous
section, where the dor solum, as in Tettigonia F., is not
covered by the jyrotJwraa:, the scuteUum, which is merely
a continuation of that part, bears some resemblance to a
St. Andrew's cross, and terminates in a fork ^ ; in Ful-
goray in which it is partly covered, it is merely the trian-
gular point of the dorsolum ; in the Cercopidce, &c., whose
dorsolum is wholly covered, the triangular scutellum is
distinct from it ; in Ce?itrotus, DarniSi and Membracis, in
which the prothorax is producted, and covers the abdo-
men more or less, the scufellum is a short transverse di-
stinct piece. In the Lepidoptera, from the difficulty of
abrading sufficiently the scales and hairs without injury,
it is difficult to obtain a correct idea of the part in ques-
tion ; in the cabbage butterfly [Pieris Brassica;) it ap-
pears to be triangular : in the humming-bird hawk-
moth [Macro-glossum Stellatanim) it approaches to a
rhomboidal shape *=; and in the Qggav-moth [Lasiocanipa
Qiicrcus) it is completely rhomboidal. In the Libellu-
Una, in the Neuroptera Order, it seems to be represented
by the posterior point of the dorsolum, which terminates

» Plate VIII. Fig. 20. h' . ^ Ibid. Fig. 16. /t'.

= Plate IX. Fig. 1. k' . N. B. This is from Cossus F.

558 EXTERNAL ANATOMY OF INSECTS,

in soni^thing lijke a St. Andrew's crops'. In niost o€
the other tnb^9 of this Order the set^elkmi i? a triangu-
lar piece, with the vertex to the head, received between
two pieces of the dorsolum ; in Psoeus it is nearly like
that of Teitigouia before described. In the HymeJio-
'ptera the seutellum is separated from the dQrsolum, which
it often embraces posteriorly, as the collar does in front,
by a suture ; it varies occasionally in shape in the diffe-
rent tribes, most commonly it is crescent-shaped, but in
many Jchneumonidc? and others it is triangular''; in X\e
hive bee, &c., it overhangs the succeeding piece of the
alitrunk; in Melecta, Crocisa, &c., it is armed with a pair
of sharp teeth <^; in others {Oxi/behis uniglumis, &c.) with
.one or more spines, and in some with a pair of long
horns'*. Before I describe this part in the DipterUy it
will be proper to assign my reasons for considering a
.different piece as its representative, from what Iias>usually
been regarded as such, and which at first sight seems
the analogue of what I admit to be the seutellum in the
Hymenoptera. The dorsolum, and its concomitant the
seutellum, belong to the first pair of the organs of flight,
which are planted usually under the sides of the former,
and in the case of wrngs, by their Anal Area, connected
eidier mediately or immediately with the latter. Now, ijf
you trace the sides of the piece that I have considered as
the part in question in Hymenoptera, you will find that
they lead you not to the base of the lo^uoer but to that of
the upper *mings % and in the saw-flies ( Tenth-edo L.)

* Plate IX. Fig. 7- k' . *> Ibid. Fig. 11, 15. k' .

•^ Mon. Aj). Angl. i. t. vu Apis. ** a./. 2. a a.
"' Stoll Cigalcs t. xxviii. /. 164.
« Plate IX. Fig. 1.2. /'.

EXTERNAL ANATOMY or IN'SIXTS. ."j.vO

you will see clearly that the Anal Area of these wings is
attached to a process of it, a proof that it belongs to tlie
mcsolhorax', or region of that pair. But in the Diptcray
the part that has been usually called the sculcllum is not
At all connected, either by situation or as a point of at-
tachment, with the wing itself, but with the lowei* valve of
the alula, which is with reason thought to be the repre-
sentative of the secondary wing of the tetrapterous Orders.
You may see this even in the common crane-fly ( Tipula\
in which there is a real aUdo^ connected by means of a la-
teral process, terminating in ligament, with this supposed
sciitellnm. If you examine further the same insect, you
will easily find what I regard as the true one in the bi-
lobed piece which receives tlie dorsolum, situated be-
tween the wings, and to the sides of which they are at-
tached. In Asilus, Tabanus, &c., this part is transverse,
and only distinguished on each side by an oblique im-
pressed line ; in the Muscidcc it is square, and marked by
a strai}>:ht transverse one.

4. Frcciium ^. This appendage to the scutellum and
dorsolwn varies considerably in the different Orders, and
in many cases, as you will see, is a very important part,
being the process by which the former is mostly con-
nected with the elytra or upper wings. In the Coleo-
ptera, the elytra of which are nearly stationary in flight,
and therefore less require any counteraction to prevent
their dislocation, this part is commonly merely a process
or incrassation of the under margin of the scutellum,
which towards the base of the dorsolwn is dilated to
form the socket for the elytra. Its use as a countercheck

' Pr.A TFs VIII. IX. XXVIII. /■.

560 EXTERNAL ANATOMY OF INSECTS.

in this Order is best exemplified in the common water-
beetle [Di/tiscus rnarginalis). This at the inner base
of the elytra has a membranous fringed alula resembling
those of Diptera ; to the lower fold of this the extremity
oithefrcenum is attached, which forms a right angle with
the scutellum, and the upper fold is attached to the base
of the ely trum *. The object of this appendage is pro-
bably to pi'event the dislocation of these organs, which
seems to indicate that they are used more in flight than
those of other beetles. The Blattce also, in the next Or-
der, have a winglet attached to the anal area of the teg-
mina. The J^rcenuvi, as in the preceding Order, lies un-
der the margin of the scutellum and dorsulum, but which
here forms one uninterrupted transverse line ; it is near-
ly vertical, and is attached to the alula. The structure
is not very different in the other Orthoptera '', but the
frcenum is surmounted or strengthened by one or two
ridges ; in Mantis it runs from the scutellum in an an-
gular or zigzag direction — but in all it is attached im-
mediately to the tegmen. In the Heteropterous He7ni-
ptera it is represented by the narrow bead adjacent to the
scutellum on each side *=, which dilates into a flat plate as
it approaches the Hemelytrum, with the Anal Area of which
it is connected. But the Homopterous section of the Order
in question furnishes examples of the most remarkable
structure of this countercheck, which proves that it is real-
ly, what its name imports, a bridle. If you examine the
great lanthorn-fly [Fulgora laternaria)^ or any species of
Tettigonia, &c., you will find adjacent to the scutellum

=> Plate XXIII. Fig. 6. e" . » Plate VIII. Fig. 12. /'.

•^ Ibid. Fig. 20. /'.

EXTERNAL ANATOMY OF INSECTS. 561

or parallel with it, on each side a flat plate ; and from the
angle of that part in tlie first case, and from one of its
processes in the last, you will further perceive a ridge or
nervure which runs along this plate, in one forming an
angle, and in the other being nearly straight, to the base
of the tegmc/if where it becomes a marginal nervure to a
membrane that is attached to the posterior part of the
base of the Anal and Costal Areas; and that this marginal
nervure, like a trachea, consists of a spiral thread, or
rather of a number of cartilaginous rings connected by
elastic membrane *, and consequently is capable of con-
siderable tension and relaxation, as the tegmen rises and
falls in flight. In the Lepidoptera it appears to be a
short piece overhung by the scutellum, which as it ap-
proaches the base of the wing is dilated. In the Libel-
lulina, to go to the Neii7'optera, it has the same kind of
elastic nervure connected with the Anal Area of the wing
which I have just described in the Homopterous Hemi-
pteru; another nervure, in jEshiia at least, appears to
diverge upwards from the scutellar angle to the Interme-
diate Area'': a structure little different distinguishes the
rest of the Neuroptera, and even the Trichoptera. In the
Hymenoptera this part varies somewhat ; in the majority
perhaps of the Order, as well as in the Diptera, it ap-
pears to be merely the lateral termination of the scutel-
lum where it joins the wing ; but in some tribes, as in
Tentliredo L. (especially Perga Leach), Sirex L., and
the Ichneumonidce, a ridge, and sometimes two, runs
from the scutellum to the wing ; the upper one, where

» Plate XXVIII. Fig. U./'.

'' Chabrien Sur le Vol des Ins. c. iii. t. viii— v. B. i,

VOL. III. 2 o

5&2 EXTERNAL ANATOMY OF INSECTS.

there are two, as in Pcrga, being the stoutest, and con-
necting with the Costal Area, and the lower one with the
Anal.

5. Pnystcga ^. We learn from M. Chabrier, that in
the common dragon-fly, a space, consisting of three
triangles, which immediately succeeds the Jrcenum, af-
fords attachment to no muscles, but merely covers aerial
vesicles''. This is the part I have called \he pnystega^.
An analogous piece may be discovered in PJiasma and
Mantis in a similar situation ; but I cannot trace it in
Loaista Leach, or in the other Orders.

Having considered the parts that constitute the meso-
thorax, we will next say something upon those, as far as
they require notice, that compose the medipectus or mid-
breast. But first I must observe in general of the me-
dipectus and posfpectus taken together, or the whole un-
derside of the alitrunk, that though usually they are in
the same level with the antepectus or under side of the
manitrunlc^ yet in several instances, as the Scarahceid^
MacLeay, the Staphyliyiida, &c. they are much more
elevated than that part; they are also usually longer,
very remarkably so in Atractocerus, but in Elater sul-
cafus and many others they are shorter. These parts
are also commonly rather more elevated than the abdo-
men,— much so in some, as Molorchus; but scarcely at all
in others, as Buprestis, the Heteropterous Hcmiptera^ &c.
In some of the latter (TV/z/ra F.) the abdomen seems
the most prominent. Another observation relating to

■' Plate IX. Fig. 7- "ni .

^ Chabrier .S'z/r /e Voldes Ins. c. iii. 354.

' From wiu to breathe and ^kyoi to cover.

EXTERNAL ANATOMY OF INSECTS. 5G3

this part must not be omitted, namely, that though in
many cases the medqwctus and postpectus are perfectly
distinct and may be separated, yet in others, as for in-
stance the Laniellicorn beetles, tlie Mymcnoptera and
Diptcra^ &c., no suture separates them; so that though
tlie upper parts, the mcsothorax and metathorax, are se-
parable, tlie lower ones just named are not so.

6. Pcristethium^. The first piece of the medipechis is
what I have called, after Knoch, the pei'istethium^ . This
immediately follows the antepcctus ; on each side it is
limited by the scapulars, and behind by the mid-legs and
mesostcrnum. Its antagonist above is usually the dorsu-
lum. In the Coleoptera Order it varies occasionally,
both in form and magnitude, but not so as to merit par-
ticular notice, except that botli are regulated by the sca-
pulars— if these are small, the peristelhium is ample; and,
vice versa, if they are large it is small. In all the fol-
lowing Orders, except the Hymetiojjtera, it is equally
inconspicuous, but in them it is often more remarkable.
I have a Brazilian species of Cimbcx (C mammifera
K. MS.) which appears undescribed, in which this part
swells into two breast-like protuberances, terminating
posteriorly in membrane, as if it had separate motion : in
the golden -wasps [Chrysis L.) it is anteriorly concave to
receive the coxce of the mid-legs; and in Siilbum, of the

=» Plates VIII. IX. n.

** At first I had named this piece the antccosla, and the mesoste-
tkium the postcosta ; and there is certainly some analogy between the
thorax of insects, consisting of several pieces that follow each other,
and the vertebral column ; between their three stermum and the ster-
num, and between their other pieces and the ribs of vertebrate
animals. Comp. Chabrier, ubi siipr. c. iv. 49. note 1 .
2 O 2

564 EXTERNAL ANATOMY OF INSECTS.

same tribe, it is armed with one or more conical obtuse
teeth.

7. Scapularia *. The scapulars are situated between the
coxa of the mid-legs and the base or axis of the upper
organs of flight, and they seem to act as a fulcrum to each.
In the Coleoptera Order they are most commonly qua-
drangular or subquadrangular, often divided diagonally,
and sometimes transversely, by an impressed line ; the
posterior part, which is usually the most elevated and
often has an uneven angular surface, is that which in-
tervenes between the coxae and elytra : where the former
are short, as in the Capricorn beetles, the scapulars are
long; and where they are long, as in the Petalocerous
ones, the latter are short. The anterior part is that
which forms the lateral limit of the peristethium, upon
which it often encroaches : this part, in conjunction with
the dorsolum above, and the last-named part below,
forms the kind of rotula that plays in the posterior aceta-
bulum of the manitrunk, as the head does in the anterior
one. In the flower-chafers {Cetonia F.) the scapulars
are very thick and elevated, and interpose between the
posterior angles of the prothorax and the shoulders of
the elytra, which is one of the distinguishing characters
of that tribe : in this case the lower angle of the scapular
connects with the coxa of the mid-leg, and the upper
angle with the axis of the elytra; and the most elevated
and thickest part of the scapular is about midway between
the two. This robust structure seems to indicate that
the scapular has to counteract a powerful action both of
the leg and elytrum. In the Orthoptera the scapulars

» Ptatfs VIII. IX. o'.

EXTEKNAL ANATOMY OF INSECTS. 565

are usually divided into two parallel pieces, corresponding
probably, though more distinct, with the two parts late-
ly noticed of those of the Coleoptera: the upper side of
the socket of the mid-leg is common to the base of both
these pieces, but the articulation of the tcgmcn is chiefly
with the anterior one. In the grasshoppers, locusts, &c.
{Grj/llus L.) in which tribe this leg is nearly opposite to
that part, the scapular inclines but little from a vertical
position =* ; but in the praying- insects {Ma7itis), spectres
(Pkasma), and cockroaches {Blatta\ in which the in-
sertion of the mid-legs is befiind that of the tcgmina, it is
nearly horizontal. In the Heteropterous Hemiptcra the
anterior part of the scapular is covered by the antepectus^
and separated by a ridge, more or less pronounced, from
the open part ; the whole is of an irregular shape, and
nearly parallel with the parapleura. In the Homopterous
section it likewise consists of two pieces, and sometimes
of more. Thus in Tettigonia F. it is bilobed, and be-
tween it and the coxa two small pieces are inserted''. In
some others, lassies Lanio F., &c., it is not very milike
the scapular in Coleoptera, being subquadrangular and
divided diagonally. In the Neiiroptera this part and the
paraplcura are parallel, and placed obliquely '^. In the
common dragon-fly [^shyia viatica) the former forms
nearly a parallelogram **, which is not divided by any
ridge or channel, but its lower half is separated into two
unequal parts by a black longitudinal line, opposed to
which on the inside is a ridge. The mid-leg in these is
connected with the scapular by the intervention of a

' Plate V^II. Fig. 12. 13. d . z'. »• Ibid. Fig. 17- d.
^ Pl.\te IX. Fig. 8. o'. z. -' Ibid. d.

566 EXTERNAL ANATOMY OF INSECTS.

triangular transverse anterior piece, which in fact seems
only marked by a black channel, to which also interiorly
a ridge is opposed *. In the rest of the Order it is divided
longitudinally into two parallel pieces. In Payicn-pa the
posterior piece is longer than the anterior and props
the coxa behind ; in Myrmeleon and Perla, &c., it ap-
peals to consist of three pieces. I hfive not been able to
obtain a clear idea of them in the Lepido}Hera, except
that they have more than one piece. Hymefiopterous
and Dipterous insects for the most part have no scapular
distinct from the j)^'istethium ; but in Cimhex, Pei'ga^
and other saw-flies, it seems represented by its posterior
depressed and sometimes membranous part : in Vespa,
&c. a small sub triangular piece, just below the base of
the upper wing, is probably its analogue^.

8. Mesosternum '^. The central part of the 7nedipectus,
or that which passes between the mid-legs when ele^-
vated, protended, or otherwise remarkable, is called the
inesosternum or mid-breast-bone. In the Colcoptera Or-
der it exhibits the most numerous variations, and is
usually the most strongly marked of any of the three
portions of the sternum^ affording often important cha-
racters for the discrimination of genera and subgenera.
It may be said to be formed upon three principal types —
the first is, where it is a process of the posterior part of
^Q peristethiiim, and points towards the anus or the
head ; — the second, where it is a process of the anterior
part of the mesostethium, and points only towards the
head: in this case there is no suture to separate the

■^ Plate IX. Fig. 8. a. •' Ibid. Fig. 13. d.

■^ Plate VIII. Fig. 3, 13./.

EKilMlNAL ANATOMY Ol INSKCTS. 561

nudipt'cius I'roui the pustpecins ; — ihc labt type is vvliere
it is -A riil<rc i'ormetl by a process both of the peristelhiwn
aiul mcsostet Ilium meetinjjj between the legs ; an example
of this you will see in the common clung-chafer {Gco-
trupcs Latr.). Uj)on the two first of these cases 1 shall
offer a few remarks ; — tlie last afibrding no variation
need only be mentioned.

If you examine the terrestrial Predaceous beetles
{Cicindela and Carabus L.) you will find that \\\q periste-
thium is usually flat, terminating towards the postpectus
in a kind of fork, the sinus of which receives the anterior
point of the mesostethium — this is the mesosternum ; but
in the aquatic insects of this tribe, at least in Dytiscus
marginalis, &c. the structure at first sight seems diffe-
rent, for apparently the prostenuim is received by the
anterior fork of the mesostethium ; but if you proceed to
separate the manitrunk from the alitrunk, you will find
that the true mesosternum of the usual form is quite
covered by this point, which curves towards the breast,
is longitudinally concave to receive the point of the p)i'o-
ster/ium, and permit its motion in the groove. In some
Heteromerous beetles, as the Helopidcc, &c. this part is
anteriorly bilobed, so as to form a cavity which receives
the point oi i\\e prosteymiim when the head is bent down:
in Hclops fiitens {Tenebrio Oliv.) this sinus represents a
crescent; in Cistela Ceramboides it is shaped like the
Greek letter y; hi the Lady-bird [Coccinella L.) it as-
sumes nearly the shape of a Saint Andrew's cross ; in
Spheniscus K.* the mesosternum is wide, concave and
wrinkled, with an anterior and posterior sinus ; while in

' lAnn. Trans, xii. /. xxii./. 4.

568 EXTERNAL ANATOMY OF fNSECTS.

the analogous genus Erotylus^ it is convex anteriorly,
and posteriorly more or less rounded ; in Doryphora it
is a long, robust, subconical horn, often standing at an
angle of about 45°, overhanging the prosternum.

In the genus last named, though its mesosternum in its
direction and appearance resembles that of many Peta-
locerous beetles, yet it is separated by an evident suture
from the mesostethium ; but in the last-mentioned tribe
its representative is a process of the latter part : yet as
the peristetkium and mesostethium are separated by no
suture, though in some cases a transverse channel, and
in others merely a coloured line, marks the point where
they may be considered as soldered together, in these
cases the mesosternum may perhaps be said to be
common to both. In this great family, which includes
within its limits some of the most singular and wonder-
ful in their structure and armour, as well as some of the
most brilliant and beautiful of the beetle tribes, — the part
in question, in a vast number of cases, will enable the
Entomologist satisfactorily to trace its numerous groups,
not only where it rises or stretches out into a horn or
ridge, but even often where it is merely a flat space be-
tween the mid-legs. I shall notice some of its most
striking variations in this tribe. In Phanceus Jestivtis,
and in Macraspis and Chasmodia MacLeay, it is elon-
gated horizontally, with the apex curving upwards ; in

* A remarkable instance of analogy is afforded by this genus. In
Erotylus there are two groups ; one distinguished by gibbous elytra,
and the other by flatter ones. The same distinction is observable in
Spheniscus ; for to this genus belongs Helops fasciatiis Oliv., which re-
presents the flat Eroiyli, and even individually Erotylus trifasciatjcs
Oliv., E.fasciahts F.

EXTERNAL ANATOMY OF INSECTS. 569

AnoplogJiathus it is horizontal, straight, and fifrures an
isosceles triangle ; in Cetonia suturalis^ vitticollis^ &c.
it is very long, passing between the arms and nearly
reaching the head ; in C. marmorea, Lam'us, &c. it is a
lofty, robust, conical prominence ; and in many Itute-
licUe, especially those with striated elytra, it is pyramidal
or four-sided ; it varies also in its termination^ particu-
larly in the Cctoniadtc ; and even where there is little or
no elevation of it, as in the Scarabccidcc MacLeay, it is
often terminated anteriorly by lines that vary in their
angle or curvature. The genus Copris, as restricted by
Mr. W. S. MacLeay, may from an inspection of this
circumstance be divided into several families. Thus in
C. Molossus and affinities its termination represents the
letter j^ reversed, or a triangle surmounted by a mucro ;
in C. orientalis, &c., it ends in an acute-angled trian-
gle •■ in C. lunaris, &c. in an obtuse-angled one ; and in
C.IaccJms^ &c., in the segment of a circle.

The part we are considering is not so important in
the other Orders. In the Orthoptera^ however, it is occa-
sionally remarkable. In Acrida viridissima [Locusta F.)
attached to the anterior margin of the peristethium are
two long triangular pieces which appear to represent this
part ; in the kindred subgenus, Conocephalus ^, it is a
single piece bifid at the apex ; in Giyllotalpa it is a very
elevated hairy ridge ; and in Loaista Leach, it is a flat
anterior process of the mcsostethium. In the Heteropte-
rous Hemiptera this part is often merely a portion of
the channel in which the promuscis reposes ; but some-
times, as in Edcssa F., it is an elevated piece varying

* I would restrict this name to the conical-headed Locustcc F.

570 EXTERNAL ANATOMY OF INSECTS.

in its termination. In the remaining Orders, as fiir as I
have had an opportunity to examine them, it can
scarcely be said to exist separately from the viedipectus,
except that in Tiimla Latr. a bipartite subtriangiilar
membranous piece seems to be its analogue.

We are now to consider the last segment of the ali-
trunk, which, as a whole, may be denominated the po-
truncus ,- it bears the second pair of the organs of flight,
and the last pair of legs. The npper side of this is the
metathorax^ and its lower side the piostpectus.

9. Postdorsolum ^. The first external piece of the
metathorax is the postdorsolum^ which presents itself
under very different forms and circumstances in the dif-
ferent Orders. In the Colcoptera it is intirely covered
by the dorsoliim and scutelhim ; it is generally more or less
of a membranous substance, or partly membranous and
partly corneous, which enables it to yield more to the
action of the wings in flight; it is usually an ample
transverse piece with tumid sides '^; but in the Scarabccida
MacLeay, it is short though very wide; and in Ci/chrus,
and probably other ajjterous beetles, it is extremely mi-
nute and almost obsolete. In the Orthoptera Order, I
observe once for all, the part in question, as well as
the postscutellum and postfrcenum are mere counterparts
of the dorsolum, scutelhim, and Jr-cenum, except that in
some cases they are larger <^. In the Heteropterous Ue-
miptera at first sight it would appear that all the parts of
the metathwax were altogether wanting or absorbed

■' Plate VIII. IX. t'. Limi. Trans, xi. t. ix./. 16. c.

b Plate VIII. Fic. 3. t',

' Ibid. Fig. 12. Comp. J', /.',/', with t' , u' , v.

KXTERNAL ANATOMY OF INSECTS. 571

in the ample scutellum; but it" you remove this with care,
you will find tinder it their representatives, its lower sur-
face beiufr hollowed out to receive them. Tiie posidor-
soliim appears in these as a transverse obtusangular band ;
in the Ncpida;^ Notoncctidcc, &c. the three parts of the
mctathorax seem united into a single plate, emerging
laterally from under the scutclliun below xha frdcjium ; in
which, however, some traces of a distinction between
them may be discovered. In the llomopterous section
the Fidgoridcc exhibit these pieces very distinctly, cover-
ed only at the base by the mcsothorax : but in Tdtigonia
they are not so easily detected ; they exist however as a
narrow strip or band, almost concealed by that part.
As to the Lcpidoptera Order, in Pieris Brassicce at least,
the postdorsolum is represented by a pair of nearly equi-
lateral triangles whose vertexes meet in the centre of the
metathoi'ax, and between which and the sciitelliun is a
deep cavity ; but in Macroglossum SteUatarum and La-
siocampa Qucrcus, there appears to be also a central
transverse piece between them. In the Ncuroptera there
is no material or strikmg difference between the parts of
the viesothorax and mctathorax ^. In the Hymcnoptera
more variety occurs in this part. In the saw-flies, &c.
{Tenthredo L.) the pustdorsolum is a transverse piece
covered by the scutelluni: in the Ichneumonidce it is
smaller, but not covered ; in the Vcspidce it is apparent,
transverse, and with the postscutellnm obtusangular ^ ; in
Apis it is overhung by the scutellum. The Dijdcra exhibit
some variations in this part. In Tipnla it consists of
three pieces placed transversely, the central one qua-

' Plate IX. Fiu. 7- /'• ^ Ibid. Fu; U.f.

572 EXTERNAL ANATOMY OF INSECTS.

drangular, and the lateral ones roundish ; in the Asilidcs
and most others of this Order, with the postscutellum, it
forms a segment of a circle*, sometimes armed with a
pair of spines, as in Stratyomis F., and is what has been
usually regarded as the real scutellum, though, as I have
endeavoured to show, not correctly^.

10. Postscutellum'^. T^he postscutellum heaxs Xh& soxae
relation to the postdorsolum that the scutellum does to the
dorsolum, but it is seldom, if ever, a distinct piece. In the
Coleoptera it is represented by the longitudinal narrow
channel that terminates the postdorsolum towards the
anus '^ : this usually figures an isosceles triangle with the
vertex truncated or open ; but in Copris the triangle is
equilateral. In the other Orders it is little more than
the central posterior point of the postdorsolum ^.

11. Postfranum ^. The part now mentioned is much
more important than the preceding one, and must not be
passed over so cursorily. In the Coleoptera it usually
presents itself under the form of two large and usually
rather square pannels, the disk of which is convex, but
the rest of their surface unequal, which are situated one
on each side of the postscutellum s ; under the anterior
outer angle of these is the socket or principal attachment
of the secondary wings, and their basal margin is at-
tached to their outer side ; posteriorly behind the vertex
of the postscutellum, the postfrcenum is crowned with a
ridge or bead, below which it descends vertically or
obliquely to the adomen ; this ridge often turns upwards,

» Plate IX. Fig. 19, 20. (. " See above, p. 5.58—.

^ Plates VIII. IX. u. •> Plate VIII. Fig. 3 «'.

• Ibid. VIII. Fig. 12. u. Plate IX. 7- u.
' Plates VIII. IX. v. J Plate VIII. Fig. 3. v.

EXTERNAL ANATOMY OF INSECTS. 573

and proceeds towards the middle of the basal margin of
the wing. In the Petalocerous beetles the part in ques-
tion is usually more or less hairy ; but in many others,
as the rose-scented Capricorn [Callichroma moschatum),
&c. it is naked. At its side you will commonly observe
several plates and tendons {osselets Chabr.) connected
inter se and with the base of the wing by elastic liga-
ments, which are calculated to facilitate the play of those
organs. In the Orthoptcra, Neuroptera, and Homopte-
rous Hcmiptera, the postfrccnum does not differ mate-
rially from \\\&fr(Enum *. In the Heteropterous section
of the last Order it is usually a transverse ridge termi-
nating the postdorsohim^ with a bifurcation where it
unites with the wing ; but in Tetyra F. (at least so it is
in Tetyra signata^) it is a nearly vertical piece, marked in.
the centre with an infinity of very minute folds, which
probably by their alternate tension and relaxation let
out and pull in the wings. Amongst the Lepidoptera it
is not remarkable. In the Hymenoptera Order it is
mostly represented, I think, by a double ridge or fork,
sometimes however obsolete, but very conspicuous in the
saw-flies, which laterally terminates the post dor solum -.
the upper branch, usually the thickest, going to the an-
terior part of the base of the underwing, and the lower
one to the posterior. You may observe something simi-
lar in the craile-flies (77p^^/a Latr.) and Asilidce. A
tendon proceeding from the point of the postscutellum
forms a fork near its end, the upper branch of which
connects with the anterior and the lower with the poste-
rior valve of the winglet; the structure is a little, but not
essentially, different in other Diptera.

' Pi.ATK VIII. Fig. 12, 16.; and Plate IX. Fig. 7. v' .

574' EXTERNAL ANATOMY OF INSECTS.

12. Pleura *. By this name I would distinguish the
part which laterally connects the metathorax and jiost-
l^ectns. It includes in it the socket of the secondary
wings. In the Coleoptera this is a two-sided piece lying
between the postframcm and the parapleural with the
upper side horizontal and the lower vertical ^ — a tendon
usually proceeds from its anterior extremity to the base of
the wing. In the Orthoptera, Neuroptera^ and other Orders,
it is merely the longitudinal line of attachment of that
part ; but in the genus Bclostoma Latreille, related to the '
water- scorpion, it presents a peculiar structure, being a
deep channel or demitube, filled at its posterior extremi-
ty by a spiracle and its appendages *^.

13. Metapni/stega '^. This part, although in the table I
have placed it as an appendage oiihepleurcE, is not always
confined to them, as you will soon see. It either covers
aerial vesicles, or is the seat of a spiracle. In the Order
Coleoptera it is of the former description. If you exa-
mine the metathorax of the common dung-chafer [Geo-
trupcs stercorarms), in the horizontal part of the pleura
you will see a sublanceolate or subelliptical rather mem-
branous silky tense plate, with its point towards the head,
— this is the part we are considering ; something similar
you will find in most beetles ; but in some, as Callichroma
moschatum, it is less conspicuous. This part, as far as I
have observed, is not so situated in any other Order, ex-
cept in some TIeteropteroiis Hemiptera : in Belostoma the
channel lately mentioned is filled up at its posterior end
by a red organ with an anterior vertical fissure, termi-

« Plate VIII, Fig. 3. w'. '' Plate XXII. Fig. 14. to.

<■ Plate XXIX. Fig. 25. w.

" Ibid, and Plate VIII. Fig. 13. ; and Plate IX. Fig. 7. /i".

EXTERNAL ANATOMY OF INSECTS. StT)

natiiii; behind in a conical bag : in Notoneda the pleura
has something of a plate like that of Colcoptcra^ but of
a horny substance. In the Orthoptera and Ncuroptera
this part changes its situation, if it be indeed synony-
mous; and as the ^j^/T/.t/rg'a follows the yJvrwww, so the
mefapnystcga succeeds the postfrcvnum. In the Libcllulina
M. Chabrier found that this as well as the other covered
aerial vesicles ^, and it probably does the same in the
other cases in which it occurs. In Mantis and Phasma
in the Orthoptera it is very minute; but in Loaista
Leach, it is more conspicuous under the form of a tense
membrane, the surface of which is depressed below that
of the abdomen : in Acrida viridissima K. it fills the
sinus of the postfrcvmim, and is vertical, as it is in
JEshna, It is worthy of remark that this piece bears
some analogy to that below the ridge of the part just
named in Colcoptera^ wliich descends either vertical-
ly or obliquely to the abdomen''. A similar space,
though often nearly obsolete, may be seen in the Hemi-
j)tera and Lepidoptera. But the Orders in which this
part is most conspicuous are the Hymenoptcra and DijHc-
ra, and in these its aerial vessels are connected with a
spiracle. In Tcnthredo L. and Sirex L., what Linne
named grana^ from their situation, should be regarded as
belonging to the pnystega, and whether there is any part
representing the metapnystega I am not quite satisfied ;
perhaps the membrane at the base of the abdomen in
Tenthredo^ and the bipartite piece, apparently its first
segment, in Sirex'^, may be its analogues : but in the great
majority of the Order, the convex or flat piece that in-

* Sur/e Vol dts Iim. c. iii. .354. '' Sec above, p. 57^.

' Pr.ATF. IX. Fig. 1 ">. /".

576 EXTERNAL ANATOMY OF INSECTS.

tervenes between the postdorsolum and its adjuncts and
the abdomen, and which bears a spiracle on each side,
is the metapnystega ^. This part is often remarkable,
not only for its size, but for the elevated ridges that
traverse it, as in Ichneumon^ Chlorion, &c. In the last
genus it is of a pyramidal shape, with the anterior part
horizontal and the posterior vertical; it is altogether
vertical in Vespa, Apis, &c. Amongst the Diptera, in Ti-
pula it is nearly horizontal, and shaped like a cushion ;
but in general in this Order it is vertical, and concealed
under the postdorsolum ^.

We are now to consider the parts that constitute the
postpectus or under-side of the metathorax, and which
bears the posterior pair of legs.

14. Mesostethium'^. This part in Co/eop^^a is termi-
nated anteriorly by the peristethium, scapulars, and me-
sosternum, laterally by the parapleura '*, and behind by
the cox(C of the posterior legs ^, which generally are in-
serted transversely between it and the abdomen. It is
commonly very wide ; but in Dytiscus L., Carabus L.,
&c., in which the coxce and parapleurce are dilated, it is
proportionally reduced : its length is regulated by the
distance of the intermediate and posterior legs ; where
these are far asunder, as in the rose-scented Capricorn
{Callichroma moschatum), &c. it is long: but where they
are near each other, as in the Scarabceidcs MacLeay, it
is short; its width, however, generally exceeds its length.
In shape it is generally subquadrangular ^, though some-

■■" Plate IX. Fig. 11. k" . » Ibid. Fig. 20. k".

•^ Plates VIII. IX. y. << Plate VIII. Fig. 4. z'.

•^ Ibid. 1)". f Ibid. y.

EXTERNAL ANATOMY OF INSECTS. 577

times rhoniboidul, and other forms of it occur. Between
the hind-legs it generally terminates in a notch or bifur-
cation distinct from the meta sternum, as in Hi/drophilus,
&c. ; in IJisfer there is no notch, and in many Scara-
bccifhe it projects between the hind-legs in a truncated
or rounded mucro; in the Vesicatory beetles, Meloe
L., it is more elevated than the mcdipectus, towards
which it descends almost vertically ; in Di/tiscus L., Ca-
rahus L., &c., this part is usually divided into two by a
transverse sinuous chamiel, and in Elater by a longitu-
dinal straight one. In many Ortliopteroiis genera, Gryl-
lotalpa, Acrida K., Locusta Leach, &c., the mesostethium
consists of t-joo pieces *. It is remarkable that in many of
these genera, in this part, as likewise in the medipectus and
antcpcctus, are one or more perforations which appear to
enter the chest, the use of which I shall explain hereafter.
In the Libellidina, as I shall soon have occasion to shew,
there is a peculiar arrangement of the legs and wings, in
consequence of which this partis placed behind the pos-
terior ones. In the remaining Orders, the mesostethium,
though it exists, exhibits no peculiarities worthy of par-
ticular notice, except in some Aptera and Arachnida:
thus, in Nirmus Anseris it is terminated posteriorly by
a pair of transverse membranous appendages which
cover the base of the posterior coxce ,- in Scorpio it con-
sists of two pieces, the pectines^ being attached to the
sides of the posterior one.

15. Parapleural. The parapleura, speaking gene-
rally, is that piece of the postpectus which, intervening
between the pleura, mesostethium, and scaptdars, is at-

» Plate VIII. Fig. 13. y. a' f. '' Plate XXVIl. Fig. 50.

■ Plates VIII. IX. z. '

VOL. HI. 2 p

578 EXTERNAL ANATOMY OF INSECTS.

tached by its posterior extremity to the coxce of the hind-
legs ; by means of the j)leura, from which it does not
appear to be separated by any suture, it connects the
secondary or under-wings with the hind-legs, as the sca-
pular does the primary ones with the mid-legs ; so that
the direction of the parapleura depends upon the rela-
tive situation of the legs and wings. In Coleopterous
insects its direction is horizontal, it being generally a nar-
row subquadrangular piece that runs straight from the
posterior coxae to the scapular *, and usually divided into
two unequal portions by an elevated or impressed line.
In the palm-weevil [Calandra Palmarum) this part is
wider than usual ; in Di/tiscus jnarginalis, — in which ge-
nus, as likewise in Carabus L., the coxoe are incapable of
separate motion, — it is nearly a right-angled triangle,
and is divided longitudinally into two imequal portions.
In the Ortlioptera Order this part usually consists of two
equal portions, and its direction is sometimes nearly hori-
zontal, as in Mantis and Phasma ; sometimes forming an
angle with the horizon, as in Blatta ; and sometimes
nearly vertical, as in Locusta Leach. In the two first cases
the wings are before the legs, and in the last their po-
sition is over them. In the Heteropterous Hemiptera
it is parallel with the scapular, is divided into two un-
equal portions, and its direction is more or less inclined
to the horizon^. As to the Homopterous section — in Fid-
gora it is of a very irregular shape with an angular surface,
and its direction from the leg to the wing is first nearly
vertical and then horizontal: in Tettigonia it is almost
vertical, and consists of two nearly equal portions. To

^ Plate VIII. Fig. 4. z . " Plate XXIX. Fig. 15. %' .

EXTERNAL ANATOMY OF INSECTS. 519

come lo the Ncuroplei'a — in the Libellulina it consists ot"
two pieces, like those of the scapulars, but smaller =', and
its inclination is towards the head : in Panorpa also it
resembles tlie scapulars both in form and other circum-
stances'". In the remaining- Orders it exhibits no very
remarkable features.

16. Mctastcriinm^\ The central part of the 7?i«05^^-
thium when elevated or porrected, or otherwise remark-
able, is calletl the metasternum. In the Coleoptei'a, in
those cases, as we have seen above '^^ in which the me-
dipectus and postpcctiis form one piece, its anterior point
becomes the mesostcrnum ; but in others, as the Preda-
ceous and Capricorn-beetles, &c., it is received in a sinus
or fork of that part, or meets it. It is usually neither
so remarkable nor important as the mesosfenmm. In
Bolboccrus K. it is a rhomboidal elevation : in Gyriniis a
ridge; as also in many Hi/drophili, in which it passes
between the hind-legs to the abdomen, and terminates in
a sharp pohif*; and in Dytiscus its two diverging lobes
cover the base of the posterior trochanters ^. In the
Orthoptera Order this part is not remarkable ; but in
Acrida viridissima K. it consists of three triangular pieces,
the lateral ones being erect, and the intermediate one ho-
rizontal : in Lociisfa Leach it resembles the tnesostetmum ^.
In the Heteropterous Hemiptei'a the whole mesostethium
is elevated, and terminates at both ends in a fork, the
anterior one receiving the point of the promuscis, and the
posterior one that of the epigastrium : in the Flomopte-
rous section, the Tettigonide F. have usually a distinct me-

* Plati; IX. Fig. 8. z' . ^ Plates VHI. IX. a f.

•• See above, p. 565. " Plate VIII. Fig. 8. a f .

« De Geer iv. /. iv./. 3. fid. er. f Pi.atf. VIII. Fig. V^. a f.
2 r 2

580 EXTERNAL ANATOMY OF INSECTS.

tasternal point between their hind-legs. In the remaining
Orders there is no metasternum^ or no remarkable one,
except in one singular Hymenopterous genus, Evania, the
parasite of the Blattce % in which there is a forked pos-
terior process of the mcsostethiimi with recurved points.

17. Opercula^. By this term I distinguish those
plates, before largely described '^, which cover the drums
of male Tettigonice F. ; and likewise those called also by
the same name by M. Chabrier '*, which cover, in many
cases, the vocal appa7-attis of the trunk of insects : those
of Melolontha vulgaris he describes as situated below the
wings, and between the two segments of the alitrunk ^ ,•
and if you take this insect and remove the elytra, the
mesothorax .and scapulars, under the latter and below the
wing you will find an oval convex plate, which is pro-
bably the part he is speaking of; — but it is better exem-
plified, I think, in the common Dytiscus marginalise in
which it is very distinct as a convex sub triangular plate
connected with the wete/Z/oracT by membranous ligament,
covering a kind of pouch, and appearing to open and
shut at the vertex ^.

I must here observe, with regard to the Aptcra and
Aracknida^ that the trunk in them is much more simple
than in those insects that are furnished wdth laings. In
the hexapods, in the former Orders, though there are

^ The history of this parasite has been traced by Dr. Reid ; but
alas ! this learned and acute observer of nature did not live to give
his discoveries to the world : it is hoped, however, they will not be
lost, being in most able hands.

" Plate VIII. Fig. 18. and XXII. Fig. 13. c f .

" Vol. II. p. 405. ^ Sur le Vol des Ins. c. i. 459.

' Ibid. 457—. ' Plate XXII. Fig. 13. c f.

EXTERNAL ANATO\(Y 01' INSECTS. ,)81

usually three pedipjerous segments, there is no distinction
of dorsolum, scutdlnmf 8cc. In the Scolopendridcc und
Scutigera amongst the Myriapods, according to the acute
observations of M. Savigny ', — on which, however, some
doubt at present rests, — there is a remarkable Ibrmation,
the whole thorax being represented by the single plate
that follows the head, to the under-side of which are at-
tached the first and second pair of palpi or pedipcdpi^
and the first pair of legs, representing the three pairs of
legs of hexapods. In the lulidce the three segments that
follow the head, each bear a single pair of legs, while all
the rest bear a double one : from whence it should seem
to follow, that these segments and their legs represent
the trunk and legs of Hexapods. In the Octopod Apiera
and the Arachnida the trunk consists of a single piece,
not separated from the head, and sometimes not distinct
from the abdomen.

V. Internal processes ^. Perhaps you will think that
this head would be better considered when I treat of the
Internal Anatomy of Insects; but as the parts included
under it are really processes of the external integument
of the trunk, it seemed to me best to treat of them under
that head. They are of two descriptions ; processes of
the thorax or upper part of the trunk, and processes of
the bread or its under part.

i. Processes of the thorax"". These are the phragma^
prophragma^ mesophragma, and metaphragma. The first
belongs to the prothorax, the second to the mesothorax,

» Mem. sur les Anim. sans Vertebr. 45 — . Hor. Entomolog. 411 — .
" Plate VIII. Fig. 3. x. IX. Fig. 2. s . and XXII. Fig. 5—
14. * Plate XXII. Fig. 8—11.

582 EXTERNAL ANATOMY OF INSECTS.

and the two last to the metathorax ; each formiug a kiiitl oi
chamber of the under-side of each .segment of the thorax.

1. Phragma. The phragm, or septwn of the protho-
rax, is most conspicuous in the mole-cricket {Grijllotal-
pa\ in which it is a hairy ligament attached to the inside
of the upper and lateral margins of the base of that part:
inclining inwards, it forms the cavity which receives
the mesotJiorax. It is not, however, without a representa-
tive in many Coleoptera^ though in these it is less striking,
from its being smaller and taking a horizontal direction.
In Elater\ by means of some prominent points received
by corresponding cavities of the vertical part of the base
of the elytrum, it forms a kind of ginglymous articula-
tion, which, probably keeps them from dislocation in re-
pose, and, by the sudden disengagement of these points
from the cavities, assists the animal in jumping ^.

2. Prophragma ^. This is a piece usually almost ver-
tical, but in Elater horizontal; of a substance between
membrane and cartilage, descending anteriorly from the
dorsolicm, and forming the first partition of the chest of
the mesothorax ; it is generally much shorter than the
mesophragm. Though very visible in Coleopicra and
the Heteropterous Hcmiptera^ in the other Orders it is
less easily detected, and is sometimes obsolete. It may
be observed here, that in the Htjmenoptera^ at least in
the wasp, the hive-bee, the humble-bee, and the Dipte-
ra mostly, the interior of the upper-side of the alitrunk,
instead of /tuo, seems at first to be divided into fou)' cham-
bers, formed by septula : but as these ridges merely mark
out the internal limits of the dorsolum, saitellum, postdor-

•> Vol H. p. 318. ^ Platk XXII. Fig. 8, 11. h' .

EXTERNAL ANATOMY OV INSECTS. 583

solum, and metapnystcga, the last but one of these being
usually less distinct, they seem not analogous to the three
partitions of the alitrunk in other Orders; so that in
these the niesophragni at least seems to have no repi'e-
sentative, and the prophragm and metaphragm include
between them only one ample chamber. In the Diptcra,
wherever there is an external depression or suture there
is a corresponding internal i-idgc or seam, so that the
parts seem more distinctly marked out on the inside
than on the outside of the crust.

3. Mcsophragma ■'. This piece also, which forms the
middle partition of the upper part of the cavity of the
alitrunk, dividing it into two chambers, is most conspi-
cuous in Coleoptera. It is usually in them a vertical
piece, resembling the prophragm in substance, but twice
its height, of a quadrangular shape with a notch in the
middle; it fills the sinus o{\hQ post dor solum, the sides of
which sometimes descend below it''. In this Order the
chamber that it forms with the prophragm is very small '^j
the motions of the elytra requiring no powerful apparatus
of muscles; but that which it forms with the metaphragm,
which is appropriated to the muscles moving the wings,
is very large ^. In the Orthoptcra the anterior chamber
is larger than in the preceding Order, which proves that
tegmina are more moved in flight than elytra. In the
Heteropterous Hemiptera a remarkable variation takes
place — the anterior being larger than the posterior
chamber; which last, in fact, consists of two, one for each
wing : in these the mesophragm towards the abdomen
forms an angle, which in Pentatoma, &c., is acute ; in

^ Plate XXII. Fig. 9, 1 1, .v'. " Ibid. Fig. 0. a a.

' Ibid. Fig. 11. a. •< Ibid. b.

584 EXTERNAL ANATOMY OF INSECTS.

Belostoma a right angle, and in Nutonecta an obtuse
one. In the two first the angle of the mesophragm sends
two short diverging ridges to the metaphragm ; and in
the last only a single one : in this also the posterior
chambers together are nearly as large as the anterior.
From this structure it should seem that in flight the
Hemelytra are more important than the wings. In the
Homopterous section the anterior chamber is the
smallest, at least in Fulgora candelaria ; and the meso-
phragm is lofty and bipartite. In the Lepidoptera the
anterior chamber is the largest, and the part in question
conspicuous ^. In the Libelhdma and Hymenoptera it
is merely represented by a low ridge, and in the Diptera
it seems evanescent.

4. MetapJiragma ^. This, in many cases, is the largest
and most remarkable of the three partitions of the upper
portion of the cavity of the alitrunk, which separates it
from that of the abdomen ; it is attached to the posterior
margin of the metatlwrax^ and is nearly vertical : in sub-
stance it may be stated as rather firmer than the two
preceding partitions. In the Coleoptera it is commonly
of the width of the posterior orifice of the alitrunk ; and
its centre is cleft so as to form a deep sinus "^ for the
transmission of the intestines, — a circumstance which
also, though less conspicuously, distinguishes the meso-
phragm '^: from this sinus it slopes gradually towards the
sides, and is sometimes armed with an intermediate pro-
cess on each side ^. This structure you will find exem-

" Plate IX. Fig. 2. s .

^ Platk XXII. Fig. 10, 11. x . Comp. Linn. Trans, xi. t. ix.
/. 16. g. -^ Plate XXII. Fig. 10, 11. d.

'' Ibid. Fig. 9. c. <= Ibid. Fig. 10. a.

EXTERNAL ANATOMY OF INSECTS. 585

plified in the connnon cock-chafer and many others of
the Order. I have not, however, discovered traces of
it either in the Silphidcc, StaphijUnidcc, or the vesicatory
beetles (Meloe L.); or even in such species o[ Carabns
L. and Cicindda L. that I have examined; while in
Dytisciis it is very visible. In the Orthoptcra it is nearly
obsolete ; but in Locusta Leach, under the mctapnystcga^
one on each side, is a pair of seemingly pneumatic
pouches which may be mistaken for it. It is almost
equally inconspicuous in both sections of the Hcmiptei'a.
As to the Lcpidoptcra., — in Picris Brassiccc, it resembles
in some degree, though in miniature, the metaphragm of
the Coleoptera ,- but in Sphinx Stellatmnim and Lasio-
campa Qiiercus it has a sinus on each side, but no middle
one. In Panorpa it nearly closes the posterior orifice
of the trunk, but in the Libellulina it is a mere ridge.
In some Hymenoptei^^ as Cimbex sericea, the drone-bee at
least, &c., it is a large convex bifid piece. In the wasps,
under the spiracle of the metajmystega on each side,
as in the Locusta, is what I also take to be a pneumatic
pouch, which might easily be mistaken for a metaphragm.
In the Diptera Order this part is very conspicuous. If
you remove the abdomen of any common Tijmla, you
will find that the posterior orifice of the trunk is closed
above by a pair of oblong, vertical, convex, diverging
plates ; — do the same by any fly [Musca L.), and you will
detect in the same situation a very large convex or gib-
bous one notched below, which occupies almost the whole
orifice : this is the metaphragm.

5. Septula *. These are the smaller ridges ol" the inte-
rior of the alitrunk, which aflbrd a point of attachment to
•' Ibid. Fig. i)-ll./".

586 EXTERNAL ANATOMY OF INSECTS.

many muscles, and run in various directions both on the
interior of the crust and of the metaphragm. These httle
seams are not to be found so generally in the other Or-
ders ; but very frequently, as has been before observed,
where there is an exterior impression of the crust, or a
suture, one of these forms its internal base.

ii. Processes of the pectus^. We are next to consider
the internal processes of the breast of insects: these con-
sist for the most j^art of the etidosternum, or internal
sternum, and its branches. As the principal feature of
this are the processes which rising from it serve as points
of attachment to the muscles that move the legs, &c., I
shall confine myself to them — they are, the antefurca, the
medifiirca, and the post fur ca.

1. Antefurca^. The first portion of the endosternum,
or the internal prosternum, branches into the antefurca.
In the Coleoptera a plate varying in shape and direction *=
sends forth a pair of mostly vertical processes of a car-
tilaginous substance ^, differing in height in different
genera. In Carabus L. there is neither this plate iior its
processes ; but in Dytiscus the latter are very visible. A
very singular and complex machine represents the part
we are considering in that extraordinary insect the mole-
cricket ( Gryllotalpa Latr. ). When we look at its prodigi-
ous arms and consider their office % we may imagine that
the requisite apparatus for moving them must be very
powerful and peculiar. Their Creator has according-
ly provided them with a machine for this purpose more
than usually complex, extending from \\\ep)rothorax to the

* Plate XXII. Fig. 5—7. "• Ibid. Fig. 7. ■= Ibid. a.

" Ibid. e. " See above, Vol I. p. 191. and II. p. 257, 366.

EXTERNAL ANATOMY Ol;- INSECTS. 587

prosternum ,- the former being its base^ and the latter its
vertex. The cavity of the manitrunk is divided longi-
tiuhniilly by a double cartilaginous partition surmounted
by a bony frame, with an anterior condyle or tuberosity,
with which the inner part of the base of the clavicle of the
arm appears to ginglymate ; and the manitrunk is pre-
served from the injury the powerful action of the arm
might occasion, by the counteraction of this machine, to
describe which fully, would demand more space than I
can afford ^. I mentioned under the mesostethium, the aper-
tures visible in the breast ot'Locusla Leach and Acn'daK.
Each of these apertures opens into an internal, tubular,
horny, process, which arching off is attached at the
other extremity to the sides of the trunk — a pair being
appropriated to each segment; the first analogous to
the anttfurca, the second to the mcdijurca, and the last
to the postfurca. In the mcdipecius and postpectus of
Acrida viridissima there is only a single aperture, termi-
nating in a single tube, which after rising vertically a
little way sends off" a branch on either hand to the sides
of the trunk. Where there are three of these holes, as
in the antepcctus and medipectus of Lomsta Dux, there
are three of these processes, the intermediate one bemg
vertical. In the subse(juent Orders the processes of the
endosternum are not sufficiently remarkable to require
particular notice : my further observations upon them
will therefore be confined to the Coleoptcra Order.

2. Medifurca ^. This part, which belongs to the mid-
legs, is in many cases more conspicuous tlian the antefurca.

* This machine is described by Dr. Eschscholtz, Bcitr'dgc ztir
Naturkundcy &c. Heft. i. 21 — . t. i. ii.
'' Plate XXII. Fic 6.

588 EXTERNAL ANATOMY OF INSECTS.

In Copris Molossus the endosternum of the medijiecius is
represented by a transverse zigzag ridge * between the
sockets of the mid-coxee, from which proceeds a pair of
branches wide at the base and growing gradually more
slender to the extremity^, which is attached to the sides
of the trunk; in Dytiscus marginalis a pair of slender, ver-
tical, straight processes, fitted with a broad cartilaginous
plate at their apex, rises from the endosternum, and sends
forth a lateral one to the side of the medipectus : and lastly,
in Carabus the medifiirca is represented by a pair of sub-
triangular lamince attached to the sides of the trunk.

3. Postfurca ". This, which belongs to the hind-
legs, is the most remarkable of the pectoral processes,
and has been noticed by more than one writer ^. It is
a kind of trident, the branches ^ of which are acute, and
on their upper surface longitudinally concave, elevated
on a footstalk ^ inclined towards the medifurca, consist-
ing of two plates, a posterior one supporting the lateral
branches, and an anterior or interior one forming a right
angle with the other, supporting the intermediate one.
This footstalk rises from between the posterior coxce,
which appear in the Lamellicorns to ginglymate with it at
its base. The middle branch of the trident dips to the
sinus of the medifurca. In Dytiscus marginalis the form
is different ; for the intermediate branch consists of two
parallel pieces, and the lateral ones are dilated into broad
vertical plates : the stalk of this is triquetrous, and a tri-
ple cartilaginous partition appears to go from its base
anteriorly, the lateral ones diverging to the sides of the

•' Plate XXII. Fig. 6. a. i- Ibid. b. '■ Ibid. Fig. 5. b. f

'' MacLeay, Horce Entoviolog. 9. Chabrier, Stir la Vol des Ins.
c. i. 417. " Plate XXII. Fig. 5. b b b. ' Ibid. c.

EXTEUNAI. ANATOMY OF INSECTS. .GSO

trunk, aiul the intermediate one running straight to the
base of the mcdifurca.

It may not be without interest to state here some of
the several objects and uses of this structure of the
trunk. AMien our Saviour says to his disciples, " But
even the very hairs of your head are all numbered" ^ —
he taught them that the attention and care of the Deity
were not confined to the mighty and the vast, but
directed to every atom of his creation — that he not only
decreed the number and magnitude of the planets and
planetary systems, and of their various inhabitants, but
that the most minute and apparently insignificant part
of each individual, both as to its number and form, was
according to the law by him laid down ; and whoever
studies them with attention will find that insects furnish a
very intei'esting homily upon this text; since in various
instances I think I have made it clear, that parts seem-
ingly of the least importance — as a hair, a pore, or a
slight impression — have their appropriate use ''. At first,
it would seem that the various pieces of which we have
seen the second primary segment of the trunk of these
animals to be composed, would be of little importance ;
but when we reflect that this multiplicity of parts is
usually not to be found in those that have no wings,
whether they be apterous sexes or tribes '^, a suspicion
arises in the mind that they must be of more consequence
than \\\e\Y prima facie appearance seems to warrant: — and
this is really the case. The manitrunk, which is destined
principally to incase the muscles that move the arms,
did not require to be so complex as the part that had to
support the action of wings as well as legs. In those that

•* Luke xii. 7- '' Sec abo\c, p. ;i07— . ' See above, p. 580,

590 EXTF.RT^AL ANATOMY OF INSECTS.

have a \arge j^rotJiorax, as the Coleopiera, it may, indeed,
be useful in flight as a counterpoise to the abdomen;
and since when the wings descend it rises, and vice versa^
it may be of some service by its vibrations * ; but for this
it required no complexity of structure. But not so the
alitnink : it consists of parts much more numerous, and
this number of parts is of great importance to the animal
in its flight. All of them are so put together, being lined
by a common elastic ligament '', as to be capable of a
certain degree of tension and relaxation, which enables
the animal to compress or dilate the trunk as its ne-
cessities require. To cause the elevation of the wings,
it must be comp-essed or have its longitudinal diameter
increased, and its vertical and transverse diminished:
this compression is produced by the condensation of
the internal air, which parts with some of its caloric, and
by the action of the levato?- muscles. To cause the de-
pression of the wings, it must be dilated, or have its longi-
tudinal diameter diminished, and its vertical and trans-
verse increased, which is eiFected by the rarefaction of
the internal air, and the action of the depressor muscles ^.
In some Orders, the Coleoptera, &c., this effect is pro-
moted by the segments of the trunk, which are attached
by loose ligamentous membranes, and received, one or
more of them, into each other, which facilitates the
above action ^. Thus much for the general use of these
parts. I shall further here mention a partial one of
two of them which seems indicated by a particular cir-

^ Chabrier Surle Vol des Im. c. i. 413 — .

•> See above, p. 402.

•^ Chabrier Sur le Vol des Ins. c. i. 446, 448, 451 — .

J Ibicl. 412.

EXTERNAL ANATOMY OF INSECTS. 591

cunistance, aiul upon which a theory may be built. In
some insects the primary and secondary wings or their
analogues are placed before the legs, in others ova' the
legs, and in others behind the legs : but whatever their
position, the pieces which I have named the scapularia
and parapleicra: invariably connect the one with the
other ; the former, the primary wings with the mid-legs,
and the latter, the sccondm-y wings with the hind-legs.
This circumstance seems to prove that the wings by the
intervention of these pieces have an action upon the legs,
and the legs upon the wings ; and this is further proved
in one case by an observation of M. Chabrier with re-
gard to Melolontha vidgaris, — that the levator muscles of
the wings, by means of a long tendon, are attached to
the lower part of the posterior coxae *. Now, more than
one medical friend has suggested to me, that what are
called the coxce in insects are really analogous to the
thighs of vertebrate animals^: consequently these parts
must represent the coxce ,• whence it would seem that the
wings are really appendages of the legs. It must, how-
ever, be observed, that were this opinion admitted, in the
Apiera, Hymenoptera, and Diptera, or even in the pro-
thorax of other insects, there would scarcely be any ana-
logue of the coxa at all distinct from the trunk itself, of
which even in the other Orders these pieces are com-
ponent parts. An instance occurs in the Strepsiptera K.,
and in which the arms are furnished with an alary ap-
pendage, and the metathorax lias none *=.

» Ubi supr. c. ii. 333.

'' According to M. Chabrier, who agrees with him, M. Latreille
also is of opinion, that the parapleura is the analogue of the poste-
rior cox<r. Ubi supra, c. ii, 312. Note 2.

'^ M. Latreillp has chansed the denomination of this Order to

592 EXTEUNAL ANATOMY OF INSECTS.

VI. Organs of Motion. We are next to consider those
orffans attached to the trunk of insects which are instru-
ments o^ motion. These are principally those by which they
are transported through the air, and those by which they
move on the earth or in the water — their uairigs and their
leirs. I shall begin with the first, the isoings ^. These
are not formed precisely after any type at present dis-
covered in vertebrate animals: in some respects they
have an analogy to those of birds '' ; in others, to the
dorsal fins of fishes : but, perhaps, altogether they ap-
proach the nearest to those of the dragon or flying-lizard
{Draco volans L.), which do not, as in birds, replace the
fore-legs, are kept expanded by diverging bony rays,
and are connected with the hind-legs ". As the Divine
Creator appears in his works to proceed gradually from
one type of structure to another, it has been supposed
by a learned physiologist of our own country, that in
winced insects, ^owr of the legs of the Decapod Crustacea

Wdplnptcra, because at first he thought that these organs were
not at all analogous to elytra or wings ; but since, upon further
investigation, he appears to admit that they assist in flight {An-
nales Gener. des Scienc. Phi/s. VI. xviii. 8. Compare MacLeay, Hor.
Entom. 423. Note *), in common justice he is bound to restore
the name originally given to the Order. In the same place of
the work here quoted, M. Latreille also speaks of these pseud-
clytra, as I would call them, as appendages of the mesothorax : but
whoever consults Mr. Bauer's admirable figures of Xenos PecJdi
{Linn. Tratis- xi. t. ix.), and is awai-e of the unimpeached and
minute accuracy of that admirable microscopic artist, will be con-
vinced that they belong to the anterior legs, and consequently to
the prothorax.

■^ Plate X. and Plate XXVIII. Fig. 18—23.

" Chabrier, Analyse, &c. 27.

« N. Diet. d'Hist. Nat. ix. 568. We have seen above (p. 578.)
that the wings of insects are connected with their legs by the scapn/a
and pnrnphntra.

KXTERNAL AN.MOMY Ul" INSLCIS. 593

are represented by the four wings ' : this opinion, how-
ever, is not yet fully proved ; a remark whicli may also be
applied to a more recent one of a celebrated French
writer, who seems to think their ori<>in and structure
aerostatic, that they are auxiliary to the legs, and bor-
rowed in part from the respiratory organs ^, Were I
disposed to enter into these subtile speculations, I might
here recall your attention to the analogy that, in their
metamorphoses, exists between the Saurian Reptiles or
lizard tribe and insects, and conjecture that the wings of
the Draco are really representatives of the mid-legs of
Hexapods, thus preparing to disappear altogether ; but
I shall content myself with throwing out this hint, which
you are welcome to pursue. The organs of flight in
general may be considered as to their mimber^ kinds, and
conipositioji.

i. Numbe?: The most natural number Is Jour, for this
obtains in the majority. In almost every Order, indeed,
there occur instances of insects that have solely a single
pair or none"^.

^ MacLeay, Hur. Entomulog. 413 — . Mr. INIacLeay's opinion seems
to receive some confirmation from a circnmstance overlookeJ when
the larvce of insects were treated of above (p. 130 — }, and to which
he alludes (411); namely, that in that state they consist of two seg-
ments more than in the iiiiogo; these follow the three pedigerous
segments, have no pro-legs, and are supposed to belong to the trunk
rather than to the abdomen. To make this circumstance bear upon
the question, it must be proved that in the perfect insect these seg-
ments in some manner become the back of the trunk and bear the
wings. This would not be more wonderful than many changes that
are known to occur in insects.

'' Latrcille, Organization ejctcrieurc des Ins. IJ-'^ — .

<= For instance Mcloe, the female glow-worm, Li/gceus brcvipcnnh,
Ephemera dipt era, Cyiiips apt era, neuter ants, &c. &c.

VOL. III. 2 p

594 EXTERNAL ANATOMY OF INSECTS.

These, however, are only exceptions to the rule; but in
the Diptera^ unless we consider the alulce, the representa-
tives of the secondary wings ^, as a distinct pair, there
are never more than two wings, and one instance is
known in which an insect of this Order has none •*.
Certain genera or individuals of the Tetrapterous Orders
are also furnished with alulce: besides Dytiscus, Blatta^
Pkalcena hexaptera, which have been before noticed '^^
they may be detected in miniature in Ammophila K. and
affinities ; these all may be regarded in some slight de-
gree as insects with six ivifigs.

ii. Kinds. Under this head we may consider the or-
gans of flight as to their situation and as to their sub-
stance. As to theh' situation, usually the first pair are
attached to the mesothorax, and the second to the meta-
tliwax ; but in one instance, as has been before ob-
served'', in the Strepsiptera K., the anterior pair belong
to the manitrunJc, and the posterior to the mesothorax.
As to their substance, they take the several denomina-
tions of elytra, tegmina, hemelytra, and wings, for the
most part according to its variations, as will be seen
more at large hereafter. Under this head I shall only
further observe, that in many instances the organs of
flight appear to be mere abortions or rudiments, which
serve to exemplify what has been more than once stated,
that the CREATOR has seen it good to approach to new
organs gradually as well as to new forms. Thus elytra are
mere rudiments that do not serve to protect the wings in
Atractocerus ; tegmina in some species of Phasma, Aery-

* See above, p. 559. ^ Chionea nmnemdes Dolm.

•■ See above, p. 560, and Vol. II. 348, 352—.
** See above, p. 591 , Note c.

EXTERNAL ANATOMY OF INSECTS. 595

(Hum., &c. ; hemelytra in the bed-bu{^*; \soings in many
female moths, in Cnfptus hemiptei'^ts a Hymenopterous
insect, &c.

iii. Composition. The structure of wings has been
before explained to you ^^ and I sliall again have occa-
sion to allude to it; but here I wish to call your attention
to a circumstance that has not hitherto, that I recollect,
been adverted to ; I mean that all kinds of organs of
flight, and it may be traced as we shall soon see even in
elytra, are divided longitudinally into three areas or folds;
the first or external one I call the Costal Area *= from its
beginning with the costal nervure ; the second is the In-
termediate Area ^ ; and the third is the Anal Area ^.

Having made these observations with respect to the
organs of flight in general, I shall now proceed to consider
more at large the elytra, tegmina, hemelytra, and "doings.

i. Elytra. These are the wing-covers of the Coleoptera
Order, distinguished from tegmina by the absence of
nervtires, from hcmclytra by the want of the membrane
at the apex, and from both by their uniting in almost
every instance at the suture. I shall consider them as
to their substance ; articulation with the trunk ; expan-
sion; parts; shape; appeiidages ; sadpture ; clothing;
colours, and uses.

1. Substance. The firmness of the substance of elytra
is usually regulated by that of the crust of the insect to
which they belong ; in hard insects they are hard, and

•' De Geer, iii. t. xvii./. 10, 11.//. M. Savigny has noticed a part
in some Annelides, which he regards as analogous to elytra. Systcme
des Annelides, 4, 9, 1 1. " Vol. II. p. 346—.

<= Plates X. and XXVIII. Ir. " Ibid. c-. ' Ibid. d\

'I o 2

596 EXTERNAL ANATOMY OF INSECTS.

in soft ones they also are soft. The most impenetrable
ones that occur to my recollection are those of lUiger's
genus Doryphoray and the softest and most flexile those
of Telephorus, Meloe and affinities. With regard to in-
dividuals, they are mostly as hard as the protliorax^ and
harder than the hack of the abdomen. Elytra also, as
far as my observation goes, are never diaphanous.

2. Articulation isoith the trunk. This is by means of
a process of the base of the elytrum which I call the axis *
or pivot, attached by elastic ligaments, and certain little
bony pieces [ossclets Chabr.) in the socket under the side
of the anterior angle of the dorsolum ^. You may easily
remove the elytra attached to the mesotliorax from Geo-
trupes stercorarius, which will enable you to see the mode
of articulation with little trouble'^.

3. Expansion. It is by means of the bony pieces just
mentioned that the organs in question are opened and
shuf* under the action of the antagonist muscles. In
opening for flight the two elytra recede from each othei-,
and are elevated so as not to retain their horizontal po-
sition, which would interfere probably with the play of
the wings, but form an angle with the body. When they
return to a state of rest, the sutures usually meet and
coincide longitudinally ; but in some cases when closed,
as in Nccydalis, &c., they diverge from each other at the
apex ; and in Meloe, like the Ort/ioptera, to which that
genus approaches, one laps over the other.

4. Parts. The parts to be considered in an elytrum
are the areas, the axis, the suture, the margin, the epi~

» Plate XXVIII. Fig. 3—5. b'" .

^ Chabrier Sur le Vol des Ins. c.i. 439.

•^ Plate XXVIII. Fig. 10. •' Chabrier ubi supr.

EXTERNAL ANATOMY Ol' INSECTS. 597

]>leura, the base and apex, the angles, and the hypoderma.
At first it should seem as if an elytrum was not like other
wings divided into areas; but I think upon examination
it will be found that, though often nearly obsolete, these
are represented in it; for the epipleura^ with the recurved
part of the external margin seems to me analogous to the
Costal Area; the inflexed part adjoining the scutellum and
often going beyond it to the Anal, and the rest of the organ
to the Intermediate. All this you may see in the dung-cha-
fer, Geott'upes stercorarius. The axis ^ or pivot by which
the elytrum articulates with the trunk is generally placed
about the middle of its base, but nearer the scutellar
than the humeral angle, and varies in length and shape
in the different tribes, but not so as to merit particular
notice ; it may be regarded as composed of three parallel
pieces, one belonging to each area, that of the costal be-
ing the longest. In many these pieces are marked by no
line of distinction, but in Macropns, Sec, they may be readi-
ly traced'^. The suture^ is the internal \naYg\x\ of the
elytrum from the point of the scutellum to the end. In
many beetles the right hand suture, looking from the
anus to the head, has a lower ledge or margin, and the
other, one more elevated, which when they are closed
lies upon the former ; in some Dynastidce there seems a
kind of ginglymous structure in this part, each suture
being fitted with a kind of ridge which is received by
a channel of the other ; in these the suture is generally
marked out by an adjacent channel : but the most re-
markable structure of this part distinguishes the genuine
species of the genus Chlamys, in which both the sutures,

' Plate XXVIII. Fig. 6—8. rf". " Ibid. Fig. 3—5. b" .

' Plate XXVIII. Fig. .3. " Plate X. Fig. 1. c ".

598 EXTERNAL ANATOMY OF INSECTS.

except at their base, are armed with little teeth, alter-
nating with each other like the cogs of a mill-wheel. In
apterous beetles the elytra are often connate, or have
both sutures as it were soldered together. The margin'
or external edge of the elytra is generally formed by a bead
or ridge, which, except in the case of the truncated ones,
in which it is straight, curves more or less from the base to
the apex; this ridge is often recurved so as to form a kind
of channel between it and the disk of the elytrum, as may
be seen in the Dijnastidxe ; in some there are two parallel
ridges, as in Copris; in Silpha the margin is dilated; in
Hel(sus and Cossyphus it is remarkably so and recurved,
so that, in conjunction with thoseof the j5ro/7zor«^ which
are similarly circumstanced, they give the animal some re-
semblance to a small model of abarge. Though the margin
of elytra is most commonly intire, yet in some beetles, as
Gymnopleurus lUig., a sinus is taken out of it; in Cetonia
it often projects at the base, and in Cryptocephalus in the
middle, into a lobe ; in Phoherns MacLeay it is denticu-
lated, and in many Buprestes more or less serrulated ;
sometimes it terminates before it reaches the apex of the
elytrum in a tooth, as in many Carabi Latr. The epi-
pleura ^ or side-cover is that part of the organ in ques-
tion, below the margin, with which it usually forms an
angle, being more or less inflexed, that covers the sides
of the body. It varies in different tribes, being some-
times obsolete, as in the weevils [Curcidio L.); in the
Capricorn beetles it is very narrow ; in Carabus, &c.,
dilated at the base ; in many Heteromerous beetles, as
Blaps, Pivielia, &c., it is very wide and conspicuous; in

' Plate X. Fig. I. c. "^ Plati; XXVIII. Fig. G~8. rf'".

EXTERNAL ANATOMY OF INSECTS. 599

Cossj/phus it stands out a little from the abdomen, so as
to form a kind of fence round it. Its shape generally a\>-
proaches that ofa scythe, being incurved and growing more
slender towards the apex " ; but it is sometimes straighter
and shorter. In Gcotnipcs and many other LameUi-
corus, the base of the elytrum is nearly vertical, forming a
right angle with the rest of it; it is usually transverse and
straight ; but in Calandra Palviainim and many Cassidic
it slants to the scutellum ; in Chlamys it is sinuate, and
in Elata' it has a deep cavity above the axis which re-
ceives the points of the phragma mentioned before^.
The apex of elytra is usually acute, the angle being
formed by the confluence of a curving and straight line :
but there are many exceptions ; for instance, in Mylahris
it is rounded ; in Hister obliquely, and in Necrojjkorus
transversely, truncated ; in many Capricorns it is emar-
ginate ; in others, as Macroptis longiinanus, it is biden-
tate; in some Prio?it, P. cintiamomeus, &c., it termi-
nates in a mucro at the internal angle ; and in Ceram-
byx BatuSf horridus, &c., at the external; and, to name
no more, in some species of Necydalis it ends in a long
acumen. The scutellar angle in insects that have a large
scutellum, as Macruspis MacLeay, is obliquely trun-
cated to admit it, but where it is small it is generally rect-
angular, with the angle rounded ; in Buprestis vittata it
is obtusangular ; and in Dijtiscus marginalis, &c., it is
emarginate. In Cassida spinijex, perforata.) &c., the hu-
meral angle is producted into an acute lobe that stretches
beyond the head, and in C. bicornis and Taurus it forms
a horn at right angles with the elytrum. In general it

' Plate XXVI H. Fig. 8. '' See alwve, |). 582.

600 EXTERNAL ANATOMY OF INSECTS.

is either rectangular or lounded, with a prominence of
the elytrum within it. The siitural and anal angles exist
only where the elytra are truncated at the apex. In this
case the sutural is generally rectangular, and the anal
rather obtusangular or rounded. The Hypoderma is the
fine soft membrane before noticed * that lines the under-
side of the elytra, the use of which is probably to prevent
injury to the wings from friction with their usually hard
substance; this membrane is Commonly of either a
pallid or brownish colour ; but in some insects, as Sta~
■phylinus hybridus, murinus, &c., Buprestis Gigas, it is of
a beautiful green or blue ; and it exhibits the puncta,
strlce, and other modes of sculpture of the elytra very
distinctly, the pores of which usually perforate this mem-
brane ^. Just under the shoulders of these organs you
may observe an oblong and sometimes roundish spot,
occasioned by the hypoderma in that part being parti-
cularly tense, and covering a cavity or pocket which ap-
pears to be connected with the axis by the hollow pait,
which I I'egard as representing the Costal Area ; this
pocket is evidently the analogue of a part in the wings
noticed by M. Chabrier <^, and named by me the phi-
alum : from its connexion with the axis by a channel,
this part in elytra should also seem destined to receive a
fluid to add to the weight of the margin and its means of
resistance.

5. Shape. The shape of elytra is various; taken to-
gether, in which case, in describing insects, they are de-
nominated coleoptra, their most common form is more
or less oblong, or forming more or less a considerably

' See above, p. 402—. " Ibid. .399.

•^ Siir le Vol dcs Ins. i. c. 4x.'8 — . c. ii. 3,?o.

EXTERNAL ANATOMY OF INSKCTS. 601

portion of an ellipse ; taken separately, it inclines to tliat
of an isosceles triangle, with the exterior sitle curvilinear:
truncated elytra are generally quadrangular, sometimes
presenting a trapezium, at others nearly a parallelo-
gram, and at others a square. With regard to their
proportions they vary considerably, but the most general
law seems to be that the length shall exceed twice the
width ; in some, as Buprestis Gigas, it is more than
thrice ,- in many Staphijlinidde they are as wide as they
are long and sometimes wider ; they are generally nar-
rower at the apex than at the base, but in some species
of Lyciis, as L.fasciatus, &c., the reverse takes place ; in
Tclephonis they are nearly of the same width every
where : with regard to their surface they are sometimes
very convex, as in Moluris ; at others very flat, as in
Eitrychora, Akis, &c.

6. Appendages. These, though not so remarkable as
those of the head and prothorax of beetles, ought not
to be ovei'looked. In many Capricorns, as Lamia Tri-
bulus, speculifera, &c., the disk and sides are armed with
short sharp spines; in others {Stenocoriis^ &c.) the sutu-
ral and anal angles or one of them terminate in a spine
or tooth ; sometimes the whole surface, as in Hispa atra,
&c., is covered, like a porcupine, with a host of slender
spines, or its sides defended by spinose lobes, as inH.eri-
nacea : the humeral prominence is armed with a spine
pointing to the head in Maaopiis longimanus, and form-
ing a right angle with the elytrum in some Curculionidcc,
as Rhynchites spitiifex ; but the most remarkable ap-
pendage of this kind is exhibited by Cassida bidens and
its affinities, — from the centre of the sutures of the elytrum
rise perpendicularly a pair of long, slender, sharp pro-

602 EXTERNAL ANATOMY OF INSECTS.

cesses internally concave, which both apply exactly to
each other, so as together to form a single horn which
rises, like a mast from a ship, from the body of the ani-
mal *. Besides the appendages here mentioned, the
elytra exhibit a variety of tubercles and other elevations
of various form and size, which it would be endless to
particularize.

7. Sculpture. The sculpture of the organs in question
is very various and often very ornamental : but as al-
most every kind of it will be noticed in the erismologi-
cal tables, it will not be necessary to enlarge upon it
here, especially since I have endeavoured upon a former
occasion to explain how it may be useful and important
as well as ornamental to the animal^. I shall therefore
only notice a few instances, amongst many, in which
a particular kind of sculpture distinguishes particular
tribes. Amongst those that are Predaceous the Cicin-
delida have elytra without striae or furrows, while the
majority of the subsequent terrestrial tribes of this sec-
tion are distinguished by them : the DynasticUe in the
Lamellicorn section are remarkable for a single cre-
nated furrow next the suture ; in the weevil tribes the
numerous species of the genus Apioji are ornamented by
furrowed elytra with pores in the furrows, which give
them the appearance of neat stitching ; in many of those
beetles that have soft elytra, as the glow-worms (Lam-
pyris\ the blister-beetles {Cantharis^ Mylahris), and still
more in (Edemera, two or three slight ridges generally
run longitudinally from the base to the apex, and are
visible also on the under-side ; as the furrows probably

•• Oliv. Ins. No. 97. Cansida, t. i. f. 10.
'' Sec .ibovc, p. 397 — .

EXTERNAL ANATOMY OF INbECTS. 603

lighten a hard elyti'um, these ridges may sex've to
strengthen a soft one, and it is by these that the first ap-
proach is made to the reticular structure of tegmina or
the wing-covers of Orthoptera: Lyciis palliatJis, &c., in
its elytra exhibits a direct resemblance of the reticula-
tions of nervures.

8. Clothing. To what I have before said on this
subject in general * I shall here add a few remarks,
which, though they more properly belong to elytra^ may
in many cases be extended to the whole body of a beetle.
In various instances it happens that the beautiful mark-
ings of these organs, as in Macropus longimanus, whose
elytra when denuded are black, are produced by short de-
cumbent hairs ; in some these variegations are the effect
of scales resembling those of Lepidoptera, often of a
metallic lustre ; from these scales is derived all the bril-
liancy of the diamond-beetle {TLntimus imperialism Germ.);
in some the scales are so minute as to resemble the
pollen of flowers, as the white marks observable on the
green elytra of the rose-chafer [Cctonia aurata).

9. Colour. The organs of flight in the majority of
the Orders with respect to colour are usually the most
gaily decorated part of insects; I therefore deferred the
notice of that subject till I came to treat of them. In
general the colour of insects is either inherent in the
substance of their crust, or produced by the hairs or scales
that either partially or totally cover it. To confine my-
self to the Coleoptera, of whose elytra we are treating, it
may be observed, I think, in general, that the majority of
those that feed upon putrescent substances, the sapro-
phagoiis tribes of Mr. W. S. MacLeay, are connnonly of a

' Sec ahovf, |). .JO!) — .

604- EXTERNAL ANATOMY OF INSECTS.

more dark and dismal aspect and colour than those which
feed upon such as are living and fresh, denominated thale-
rophagous by the same learned author ; this you may see
exemplified in his ScarabceidcB and Cetoniadce. Again, in
the Predaceous beetles a smilar contrastof colours is often
observable. How brilliant and gay are the fierce Cicindelce !
those tigers of insects, as Linne calls them ; how black
as to colour, how horrible in aspect is their near relation
the Mayiticora : what difference exists in the economy of
these animals is not known, except, as I learn from Mr.
Burchell, that the latter is subterraneous, whereas the
former seek the sunbeam and fly rapidly. I shall now
point out a few instances in which the colours of their
elytra distinguish tribes or families. Amongst the Pre-
daceous beetles a large family of the Cicindelid(B are
distinguished by a middle angular white band, and se-
veral white dots on their green or brown elytra, as in
C. sylvatica ; a family of Brachinus, and the majority
of MylabriSf Lamia capensis and fasciatus, &c., by
black elytra, with yellow or red bands ; Carabus vtolacea
and affinities by the violet margin of these organs ; Cal'
liochroma Latreille by their sericeous, and Eumolpus by
their metallic, lustre. These instances will be sufficient
to turn your attention to this subject, which though not
of primary importance in discriminating genera &c., is
not without its use in a secondary view.

10. Uses. I must not quit this subject without saying
something upon the ends which elytra seem designed to
serve. Their first and most obvious use is the protection
of the wings when unemployed, that they may not be
lacerated or soiled, and rendered unfit for flight in the
various retreats to which these animals betake themselves

EXTERNAL ANATOMY OF INSECTS. (JO.j

either for food, repose, or to lay tlieir eggs ; to promote
this purpose more efl'ectually, the wings arc usually cmi-
riously folded and laid up imder tliem; and where the
elytra are very short, as in the Staphylinidcc^ these folds
are very numerous and conij^lex. In some instances,
however, as in Mulurchiis F., Atractoccrus, 8:c., the wings
are only partially protected by the elytra and not folded
under them; probably they are less in danger of laceration
from their peculiar habits than the generality. Another
use is to protect the upper-side of the alitrunk, which for
reasons before assigned is usually softer than the under-
side, and also of the abdomen, often above nearly mem-
branous, from the injury to which they would otherwise
be exposed ; in the latter part also the spiracles in Co-
leoptera are not covered by the inosculations of the seg-
ments, as is the case in most other Orders, and therefore
probably require some covering when the insect is not
flying. In the Apterous beetles this appears to be their
principal use ; where these organs are connate, or as it
were soldered together, the back of the abdomen is a
thin membrane ; the appearance of tjco elytra in these
cases is given, doubtless, for the sake of symmetry and
beauty, a subordinate attention to which may be traced
in all the works of creation. If we consider the bulk and
weight of many flying beetles, we may imagine that they
want some assistance, more than the extent and dimen-
sion of their wings seem to promise, to support them in
the air, and to enable them to move more readily in it ;
and although it seems clear from the state of their mus-
cular apparatus that elytra do not move much in flight,
yet by giving a broad and concave surface to the air, for
then they are usually nearly vertical, they may assist in

606 EXTERNAL ANATOMY OF INSECTS.

some measure as sails, and help them in flying tra-
versely and before the wind *.

JL Tegmina ^. By this name the learned Illiger has
distinguished the upper organs of flight of the Ortho-
ptera and Heteropterous Hemiptera •=. They may be
considered under the same heads nearly as elytra.

1. Substance. Tegmina differ very materially from
elytra in their substayice, being generally more or less
diaphanous, though in Blatta Petiveriana the dark parts
are as opaque as elytra, and those of the Mantes that
resemble dry leaves are only semidiaphanous. These
organs are also of a less dense substance than elytra,
something between coriaceous and membranous, which I
shall express by the term pergame7ieous, as somewhat re-
sembling parchment or vellum. Another circumstance
relative to this head also distinguishes them, — they are not
lined with membrane. In some instances, as in B. Petive-
riana just named, they approach nearly to the substance
of elytra, and in J5. vh-idis, some Mantes, and Tettigonia,
&c., they are little different from wings in their substance;
but this does not diminish their right to be considered
as tegmina, since their structure is altogether the same.

2. Artictdafio?i •with the trunh, I observed above that
the axis of elytra may be regarded as formed of three
parts, one appertaining to each of the areas or their re-
presentatives'^; in tegmina, and indeed in wings in gene-

" M. Chabrier says that the arc described by the w'lvgs of Melo-
lontha vulgaris to that of the elytra, is as 200 to less than 50. Sur le
Vol des Lis. c. i. 440.

" Plate X. Fig. 2. and XXVIII. Fig. 18—20.

•^ Magas. 180f). Terminologie dcr Insekt. 18. 1675.

"' Pi.ATK X. Fig. 2. is the tegmen oHBIntfa divided into arc:is.

EXTERNfAL ANATOMY OF INSECTS. 607

ral, these parts are separate and may be more distinctly
traced, the axis of the Costal Area being generally the
longest, and that of the hitermediate often the shortest;
these axes are suspended in the wing-socket by elas-
tic ligaments, intermixed with hard bony plates, the
principal one of which, called by M. Chabrier the hu-
viams ', is connected boUi with the tegmcn and the
trunk, and in some a little resembles the head and neck
of a swan. This structure permits the animal to move
the lateral areas in some degree separately, so that each,
especially the anal, shall form an angle with the inter-
mediate ; as the motion of the latter is not wanted, its
axis often falls short of the base, or is obsolete, as in
Blatta.

3. Composition. Tlie three areas, traces of which we
had discovered in elytra, are particularly visible in teg-
mina. If you take any cockroach [Blatta), you will at
first sight see that in it they ai'e divided into three larger
portions by stronger nervures or folds ; and if you also
take a Majitis, or Locusta Leach, a Ftdgora or Tettigo-
nia, the same circimistance will strike you, only you will
see that in these the intermediate portion terminates also
in an axis ; these are what I call the three areas. The
external one or Costal is usually the longest and nar-
rowest''; the Intermediate one is commonly triangu-
lar, with its inner side curvilinear *= ; and the interior
one, or Anal area, in the Otthoptej-a is rather oblong ;
in Fulgora angular, and in Tettigonia it presents an
isosceles triangle ; with its vertex to the apex of the
wing''. The first of these may be defined as that por-

" Sur le Vol (lex Ins. r. ii. 3*27 — . '' Pi.ATK X. Fin. 2. b\

'■ Ibid. (-. ■' Ibid. d-.

608 EXTERNAL ANATOMY OF INSECTS.

tion of the wing that lies between the cosial and post-
costal nervures; and perhaps, in some cases, as in Mantis^
for there is the fold of the tegineti, the mediastinal may
be regarded as its limit; the Intermediate Area is that
which lies between the postcostal or mediastinal nervure
and the anal fold of the wing ; and the Anal Area is the
remainder. These areas may perhaps best be made out
by tracing each to its axis. To study them carefully in
tegmina and hemelytra is of considerable importance;
for in them we find the first oudine of the general plan
upon which the wings of insects are constructed, and
which, as we shall see hereafter, more or less enters into
the composition of them all.

4. PositioJi, a?id folding in repose. With regard to
their position when not expanded, tegmina vary some-
what in the different tribes. In the Coleoptera we have
seen that, except in a few instances, the elytra unite at
their suture. Something like this takes place in Fulgora,
Cercopis and affinities, in the Homopterous Hemiptera ;
in these, though the union is not near so exact, yet the
tegmina do not lap over each other; they are usually
more or less deflexed, with scarcely any portion in a ho-
rizontal position : in Tettigonia F., Chermes, Aphis, &c.,
the middle part only of these organs meets, from which
point they diverge both towards their base and apex ^.
In the Orthoptera the position is quite different, for one
tegmen more or less lies over the other. In Blatta, in
which the tegmina are nearly horizontal, the left hand
one covers almost half the other ^ : in the other tribes of
the Order, with little variation, the Anal Area of the teg-

* Stoll. Ctgales, t. viii. /. 39. ^ Plate X. Fig. 2.

EXTERNAL ANATOMY OF INSECTS. 609

meii is horizontal, and covers the back of tlie animal, and
tlie Intermediate and Costal are vertical and cover its
sides ; the former, however, in some cases, only forms the
angle between them. Sometimes in these the right-hand
one is laid upon the left, as in Acheta ,- and sometimes the
reverse of this takes place, as in Acrida K. With regard
to the folding o^ihetcgriiina, the most remarkable instance
that occurs is that of Acheta jnonslrosa, in which the ends
of both these organs and the wings, in repose, are folded
like a fan, and then rolled up like a serpent*.

5. Shape. The shape of tegmina is various. In the
Blatta; and some Mantes they are more or less oblong,-
in Mantis precaiia, strumaria^y and others, they incline
to elliptical; in Phasma Gigas and Acheta ?nonstrosa they
are rather pandurifoyin^ ; in M. go7igyloides they are
semi-cordate'^ ; in Plerophylla trapeziformis they are
rhomhoidaV ; in Conocephalus erosus they are sinuated ;
in Locusta Leach they are usually linear or linear-ob-
long ^ ; in Pterophylla K. they generally terminate in a
short mucro^; and in some of those Ma7itida whose
tegmina simulate arid leaves, in a recurved one ''. In
the Homopterous Hemiptera the shape? of these organs
is less various. In the FulgoreUa Latr. they incline to
a trapezium, sometimes to a pentagon ' ; in the Tet-
tigonicE F. they approach to an obtuse-angled trian-

=* Stoll Grillons I. i. c.f.2. '' Ibid, Spectres t. xxv./. 95.

and xi./. 42. •• Ibid. /. ii./. 5. Grillom t. i. c./. 1.

'' Ibid. Spectres t. xvi./. 58. ' Ibid. SautercUes a Sabr. t. iii.

/. 7. By this name {Pterophylla) I distinguish those Locustce F.
without a conical head that are veined like leaves.

f Stoll Ibid. t. vi. a./. 18. and Pf.ate XXVIII. Fig. 19.

* Stoll Sauterel. a Sabr. t. i — iii. *" Ibid. Sped res f. 'w. f. 14.

' Ibid. Cigalest. If. 1, 3—5. and t. vi./.31.
VOL. HI. 2 R

GIO EXTERNAL ANATOMY OF INSECTS.

gle ; and in others of the tribe they are nearly wedge-
shaped *.

6. Neuration. The circumstance that most strikingly
distinguishes tegmina from elytra is their neuration or
veining ; which adds much to their strength, without in-
creasing their weight so much as to render them unapt
for flight. To look at these organs in Blatta Petzveria7ia,
you would imagine them at first to be deprived of this
distinction ; but if you observe them attentively, particu-
larly their white spots, you will soon detect their ner-
vures ; and if you further examine their lower surface,
you will find them very visible. The gibbous Blattce
also, Blatta picta and affinities, the analogues of Erotylus
amongst the Coleoptera, have tegmina which, except at
their apex, exhibit but faint traces of the nervures of their
tribe, and approach to elytra besides by the innumerable
minute impressed points that cover them. In the Ortho-
■ptera and some Homopterous Hemiptera the nervures may
be divided into longitudiyial ones more or less ramified,
and traversing ones. In the Blatta the traversing ner-
vures cut the longitudinal ones nearly at right angles, but
not at regular intervals, so as to cover the tegmen with
quadrangular areolets ; in Mantis precaria and affinities
the longitudinal nervures of the Anal Area diverge from
the base, and are traversed nearly as in Blatta, while
those of the Costal diverge from the mediastinal nervure,
but the traversing ones form innumerable irregular re-
ticulations; in Mantis sinuata K.'' the whole tegmen has
such reticulations but less numerous ; in Locusta Leach
it is regularly reticulated at the base, but the areolets of

* StoU Cigales t. iii,/. 12—15. and t. xvii./. 92.
'' Linn. Trans, xii. 449, no. 96.

EXTERNAL ANATOMY OF INSECTS, f > 1 1

the apex are quadranoular ; in the Mantes^ with oblong
wings, all are quadrangular ; in Pterophylla K. the
longitudinal diverging nervures are not numerous, and
the traversing ones cut them into quadrangular and tri-
angular areolets, besides which they are covered by in-
numerable impressed points, so as altogether to exhibit
a most exact resemblance of the leaf of some evergreen :
in Gryllotalpa the longitudinal nervures of the Anal Area
rather converge towards the apex, are traversed by few
transverse nervures, and those of the Costal Area which
diverge from the mediastinal nervure by still fewer ; the
neuration of Acheta F. has been before described ^ ; I
shall only observe here, that the constructors oi stringed
instruments of music might, perhaps, from the tegmina
of the male, the nervures of which probably modulate
the sounds which it produces, take a hint for giving the
strings in them a serpentine or convolute direction, and
so might produce something new in that department,
corresponding with the serpents and French-horns in
wijid instruments. Of the Homopterous Hcmiptera in
the FidgorellcB Latr., which are most analogous to the
Orthoptera of all that tribe, the longitudinal nervures are
more numerous and branching, more especially toward
the apex of the tegvien, and are traversed as much by
transverse ones, sometimes reticulating the wing with
roundish areolets, as in F. laternaria, and at others with
quadrangular ones, as in F. cayidelaria ; in some of these
however, as Otiocerus K., Flata F., &C.'', there are no
traversing nervures ; and these lead to the Cercopidcc
and others in which the longitudinal nervures become

» Vol. I. p. 395 -.

'' JAnn. Tram. xiii. t. \.f. 1 4. Flata should come before this gemis.
2 R 2

612 EXTERNAL ANATOMY OF INSECTS.

few, and some are without any*, and these terminate
those of this section of the Order in which the nervures
in question are continued to the margin of the wing. We
next come to those, Dmmis, Centrotus, Membracis, &c.,
in which they are circumscribed a httle within the apex by
a traversing nervure, so that the tegmen ends in a margin
of pure membrane, and thus some approach seems to be
made to the Hemelytra, from Tettigoiiia, the most con-
spicuous genus of this tribe, in which the areolets, few in
number, Uke those o^ Lepidoptera, are not formed, except
the terminal ones, by traversing nervures, but by the
ramifications of the longitudinal ones ; in C/iermes the In-
termediate Area, which is connected with the base of the
wing by a single nervure, is the only part that has any
areolets ''.

7. Coloui\ Orthopterous insects are seldom remark-
able for tegmina of brilliant colours; there is in them none
of that gilding or metallic lustre which so often distin-
guishes elytra: they are also frequently less ornamented in
this respect than the wings, with which they usually form
an agreeable contrast. Their reticulations and nervures,
which are sometimes of a different colour from the rest
of the tegmen, decorate them considerably : a remarka-
ble circumstance belonging to this head attends the black
tegmina of Blatta Petiveriana ; one hsi&four white spots,
and the other only three ; but as one laps over the other,
the symmetry of the arrangement is preserved : the Ho-
mopterous Hemiptera are more distinguished in this re-
spect, and some of the Fulgorida imitate the Lepidoptera
both by their ocelli and spots : Ftdgora laterjiaria, Can-

» Of this kind is one of Stoll's C'tgaks, t. xxv. /'.HI.
'' Plate XXVIII. Fig. 18

EXTERNAL ANATOMY OF INSECTS. 613

cielarioy seirata, and Diadema, sufficiently exemplify this
remark, as do several Flatcc likewise *.

^'ii \w\\y observe here — that tcgmina are more calcu-
lated lor flight than elytra, both from their thinner sub-
stance, and from the angle that their Anal Area, and often
the Costal, forms with the rest oi ih^ tegmen ; a circum-
stance which, in wings, M. Chabrier thinks presents some
facilities in that kind of motion.

iii. Hemelytra ^. The next species of wing-covers,
which though varying in the substance of their base, ter-
minate in a part distinct from the three areas, consisting
in almost every case of mere membrane, peculiar to the
Heteropterous Hemiptera^ are called hemelytra, or half^
elytra : — this term was also formerly employed, but cer-
tainly incorrectly, to denote tegmina. I shall consider
them with respect to such of the particulars noticed under
the former heads as apply to them, but without repeating
them formally.

I. \s>\.o\}[i^\x suh&tancc, they must be separately consider-
ed with regard to their base and apex. In various instances
the base, or part consisting of the three areas, is almost
corneous, asm Cydnus Morio andbicolo); bugs not uncom-
mon with us, and many others ^ ; in these cases it is lined
with a hypoderma like elytra; and in many the points,
which are impressed upon it, also perforate the hemely-
trum, and seem to act as pores: but in Lygcmis, Redtivius,
Capsiis, Miris, and the majority of the Heteropterous He-
miptera, the organs in question being soft and flexible,

» Stoll Cigalt's t. i./. 1. /. x. /. 4G. t. xxix. /. 170. t. v. /. 22. t. iv.
/ 19. &c. " Plate X. Fig. 3.

•" In Latreille's whole genus Pentatoma,inc\\\A\ng several Fabrician
genera, the Hevielytra are more substantial than in the subsequent
tribes.

614 EXTERNAL ANATOMY OF INSECTS.

may be stated as rather resembling leather than horn ; — on
this account this part of a hemelytrum is denominated the
corium. In Scutellei-a the portion covered by the scu-
tellum is membranous; and in Acanthia paj-adoxa, and
the cucullated species of Tingis, the wing-covers are en-
tirely so. The apex of these organs is almost universally
either membranous or coriaceo-membranous, on which
account it is called the membrana. I say almost, because
in Aradus and the HydrocorhcB Latr., this part, though
rather thinner than the rest of the Hemelytrum, is also
coriaceous ; in the latter tribe usually with a very narrow
membranous edge ; and in many Reduvii and Zeli there
is scarcely any difference in the substance of the base and
apex.

2. As to the artiadation oi Hemelytra with the trunk, it
seems not strikingly different from that of tegmina : the
point or base of the Intermediate Area, which falls short
of that of the lateral areas, seems connected by a slender
ligamentous piece, with its axis, which is thick; and I do
not discern Chabrier's humerus shaped like a swan's head
and neck*

3. The composition of these organs differs from that of
tegmina in more respects than one : in the first place, they
consist, as was lately observed, of four instead of th7'ee
areas ; in the next, they appear to have, at least several
of them, a part, which I suspect to be analogous to that
above described in Coleoptera, supposed to represent the
phialum of wings''. I shall first speak of the areas. In
some apterous species related to the bed-bug, Lygceus
brevicollis Latr. '^, &c., there is no trace of the usual areas,

■* See above, p. 607. ^ Ibid. p. 600,

' My insect, which nearly resembles the Coleopterous geniib Cery-

EXTERNAL ANATOMY OV INSECTS. ()15

ami the membrana is a very narrow strip ; in L. apterus
the former are very faintly traced out, but they are pre-
sent in all those that are furnished with wings ; whence
we may conjecture that they are of the same importance
in flight with the folds observable in those organs'". The
three basal areas may be said most commonly to present
three isosceles triangles, the Costal one being narrow and
curvilinear ^, the Intermediate tiie most ample '^j and the
Anal one the narrowest and shortest **, with its vertex to-
wards the apex of the Hemelijtrum^ while in the two former
it is at its base. In Lygccus compressipes [RJiinuchus
K.MS.) the Anal Area is cultriform; and in most of the
HydrocoristE it has an angle in the middle of its posterior
margin. The proportion that ihememhaiia or apical area
bears to the rest of the wing varies in the different tribes.
In some, as before stated, it is obsolete, in others nearly
so ; in the majority, perhaps, it occupies about a third of
the hemclijtrum ,- in Lygccus compressipes, cruciatus, &c.,
full half: in Alydus calcaratus, two-thirds ,- in Reduvitis,
nearly three-quarters'^ ; and in Aradus depressus the cori-
um, — divided, however, though indistinctly, into the three
areas, — is driven to the base of the wing : two ends are
answered by this structure — as this insect lives under
bark, its thin hemelytra take less room ; and as it flies,
though it has only rudiments of wings, they are more fit
to supply their place : the part we are speaking of usually

Ion Latr., agrees with Latreille's description in all respects, except
that it cannot be said to be memhrana nulla apicali.

' Chabricr Analyse, &c. 24. •> Plate X. Fig. 3. b:

"^ Ibid, c: •' Ibid. d.

* Plate XXVIII. Fig, 23./'" is the corium and g" the membrana
of a species of Beduvius F.

616 EXTERNAL ANATOMY Of INSECTS.

runs obliquely from the vertex of the Anal Area to the
base of the Costal.

4. As tothelrposiiiofi andfolding inrepose, Hemelytraaxe
usually nearly or altogether horizontal; but in 'Notonecta
und Plea they are dejiexed and cover the sides of the body;
and the apical area of one wing precisely covers that of
the other ; where the scutellum does not intervene, as in
Scutellera^ Pentatoma, &c., the vertical angles of the Anal
Area meet in the middle of the back, so as to exhibit
the appearance of a cross. In Notonecta, in which the
hemelytra are deflexed, at the apex of the memhrana is
a fissure which permits the two sides to form an angle
with each other, and to apply exactly to the body. In
Plea, in which there is no apical area, the posterior
margins of the tegmina, as they ought rather to be term-
ed, unite, but do not lap over each other. With regard
to the appearance of something like a ^7z/a/?«n, if you ex-
amine the hemelytra of most species of bugs on the un-
derside, you will see that the costal nervure at the base
is inflexed and covers a kind of channel ; if you next take
one of Belostoma graiidis, where the structure is most con-
spicuous, or even the common Nepa cinerea, you will find
in the same situation, adjacent to the inflexed costal ner-
vure, a hollow tube running from the base of the wing,
and terminating, after proceeding about one-fourth of its
length, in a hollow cavity, which, as it is covered by a
membrane, appears to me to be a collapsed pouch. This
circumstance is worthy of further and more general in-
vestigation.

5. In their shape, with few exceptions, hemelytra more or
less represent a wedge, being wider at their apex, where

KXTlillNAL ANATO.MY ()!• INSECTS. 617

they are usually obliquely truncated, than at the base ;
but in Plea Leach they are obtusangular, with the angle
in the sutural margin ; in Noionecta, on the contrary, an
obtusangular sinus distinguishes that part ; m Nancoris
they are curvilinear and every where of equal width ; in
Ranatra they are linear and straight; in Aradus they
are oblong, usually with an external lobe or dilatation at
their base: a remarkable instance of the intention of tliis
is observable in a nondescript Brazilian species, in which
the head, prothorax, and abdomen, are edged with a
number of broad foliaceous appendages ; if the base of
the hcmelytrum had not been furnished with a similar
aj^pendage, the synunetry of the whole body would have
been destroyed by the hiatus between the prothorax and
abdomen, as may be seen by removing the hemelytra ; but
by this compensating contrivance of Providence, the gap
is filled, the above lobe fittijig exactly into it.

6. The wtM7a^20w of these organs will not occupy us long,
since the corium or harder part, though in some species
there are traces of nervures, is often without them. Those
of the cucullated species of Tingis resemble many tegmina
in being ornamented by them with a kind of network,
which looks like the finest lace; in several Lygai, Edessa,
and some Itcduvii, there are a few diverging longitudinal
nervures which occasionally by a ramification here and
there form an areolet^, but there are seldom any tra-
versing nervures. The Apical Area is usually most di-
stinguished by nervures, in some forming several areolets,
as in Aradus, in others running parallel to each other,
neai'ly to the end of this area, as in Belostoma grandis^

' I\axi. XXVIH. KiG. 23.

618 EXTERNAL ANATOMY OF INSECTS.

where they are met by a traversing nervure ; the object
of this is doubtless to strengthen the membrane.

7. Both tegmijia and hemelytra are most commonly
naked, yet very short hairs are found on those of some
species of Cercopis, and in many more instances in those
of the latter description, as in Notonecta, several Lygai
and Reduvii, &c.

8. Colours in hemelytra are very various, and in many
instances are peculiar to families ; in certain Lygcei {L.
Hyoscyami, &c.) black and red ; in Lygceus compressipes
and affinities a dingy black ; in some Reduvii black with
a large white spot ; — but it is needless to enlarge further
on this subject.

9. That hemelytra are used in flight is evident not only
from the large space allowed for their muscles ^, but like-
wise from a circumstance noticed by M. Chabrier, that
in flight, in the Pentatomce Latr., the corium of the he-
melytrum is fixed to the wing=^; in which case both must
describe the same arc.

iv. Wings. We are next to consider organs which are
exclusively appropriated to Jlight, and therefore are pro-
perly denominated laiiigs. These in the Orders that have
elytra^ tegmina, or hemelytra, are the pair that correspond
with the secondary wings of the other Orders. It may
be said, indeed, that in several instances both tegmina and
hemelytra do not differ at all in substance or use from the
wings that they cover. This is true ; but as their struc-
ture in other respects is the same with that of those that
are more solid and less apt for flight, it was convenient to
consider them under the same name.

^ Chabrier Analyse, &c. 23.

EXTERNAL ANATOMY Ol" JNSECIS. G19

1. To begin with the oriiculatiofi of these organs isoith
the trunk ; in general it may be stated that this, as in
tegmina and hemelytra^ is usually by the intervention of
three axes, formed by the conflux of the nervures of the
three areas at the base of the wing, which either imme-
diately or by other pieces are im])lanted in the trunk, so
as to receive from it the aerial and other fluids, neces-
sary for its expansion and motions*. Having given this
general statement, I shall next apply it to the wings in
some of the different Orders. If you carefully extract one
from the stag-beetle [LucaiiusCervus) or any large species
of the Dynastidcc, in the Coleoptera ,- the first thing that
will strike you, upon examining the base, will be the plate
before mentioned called by Chabrier the humei'us, which
is a stout transverse corneous piece, with a deep sinus to-
wards the wing, filled with ligament : if you again follow
the costal, mediastinal, and postcostal nervures, you will
find them unite to form an axis, consisting of three pa-
rallel pieces, which connects by its intermediate internal
piece with one end of this plate. The nervures of the In-
termediate Area terminate also in a corneous axis at a
greater distance from the base than the other two, which
connects with Chabrier's humerus by means of the liga-
ment of the sinus just named. Those of the Anal Area
are received by a ligament attached to a transverse plate,
widest at its anterior end, which connects with the poste-
rior part of the said himenis ; and at its posterior end is
united to the postfrcenum^ , with which it forms a right
angle. In the Orthoptera Order the structure is not very
different, but the axes and other plates of the base of the

' Chabrier Surh Voldes Ins. c. ii. 3'i5— . and 326. Note 1.
'' See above, p. 572 — . ,

6^0 EXTERNAL ANATOMY OF IN8ECTS.

wing are less distinct and rather cartilaginous ; the ner-
vures of the Anal Area often terminate in a transverse one
that there forms the segment of a circle*; the inner base
of this circle is ligament connected with the postfranum^ .
In the Homopterous Hemiptera the three axes may be
readily traced, but the humeral plate, with which they all
are connected, is more irregular in shape, and in Fulgora
longitudinal, with an angular surface ; in this Order the
nervure, in some cases consisting of cartilaginous rings *=,
in which the frcemmi and postfrcEniim terminate in the
tegmina and wings, is attached posteriorly to the ligament
of the Anal Area. In the Heteropterous section the three
axes are evident, but the humefal plate is not easily made
out. In the Libellulma the axes of the Costal and Inter-
mediate Areas are the coloured broad plates at their base,
formed by the dilatation of their nervures ; that, however,
of the Anal is not dilated, but forms one nervure, in the
primary wing, with thefranum, and in the secondary with
the postfrcBJium. Having given you this clue to trace the
axes in those tribes in which they are most conspicuous,
it will assist you in searching for them in the remain-
ing Orders, in all of which they may be traced, except
perhaps in those minute Hymenoptera whose wings have
solely the costal nervures ; probably in these there is only
one axis. In the Lepidoptera and Hymenoptera a cir-
cumstance connected with the present head is observable,
which is not to be discovered in the other Orders : these
are the tegulce or base-covers, which appear intended to
defend the base of the anterior wings. They are con-
cavo-convex scales, which in the Lepidoptera are large

^ Plate XXVIII. Fig. 9. a. ^ See above, p. 572.

^ Ibid. p. 560. and Plate XXVIII. Fig. U. a.

EXTERNAL ANATOMY OF INSECTS. 621

and of an irregular shape ', but in the Ht/vienoptera are
smaller and semicircular ''.

2. Wings, with regard to their substance, may generally
be termed membranous ,- but they vary in this respect, some
being much thicker than others, either j;;ff/-^/fl//j/ or total-
ly: in spotted wings, as in those of many Libellulinaf
Teftigom'ce F., &c., the dark opaque parts are denser than
those that are transparent : in several Orthoptcj-ous in-
sects, as in Phasma, some Mantes, &c., the Costal Area
or covering part of the wing is of a substance equally
fii'm with that of the legmen. This is a compensating
contrivance, that where the latter is shorter and smaller
than the former, its membranous part, when folded, may
be protected from injury. Another similar contrivance
of Divine Wisdom is exhibited by those Pterophyllce
K. [Locusta F.) whose tegmina resemble the leaves of
plants (P/. laurifolia, &c.); in these the tip of the wings
when folded being longer, is not covered by the tegmina,
and therefore exposed to injury ; to prevent which this
small piece, while the whole wang, as far as covered by
those organs, is membranous, is of the same substance
with them'^. The wings of most Coleoptera, Orthoptera,
Hemiptera, and Thereva coleoptrata, in the Diptera, &c.,
are of a firmer substance than those of the other Orders;
in many Locustce Leach, Fulgorce, &c., they are nearly as
firm as the tegmina; and ui Ascalaphus italicus, exce[)t
at their base, the secondary wings are less membranous
than the primary. M. Chabrier has observed '^ that the
wings of insects in general diminish in thickness from their

» Plate IX. Fig. 5. " Ibid. Fig. 11. 12. g".

•^ Stoll Sauterelles a Sabr. t. iv./. 12. /. vi. f. 21. &c.
'' Siir If Vol den Lis. c. i. 424.

622 EXTERNAL ANATOMY OF INSECTS.

base to their apex, and from their anterior to their pos-
terior margin.

3. I should have had, it is probable, but little original
matter to communicate under the head of the composition
and neuration of wings, had M. Jurine, who has written
so ably on those of Hymenoptera^ undertaken a survey of
the organs of flight in every Order of insects: but as his
views were confined to only two of the Linnean Orders,
it is not wonderful that his system and set of terms should
fail where a generalization is necessary; and I may stand
actjuitted of presumption and conceit if I attempt to sub-
stitute a system and body of terms more universally ap-
plicable. Had the plan of this able Entomologist led
him to pay attention to tegmina and hemelytra, their
division into three longitudinal areas would have imme-
diately struck him ; and having acquired this outline of
the greater natural divisions, he would have applied it to
the Orders that have wings only, and having discovered
that it is to be traced in all, the result would have pro-
bably superseded my labors. Had his life been longer
spared, perhaps something of this kind would have been
effected by him ; but as he, alas ! is gone, and no abler
hand seems to have undertaken the task, I will do what
I can to give you satisfaction on this subject*. You

^ The idea of dividing the wing of an insect into larger areas seems
first to have been acted upon in Monogr. Apum Angl. (1801 ), in which
those of Hymeiwptera were stated to consist of three portions, viz.
Basis, Medium, Apex (i. 211.); which mode of dividing them was at
first adopted by M. Latreille (Gen. Cnist. et Lis. iii. 226. Note 1.)
The same learned author (Ibid. iv. 239.), with regard to the Diptera,
made a near approximation to the plan of dividing wings into longi-
tudinal areas, but by the addition of a basal area, which interrupts
the attention to the communication of the areas with their axes, he
has rendered his system less perfect. Two of his terms — Costal Area

EXTERNAL ANATOMY OF INSECTS. 623

have already got a tolerably good idea of these areas from
what has been said upon the subject under tegmina and
hcmdylra; but I shall now more particularly state to you
liow they are circumstanced in wings. I shall first ex-
plain the general law as to their limits. The Costal
Area^ is all that longitudinal portion of the wing that lies
between the anterior margin and the postcostal nervure;
the Interviediate Area ^ is all that longitudinal portion of
the wing tliat lies between the postcostal and the anal
nervures; and the Afial Area^ is all that longitudinal
portion of the wing that lies between the anal nervure
and the posterior margin. But there are other helps to
enable you to distinguish the areas in the different Orders.
The Anal Area in all Orders forms the posterior ybW of
the wing; in Colcoptera turned under when in repose; in
Orthoptera folded like a fan; in Lepidoptera, in some
Papilionida;, forming an arch over the abdomen. Again,
in Blatttty the Costal Area is distinguished chiefly hylojigi-
tudi nal ner\ures ; the Intermediate by oblique ones; and
the Anal by radiating ones ; and in both this tribe and
the Mantidce this last Area is marked out from the Inter-
mediate by a marginal notch, which is not present in
Phasma, but is found in both sections of the Hemiptera.
In Locusta Leach the notch is between the Costal and
Intermediate Areas : in Phasma the nervures of the In-
termediate Area are branches of the externo-medial, while
those of the Anal, as they do in all the Orthoptera^ diverge

and Intermediate Area, are here adopted; but his Internals changed
to the Anal Area, for the term internal belongs rather to the base of
the wing. M. Latreille afterwards relinquished both these plans,
N. Diet. d'Hist. Nat. i. 248- .

* Plate X. and XXVIII. b\ i'. is the Postcostal Nervure.

•> Ibid. €'. n'. is the Anal Nervure. "^ Ibid. d'.

624 EXTERNAL ANATOMY OF INSECTS.

from the base of the wing : in many, as in Pterophylla K.,
the part of the wing lately alluded to, that is longer than
the tegmen, and of the same substance, points out the limit
of the Costal Area ; and in others this part terminates in
a segment of a circle and is differently reticulated at the
apex from the Intermediate : in the Homopterous Hemi-
ptera and the Lihellulina, in which the areas at first seem
indistinct, they may generally be easily traced by follow-
ing them from the axes. The separation of the Costal
from the Intermediate in the remaining Orders seems less
easy on account of the branching of the nervures : in the
rest of the Neuroptera and the Lepidoptera, if the poste-
rior branches of the postcostal nervure are not included,
you will have a narrow Postcostal Area, which in most
cases forms an angle more or less prominent, in Corydalis
almost a right angle, with the Intermediate : in Hemerohhis
and affinities this part is distinguished by areolets form-
ed by transverse nervures, while those of the rest of the
wing are lorigitudinal^: but if the posterior branches are
included, the Costal Area will be more ample : a similar
observation applies to the Hi/menoptera and Diptera; in
these, in all cases, the areolets adjoining the anterior mar-
gin, which follow the stigma^ should be regarded as be-
longing to the Area in question ''. In those tribes of the
former Order, whose wings are without nervures, the
areas are often marked hy folds.

M. Chabrier has observed that in Coleoptera the spe-
cific weight of the margin of the wing, and its means of
resistance, are augmented by a liquid which is introduced,
at the will of the animal, into a long pocket under the

» Plate X. Fig. 7. Ir. r. /r. ^ Ibid. Fig. 8. 9. le. a *.

EXTERNAL AN' ATOMY OF INSECTS. 625

brachialy here called the roi/r// and mediastinal nervures,
covered by a supple membrane, which in a state of repose
l)ecome.s flaccid * : it is easily detected, being of a paler
colour than the nervures between which it lies ; this is
what 1 call the Phialum ,- we have before seen that it
exists also in Elytra and some Ilcmdijfra^ ; but I have
not detected it in any other wings.

I have before given you a sufficiently full account of
the ah/l(e or winglets of Diptera '^ ,- and shall here only
observe that they are not confined to o??£? particular tribe,
as has been usually imagined; but though sometimes
extremely minute, simple, and not easily detected, are an
universal distinction of the Order.

Having thus endeavoured to elucidate the larse?- Areas
into which wings appear to be divided ; I shall next
say something on the smaller ones produced by the in-
tersection or ramification of the nervures ; these had
been named areolets {areolce) several years before M.
Jurine's work, in which he calls them, I think improper-
ly, cellules {cellulcB), was published ; I therefore retain
the prior term. The general structure of the nervures
of the wings of insects having been before explained '*, I
shall nothere repeat what I then said ; but there is a curious
circumstance connected with it, particularly visible in the
wings of certain Hijmeyioptera, that I must not pass with-
out notice. If you examine attentively with a microscope
against the light the wing of any Nomada or Andrena,
you will discover little transparent pomts in some of the
smaller transverse nervures that form the middle areolets,
in which the nervure becomes white and looks as if it

" Sur te Vol. dcs Im. c. i. 428. •> Sec above, p. 600. 616,

' Vol.. 11. p. 3.58-. See above, p. 5.59. ■* Vol.. II. p. .346—

VOL. III. 2 s

6'26 EXTERNAL ANATOMY OF INSECTS.

was interrupted, though in substance it seems continued ;
these little points, somewhat resemblhig minute air bub-
bles detained in the tubes, are what M. Jurine, who first
discovered them, has, on that account, named btillce, which
he thus further describes: — " When the tube (of the ner-
vure) arrives at the spot where a bulla is to be formed, it
extends itself on all sides in minute threads in the upper
membrane of the wing, losing its colour and tubular struc-
ture, which it resumes immediately after the formation
of the bulla ^." But if you look closely at them you will
find that there is always a slight Jold of the wing that
cuts the nervure exactly at the bullce, and if the fold
changes its direction they accompany it ; their object,
therefore, is clearly to relax the tension so as to admit a
little motion where the fold is; consequently, rather than
buUcs (bubbles), they should be denominated articulations.
A similar construction, but on a larger scale, may be ob-
served in the wings of Coleoptera^ and some others, as
Psocus, where the folds traverse the nervures. I shall next
make afew observations on the principal nervures ; and first
a word upon their ?iames. M. Jurine, being of opinion
that a striking analogy exists between the wings of insects
and those of birch, in which M. Chabrier seems to agree
with him, has named the nervures in the anterior margin
of the wings of the former, radius and aibitus, as corre-
sponding with the bones so named in the fore-arm of the
latter, and the plate which often terminates these ner-
vures in Hymenoptera, he names ihe carpus; it may look
like presumption to differ from two such weighty autho-
rities, but as their observations seem to have been too

* Jurine Hi/vienopf. IJ). and t. v. '' Plate X. Fic. 4.

F.XTEnNAI. AVATOMV OF INSECTS. 627

limited, in one case to the Hymenoptera and Diptcra on-
ly ; and in various Orders there is nothing analogous to
the stigma or cmpus, and all the other nervuresof an in-
sect's wing have no analogue in that of a bird, but more
especially as M. Latreille seems to think with me on this
subject ^i I have retained Linne's term for the marginal
nervure, and for most of the others have adopted those
of the great French Entomologist just mentioned. I
shall here only further observe, — and it seems to me an
observation of prime importance, in the determination of
the question of the analogy of the wings of insects, — that
they are not, as in buds, the fore-leg converted into an
organ of flight, but, like the wing of the Draco^ an organ
supoadded to the legs ; and, further, that the connection
is not with the fore-legs, but, as has been before ob-
served'', with the two posterior pairs.

The Costa'^ is usually the strongest of the nervures,
and that upon which the wing seems to be built ; but in
some cases, as in Blatia, Scutellera, Cynipsy &c., it is re-
presented by the mere membrane of the anterior margin ;
in some Coleoptera^ as in Geotrupes, Dytiscus, &c., its struc-
ture, except at the base, appears to be annular or nearly
so, at least a vast number of corrugations, running trans-
versely, are observable on its upper and lower surfaces ;
it is thus capable of greater tension and relaxation, and
more flexile. The stigma or carpus **, though most conspi-
cuous in the Hymenoptera Order, may be traced in some
Coleoptera, Heteropterous Hemipitera, the Libelhditia,
&c. ; but it has no representative in the Orthoptera, Le-
pidoptera, Trickoptera, &c. The mediastinal is usually a

» N. Diet. d'Hist. Xat. i. 251 . '• See above, p. 564, 578, 591.

r Plate X. tr. ■* Ibid. Fig. 4. 11, m'".

'2 s 2

628 EXTERNAL ANATOMY OF INSECTS.

very slender nervure, placed between the costa and post'
costa^ sometimes terminating in the former^, and at others
in the latter": in the Orthoptera, Lepidoptera, &c., how-
ever, and some others, it is a very conspicuous and prin-
cipal one ^ ; in the Hijmenoptera it is obsolete, merging
in those nervures*^. The Postcosta is the principal ner-
vure of the wing in Scutellera, but in Staphylinus it is
wanting ; in Chalcis sispes it is the only true nervure of
that organ, the others being represented by spurious
ones ''. The externornedial and internomedial are some-
times distinct at their origin, but more frequently are
branches from a common stem.

Having made these general remarks, I shall now con-
sider particidarly the neuration of the wings in the dif-
ferent Orders, beginning with the Coleoptera. The first
thing that strikes the physiologist in surveying a wing be-^
longing to an insect of this Order, is the general arrange-
ment of the nervures ^ ; which are so placed that the
required degree of tension may be given to every part of
this organ: thus some are nearly straight*^; others run in
a serpentine direction ? ; others are forked with one branch
recurrent and another proceeding onwards ''; others again
are insulated, or do not originate from the base of the wing,
or from other nervures, but are merely placed to strengthen
an open space of it': these nervures are also usually
broader and more substantial than those of the wings of
the subsequent Orders. Another striking circumstance
with regard to them is that the nervures form few or no

* Plate X. Fig. 14. t. ^ Ibid. Fig. 12. k\

* Ibid. Fig. 8. 9. •> Jurine Hynienopt. t, v. Gen. 47.

* Plate X. Fig, 4. f Ibid. a. w, o\ « Ibid.jn-.
" Jbid /•. » Ibid. a.

KXIKKNAl. ANAIO-MV OF IXSIXTS. 629

closed areolets, except in the Costal Area, where they
are inconspicuous; in Djjiisciis marginalise indeed, and
Tenebrio Molitor one or two may be found, but in ge-
neral there are none. In many of this tribe the post-
cosia, which terminates at the joint of the wing, becomes
recurrent, so as to form a hook, which perhaps repre-
sents the stigma, as in Dijnastcs ^ ; in Creophilus K., n
rove-beetle, there is no hook but a broad plate adja-
cent to the costa. In the Strepsiptera Order the neu-
ration is extremely simple, the nervures, except one
insulated one, diverging from the base of the wing*":
in this respect, as well as in the form of that organ,
an approach is made to the Orthoptera. In the Dcrma-
ptera this approach is still more evident ; in the common
earwig *=, the diverging nervures become numerous; be-
tween each is an insulated one, taking its origin in the
middle of the wing, and running to the margin ; a little
nearer to the latter all the nervures are dilated into a
plate; those of. the anal area are angular **, and the ex-
posed part of the costal is as hard as the elytra. The
neuration in the Orthoptera Order may be called radiate^
the longitudinal nervures for the most part diverging from
the base of the wing like rays: in some few instances *,
but not often, I believe, an insulated nervure intervenes
between each ; traversing or connecting nervures, cutting
the longitudinal ones in various directions, ornament these
wings with an infinity of areolets, causing them to resem-
ble fine gauze or beautiful lace or net-work ; very often
these areolets are quadrangular, sometimes rhomboidal,

" Ibid, o" . ^ Plate II. Fjg. 1. Comp. Linn. Trans, \i^

t.ix.f. 1. ' Plate X. Fir,. 5. " Ibid, w, o-,p\

• Stoll Spectra, t. xviii./. fi."!.

630 EXTERNAL ANATOMY OF INSECTS.

frequently nearly circular, and differing occasionally, as
has been before observed ^, in the different areas: it some-
times occurs that there are no traversing nervures'', when
the winff of course is without areolets. In the Hetero-
pterous Hemiptera the type of neuration, as to the wing,
seems borrowed from the CoLeoptera, a further proof that
these are the analogues of that Order amongst the Hmi-
stellata Ciairv. In these the nervures usually are few
and dispersed, and seldom form any closed areolets. If
you examine any Scutellera, Peiitatoma, or Lygaus^ you
may trace the uncinated, forked, serpentine, and insu-
lated nervures of Coleopterous insects; in Gerris and
Velia there is an approach to the neuration of some
Homopterous species, and in Belostoma &c. the wing is
reticulated by spurious nervures. In the Homopterous
section there are several types of neuration ; thus the Ful-
gorcE resemble the Orthoptera in this respect ; while the
TettigonicE F., &c., approach nearer to the Hymenoptera
and Diptera, and have their apical areolets circumscribed
'within the margin by a traversing nervure ; in Flata,
&c., the areolets are mostly formed, not by traversing
nervures, but by the branching of the longitudinal ones;
in this respect they are not unlike the Lepidoptera. In
this last-named Order there are some variations with re-
gard to their neuration — thus, amongst the hutterjiies in
Urania^ &c., there is no closed areolet in any of the
wings, and almost all the nervures diverge from the base *^;
in Motpho, &.C., there is only one in the primary wing**;
in Helico?iia, &c., there is one in both wings ; amongst

* Sec above, p. 624. •= Stoll figures Empusa as without

them, t- ix./. 35. but? I have a nondesc. Phasvui ? without theui.
■■ Jones in Linn. Trans, ii. /. viii. /'. 2. '' Ibid.f. 5.

EXTKRNAL ANATO.MV 1)1 INStC'IS. (S'M

tlie mothsy in i\\e Bomhyces L., this is divided into^tuo, and
in Cossus labyrinthicm Don. into three areolets : in some
butterflies {Lycccna) there is one insulated nervure*, and
in others {Hcspcria) there are two''; in these two last,
and Heliconia, Urania, &c., the end of the Costal Area
is divided into several areolets by oblique nervures'^,
which gives them some analogy to the wings of many
Ncuroptera ,- and at the base of this Area, in Morpho, is
a roundish areolef*. In this Order the externo-medial
and interno-medial nervures coalesce into one, and are
only represented separately by their first and third
branches '. In the Neuroptera Order the general type of
neuration is boiTowed from the Orthoptera ; but in Os-
mylus, Termes, &c., there is an approach to that of Flata
in the Homopterous Hemiptera, and in Psocus to othei's
of that section ; in the second of these genera the ner-
vures, except those of the costal margin, are spurious.

I now come to the Order in which M. Jurine has la-
boured with so much success, I mean the Hxjmenoptcra ,•
and I only regret that his labours were directed to so
small a portion of the Class Li^ecta, and in that portion
only to a part of the upper wing ; I say only a part, be-
cause all those areolets of the posterior part of the wing,
in some cases amounting to Jive % that lie behind his cu-
bital cellides, are not employed by him as diagnostics, and
are left without a name. By dividing the areolets of the

* Jones in Linn. Trans, ii. /. viii.y. /• •" Ibid.f. It.

<" Ibid.f. 2, 3,6—9. <* I wonder Mr. Jones's plan ol

ascertaining the divisions or subgenera of butterflies by the neuration
of their wings has never been followed up ; it would I think furnisli
an casj' clue for the extrication of the triiics of all the Lcpidoplcra.
I mean as subsi I'ary to more imj)<)rtant characters.

• Plaxf. X. 1 10. (!. /•, m-. ' Jbid. Fig. 8.

632 EXTERNAL ANATOMY OF INSECTS.

Intermediate Area of these wings into ///re<' portions, the
basal, medial^ and apical^, I have endeavoured to re-
medy this defect, and by naming each set of areolets in
the middle portion, as you will see in the Orismological
Definitions, under the term Areolets, you will find it
easy to describe any given areolet and its place in the
wing; those of the base may be called the anterior, in~
tn^mediate, and posterior, where three occur; and the first
and last of these terms will suffice where there are only
two ; the apical areolets, or those that are open to the
margin, may be called, ^first, second, and third in the
order of their occurrence, reckoning from the anterior or
costal margin.

In this Order it is curious to trace the progress of neu-
ration in the wings of different genera. Thus in Psilu^
only the co^^a/ nervure and the stigma are to be traced'*;
in Chalcis the postcostal and stigma '^ ; in Codrus and Leu-
cosis the costal, postcostal, stigma, and a nervure repre-
senting the ejrtertio-medial and i7iter?io-medial coalescing
into one"^; in Omalus the basilar areolets appear*; in
Crabro both basilar and medial^; in Cynips basilar,
medial, and apical^ \ and in Hylotoma the wing is filled
with its greatest complement of areolets ''. The medial
areolets of the Intermediate Area, as you will see in the
definitions, form ^/ir<?(? distinct series ; these may be called
the protomesal, deuteramesal, and tritomesal, reckoning
from the postcostal areolets ; the first of these corresponds
with the cubital cellules of Jurinc. These series may be

* Plate X. Fig. 8. basal <?•, medial/-, apical g\

^ Jurine Hymenopt. t. v. Gen. 48. « Ibid. Gen. 47.

'' Ibid. Gen. 45, 46. Conip. Plate X. Fig. 1 ] .

* Jiirine Ibid. Gen. 43. ' Ibid. f. iv. Gen. 47.
^ Ibid. t. V. Gen. 40. " Ibid. i. ii. Gen. 2.

EXTKKNAL ANATOMY OK INSECTS. 6ti3

expressed, according to the number of their areolets; by
figures, the protomesal standing first. They vary much
in this respect in the different genera. Tlius in Cyclo-
stoma K. *, reckoning the didymous ai'eolet as two, the
numbers will stand 4:2:1; \n Hi/lotoma, &c., 3:2:1'';
in Aidacus, &c., 2:2:1*=; in Braconj &c., 2:1:1''; in
Ckclomis, 2:0:1^; in Cj/nips erythrocephahcs Jur., 2:0:0*^;
in Formica, 1:1:1^; in Oxi/belus, 1:0:1*^; in C/irysiSy
0:1:1'; and in Ct/nips Rubi K., 1:0:0". The most
natural number is 3:2: 1. The next in importance to
the medial areolets of the Intermediate Area are the
apical, or those open to the margin ; the most usual num-
ber of them, excluding the postcostal areolets which be-
long to the Costal Area, is three ; but in Sirex there is
an approach to four ' ; in Evania there are only hvo^ ;
and in Philanthus there are none " ; in many, as Proso-
pis, Notnada, Andrena°, though there is the usual num-
ber, they are incomplete and do not reach the margin.
The basal areas are of little im})ortance in assisting to
determine genera; they are most connnonly two in num-
ber, bul in Cyiiips, &c., there is .only one p. The shape
and other circumstances of the areolets vary consider-

^ This is a remarkable insect belonging to Vcspa L., related to the
hornets ( V. Crabro), distinguished by having a semicircular piece taken
out of the internal margin of each mandible, so that when these or-
gans are closed there is a circular orifice, — whence the name Cyclo'
ttmna. '' Jurine Hj/meiiopt. t.'u. Gen. 2. ' //y«V/. Ord. ii. Gen.2.

J Ibid. t.in. Gen.'s. * Ibid. t. v. Gen. 41.

' Ihid. t xii. Gen. 40. ^ Ibid. I. v. Gen. 39.

" Ibid. t. iv. Gen. 29. ' Ibid. t. v. Gen. 42.

^ This Cyiiips inhabits a long polythalamous gall of the bramble.

' Jurine Ibid. I. ii. Gen. 11. "' Ibid. Ord. ii. Gen. 1.

" Ibid. t. iv. Gen. 2'^ " Ibid. Gen. 30—80.

'' Ibid. t. V. (Jen. 40

634 EXTERNAL ANATOMY OV INSECTS.

ably in different genera and species : upon these however
I shall not enlarge further, but proceed in the next place
to consider very briefly the wings of the Diptera Order
as to their neuration. These are not so easily made sub-
servient to a general plan. The basilar areolets are now
reduced considerably in length, occupying merely the base
of the wing*; the medial are become less numerous and
important^; and the apical^ in a variety of instances, are
the most conspicuous"^; in some wings, as in those of
Penthetria, the Intermediate Area has no nervures or
areolets, or only spurious ones; in Psychoda the nervures
diverge from the base almost without branching, so as to
form no closed areolets '^y in many, the lower medial
areolets are very long, resembling the basilar in Hymen-
optera'^ : these are often crowned by a single small one,
as in the Stratyomid^s, Tipula, &c., from which nume-
rous branches proceed to the margin '^; but in Miisca two
large ones approach the margin, the anterior one having
an angle open to it^^; in the Hippoboscidce almost the
whole of the wing is occupied by the apical areolets '';
though in some cases they are incomplete '.

4. I am next to consider the positioTi of wings in repose
and Xheh' folding. The most important object of this is
that when unemployed they may occupy less space, be
less in the way of the insect, and be most effectually pro-
tected from injury. Another end is also served by this
structure, — that wings can thus be very ample, and pre-

•' Pi.ATr X. Fig. 12, 15, c-. ^ Ibid. Fig. 15./.

' Ibid. Fig. 12. g-. " Ibid. Fig. 13.

« Ibid. Fig. 15. c. f Ibid. d.

" Ibid. Fig. 14. e. ^ Leach on Eproboscideous Insects,

Mem. Wern. Soc. 1817. t- xxv.f. 3, 5, 8, &c.
' Ibi(i. I.xwl/.J, 10, la.

EXTKKNAL ANAIO.MV OJ INSKCTS. ti.'iS

sent a large surface to the action of the atmosphere with-
out incommoding the insect when it has not occasion to
use them.

With respect to this head, insects may be divided into
lux) classes — namely, those whose wings in repose are
covered by wing-cases harder than the wings themselves,
and those that have no such protection. In the former
the wings, though the rule admits several exceptions, have
more folds than in the latter. As the different mode of
folding the wings has been assumed for a characteristic
of the earlier Orders, I shall explain to you with as much
brevity as possible how each is circumstanced in this re-
spect, beginning as usual with the Colcoptera.

There are two principal folds of the wing in this Order,
which may be named the anal and the apical: i\\e for-
mer is when the Anal Area or part of it is folded on the
under surface of the base of the wing; this fold is always
more or less longitudinal: the latter, the apical fold, is
by means of the commissura or joint of the postcosta lately
mentioned : which in Hister, Staphylinus, &c., for obviou s
reasons * is nearer the base of the wing ; in Necropho-
rus in the middle ; in Dynastcs Aloeus beyond the mid-
dle''; in Tencbrio MoZ/Vor near the apex; and in Dijtiscus
marginalis there appears to be no joint at all ; but the
fact is, that in this insect the postcosta, — the termination
of which really forms the joint, the costa itself being only
flexible at that point, — stands at a greater distance from
the latter at its end. Well, at this joint the above fold
is made, the apex of the wing, being first folded longi-
tudinally, turning under and inwards, and forming an

' Insects with shmi elytra ot course must Fold their wings nearer
the base than those with Inns ones. '' Piatf. X. Fig. 4, d" .

636 EXTERNAL ANATOMY OF INSECTS.

angle, more or less acute, with the joint or costal margin,
so that the fold is not quite but nearly transverse : this
at least is the case in Geotrupes stercorarius and other
Lamellicorns : in Staphylinus^ Sec, there are several
transverse and longitudinal folds, and thus the wing is
more easily packed under the short elytra; in MolorchtcSf
Nea/daliSf &c., in which it is left uncovered, except at its
base, the anal fold takes place, and the apical in some
degree; a short portion near the apex forming an obtuse
angle with the margin ; in Atractocerus the wing appears
to be only longitudinally folded; and in Buprestis vittata
only the ajial fold is to be detected. Besides these trans-
verse and longitudinal folds these organs, in many bee-
tles, have an infinity of fine corrugations, which ramify
like thenervures of the tegmina o^ Flat a *, &c., proceeding
from the Costal Area or the disk of the wing to the pos-
terior margin ; the object of these plicatures is doubtless
to present a more ample surface to the action of the at-
mosphere in flight^. Wlien all these folds have been
made in a Coleopterous wing, the apex of the one at its
posterior margin crosses or rests upon that of the other ^.
In the Dermaptera^i at least the common earwig,
there is a triple transverse fold of the wing, and besides
this it has numerous longitudinal ones like those of a fan,
each of the diverging nervures representing one of the
sticks. In the Strepsiptera the folds are only longitudi-
nal ; a circumstance which, besides the form and neura-
tion of the wing, sufficiently attests that its station is more
near the Orthoptcra and Coleoptei-a than the Dijotera.

* See above, p. 611. '' See above, p. 613, and Chabrier

Analyse, &c. 24. ' Plate XXIII. Fig. 5.

" Plate X. Fig. 5.

EXTEKNAl. ANATOMY OF liVSF.CTS. 637

We next come to the Orthojitera " ; in these the folds in
general are longitudinal ; and those of the Anal Area in
particular, either in whole or in part, exact counterparts
of a fan : wherever there is a straight nervure, there is
usually a fold or a tendency to it; this is the case even
with the short obli(jue ones observable in the Interme-
diate Area of Blatta : in this tribe the Anal Area, or a
considerable portion of it, is folded under the rest of the
wing, and the whole lies on the back of the animal, so
that in this wing there are only two primary folds ; but
in those with a narrower body, as Phasma, &c., there
are more, and the Anal Area, folded like a fan, lies hori-
zontally on the back ; the Costal is vertically applied to
the sides, and the Intermediate is between both, as in the
tegmhia^. In Grylhia Latr., Gri/llotalpa, See, when the
wings are folded, the end of the Anal Area projects so as
to present the appearance of two tails '^ ; and in that re-
markable Chinese animal Gryllus 7nonstrosus, in which
these tails are very long, they are convolute like those
of some quadrupeds ''. It is to be observed that in the
secondary folds of these wings the angles of the folds are
surmounted by a nervure.

In both sections of the Hcmiptera Order, as in the Co-
leoptera, the Anal Area is turned under the wing and lies
over the back of the insect; this is the or\\y primaiy fold,
but besides there are several longitudinal semifolds or
secondary ones, in which one part of the surface forms an
obtuse angle with another; and in Tettigonia^ &c., these
folds ramify in the wings as well as in the tegmina at the

• Platk XXVIII. Fig. 22. »• See above, p. 608—.

« Stoll Grillont. t. iii. c. /. 11 — 13. " Ibid. I. i. c./. 1, i.

f)38 f.xtt:i'.\al anatomy or inskpts.

marein : a number of semifolds also, sometimes trans-
verse and sometimes oblique, run in pairs from each side
of every nervure of the disk of both tegmina and wings in
the genus last named, the use of which has been before
mentioned*.

We now come to those Orders that have yb^^r mem-
branous wings : first, I shall consider the Lepidoptera.
With respect to the position of their wings in repose some
variations take place. In the majority of the dai)-jiier&
[Papilio L.), when the animal reposes the wings are ap-
plied to each other by their upper surface so as to be
vertical; but in the skippers {Hesperia), the secondary
wings assume a horizontal position, while the primary are
vertical but applied to each other. In the Crepuscular
tribes {Sphinx L.) the upper wings are incumbent on the
lower, and deflexed. In the night-^iers {Phalcena L.)
the types of position are various. In some Attacus, Sa-
turnittf Noctua, &c., the wings cover each other, and are
a little inclined from a horizontal position; in Gastro-
pachttf OdenesiSf and some other Bomhycidce, they are de-
flexed, and the anterior margin of the under wing pro-
jects beyond that of the upper: in some of the TinecE L.,
as Crambus, the wings are convoluted, and in others,
Galler'ia, they are applied close to the sides of the body,
and being elevated at the apex, terminate, to use a French
term — eri queue de coq : in Noctua, Geometra, &c., the
wings usually cover the abdomen, and are nearly hori-
zontal. With regard to the folds of their wings, the
Anal Area of the secondary is the only part that has any
striking one; in Papilio Hector and affinities it turns

* See above, p. 636.

F.XTF.nNAT. ANATO>rY OF INSECTS, 639

up SO as to defend the sides and part of the back of the
abdomen ; in Morpho Tciicer it turns down, and meeting
that of the opposite wing, forms a semitube which re-
ceives and shelters that part below. In the Crepusadar
and Nocturnal Lepidoptera this fold, especially in the
former, is very slight. With respect to semifolds in the
Diurnal^ there is one originating in the disk, between each
of the nervures, that goes to the margin of the wing; like-
wise the under wings, particularly of many Noctua, Arc-
ttce, &c., have many longitudinal semifolds.

In the Neuropteia Order several variations take place
with regard to the position of these organs in repose :
thus, in JEshiia, Libellula, &c., they continue expand-
ed ; in Argion they are applied to the body ; in MyrmC'
leon the upper are horizontally incumbent on the lower ;
in Hemerobius they incline to the horizon. With regard
to their Jolds in JEs/ina, &c., the longitudinal nervures
alternately form the summit or the bottom of a semifold,
as do those branches that terminate in the posterior mar-
gin ; this kind of plicature may be observed, but in a less
degree, in Ascalaphus^ Mi/rmeleon, &c. ; in Panorpa every
nervure is the ridge of a slight fold ; in Termes, on the
contrary, it forms its bottom. In the Trichoptera^ the
under wing being much more ample than the upper, the
Anal Area forms a fold under the wing, and there seem
longitudinal secondary folds besides.

We now come to the Hymenoptera. In this Order
the wings, as to their position in repose, are usually in-
cumbent upon each other, and cover the abdomen ; in the
Vespidce, however, they are placed parallel to the body,
but do not cover it. Before I notice the plicature of
these wings, I must recall your attention to what I lately

640 EXTERNAL ANATOMY OF INSECTS.

observed * with regai'd to Jurine's huUce (bubbles), but
which are really the joints of the nervures, as they are
to be found only where the folds pass ; and where they
exist they are an index by which the folds, or rather se-
mifolds, may be traced. I counted eleven of these little
joints in the upper wing ofA?idrena cineraria; sometimes,
however, instead of a hidlaj a nervure stops short to ad-
mit the fold. Wings in this Order have often three
longitudinal semifolds more or less conspicuous ; these
you may trace in the saw-flies {Tenthredo L.), whose
wings Linne terms tumidce, by which term he would in-
dicate the elevation of the whole surface produced by this
structure ; in the under wings of these, and Scolia, Bem-
bex, &c., the Anal Area is turned under the wing, as in
many preceding tribes '' : in Sirex, &c., that Area of the
upper wing turns upwards, forming an acute angle with
the rest of the organ; the same circumstance distinguishes
the under wing in the Iclineumonidce. Several apical
semifolds, marked by a pellucid streak, distinguish
Tiphia F., and in Bomhis, Bembex, &c., an infinity of
branching ones, like those before described in Coleoptera^
corrugate the apical margin. In the Vespidcs the upper
wings are folded longitudinally into thi-ee nearly equal
portions, but in the iinder ones the Anal Area only forms
the fold.

In the Diptera Order, as to their position when at rest,
the wings are mostly incumbent one on the other; but in
Psychoda they are deflexed, so as to form a kind of pent-
house. With regard to their plication, in some, Tipula
oleracea, &c., a slight oblique semifold runs from the

' See above, p. 625. *" Ibid p. 633, 637, &c.

EXTERNAL ANATOMY OF INSECTS. (j i 1

s/igma totheapictil margin, and the Anal Arcahastvvo, as it
has hi many Aliiscichc^ itself tbiniing nearly a )-ight angle
with the rest ot" the wing; besides these it is corrugated
with minute transverse seniilblds, which are observable also
in several other Dipterous insects ; in niany Stratyomidcc
they are obli(jue, and run from the disk to the posterior
margin ; antl in Asi/us, Bombijlius, &c., they are wavy.

5. We are next to say something upon the shape of wings :
this, though apparently extremely various in the different
Orders and tribes, may I think be traced in every wing-
to one original prototype, a triangle with the largest angle
rounded and subtended by the anterior or costal margin :
in some, as the Coleoptera, Orthoptcra^ &c., this type of
formation is a >7<>///-aw^/t'</ triangle ^ ; and in others, as in
the Hi/menoptera, Diptera, &c., the majority of the Neuro-
ptaa^ &c., it is an obtusangled one^; it may be further
observed, that in receding from these forms wings very
often assume that of the half or quadrant of some regular
figure, as we shall see when we consider those of the diffe-
rent Orders. Anothergeneral observation I shall first men-
tion,— that these organs are universally narrowest at their
base and widest at the apex, provided we consider as the
apex the termination outwards of the three Areas ; otherwise
we might say that wings in the Coleoptaa, Orthoptera^
&c., were wider at the base than at the apex *^. The wings
in the former Order, and in several of the Heteropterous
Hcmiptera, as GcrriSi Velia, &:c., may in general, as to
their shape, be termed semicordate or semiovate "* ; in the
Dermaplera they incline to an oval figuie*^; in the Stre-'

' Pi ATE X. Fig. 4, .:•. and XXVHI. Fi... 21,25?.
*> I'l.ATc X. Fiv!. (1-14. '■■ Ihif!. Fic. 4, :.. ami XXVHL

Fig. 21. 22. " Flatj; X. Fir.. 4. ' Ibid. Fig. 3.

V(,)[.. iir. 2 T

(J'lS EXTEUNAI. ANATOMY OK INSECTS.

psiptcrn, OrtJioptera^ most Homopterous and many He-
teropterous Hcmiptera, they approach to the quadrant of •
a circle ; in a considerable portion of the Lepidoptera the
two under wings, if imited at their posterior margin, ap-
proach a circular form ; the upper ones vary a little from
the prototype of the under ones, forming an obtusangled
triangle * ; in many Neuroptera the primary wings may
be called oblong or linear-oblong, while the secondary
betray more evidently the right-angled or obhisangled
triangle; in the Hymenoptera this latter form is every
where conspicuous, with little deviation, except in the
rounding of the angles''; and, finally, in the Diptera this
form shades off again into an oblong, ovate, or linear
shape, the wing being most commonly attenuated at the
base into a kind of footstalk '^. Some singular variations
with respect to the termination or marginal processes of
the wings are exhibited by many Lepidoptera; thus in
Attacus Atlas, &c., the primary wings are falcated or
hooked at their apex •' ; and in great numbers both wnngs
are there scolloped into alternate bays and capes, if I
mav so speak, varying in depth and length ^. There is
usually a sinus between every pair of nervures, each of
which terminates in the adjoining prominence, as a fold
does in the sinus ^. Where present, in the primary wings
there are eight of these sinuses, and in the secondary,
where they are most usual, seven; some are remarkable
for the long tails which distinguish their secondary wings;
those in Papilio are usually an elongation of the fifth, from

•' Plate X. Fig. G. ^ Ibid. Fig. 8-11.

' Ibid. Fig. 12— lo. " Plate XIV. Fig. 4.

* Ibiil. Fig. 2. ' In Gastropachn quercifolia,&c.,

amongst the Xoctumal Lepidoptera, these sinuses exist, in the upper
wing ten, and in the lower tiine, but without the folds.

F.XrERNAI, ANATOMY OF INSKCTS, GiS

the anterior margin, of the prominences before mentioned,
into a spathula-shaped diverging process, vmying in
length and widtii^*: but in P. Ulysses it does not diverge ;
and in P. Podalirius it is linear. They are found also in
other subgenera; thus in Urania Patroclus there are Ixvo;
in U. Riphceiis three; in Erycina Ciqndo five ; and in
Fa. Endi/mion six of these tails; in some, as in E. Don/las,
the whole wing seems to form the tail ; in others again, as
in Hesperia Proteus and Bomhyx Ijima, it is an elongation
of the anal angle. Other wings in this Order are divided
into lobes resembling feathers, as you may see in Piero-
phorus hexadactylus, Sic.^

6. We are next to consider the clothingoi wings : these,
in the Orders in which they are covered bv elytra, teo-
mina, or hemelytra, are generally naked, except that the
spots in those o^ Fulgora laternaria^ serrata, &c., and the
whole wing in Plata, Aleyrodes, and otliers, are covered
with a kind of farinaceoUs powder; but in all the remain-
ing Orders, hairs or scales are more or less implanted in
these organs: as the Lepidoptera are the most remarkable
for tliG clothing of their wings, I shall leave them till
the last, an<l begin with the Neuroptera. If you lightly
pass your finger over the wing of any dragon-fly [Libel-
tula F., JEshna F.), from the apex towards the base, you
will find that the longitudinal nervures are, as it were,
serrulated with very minute bristles, which point towards
the extremity ; if you next move the finger across the
wing, fron\ the posterior to the anterior margin, a simi-
lar circumstance will strike you. M. Chabrier conjec-
tures that, amongst other uses*^, these hairs may contri-

' Pi.ATK XIV. Kk;. J. «. '' Jbid. FtG. .3.

For some nses ol' hairs sec ab<nc. p. .*>!<!) — .

2 T 2

{>4'4 EXTERNAL ANATOMY OF INSECTS.

bute to fix the atmospheric fluid when the wings are
depressed in flight, while it glides over them as they
rise * ; in Ascalaphus, Myrmelcon, Nemopteroy Hemero-
bius, &c., the nervures are more visibly bristled ; the
bristles diverging on each side from the longitudinal ones,
but all pointing towards the apex from the connecting or
transverse ones ; in Panorpa^ besides these bristles, short
hairs, pointing the same way, are thickly planted in the
membrane of the wing ; and in Heme^'obivs the margins
of the wing are fringed ; in the Ephemerina^ Cm-ydalisy
&c., the wings are naked. In the Trichoptera Order, as
their name imports, they are covered with minute decum-
bent hairs, less easily seen but still existing in the se-
condary pair. In the Hymenoptera in general the wings
are covered with minute hairs or bristles; but in Tiphioy
Scolia — with the exception o^ S. Radula and affinities in
which they are hairy — and others, the wings are nearly
naked ; in Pompilus, JPepsis, &c., the hairs are infinite-
ly numerous and very short ; in the SphecidcE^ Mutilla^
&c., they are more distinct, longer, and less numerous;
in the humble-bee [Bombus) and many others the apex
of the wing is darkened by a large number of more con-
spicuous hairs, each of which seems to spring from a mi-
nute tubercle : as these tubercles are in a part of the wing
that is strengthened by few nervures, they may probably
be intended to supply their place, in giving firmness and
tension to this part. The wings of Diptera, under the
present head, may be viewed with regard to the hairs
that are implanted in the membrane of the wing, in its
nervures^ and in its viargin. In the first view, in Slra-

^ Aimlysc\ 24. He seems to think that certain crooked hairs, in
some wings, supply the plure of folds. Ibiu.

tXlLKNAL ANAIOAtV Ol INSECTS. (ii-5

tr/omis and immediate affinities the wing is nearly naked;
but in Xylophagus^ Berts, and the great majority oitlie Or-
der, the membrane of the wings is thickly planted with in-
numerable very minute bristles;, not to be seen but under
a powerful lens, often black, and seemingly crowning a
little prominence, and giving the wing an appearance of
the finest net-work. As to the clothing of the nervures,
the costal, in Anthrax, Bombi^Uus, &c., is often remark-
ably bristly at the base, with hairs intermixed; in (Estrus
Ovisy in tlie inner margin or edge of this nervure, is a
single series of bristles, or rather short spines, like so
many black points; in CE. Equi the whole costa is co-
vered with short decumbent hairs or bristles; in Miisca
pagana F., j ust at the apex of the costal areolet, that ner-
vure is armed with a spur or diverging bristle larger
than the rest, which is also to be found in many others
of the Muscidie^ some of which have two and others more
of these spurs. The little moth-like midges [Psychuda
Latr., Hirtcca F.) at first appear to have the whole sur-
face of their wings covered with hairs ; but upon a closer
examination it will be seen that they are planted in the
nervures, from each of which they diverge, so as under
a lens to give it a very elegant appearance*. This fly
has its wings beautifully fringed with fine hairs, the
third circumstance to be attended to under this head; iu
the Tipulidans, and many others of this Order, the apex
and posterior margin are also finely fringed with short
hairs. Some Dipterous insects make a near approach
to the Lepidoptera in the covering of their wings : in the
connnon gnat, when the wings are not rubbed, the ner-
vures are adorned by a double series of scales, and the

• Plate X. Fig. 1,'{.

646' EXTERNAL ANATOMY OF INSECTS.

nuu'ginal fringe also consists of them ^; luid in a Georgian
genus, which appears in some degree to connect Culex
with Anthrax &c., there are scales scattered upon the
membrane as well as upon the nervures; besides, its an-
tennae ^ and abdomen are also covered with them.

The Order, the clothing of whose organs of flight
excites the admiration of the most incurious beholder, is
that to which the excursive butterfly belongs, the Lepi-
doptera. The gorgeous wings of these universal favour-
ites, as well as those of the hawk-moths and moths, owe
all their beauty, not to the substance of which they are
composed, but to an infinite number of little jAumes or
scales so thickly planted in their upper and under sur-
face, as in the great majority entirely to conceal that
substance. Whether these are really most analogous to
plumes or scales has been thought doubtful. De Geer
is inclined to think, from their terminating at their
lower end in little quills and other circumstances, that
they xese\nh\efeathc7-s as much as scales'^: Reaumur on
the contrary suspects that they coine nearer to scales '^.
Their substance, approaching to membrane, seems to
make further for the former opinion, and their shape and
the indentations that often occur in their extremity, fur-
nish an additional argument for the latter. Their num-
bers are infinite; Leeuwenhoek found more than 400,000
on the wings of the si Ik- worm moth {Bo7nbj/x Mori)'^;
and in those of some of the larger moths and butterflies
the number must greatly exceed this. You will observe

" Reaiim. iv. /. xxxix. /. 4 — 11. ti A portion of the an-

tenna of the insect here mentioned is figured Plate XII. P"'ig. 33.
" Dc Geer i. 63—. •' Re:uini. i. 200.

*■ Hook's Leemvenhoek. i. 63--.

EXTERNAL ANATOMY OF INSECTS. 647

however that in many Lepidopt era the wings are partially^
and in some instances grncrulli/, transj)arent : thus in
Hcsperia Proteus, a butterfly beloie noticed lor the long
tail that distinguishes its secondary wings, there are many
transparent spots ; in Aitaciis Atlas, one of the largest
of moths, and its alHnities, there is as it were a window
in each wing formed by a transparent triangular space ;
in A. Polyj)hemus, Fap/iia, &c., the pupil of the ocellus is
transparent, which in the former is divided by a ner-
vure. In several of the Heliconian butterflies, and in
Zj/gcetm F., &c., the greater part of both wings is trans-
parent, with scales only upon their nervures, round their
margin, or forming certain bands or spots upon them ;
in Parfiassius Apollo, Mnemosyne, Sic, the scales are so
arranged as not wholly to cover the wings, which renders
them semidiaphanous; and in some {Nudaria) the wings
are intirely denuded. With regard tosize, the scales vary
often considerably in different tribes; in Pleliconia they
appear to be more minute than in the rest ; and in 6'a.s-
tnia they are the largest and coarsest; the extremity of the
wings of Lepidopterous insects in general is fringed with
longer scales than their surfaces, and even thoseofthe last
in the same winnr sometimes vary in magnitude. The little
seeming tooth that projects from the middle of the pos-
terior 4nargin in the upper wings of Notodonta, a subgenus
of Bombyx L., is merely produced by some longer di-
verging hairs. The shape and Jigure also of scales are
very various — some being long and slender ; others short
and broad ; some nearly round ; others oval, ovate, or
oblong ; others spathulate ; others panduriform or para-
bolical ; some again almost square or rhomboidal ; many
triangular ; some representing an isosceles triangle, and

(jI-8 external anatomy or insixis.

others an equilateral one; lastly, some are lanceolate and
others linear; again, some have a very short pedicle and
others a very long one : with regard to their extremity;
some are intire, without projecting points or incisions,
while others are furnished with them : of these some ter-
minate in a single long mucro, others have several shorter
ones ; some are armed with teeth, varying in number
from two to thirteen in different species '. Many other
forms might be enumerated, but these are sufficient to
give you a general notion of the infinite variety of this
part of the works of the Creator. I must next say a
word or two upon their arrangement on the wing. In
most instances this is in transverse lines, which some-
times vary a little from a rectilinear course, and the ex-
tremity of the scales of one row reposes on the base of
those of the succeeding one, so that in this respect their
arrangement is like that of tiles in a roof: in some cases
it is not so regular: thus the minute scales on the
wings of Fa ma ssius Apollo, and others with subdiapha-
nous wings, are arranged without order ; in Piais and
other Diurnal Lepidoptera, and many of the Crepuscu-
lar and Nocturnal, there appears to be a double layer of
scales on both sides of the wing ; the under layer usually
consisting of white ones. If you denude the wings of any
butterfly, which you may easily do by scraping it hghtly
on both sides with a penknife, you will be amused to
trace the lines in which the scales were planted, consist-
ing of innumerable minute dots: the lines of the under
side, in some cases, so cut those of the upper side, as by

" De Geer has given 'M figures of" difterent scales (i. /. ii\.f. 28) ; ami
in Platk XXII. Fig. 6. a — w. 2^? others, collected from Rcavimur.
are given.

r.XTKKNAL ANATOMY Ol l.Wsl.CTS. (ji9

their intersection to form lozenges. With regard to the
position of the scales on the wing, they usually lie flat,
but sometimes their extremity is incurved : in the beau-
tiful Argynnis Vanilhe a very singular appearance of nu-
merous transverse ridges is produced by the extremity
of those scales that cover the longitudinal nervures of
the primary wings, except at the base, being recurved.

But though the general clothing of the wings oi Le-
pidoptcra consists of these little scales, yet in some cases
they are either replaced by hairs or mixed with them.
Thus, in the r/r«; parts of the wings of Heliconians, At-
taciy &c., short inconspicuous hairs are planted ; in a
large number of the Orders the upper side of the Anal
Area of the secondary wings is hairy ; in several Crepus-
cuhirs {Sp/iinx Phcenix, &c.), where there is a double layer
as before mentioned, the upper one consists of dense
hairs, except at the apex, and the lower one of scales;
and in most of them the scales of the primary wings are
piliform, and the secondary are covered by what ap-
proach very near to real hairs ; many of the Aiiaci are
similarly circumstanced: the four wings oi A.Cytherea
are also covered externally with hair.

7. Before I conclude this long diatribe on the organs of
flight of insects, I must not omit some notice of the infi-
nite diversity of colours with which their wings are often
variegated and adorned by the Creator, who loves to
delight us by the beauty, as well as to astonish and awe
us by the immensity and grandeur of his works. Though
the wings in every Order exhibit instances of brilliant
and beautiful colouring, yet those of the Lcpidoptera in
this respect infinitely excel them ajl, and to these, under
this head, after noticing a few in the less privileged Or-

650 EXTERNAL ANATOMY OF INSECTS.

ders, my observations will be confined. Although in the
Coleoptera the wings are seldom distinguished by their
splendour; yet those of some Cetoniadce, as Cetoida
africana^ are extremely brilliant, and resemble those of
many Xylocopa; in the lovely violet hue that adorns them :
amongst the Orthoptera some Pterophyllce, and in the
Homopterous Hemiptera some Fulgo'rcc, emulate the Le-
pidopiera in the ocelli that give a kind of life to these
organs * ; and a vast number of the destructive tribe of
locusts {Locusta Leach) are remarkable for the fine
colours and gaiety of their wings''; in the Neuroptera nu-
merous Libellulince emulate the Heliconian butterflies by
their maculation; and in the genus Ascnlapkus, which
represents the Lepidoptera by its clubbed antennae •=, many
also have the resemblance increased by the painting of
their wings, so that some Entomologists have actually
considered some of them as belonging to that Order'*;
the wings of the Xylocopce, before alluded to, sometimes
add to the deep tints of the violet^ which also prevail in
the wings of several Diptera — towards their extremity
the most brilliant metallic green or copper varying,

" As the site varies in the guzer's hand,"
and even those wings that consist of clear colourless
membrane are often rendered extremely beautiful from the
reflection of the prismatic colours. I should undertake an
endless task did I attempt to specify all the modes of mark-
ing, clouding, and spotting, that variegate a wing, and all
the shades of colour that paint it, amongst the Lepidopte-

* Stoll Sauterelles a Sabre. Plerophylla ocrllata t. i. ii., Cigales, Fid-
gora Intcrnnria t. \.f. i , and F. scrrnta t. xxix. /' 1 70.

*• Vnd. Sauter. de Passage, Locusta Dux i.i. o. L. carina fa f. v. b.
/ 16. L.crisfafa i.ix h. f. 30. &c. &c. ' PLAXfi XXV. Fir. 30.

■' Scopoli, Hubner.

KXIEKNAL ANATOMY Ol INStCTS. G51

rous tribes; 1 shall therefore confine myself to a few of the
principal, especially those that distinguish particular tribes
and families. Of whole coloured wings — I know none that
dazzle the eye of the beholder sonuich as the upper sur-
face of those of Morpho Menelaus and Telemachus : Linne
justly observes that there is scarcely any thing in nature
that for brightness and splendour can be pai-alleled with
this colour ; it is a kind of rich ultramarine that vies with
the dee})est and purest azure of the sky; and what must
cause a striking contrast in fliglit, the prone surface of
the wings is as dull and dark as the supine is brilliant,
so that one can conceive this animal to appear like a
planet in full radiance, and under eclipse, as its wings
open and shut in the blaze of a tropical sun : another
butterfly, Papilio Vlysscs^ by its radiating cerulean disk,
surrounded on eveiy side by a margin intensely black,
gives the idea of light first emerging from primeval ob-
scurity; it was probably this idea of light shining in dark-
ness that induced Linne to give it the name of the Avisest
of the Greeks in a dark and barbaious age. I know no
insect upon which the sight rests with such untired plea-
sure, as upon the lovely butterfly that bears the name of
the unhappy Trojan king [P. Priamus); the contrast of
the rich green and black of' the velvet of its wings with
each other, and with the orange of its abdomen, is beyond
expi'ession regal and magnificent. But peculiar beauties
of colour sometimes distinguish whole tribes as well as
iiidividuah. What can be more lovely than that tribe
of little butterflies that flit around us every where in
our sunnner rambles, which are called bhws, and which
exhibit the various tints of the sky? LifCtcna Adonis of
this tribe scarcely yields to nny exotic butterfly in the

652 EXTERNAL ANATOMY OF INSECTS.

celestial purity of its azure wings : our native coppers also,
Lycana dispar^^ Virgaicrea^ &c., are remarkable for
the fulgid colour of these organs; in Argj/tmis the upper
side of their wings is tawny, spotted with black, while the
under side of the secondary ones is very often adorned by
the appearance of silvet- spots. How this remarkable effect
of metallic lustre, so often reflected by spots in the wings
of butterflies, is produced, seems not to have occupied
the attention of Entomologists. M. Audebert is of opi-
nion that the similar lustre of the plumes of the humming
birds ( Trochilus) is owing to their density, to the polish
of their surface, and to the great number of little minute
concave mirrors which are observable on their little
beards^. But these observations will not apply to the
scales of the wings of butterflies, which are always very
thin and generally very flat: in some instances, as in
Morpho Menelam, there appears more than one very slight
channel upon a scale; but this takes place also in others
that reflect no lustre. Their metallic hues must there-
fore principally be occasioned by the high jiolish of their
surface and the richness of their tints. It is the purity
of the white, in conjunction with their shining surface,
contrasted with the dull opaque colour of the under side
of the secondary wings, that causes the spots thatdecorate
those of the Fritillaries ( ArgT/nnis) to emulate the lustre
of silver. In Papilio the Trojans are distinguished by
the black wings with sanguine spots, and the Greeks by
the same with yellow spots; but these have proved in
some instances only sexual distinctions'. In the Daiiai
candidi L. the colour of the tribe may be described as

" Plate III. Fig. 1. "- X Diet. d'Hist. Nat. viii. 25/.

* See above, p. 303.

EXTEUNAI. AN'ATO.MV OP IN.sFCTS. (J53

sacred to the </ay, since every shade, from white or the
palest yellow to full orange, is exhibited by them. The
yellows prevail also in those Noctjur, the trivial names of
w hich Linne made to end in ago, as N. Fulvago, CitragOy
&c. I must not conclude this part of my subject with-
out noticing one of the most striking ornaments of the
wings of Lepidopfcra, the many-coloured ei/es which de-
corate so large a number of them. Some few birds, as
the Peacock and Argus Pheasant, have been decked by
their Creator very conspicuously with this almost
dazzling glory; but in the insects just named it meets us
every where. Some, as one of our most beautiful but-
terflies, Vanessa Jo^y have them both on the primary and
secondary wings; others, as Noctua Bubo^, only on the
primary ; others again, as Smerinthus ocellata *=, only on
the secondary: in some also they are on both sides of the
wing, as in Hipparchia jEgei'ia'^, and in others only on
the upper side, as in Vanessa lo; in others again only on
the under side, as in Morpho Teucer^ : in some likewise
they are very large, as in the secondary wings of the same
buttei-fly: and in others very small, as in those in the
wings of the blues [Lycaena). Once more, in some they
consist only of iris and pupil, as in Hipparchia Semele,
and in others of many concentric circles besides, as in
Moipho Teucer, &c.

v. Legs ^ We are next to consider those organs of
motion affixed to the trunk, by which insects transport
themselves from one place to another on the earth or in

■* Sepp. I. i. /. vii./. 6. •• Roemer Genera t. xxii./. 2.

' Sepp 1. iii. /. ii. /. 7. " Ibid. i. /. vi. /.J,

' Rcemer ub'i mpr. t. xiv. /.I. ' Plates/', /•', d\.

654 EXTERNAL ANATOMY Ol^ INSECTS.

the water, and by which also they perforin various ope-
rations connected with their economy *. In treating of
them we should consider their numher ; kind; substance ;
articulation with the trunk ; positioti; proportions; cloth-
ing; composition ; folding; and motions.

1. Number. Having before very fully explained to you
the number and kind of the legs of insects in their p7'e-
paratory states '', I shall now confine myself to the con-
sideration of these organs in their perfect or last state ;
beginning with their number. Insects, properly so call-
ed, as I formerly observed'^, in this state, including the
anterior pair or arms, have only six legs, none exceeding
or falling short of this number ; but in several of the
Diurnal Lepidoptera [Vanessa^ &c.) the anterior pair
are spurious^ or at least not used as legs, the tarsi having
neither joints nor claws'^; this in some cases is said to be
only a sexual distinction ^. In Onitis, PhancEus, and some
other Scarabceida'M^^l^.., the arm has either none or a spu-
rious tarsus or manus^; which in the first of these genera
is also a sexual character. From both these instances
we see that walking is only a secondary use of fore-
legs in the insect tribes. Besides insects proper, a whole
tribe of mites {Can's Latr., Leptus Latr., Astoma Latr.,
Ocypetc Leach) have only six legs; the rest, and the
Arachnida in general, have eight; in the Myriapods^
Pollyxetius has twelve pairs; Scutigera has Jiftee7i; the
terrestrial Glomerides (G. Armadillo, &c.) sixteen; and
the oceanic (G. ovalis) twenty ; the oriental Scolopendres
Leach, twenty-one ; Polydesmus has usually about thirty

» See above, p. 546 . >• Ibid. I31~.

= Vol. it. p. 307- •' De Geer i. t. xx. /. 1 1.

« Jicgm Animnl. iii. 546. f Plate XXVII. Fig. 44,45.

EXTERNAL AN'ATOMY OF INSECTS. 665

pairs : Craspedosoma, J^fiy i Geophilus elcctricus at least
sixty ; in Inlus ferrcs/ris there are more than seventy; in
/. sabidosus nearly one hundred; in I.Juscus, 124'; and in
/. viaximus 1 34 pairs or 268 single legs. But with respect
to the Geophiliy luli^ &c., it is to be observed, that the
number of pairs varies in different individuals; and the
circumstance that has been before mentioned*, that these
animals keep acquiring legs in their progress to the per-
fect state, instead of losing them, renders it difficult to
ascertain what is the natural number of pairs in any
species.

2. Kinds. Upon a former occasion I gave you a suffi-
ciently full account of the kinds of legs', and I have also
assigned my reasons for giving a different denomina-
tion to the anterior legs under certain circumstances''; I
shall not therefore enlarge further upon this head.

3. Substance. The substance of the legs is generally
regulated more or less by that of the rest of the body,
only in soft-bodied insects they seem usually more firm
and unbending. Each joint is a tube, including the mov-
ing muscles, nerves, and air vessels.

4. Articulation with the Trunk. M. Cuvier has ob-
served that the hip [coxa), which is the joint that unites
the leg with the body, rather inosculates, in its acetabu-
lum, than articulates in any precise manner <=; but this
observation, though tiue of a great many, will not apply
universally, for the legs of Orthopterous insects, and of
most of the subsequent Orders, are suspended rather than
inosculating. Even in many Coleoptera a difference is ob-
servable in this respect. I have before mentioned that

^ Vol. II. p. 312, o6:{, 365. ^ See above, p. 546— .

"■ Anatom, Conipar. i, 453.

G36 EXTERNAL ANATOMY OF INSECTS.

whatarecaWedthe punctao7-dinaria, which distinguish the
sides of the proihorax of many Scarabceid(S and Geotm-
pidce, form a base for an elevation of the interior surface
with which the extremity of the base of the clavicle,
which plunges deep into the breast, ginglymates =^ ; this
structure may also be found in other Lamellicorns, as
the stag-beetle [Lucarius) and Dynastcs, that have not
those excavations ; in these last it is an elevated ridge
forming a segment of a circle with, it should seem, a pos-
terior channel, receiving a corresponding cavity and pro-
tuberance of the clavicle. With regard to the mid-leg,
in Copris, the coxa is emboxed in a nearly longitudinal
cavity of the medipectus , and the coxa of the hind-leg an-
teriorly is suspended to a transverse cavity of the post-
pectus, but posteriorly it is received by a cavity of the
first segment of the abdomen ; so that it may be regard-
ed as suspended anteriorly, and inosculating posteriorly.
In some tribes of this Order, as the Weevils [Curcidio
L.) and Capricorns {Ceramhyx\ the coxae of the four an-
terior legs are subglobose'' and extremely lubricous, and
are received each by a socket that fits it, and is equally
lubricous. In the bottom of this externally, and in the
head of the coxa, is an orifice for the transmission of
muscles, nerves, and bronchiae ; but the coxa is sus-
pended by ligament in the socket. This structure ap-
proaches as near the ball and socket as the nature of the
insect skeleton will permit ; the high polish of the arti-
culations acts the part of synovia^ and the motion is in
some degree rotatory or versatile, whereas in Copris, &c.,
lately mentioned, it seems to be more limited, and is pro-

» See above, p. 308. ^ Pr.vTE XXVII. Fig. 18, 19.

EXTERNAL ANATOMY OK INSECTS. 05^

bably, at least in the mid- and hiiul-lcfrs, only in two di-
rections ; in the middle j^nir, probubly, from the coa-rc
being in a position j)arallel with the breast, oj)posite to
that of the hind pair. In Diftiscus L., Carabm L., and
some other beetles, the coxa*, especially the posterior pair,
appear to be fixed and incapable of motion. In many
insects these coxa? seem to belong as much to the abdo-
men as to the trunk. We have just seen this to be the
case in Copri% !kc. ; and in the Lcpidoptera, if tiie former
be separated from the latter, the legs will be detached
with it.

4. Location. We are now to consider the location and
position of the legs, both in general and with respect to
each other. And first, as has been before stated, we may
observe that, in the hexapods w ith wings, the arms belong
to the maniti'unk^ and are attached to the antcpcciiis on
each side the prostcrnum ; and the two pair of legs to
the alitnmk, the mid-legs being attached to the medipcc-
tus, between the scapularia and mesostcrnum ; and the
Jwid-legs to the j^ostpecttis, between the parapleura and
the postcrmun ; and further, that the arms are opposed
to \\\e prothorax : the mid-legs to the mesot/iorax and the
primary organs of flight; and the hind-legs to the mc-
tathorax and the secondary organs of flight; though in
some cases the wings appear to be behind the legs and
in others before them : thus, in Panorpa, the former are
nearer the head than the latter; but in the Libellulitia the
reverse of this takes place, the legs being much nearer
the heatl than the wings : in both cases, however, the
scapularia and p)arapleurcc run from the legs to the
wings, but in an oblique direction; and in Panmpa these
pieces assume the appearance of articulations of the legs.

VOL. III. 2 u

658 EXTERNAL ANATOMY OF INSECTS.

In most of the apterous hexapods they appear to be
attached laterally between the thorax and the pectus^ ;
but in the flea {Pulex) they are ventral. In this tribe the
arms are usually stated to be inserted in the head^: but
I once succeeded in separating the head of a flea from the
trunk, and these organs remained attached to the latter*^.
As to the Octopods and Arachjiidce, in the mites {AcarusL..)
they are lateral, and in their analogues, the spiders
{Aranea L.), they emerge between the thorax and the
breast, which last they nearly surround ; in the Phalan-
gidce the bases of the coxae appioach near to each other,
being separated only by a narrow sternum ,- in their an-
tagonists, Chelifer and Scorpio^ they apply to each other,
the anterior ones acting as maxillce. In the myriapods
the legs of the Chilopoda Latr., and some Chilognatha,
as Glomeris, are inserted laterally, a single pair in a seg-
ment ; but in lulus L. their attachment is ventral, the
coxae seem to spring from a common base, and there are
two pair to each segment '*, except the three first, which
bear each a single pair.

I shall next consider how the legs are located with re-
spect to each other. To render this clear to you I shall
represent each of the variations, which amount in all to

•' Mr. Montague describes the legs of Xi/ctenbia, as dorsal {Linn.
Trails, xi, 13); but Dr. Leach calls them lateral (Samouelle, 303).

■^ N. Diet. d'Hist. Nat. xxviii. 247. '^ Plate XXIII. Fig. 4.

•' Plate XXVII. Fig. 58. M. Savigny affirms that these insects
cannot have, and really have not, but one pair to each segment ; only
that the segments are alternately membranous and shelly, and that
the former are concealed under the latter (Aniin. sans Vertebr. I. i.44.):
but, pace tanti viri, I cannot discover that any sjdure separates these
portions from each other : so that, admitting his theory, they must
be regarded as two segments soldered together.

KXTERNAT. ANATOMY OF INSKCTS. 659

twelve in tlie hexapods that have fallen under my notice,
by six dots.

1. \: In this airangeniont the legs are all plantetl
near to each other, there being little or no interval be-
tween the pairs, and between the legs of each pair. It
is exemplified in the Lrpidop/cra, Blafta, and many
Drpfrra.

2. :i Similar to the preceding, but the anterior pair
are distant from the two posterior ; exemplified in the
hees {Apis) and most Hi/menopf era ; Chi7-o7iomus ; Scu-
tellera; PacJtysoma K.*

3. :: Like the last, but the posteiior pair is distant
from the two anterior. Examples: Silpha, Necrophortis,
Telcphnrm^ &c.

4. . ". Similar to the last, but the legs of the posterior
pair are more distant from each other than the four an-
terior. Ex. Curculio L.

5. •• The legs of each pair near each other, but the
pairs distant. Ex. Gibhium.

6. \ • Both the legs of each pair and the pairs distant.
Ex. Blaps, &c.

7. ..\ Anterior pair distant from the two posterior,
and the legs of the middle pair rather more distant
from each other than those of the other pairs. Ex. Sea-
rabcBus M'^L.

8. ,". Like the preceding, only the legs of the mid-
dle pair are at a much greater distance fi-om each other.
Ex. Copris M'=L.

9. :'; Legs of the two posterior pairs distant. Ex.
Hister, Scaphidium.

^ It is by this arrangement of the legs thai Pachi/soma is princi-
pally distinguished, as a subgenus, from Srrtrnbmis ML.

2 U 2

660 EXTERNAL ANATOMY OF INSECTS.

10. :\ Like the preceding, but the posterior legs
more distant than those of the middle pair. Ex. Lygceiis.

11. ;' *• Like the last, but the legs of the anterior
pair also distant. Ex. Velia.

12. •• ■• The arms distant, intermediate legs more di-
stant, posterior legs close together. Ex. Byrrhus L.

5. Proportions. In general the legs of some insects
are disproportionally long and slender, as in Plialan-
gium Opilio and some species of Gonyleptes^ : those
of others are disproportionally sJiort, as in Elater, &c.
With regard to their relative proportions, the most ge-
neral rule is, in Hexapods, that the anterior pair shall
be the shortest and most slender, and the posterior the
longest and thickest ; but there are many exceptions :
thus, in Macropus longimaniis, Clytra longiniana, &c., in
the male the arms are the longest ; again, a thing that
very rarely occurs, in the same sex of Podalirius rctusa
the intermediate legs are the longest''; but in Hhinahar-
birostris and many weevils they are the shortest : ixi Sa-
perda hirtipes Oliv. ^ the hind-legs are disproportionally
long: with regard to thickness, they are in general extreme-
ly slender in Cicindela, and in the Scarahceidcs very thick.
In Goliathus Cacicus the arms are more robust than the
four legs'*; in Gyriiius the latter are more dilated than the
former ; in many Riitelidcs, and particularly in the cele-
brated Kanguroo beetle [Scarabcvus Maci'opits Franc.) the
hind -legs are much the thickest ; in a new genus of wee-
vils from Brazil {Plectropus K.), the intermediate pair are
more slender than either the arms or the posterior pair

' See above, p. 37-

•' Monogr. Ap. Aiigl. i. t. xi. Apis * *. d. 2. «./. 18. ii. 296—.

' Oliv. /«i. G8. L i. /. 8. ^1 Ibid. n. 6. t. iv.f. 22.

EXTERNAL ANATOMY OF INSECTS. 661

6. Clothing. The hairs on the legs of insects, though
at first siglit they may seem unimportant, in many cases
are of great use to them, both in their ordinary avocations
and motions : but as most of these were sufficiently no
ticed when I treated of the sexes of insects*, I shall not
here repeat my observations, but confine myself to cases
not then adverted to. Some insects have all their legs very
hairy, as many spiders, the diamond beetle {Entimus im~
pcrialis\ or at least a species very near it and common
in BraziP\ &c.: in others they are nearly naked, as in
the stag-beetle. In the Crepuscular Lepidoptera [Sphinx
L.) and some of the Nocturnal ones [Bomhi/x L.) the
thighs are much more hairy than the rest of the legs :
and in Lucanns, Gcoh-npes, and many other Lamellicorns,
&c., the anterior ones have a yellow or golden spot at
their base, composed of decumbent hairs, which prevent
them from suffering by the violent friction to which they
are exposed in burrowing. In most Petalocerous beetles
the tibiae are set with scattered bristles, and sometimes
the thighs. The Tiger beetles [Cicindela) are similarly
circumstanced: but the bristles, which are white, are ge-
nerally arranged in rows. In Di/tiscus, Hijdrophiliis, &c.,
the four posterior tarsi ; and in Notonecta the posterior
pair, and also the tibiae — are fringed on each side with a
dense series of hairs, which sti'ucture assists them in
swimming *=. The tarsi, especially the anterior pair, in a
certain family o^ Lamia F. [L. papulosa, &c.''), are simi-
larly fi-inged, only the hairs curl inwards ; and the hand

* See above, p. 305 — . ^ This variety appears to ilifFer

very little from the Curculio iviperuilit of Fabricius and Olivier, ex-
cept in the remarkable hairiness of its legs. * Vol, II. p. 563.

•' Oliv. Ins. n. 67. t. xx./. 156.

662 EXTERNAL ANATOMY Ol- INSECTS.

in Sphex and Ammopkila, but not in Pelopceus and Chlo-
rion, is fringed externally with long bristles.

7. Composition. With regard to their composition,
both arms and legs generally consist o^Jive pieces, which
Entomologists have denominated — the coxa or hip — the
trochanter — the femur or thigh — the tibia or shank — and
the tarsus or foot. Where the structure and use of the
fore-leg is different from that of the four hind-legs, I pro-
pose calling these pieces by names corresponding with
those which anatomists have appropriated to the arm in
the higher vertebrate animals : thus, as you will see in
the table, 1 call the whole fore-leg the hrachium or arm ;
and the coxa becomes the clavicula or collar-bone ; the
trochanter; the scajmla or shoulder-blade ; \he femur, the
humerus or shoulder ; the tibia, the cubitus or arm ; the
tarsus, the manus or hand. But let me not lead you to
suppose that the pieces, either in the arms or legs of in-
sects, which are there named after certain others in verte-
brate animals, precisely correspond with them — by no
means — since that is a very doubtflil point ; and some of
them, as the trochanter, clearly do not. Many gentlemen
skilled in anatomy, as I have before observed*, have
thought that what is regarded as the coxa in insects really
represents 'Ocis. femur: but there are considerable difficul-
ties in the way of this supposition, several of which I then
stated. I shall not however enter further into the sub-
ject, and take the above names ; since this application of
them is so general and so well understood, except with

* See above p. 591. Some physiologists have been of opinion,
that in Urds, what is called the thigh should properly be denominated
the tibia, and that this last is really the tarsm. Illiger, Terminologie,
184. § 185. n. li?46.

KXTERNAL ANATOMY OF INSECTS. 663

regard to the fore-leg, under certain circumstances, as 1
find them. I shall now consider them in the order in
which I have named them.

a. Coxa or Clavicula *. The coxa is the joint that
connects the leg with the trunk of the insect. With re-
gard to their shape, the most general form of the four
anterior is more or less that of a truncated cone : in the
Staphylinidtt, however, they tend to a pyramidal or four-
sided figure; as do the whole six in the Trichoptera : in
numbers of the weevils and capricorns they are subglo-
bose; in the Lamellicorns they are mostly oblong, and
not prominent : the posterior pair in the Coleoptera are
generally flat and placed in a transverse position, and more
or less oblong and quadrangular : in Elatcr, &c., they are
cuneiform : in Halipliis Latr. they are dilated, and cover
the thigh '' : in Bup'estis, Coprist &c., they have a cavity
that partly receives it : the corresponding part, the c/a-
vicle, in the arm of Grijllotalpa, is very large and re-
markable; viewed underneath it is triangular, and trifid
where the trochanter articulates with it : in that of Me-
gachile Willughbiella the clavicle is armed with a spine *^.
As to their proportions, the most general law seems to be,
that the anterior pair shall be the shortest and smallest, and
the posterior the longest and largest. In some instances,
as in Btiprestis, the two anterior pair are nearly equal ;
in others [Mantis, Eurhiyms K.), the anterior are the
longest, in the former as long as the thigh, and the four
posterior the shortest : in the Trichoptera, Lepidoptera,
&c., all are nearly equal ; in Mantis the two posterior,
and mPhcngodes the intermediate pair are the largest; but

- Plates XIV. XV. XXVII. ;.. " Plate XV. Fig. I. ;/', r".

' Platf XXVII. Fig. 27-

664) EXTERNAL ANATOMY OF INSECTS.

in NecropJiorus they are the smallest : — though almost
universally without articulations, in Galeodes the clavicle
consists of two and the coxa of three^.

b. Trochanter or Scajmla ^. This is the second joint
of the leg: and if the coxa is regarded as the analogue of
the thigh in vertebrate animals, this should seem to re-
present the patella or rotula, vulgarly called the knee-
pan. Latreille and Dr. Virey consider this articula-
tion as merely a joint of the coxa ^ ; but if closely exa-
mined, especially in Coleopterous insects, you will find
it so fixed to the thigh as scarcely to have separate mo-
,tion from it, and in many cases it seems to be merely its
fulcrum ; but I am not aware that any instance occurs in
which it has not motion separate from that of the former
joint.

As to its artiadation with the coxa, — in the Cole-
optera it appears to be of a mixed kind ; for it inoscu-
lates in that joint, is suspended by ligament to its ori-
fice, and its protuberances are received by correspond-
ing cavities in it ; and its cavities receive protuberances,
which belongs to a ginglymous articulation. I have
observed two variations in this Order, in one of which
the motion of the thigh and trochanter is only in tiw di-
rections, and in the other it is nearly versatile or rotato-
ry. The Lamellicorns afford an example of the first, and
the Rhyncophorous beetles or weevils of the second. If
you extract from the coxa the thigh with the trochanter
of the larger species of Dynastes M'^L., you will find that
the head of the latter is divided into two obtuse incurv-

* L. Dufour, Descr. des six Arachn. &c. : Annates Generates, &c.
1 820. 1 9. U Ixix./. 7. d. '• Plate XIV. XV. XXVII. 7".

'■ N, Diet. d'Hist. Kat. xvi. 1.V5. xxvi. 157.

EXTERNAL ANATOMY OF INSECTS. 665

ing lobes or condyles : that on the inner side being the
smallest and shortest, and constricted just below its a)iex:
and that under this is a shallow or glenoid cavity, ter-
minating posteriorly in a lubricous flat curvilinear ridge.
If you next examine the trochanter in articulation with
the coxa, you will perceive that the head of the former
inosculates in it, that the lower condyle is received by a
sinus of the coxa, which also has a lubricous verj/ shallow
cavity corres])onding with the ridge, in which it turns ;
and in the head of the coxa, on the lower side, is an ex-
ternal condyle, which is received by a sinus common to
both, of the head of the thigh and of the exterior side of
the trochanter*, in which it likewise turns: this last con-
dyle has also an intei-nal protuberance, which appears to
ginglymate with a cavity of the trochanter : from this
structure the leg is limited chiefly to a motion up and
down upon two pivots, or to fold and extend itself. You
will find an articulation very near this, but on a smaller
scale, in the stag-beetle. In the other kind of articula-
tion, which admits of freer motion, the head of the tro-
chanter is prolonged, and the process terminates in a
short interior condyle, which appears to work in a cor-
responding cavity of the interior of the coxa ; and the
base of the process is encompassed by a ridge with a
cavity behind it, which is received by another of the
lower part of that piece, and admits a corresponding
ridge — a structure that allows a rotatory motion. In the
hind-legs of this tribe the motion is chiefly limited to
folding and extending; in Carahis, &c., also the head of
the trochanter is nearly hemispherical, and the articula-

' Plati. XXVII. Fir.. 12. b.

666 EXTERNAL ANATOMY OF INSECTS.

tion approaches ball and socket. In most of the other
Orders, the Hymenoptera excepted, there is little or no
inosculation, the trochanter being simply suspended by
ligament to the coxa as well as to the thigh ; its connec-
tion with the latter is similar in Coleoptera ; but in Ci-
cindela^ &c., it inosculates in it. The part we are con-
sidering varies in its position with respect to the thigh :
in the hind-legs of Carabus, &c., it forms a lateral ful-
crum on the inner side of that part, and does not inter-
vene between its base and the coxa ; the muscles from
the latter entering the former, not at the bottom of the
base, but at its side : but in the four anterior legs it
forms their base, as it does in all the legs in Apioti, and
in all the Orders except the Coleoptera, cutting them en-
tirely off from contact with the coxa : in the Lamellicorns
they cut off part of the base obliquely, but so as to per-
mit their coming in contact with the condyle of the coxa,
as before mentioned. In the Ichneumonidi^ and some
other Hymenoptera the trochanter appears to consist of
^two joints particularly visible in the posterior legs*.

As to size in general, — the part in question is smaller
than the coxa ; but in Notonecta it is larger, and in the
dog-tick {Ixodes Ricinus) longer than that joint. It ex-
hibits few variations in its shape or appendages worthy
of particular notice. In general, in the Coleoptera it is
triangular or trigonal; but in Carahus L., in the hind-
leg it is oblong or rather kidney-shaped ; in that of Ne-
crophorus^ it terminates in one or two teeth or spines,
varying in length in the different species : in the other
Orders it is not remarkable in this respect.

' Plate XXVII. Fig. ^^0. 7". " Ibid. Fig. 'J8.

EXTERNAL ANATOMY OF INSECTS). 667

c. Femur or Humerus ^. Tlie femur or tliigh is the
thirdy and usually the largest and most conspicuous joint
of the leg. In the hypothesis before alluded to'' it is
considered as the analogue of the tibia of vertebrate
animals. With regard to the articulation of this part
with the trochanter, it has been sufficiently exphiined
under that head, and that with the tibia I shall treat of
when I come to tluit joint. As to the size of the thighs,
and their relative proportions to each other and to the
remaining joints of the leg, the most general law is, that
the anterior pair shall be the shortest and smallest, and
the posterior the longest and largest. With respect to the
remainingarticulations, most commonly the //^/g/? is longer
and larger than the tibia, and the tibia than the tarstis.
But there are lunnerous exceptions to both these rules.
With respect to the />s/, we may begin by observing that
the increase of the magnitude of the thigh, from the an-
terior to the posterior pair, is usually gradual : but in
many jumping insects, and likewise many that do not
jump, the posterior pair are suddenly and dispropor-
tionally thicker than the rest *^. Again, in many insects
the anterior pair arc the longest and thickest, as in Ma-
crojn-is longimanus, Bibio, Nabis, ike: in others, the in-
ter-mediate exceed the rest in magnitude, as in Onitis
Aj/gulus, cupreiis ; Sicusjlavipcs, he. ; in many Lamelli-
corns all the thighs are incrassated and nearly equal in
size: but in some, as Ri/ssonotiis nebulosus M'^L.^, the
intermediate pair are rather smaller than the rest. W^ith
respect to the second rule — in some, as in the male of
Macropus longimanus, the anterior tibia, though more

* Plate XIV. XV. XXVII. / . " Sec above, p. 591, 662.

'- Vol.. II. p. 314—. ■' Linn. Tram. xii. /. xxi./. 12.

66B EXTERNAL ANATOMY OF INSECTS.

slender, is longer than the thigh ,- in Hololepta maxil-
losa it is longer and more dilated ; in Lamia marmorata,
or one related to it from Brazil, the i7itermediate pair are
longer; in Ateuchus gibbus and others of that tribe the
posterior thighs are smaller than the tibia; : and, to men-
tion no more ; in Callichroma latipes the posterior tibia
is wider than the part last named. Again, the tarsi are
as long as either tibia or thigh in many of the larger Dy-
nastidcE, as Megasoma ActceoTi, &c. ; longer than either
in Melolontha subspinosa F. ; and in Tiphia, Scolia and
affinities, often as long, or longer than both together.

As to shape, — the thigh, especially in the fore-leg, varies
considerably : most generally it is flat, linear, and a little
thicker where it is united to the tibia, on the outer
side convex, and concave next the body ; but in many it
is gradually thicker from the base to the apex : in some
Cerambyces {C. tho7'acicus) it is clavate; in others of this
genus and Molorchiis they may be called capitate ; in
Pterostichus they are rather lanceolate ; in Onitis Sphinx
the humerus is triangular, and the intermediate thigh
rhomboidal ; in Bruchus Bactris it is bent like a bow ;
and in some Brazilian Halticcc it is nearly semicircular.
The humerus in Phasma is attenuated at the base ; in
Empusa gongyloides it is at first ovato-lanceolate, and ter-
minates below in a kind of footstalk ^ ; in Phasmu Jla-
helliforme it is dolabriform ^ ; in Mantis often semioval
or semielliptical, and thickest at the inner edge, which
affords space for two rows of spines with which it is
planted. In Phyllium siccijblium all the thighs are fur-
nished on both sides with a foliaceous appendage nearly

» Stoll Spectres t. xvi. /. 58, 59. •' Ibid. /. xviii. /. 65.

EXTERNAL ANATOMY OF INSECTS. 66i)

from base to apex*: in a species oi Empusa (E. macro-
ptera), the four posterior ones are so distinguished only
on their posterior side '' : others of this last genus, as
E. go7igyloidiss, have an alary appendage on both sides
at tlie apex of these thighs ■= ; and another family, as
E. paupcrata^ have only one on the posto'ior side '^, The
thighs of no insect are more remarkable for their elegant
shape, — tapering gradually from the base to the apex,
where they swell again into a kind of knee, — than the pos-
terior ones of the locusts {Locusfa Leach) ; each side of
these thighs is strengthened with three longitudinal nearly
parallel ridges, and the upper and under sides are adorn-
ed by a double series, in some coalescing as they ap-
proach the tibia, of oblique (juadrangular elevations re-
sembling scales ^

I shall next say a few words upon the spines and other
processes which arm the thigh. Those moveable ones of
Mantis which help to form a fearful instrument of de-
struction, have just been mentioned, and similar ones, but
less conspicuous, arm the intermediate thighs of Siciisjla-
vipes : other appendages of this kind are for a less de-
structive purpose — to keep the tibia when folded in its
place. This seems to be the use of the serratures and
spine that arm the thigh of Bruchus Bactris, or the
Hymenopterous geneni Leucospis, C/ialcis, Sic; in Ofiitis
Aijgulus a short filiform horn arms the humerus, and a
longer crooked one that of many species of Scaurus ^. In
many Stenocori the thighs terminate in two spines, and

• Stoll Spectres t. vii./. 25. '' Uid. t. viii./. 30,

«= Ibid, uhi supr. <» Ibid. t. x. / 40.

' Plate XIV. Fig. 5. This app'jarance of scales on the thighs is
principally confined to this tribe. ' Platl XXVII. Fig. 23.

670 EXTERNAL ANATOMY OF INSECTS.

in Gonyleptes K. the posterior ones are armed internally
with very strong ones; with which, as the legs converge
at their knee *, they may probably detain their prey. The
knee-pan [Gonytheca) of the thigh, or the cavity at its
end, which receives the head of the tibia, is very conspi-
cuous in the weevils ; but in no insects more than in
Locusta ", in which tribe it deserves your particular at-
tention.

d. Tibia or Cubitus ^. The tibia or shank is the fourth
joint of the leg, which according to the hypothesis lately
alluded to is the analogue, in the anterior leg of the car-
pus or carpal bones, and in the Jojir posterior ones of the
ta7'sus or tarsal bones of vertebrate animals. This may
be called the most conspicuous of the articulations of the
leg ; for though it is generally more slender and often
shorter than the thigh, it falls more under the eye of the
observer, that joint being more or less concealed by the
body: it consists in general of a single joint; but in
the Araneida and PhalangidtE it has an accessory one,
often incrassated at its base, which I have named the
Epicnemis^.

With respect to the articulation of the tibia with the
thigh — we may observe that in general it is by means of
three processes or condyles, two lateral and one interme-
diate, of the head of the former jointer the lateral ones
are usually received by a cavity or sinus of the gonytheca

"" Linn. Tram. xii. t. xxii./. 16. •> Plate XIV. Fig. 5,

and XXVII. Fig. 15. r'". - Pl4TE3 XIV. XV. XXVII. s".

^ Plate XXVII. Fig. 21. s" . M. Savigny (Anim. sans Vertebr. I.
i. 46. Note b.) seems to think that this structure obtains in all his
Apiropods; viz. the Octopod Aptera, Arachnida, and Myriapoda: but
it seems to me evident only in the two tribes mentioned in the text.

' Plate XXVII. Fio. G, 16, 17. t'" .

KXTERNAL ANATOMY OF INSECTS. 671

of the thigh " ; and upon these the tibia turns, with a
semirotatory motion up and down as upon a pair of pivots:
at the same time the viola or head of the latter joint,
which lias often a flexure so as to form an elbow with the
rest of it, inosculates in the gonytheca, and is also sus-
pended by ligament to the orifice through which the
muscles, nerves, and bronchiaa are transmitted: so that
in fact the artieulation, strictly speaking, belongs exclu-
sively to none of tlie kinds observable in vertebrate ani-
mals, but partakes of several, and may properly be de-
nominated amixed articulation, — a term applicable in nu-
merous instances also to the other articulations of the legs
of insects. In the different Orders some variations in this
respect take place, — I will notice some of the most re-
markable. In no Coleopterous insects is the structure
more distinctly visible than in the larger Lamellicorns.
In Cop-is bucephaliis, for instance, if you divide the thigh
longitudinally, you will find on each side, at the head,
that it is furnished with a nearly hemispherical protube-
rance, perforated in the centre for the transmission of
muscles, and surrounded externally by a ridge, leaving a
semicircular cavity between them ^ : if you next examine
the tibirr, after having extracted it, you will find on each
side, at the base, a cavity corresponding with the protu-
berance of the thigh which it receives, having likewise ^
central orifice, and surrounded by a semicircular ridge
corresponding with the cavity in the thigh in which it
acts : below this ridge another cavity, forming a small
segment of a circle, receives the ridge of the thigh *=, You
will observe that the ridge of the tibia represents the

' Pr.ATE XXVII. Fic. 15. »•'". •• Ibid. Fig. 11. r".

" Ibid. Fig. 10. t'".

672 EXTERNAL ANATOMY OF INSECTS.

lateral condyle lately noticed : in the Dynastidce this is
more prominent, and often forms a smaller segment of a
circle. In these also the protuberance of the thigh is
more minute, and its ridge is received by a cavity of the
tibia nearly semicircular*; in Geotrupes Latr. the articu-
lation is not very different, though on a reduced scale ; in
Calmidra Palmarum the lateral condyles of the tibice are
flatter and broader ''; and the articulation not being quite
so complex, this joint is kept steady by an intermediate
process observable in the gonytheca'^. From the above
description it appears that the dislocation of the tibia is
effectually prevented in the Lamellicorns by the protube-
rance and ridge of the thigh working n their correspond-
ing cavities, while the condyle of that part turns with a
rotatory motion in the cavity of the thigh. In the Or-
tlioptera Order the tibia is suspended by a ligament, in
the gonytlieca the lateral condyles, which ai'e very pro-
minent, working in a sinus of that part ^. The subse-
quent Orders exhibit no very striking variations from
these types of articulation, I shall therefore not detain
you longer upon this head.

With regard to the 'proportions and magnitude of the
joint we are considering, — the most general law is, that
the anterior pair should be shorter and more slender than
the intermediate; and the intermediate than the postemor ;
and that all the tibice should be shorter and more slender

* Plate XXVII, Fig. 8. Thigh, a. Protuberance, b. Semicircular
cavity, c. Ridge. Fig. 9. Tibia, a. Central cavity, b. Ridge, c. Exte-
rior cavity. ^ Ibid. Fig. 6. a. '■ Ibid. Fig. 7- a.

"' Ibid. Fig. lo. Thigh oi Locusta Leacli, a. Sinus in which the con-
dyle of the tibia works. Fig. 16. Tibia of Do. aa. Lateral condyles,
b. Intermediate one.

EXTERNAT. ANATOMY OF INSFXTS. G73

than tlje thighs^ and longer and lliicker than the tarsi.
Various exceptions, however, to this rule in all these cases
might be produced; but I shall only observe that in all
those insects in which the fore-legs are calculated for dio-
ging or seizing their prey, as in the Pclaloccroiis beetles,
the GrijUotalpu^ Mantis^ &c., this joint of the leg is
usually much enlarged and more conspicuous than tlie
others.

As to its^V^7/;r and shape — most commonly the tibia
grows thicker from the base to the apex, as in the majority
of Colcoptcra, Hynienoptcra, &c. ; in the Orthoptcra^ Neii-
roptera^ Sec, it is generally equally thick every w-here.
Another peculiarity relating to this head observable iii
it, is its tendency to a trigonal figure : this, however,
though very general, is not universal; — thus, in some
Ort/io2)tera, as PtcropJnjUa K., its horizontal section is
quadrangular; in others, as Lociista Leach and many
other insects, it is nearly a circle ; in some scorpions it
is almost a hexagon. The superficial shape also of this
joint in numerous instances is more or less triangu-
lar, but it sometimes recedes from this form : — thus, in
Callichroma latipes it is a segment of a circle ; in some
Empidcs it is clavate ; in Onitis Sphinx, dolabriform ; in
the Orlhoptera, 'Neiiroptcra, &c., it is usually linear; in
some Lygtvi it is angular^: but the most remarkable
tibiae in this respect are those of such species of this last
genus as have the posterior ones winged or foliaceous,
so that they resemble the leaf of some plant — the tibia
being the rachis, and the wifig (which in some species
is veined) representing the /<?^itself. This structure is

a Stoll rum'iscx, I. x./. 07. ^xvi./. 114.

VOL. in. 2 X

674' EXTERNAL ANATOMY OF INSECTSi

exemplified in LygcEiis compy^essipes, phyllojnts^ foliaceu^
&c.* Under this head 1 must say a few words upon
the Jlexiire of this joint, which in some cases merits no-
tice. I have before mentioned its bend at the knee '' or
base : the apex also is sometimes incurved — in the ante-
rior one of the male o^ Macropus lotigima?ius so as almost
to form a hook*^: in Lygceus Pharaonis the posterior pair
are flexuose ^ ; in Bn(chis Bactris, Leucospis, and several
species of C/ialcis, these tibiae curve so as to adapt them-
selves to the bend of the thigh when folded. The notch
on the inside of the anterior pair, in a large majority of
Carahus L., armed above by a spur % a structure which
probably assists them in seizing and detaining their prey,
may also here be introduced : in the generality it is a lit-
tle removed from the apex of the joint in question; but
in Pamboriis it is very near to it, and in Cychrus, Cava-
bus, &c., it becomes obsolete. I may mention here also
a singular character which distinguishes the cubit of both
sexes of Grylhis campestris, domesticus, &c. At the base
there is an aperture which passes through the joint — an-
teriorly it is oval, and posteriorly elliptical and much
larger, and on both sides is closed by a tense membrane.
The most striking peculiarities as to the clothing of
his joint have been chiefly noticed under the sexual cha-
racters of insects ^, but some appear not to be of that de-
scription. In Sp/iceridium Leach, while the thighs and
ta7'si are naked, the posterior tibice are remarkably beset

» Stoll Punaises, i. ii. /. 14. t. viii. /. 54. t. xxviii. /. 201. Plate
XV. Fig. 2. " See above, p. 671.

•^ Oliv. In$. n. 66. t. iii. /. 12. Compare ScarabcBtis longimantis.
Ibid. n. 3. t. iv.f. 27. ^ Stoll Punaises, t. iii./. 20.

* Plate XXVII. Fig. 31. ' See above p. 306—

f.ktRunal anatomy of insects. 675

with stiff bristles ; in Empis pciwipcs they are thickly
fringed on botli sides; in Scarabams M'=L. only exter-
nally, and in Dytisais saTlcornis internally ; in Nccydalis
barpipcs K. this fringe is longer at the apex ; and in Sa-
jicrda hirfiprs Ol. the same tibifC at that part are adorned
with a large brush, like that observable in the antennas
of some Lami(C^.

I must next call your attention to the tecfh, spines, and
spjirs with which the ^/Z»/^ of insects are sometimes armed.
With regard to teeth, you have doubtless often observed
those that distinjiuish the cuhitus of the arm of most La-
mellicorn beetles : these vary in number from one, as iii
Trox snberosns, to seven, as in Geotriipes autnmnalis ; but
the most universal number is three : in some species of
Geotmpes, as G. sfercorarius, &c., the third tooth from
the apex, and those that follow it, may be called double.
These teeth, in their cubit or anterior shank, doubtless
assist these insects in burrowing. The four posterior
tibia in this tribe are also distinguished by a kind of teeth
which occupy their whole diameter, and resemble so
many steps. I have before noticed the remarkable cubit
of the Gryllotalpa, and likewise that of Scarites, Pasi-
viachus, &c., in which some of the teeth are prolonged
into spines ^, which are the next description of tibial arms
that I mentioned. Spines are of tts^o kinds — those which
are mereXy processes of the crust oithetibia, and those that
are implanted in it, and seem to have a gomphosis or per-
liapsan amphiarthrosis articulation '^. An instance of the
^rst kind may be seen in the hind-legs of some grasshop-

» Oliv. Ins. n. G8. t. i. /. 8. comp. n. G7. t. xii. /. 83. and Plate
XII. Fig. 25. a. •• Vor.. II. p. 3G5. and Pr.A te XV Fig. 5. G.

«^ See above, p. 433, Note b. and 404, Note a.
2 X 2

G76 KXTERNAL ANATOMY OF INSFXTS.

pers^ (Loa/sfa'Leach), the Rutelidcc^ &c. thougli in others
they are implanted : — of the seco7id, in the cubitus of the
Mantidce^ and o{all tlie tibice of the draaon-flies ( LihelluUna
M'^L.) ^; — and o^both kinds in the hind-legs of ^crzWaK.,
those which arm the upper angles of the tibiae being j^t'o-
ces^es, and those of the lower being implmited. The term
spine I think ought to be restricted to the first kind ; the
second ought rather to be denominated sjmi-s (calcaria),
and may perhaps be i-egarded as in some degree synony-
mous with those most important appendages of the joint
in question, that are implanted in or near their apex,
which have been hitherto distinguished by this last deno-
mination, and which I am next to consider. But though
I have not altered a term generally adopted, I must here
express my opinion that they ought rather to be considered
as minute toes or ^ngers, and that the denomination best
agreeing with their functions, as accessories to the main
toe, would be digituli: this is proved particularly by a
character peculiar to those of many species of the genus
Cimbex amongst the saw-flies, in which these organs are
furnished with a sucker or ptdvillus (as they are also in
CE?ias a kind of blister beetle), as well as the joints of the
tarsi ^ ; which makes it evident that they are applied by
the animal to surfaces, and assist it in walking or climb-
ing ; and in general it may be observed that in most in-
sects their principal use is connected with these motions,
and with burrowing. This circumstance tends to prove

* Plate XIV. Fig. 5. '' It is remarkable that in this

tribe «// the legs may be called 7'aptormis, though the thighs are not
incrassated, for they are armed with a double series or more of fine
long spurs, which enable them to catch and retain their prey.

^ Plate XXVII. Fig. .'^5. v". PJnlos. Tram. 1816. /. xix. /. 8,9,
See ahore, vol. ii. p. .3.'}1.

EXTERNAL ANATOMY Ol INSECTS. ()77

that the generality of insects (for all have not these
organs) have really a didactyle or tridactyle hand or
foot; and the hyj)othesis so often alluded to — that the
cubitus or tibiae &c., is really analogous to the carpus or
tarsus in vertebrate animals* — seems to receive no small
confirmation from it ; since, if the sjrurs be really ana-
logous loungers or toes, the part they articula te with
cannot be the tibia, &c. Though the parts in ques-
tion did not escape the notice of Reaumur, Linne, Dc
Gecr, Latreille, &c., yet they have not been employed
in the determination of tribes, genera, &c., except by the
author last named, but perhaps adopted from Bonelli'^,
in the subgenera Zabrus and Pelortis : in many instances,
however, they afford excellent subsidiary characters,
sometimes conunon to a whole Order, and at others di-
stinnjuishinfT its various subdivisions. With regard to
their number — I havenoticed many variations which I will
now state to you, first observing that I shall express them
by three figures, \\\ejirst representing the number of spurs
on the anterior leg, the second that of those on the inter-
mediate, and the third on the posterior ; and where there
are spurs, as in the Trichoptera and Lepidoptcra, on the
middle as well as at the end of the tibia, I shall exjiress it
by one figure oi)cr another, the upper one rei)resenting the
number of the middle spurs. If you make an examina-
tion yourself, it will be proper to remind you that these
little organs are extremely liable to be broken ollj but the
socket in which they were planted is usually very visible.
The most natural number is represented by 2:2:2; this

* See above, p. 591, 667, &c. •* Rcgnc Animal, \\\. ]0l. I have
never liad an opportunity to consult Bonclli's Obscrv, Eufomo/og. on
the genus Caiabim L. in the Memoirs of" the Turin Acacfemy.

678 EXTERNAL ANATOMY OF INSECTS.

you will find very prevalent in the Coleoptera Order,
as in the Predaceous and numerous other beetles : in
the Orthoptera and Hemiptera Orders, however, I have
not discovered an instance of it ; but in all the rest it
more or less occurs : next to this number — tibice with
obsolete or no spurs seem most prevalent, particularly in
the Hemiptera ; not a single instance of an insect fur-
nished with thpm occurring to me in the Heteropteroiis
section ; and it is doubtful whether there are any in the
Homopterotis. — Having stated the most \miversal struc- -
ture in this respect, I will next consider the Orders se-
riatim. Amongst the Coleoptera though the numbers
2:2:2 are most frequent in occurrence, yet there are
numerous exceptions. Thus, in the Lamellicorns, 1:1:1
represents the calcariaofone tnheof the Scarabcuidcel^l^Ij.
formed of the genus Scarahceiis M'^L. ; 1:2:1 represents
those of another tribe of that family, including the sub-
genera Atetickus, Copris, Phanccus, &c.; 1:2:2 again
forms the character in this respect of Aphodius and the
great majority of the Lamellicorns; while 2:2:2 is con-
fined in this section to jEsalus F. and Melolontha c/nyso-
meloidcs Schranck [Psephiis M'^L. MS.). In the other
tribes of Coleoptera other numbers occur. Thus, 0:1:1
characterizes Hylcecetus; 0:1:2 Mordellu; 0:2:2 Ma-
cropus; ■f:2:2 Harpalus, and all those Carabi L,., ex-
cept Zabrtis, that have a notch in their anterior tib'ue ;
4^:2:2 Zabrus. In the Orthoptera Order it is not easy,
to distinguish the real spurs from the implanted spina
that frequently arm the legs : these in Blatta are ex-
tremely numerous, even at the apex of the tibi<^ ; but I
cannot distinguish any that can be regarded as true ana-
logues of the former: the most natural number of spurs

EXTERNAL ANATOMY OF INSECTS. 679

m this Order is represented by 0:0:4; this you will sec
in all the Locusts; in Ac rid a , Conocrphala, P/erop/ii/lla ;
and in Tnualis, Pncumora, &c.; in Phasma there are
none. In Maniis, if the terminal process of the cubitus
is excluded, it will be 0:2:2; in Gri/llolalpa, admitting
the terminal teeth of that part^ as analo<rues of spurs,
the number is 4-:4': t; in Ttiduclijlus Latr. 0:0:5^; in
Gryllus Latr. 3:3:5; in Gryllus mojislrosus, 4:4:6. In
tlie whole Hcmiptcra Order I have discovered no instance)
of an insect furnished with the real spurs : for though in
Tettigonia F., Cercopis^ Sec, there are implanted spines in
the posterior tibia, and several at the apex, there are none
of them clearly analogous to real spurs. In the Lcpido-
piera the most general arrangement appears to be i : 2:^;
and next to this, ^:2:2. In tliis Order most commonly
there is no spur at the end of the cubit, but one resem-
bhng a thumb "^ arms its middle; m Pieris, &c., diis
thumb is not present, so that the number is 0:2:2; in
Agarista heach, Erebus, &c., you will find -J^: 2: 4, the
posterior calcaria being all terminal ; and in Attacus
Atlas, all these organs are obsolete excej^t tlie thumb.
In the Ncuroptera the most general arrangement is
2:2:2; hut in \he Libellulina, although the legs are very
spinose, there are no spurs. In the Trichoptcra K., in
Phryganea rhombica and affinities, the number of them
is expressed by -i-:^:^; and in tliose with long antenna?,
P. atra, &c., by ^:f :-}. In the Hijnienoptera the number
1:2:2 is most prevident; and next to this, as in Apis L.^
1:1:2. In ihe Ichucumo)ics minuti L. the spurs are

' Plate XVM"'iG. G. u". '' Coqucbcrt ///k«/;-. /c. iii.

/. xxi./. 3. D. " Plate XXVII. Fig. ^9. v".

680 EXTERNAL ANATOMY OF INSECTS.

1:1:1; in Atta Latreille, a kind of ant*, 1:0:0. In the
Diptera it is often difficult to distinguish the spurs from
the spines ; but the number most universal is, I think,
2:2:2; in Tijmla it is 1:2:2; hi the Tabaniche 0:2:0;
and in Culex, Limonia, &c., there are none. Amongst
the insects with more than six legs, most commonly the
tibiae have no spurs ; but in the Arancidce each is armed
with /wo, a circumstance which also distinguishes the
corresponding joint of the pedipalpi.

These little organs inosculate each in an appropriate
socket of the end, or in many cases of the middle of the
libia; and that part of their head or base that is receivetl
by it, is often constricted for the j)urpose : from hence
it follows that they are capable of some degree of motion,
but in some insects, as those on the four posterior legs of
Scarabceus sacer and its more immediate affinities, and
those at the end of the cubit of Gri/llotaljya, they are im-
moveable, and appear almost processes of the joint to
which they belong. They are commonly sharp, of a
subtriquetrous figure, with the lower side flat: where
there are two, the outer one is usually the longest ; and
in general the spurs on the hind legs are longer than
those on the four anterior : but there are exceptions —
thus, in Acardhopiis Latr. the intermediate spurs are the
longest; and in Cicindcla the antci'io7' are longer than
the former ; in Blaps mortisaga those on all the legs are
nearly equal in length. They vary sometimes m shajje —
those on the middle of the cubit of many LepidopteiOy

" Most of Latreille's genera of ants are confirmed by differences
in their spurs. Thus Formica is 1 : 1 : 1 ; Punera 1:2:2 with tiie
mtenial inlcrnicdiate one pectinated: Mi/nnica 1:2:2 with all sym-
metrical, &c.

EXTLllNAL ANATOMY Ol' INDUCTS. f)8 1

which may be regarded as a kind ot thumb % are of a
Junceohite shape ; in Meloe the external posterior one is
Hat and obtuse ; in (Enas Latr. it is obconical, concave
at the extremity, and ajiparently lurnisiicd with a suclver;
ill Ateiichus smaragdulus the anterior, and in Copris Ca-
rolina the posterior is forked and emaiginate; in Sirex the
rormer is hooked and winnjcd ; in Lamprima it is trian-
ijfuhir and dilated; in Aphodius analis it is dolabriform ;
in Dijnastcs retusus and Juve?ictcs the spurs are bent like
a bow. In many Ilj/rncnojitera, as the Sp/iecidcc, they are
pectinated^, with a series of minute parallel spines — a
structure which assists the animal in burrowing*^; in
Acanthopiis Latr. they are armed with little teeth or
spines'*; in tlie hive bee the spur of the cubit is furnished
with a membranous ajipendage which I have called the
velum'^; and in a subgenus related to Saropoda Latr.
{Ctenoplectra K. MS.), the interior s})ur of the posterior
leg is crescent-shaped, fixed transversely, and fitted on
the inner side with a membrane, the edge of which is
finally pectinated.

e. Tarsus or Manm^. This is the last portion of the
leg, usually su})posed to be analogous to the liand or
loot of vertebrate animals ; but, accoiding to the hypo-
thesis so often alluded to, rather the representative of
their jointed finger or toe. In treating of this part I
shall consider its articulation with the tibia, and of its
joints inter se ; the number of those joints ; their ^;/6»/?w-
tion and shape; iXxeir j)arts and appendages,

» Platk XXVII. Fig. 29. v" . ^ Ibid. Fig. ;{3. v" .

" Linn. Trans, iv. 200. Note «. <^ Platl XXVII. Fig. '62. u" ,

' Ibid. Fig. 3fj. a:

• Plaxls XIV. XV. XXVI. XXVII. «",/".

682 EXTERNAL ANATOMY OF INSECTS.

I seem to have observed three kinds of tarsal articular
tion. l^hejirst is a species of enarthrosis or ball and socket,
the joints terminating in a globular head, perforated in-
deed for the transmission of muscles, &c., and which is
received by a corresponding cavity of the tibia or pre-
ceding joint, as may be seen in many weevils [Curculio
L.*). This admits of some rotatory motion. — The second
is a mixed articulation between enarthrosis and gingljj-
nms, when at the base of the ball a deep transverse
channel receives a corresponding ridge of the tibitu or
preceding joint : this may be found in RiUela and pro-
bably many other Lamellicorn beetles ; and something
very similar in the Predaceous ones. — The third kind is
where there is little or no inosculation, and the joints are
scarcely more than suspended: this takes place in the
Orthoj)tera, Neuroptera^ &c. ; but in Blatta and the hind
legs of Mantis there is some approach to the foregouig
kinds.

We are now to consider the number of joints of the
tarsus, which varies considerably in the different Orders,
and in one has been assumed as a clue for a subdivision
of it into sections^, which, though not perfectly natural,
is very convenient, and has been adopted by most modern
Entomologists. In treating of this head, I shall use
those denominations that have been employed by M. La-
treille and others to express the variations of the num-
ber of the tarsal joints in the Coleoptera^ but shall apply
them to insects in general. Insects in this view, there-
fore, may be called pentamerous ; heteromerous ; tetra-
meroHS; trimerous ; dimerous; or tnonomerous.

• Plati; XXVI. Fig. 44, 46, 4/. a.

>> By Gtoffwy—HisL Lis. i. 58.

EXTKHNAL ANATOMY OF JNSECTS. 683

Pcntameruus insects are those which have /"w joints in
all their tarsi. Tiiis is the most universal, and may be
called the natural number of these joints. More tlian half
the Colcoptcra belong to this section ; in the Orthoptera
— the BlattidiC, Maiitidce, and P/iasmida; ; all the Lepi-
doptcra except those butterflies called telrapi ( Vanessa,
&c.); all the Trichnptcra, Hymcnoptcra, mid Dipicra;
in the Ncuroptera — Ascalaphus, Mynnclcon, Hancrobmsj
CorydaliSi &c. ; and in the Aptera — Pidcx *.

Hetci-omcroiis insects are those in which the number
of these joints varies in the different pairs of legs*^. These
variations, like the spurs, may be expressed by three
figures, the first representing the anterior tarsus, the
second the intermediate, and the third the posterior. I
begin with 5:5:4'. This number represents those beetles^
that have been exchisively regarded as hcteiomerous by
modern Entomologists — of this description is tlie Lin-
nean Tenehrio, Meloe, &c., now subdivided into nume-
rous genera ; they have Jive joints in the two anterior
pair, andybwr in the posterior. The tarsal joints of the
a(|uatic genus Hi/droporus (a singular anomaly in the
Order to w Inch they belong) are expressed by 4- : 4 : 5,

* The CleridcCy which M. Latreille has placed in the peiitamerotis
section, vary considerably in the number of their tarsal joints. -Thus
in general in Tkanasbnus the tarsi arc pcukn)ierous ; but in T.for-
micarins they appear to be heteromcrous ; and in Enupliuni, Opito,
Cirrus -iXnd Kccrobin they are tetramerom. M Latreille's expression,
( y. Diet, d'llist. Nat. vii. 172.) " le premier article etant fort court ct
cache sous le second," seems to indicate that there is ajifl/i joint in
some of these, the first being concealed under the second ; but I have
never been able to discover it. Perhaps he reckoned the putvitlus as
a joint ?

^ Tiie term tieleromerom properly belongs to a/f insects in which
the diflcreut pairs of tarsi vary iitltr se in the number of their joints,
and it is here used in that large sense.

G84 EXTERNAL ANATOiMY OF INSECTS.

thus reversing the number in the preceding tribe : other
Heteromerous genera are to be found amongst the He-
miptera. Thus, in Ranatra the numbers are 2. 1.1.; in
Sigai'a and Nauceris 1:2:2; in a new subgenus between
Belostoma and Naucoris {Xijjhostoma K. MS.), brought
by Dr. Bigsby from Canada, 3:2:2: in the Lepidoptera
the butterflies called tetrapi (Vcmessa, &c.) may be ex-
pressed by 1:5:5. Amongst the Aptera and Arachnida
there are three remarkable genera, which if their pedi-
palps are included may be deemed Heteromerous. I
mean Phiynus, Thelyphena, and Galeodes; — in the for-
mer the numbers will be * : 4- : 4 : 4, the asterisk denoting
more than ten ; in the second, 8:4:4:4.; and in Gale-
odes) in which the first pair of pedipalps are not chelate,
the mandibles performing their office) the numbers are
1:1:3:3:3.^

Tetrameroiis insects are those in which all the taisi
consist ofyb?«' joints ; these in the Coleoptera are next in
number to the petitamerous — indeed a very large propor-
tion of them strictly speaking are really of the latter
description, since in Linne's four great genera, Curculio,
Ceramhyx, Chrysomela, and Cassida and some others,
the claxv-joint [wigida) consists of /too articulations, one
very short, forming merely the ball at its base'', which
inosculates in the socket of the preceding joint, and the
other constituting the remainder: if you carefully sepa-
rate these two pieces, you will find that the last inoscu-

■' These three genera appear reallij to have only sijc legs, since the
pedipalps or maxillary legs are not armed with claws, while the
real representatives of the legs, or three last pair, are so distin-
guished. In Phrynus and ThehjpJwna the anterior pair arc chelate ;
but in Gulcodcs they are pediform, as in the Araneidir, and the great
chela; arc the mandibles. '' PtATE XXVI. Fig. 47, 48. rf *.

r.XTERNAL ANATOMY OF INSECTS. GS.'J

Jatos ill tlie summit of the ball, and is moved by appro-
priate imiscles*. This structure probably permits the
roiulier elevation and depression of this joint. In the
Orthopfcra the tetramerous «ijenera are those which
Linne called Tctligonia amongst his Gnjlli [Luaisla F.);
Achflit mo}istrosa also, and in the NeuropterUj Raphidia
belong to this section.

Difiwrous insects are those whose /flr;« consist of onl}'
t?irec joints. Amongst beetles the Lady-birds [Cocci-
neUu L.) are remarkable for this structure, but in them
the claw-joint is also biarticulate, so that strictly speak-
ing they are tetramerous ; in the OrtJiopteroiis Order the
migratory locusts {Locnsta Leach) belong to this sec-
tion, as likewise Gnjllus Latr. and Gryllotalpa Latr. :
in the first of these genera is an appearance of there be-
ing more joints in the tarsus, because there is more than
one cushion below the first **. To this section also belong
the great majority of the Ilemiptera, excluding only those
tribes that connect the two sections of the Order consti-
tuting the two Lliniean genera Nepa and Xotoneeta ; the
Libelbdina likewise belong here, as do also the Scor-
pioiiid^e and Scolopendridtv.

Dimerous insects are those that have /too joints in
all their tarsi. Such are the Pselaphidrc in the Co-
leoptera Order •= ; in the Hemiptera — Belostoma and No-
tonecta ; in the hexapod Apt era — Pedic?dus; in the octo-
pod — the Acari of Liime; in the myriapod — lulus; and
in the Arachnida — the Arancidcc.

» PtATE XXVI. Fig. 49. .?•. a. *■ Vol.. II. |). 330.

'-■ Dr. Leach says tliere are three joints in this tribe. Xat. Misc.
iii. 80.

686 EXTERNAL ANATOMY OF INSECTS.

Monomei-oiis insects are those which have only a single
tarsal joint. Only one Coleopterous and also one He-
mipterous genus is so distinguished : the first is Der-
mestes Armadilliis DeGeer^, and the second the common
water-scorpion, l<[epa Latr. Among the Aptera we
find Nirmiis, Podura, Sminthurus, &c., that belong to this
section.

To the above sections another may be added for those
insects whose tarsi have more than^ue joints, which may
be denominated Polymeroiis. Here belong the genera
Gonyleptes K., Phalangium and SciUigera Latr. In the
first the number of joints varies from six to eleven, and
in the two last they far exceed that number, amounting
in some species of Phalangium to more than Jifty, and
becoming convolute like the antennae of Ichneumons ^.

I am next to notice the proportions and shape of the
tarsus and its joints. The most general law is, that it
shall be shorter and more slender than the tibia ; but it
admits of several exceptions — thus, in Megasoma K. '^, in
all the legs; in Agrostiphila M'^L. MS.'^ in the inter-
mediate, and in Amphicoma lineata in the posterior pair
the tarsi are the longest ; in Trichius Delta these last
are longer than the thigh and tibia together. In some
insects the tarsi are disproportionally short, as in Cas-
sida, the Pselaphidde, Locusta Leach, &c. Though ge-
nerally more slender than the tibia, in several instances

" From De Geer's description this insect seems related to AgatJii-
dlum (iv. 221 — . t. viii./. 21—23). M. Leclerck de Laval discovered
it to be monomerous. Rcgne Animal, iii. 365,

b Plate XXVII, Fig. 22. '= See above, p. 31 1. Note a.

** Melolontha sericea and auriilenta. Linn. Trans, xii. 463. 400. be-
long to this subgenus.

EXTERNAL ANATOMY OF INSF.CTS. 687

they are as tliick or thicker, or more dilated, as in most
of the tetranierous beetles, wliich being climbers require
a dilated farsus. Again, comparing the three pairs of
this joint with each other, the most general rule is, that
the afiicrior should be the shortest.) and the imsteiior the
longest : but in some, as the Capricorn beetles, &c., they
are nearly equal in length; in others, as Lijtta marginata,
tlie atifen'or pair, and in Rhipiphorus the intermediate^
are the longest ; in Trichii(S Delta these last are the
shortest. With respect to thickness, the anterior tarsif
except in many males", are not very strikingly different
from the rest.

With regard to the proportion of the joints of the
tarstis toeach other, — according to the most general law,
the first is the longest, the last next in length, then the
second and third, and the fourth is the shortest. In Gony-
leptes K. and other Phala?igid(V the first is almost thrice
the length of all the rest taken together; but there are
numerous exceptions to the rule. In the female Carahi
the first joint is not longer than the last, and in the males
not so long ; and in Hydrophihts, &c., it is the shortest of
all. Again, the second joint is longer than the three fol-
lowingonesin Dasytcs ater^; and than the last in CiciJidela
sylvatica : the third ]dm.t is shorter than the fourth in Lam-
pyris ignita : it is longer than the first in Donacia, many
Meloloiithidtje, &c. Once more, the fourth joint, usually
the shortest of all, is longer than the second and third
in Afithia, &c. Lastly, the claw-joint, usually the second
in length, in the Eprohoscidea Latr. {Hippobosca L.) is
very long and large, while the four first joints are so

» See above, p. 3.15— . ^ Piate XXVII. Fig. 25.

688 EXTERNAL ANATOMY OF INSECTS.

extremely short as to be scarcely distinguishable from
each other : it is the shortest of all in Colymbetes, &c. ;
it is of the length of the third in Cicindela sylvatica, of
\\\e fourth in C. sexguttata. Though commonly the slen-
derest joint of all, particularly so in Raphidia, in many
Heteromerous and Lamellicorn beetles it is the largest,
conspicuously so in Mellimis tricinctus. Sometimes, as
in Buprestis chysis, &c., all the tarsal joints are nearly
equal in length and thickness.

We are next to say something upon the shape of the
tarsi and their joints. In general we may first observe
that their upper surface is commonly more or less con-
vex, and the lower flat or concave : in insects that are
swift runners, as the terrestrial Predaceous beetles, they
are usually slender and filiform*; in those that swim, as
Dijtiscus, the two posterior pair taper nearly to a point
from the base to the apex^; in some that climb, as Bii-
prestis, they are rather flat and linear ; and in others (the
Weevils, Curculio L.) they grow gradually wider towards
the claw-joint*^; sometimes, as in Mordella Latr., the four
anterior tarsi are of this shape, and the posterior pair
setaceous. In Gyrinus the four posterior are flat and
triangular; and in that extraordinary insect Gryllus mo7i-
strosus the tarsi are foliaceous and lobed^. In many
males and some others the anterior pair or hands are of
a different shape from the two posterior : thus, in several
Carabi they are lanceolate; in Staphyli7ius, Creophilus,
&c. in both sexes they are often nearly circular, like
those of male Dytisci^. With regard to the shape of

" Plate XIV. Fig. 7- f. •' Ibid. Fig. 6. t".

' Plate XXVI. Fig. 47. " Plate XXVII. Fig. 41.

' Platr XV. Fig. 9.

EXTERNAL ANATOMY l)F INSECTS. 689

individual joints it may be said in general tliat they are
rather triangular, with an anterior sinus for the reception
of the succeeding joint: the first joint usually departs most
from this form; in the bees it is commonly much larger
than the rest, especially in the last pair of legs, and nearly
forming a parallelogram ' ; in Euglossa it is trapezoidal ; in
the majority nearly linear or filiform. With regard to
tlieir tei-mination — in Brachycenis and some ants {Ponei^a,
Myrmica^ &c., Latr.) the three Jirst ]o\nis \ in Dascillus,
Lj/ciis reticulatus and afTinities, the third and fourth; and
in the great majority of the Tetramerous insects the
penultimate joint is bilobed ; although in most Predaceous
beetles this joint is entire or simply emarginate, yet in
Colliuris it terminates in a single oblicjue lobe; and in
Lebia, Diypta, Sec, it is nearly bipartite. I must now
advert to the U?igula or claw-joint : it is usually clavate
or thickest at the end and curved ; but in the Asilidce it
is shaped like a vase or cup ; in Phanaus, in the four
posterior tarsi, in which the claws are obsolete, it is
thickest at the base and sharpest at the extremity*^; it
usually forms an angle with the rest of the tarsus, rising
upwards, which enables the insect to move more easily
without hindrance from the claws, and also more readily
to lay hold of any object it meets with ; but in the La-
mellicorn beetles and many other insects it is in the same
line with it. As in the beetles last mentioned this joint
is often inserted in the extremity of the preceding one;
but in QLdcmera it articulates with the middle of its
upper surface; and in Lyons and a numerous host of

" Alon. Ap. Aug!, i. t. xii. ncuf.f. 20.
'' Plate XXVII. Fio. 44. i".
vol.. III. 2 V

^90 EXTERNAL ANATOMY OF INSECTS.

Tetramerous beetles it springs from its base, just behind
where it diverges into two lobes.

I shall next call your attention to the different kinds
of appendages with which the tarsi are furnished. They
are seldom armed, like the tibice, with teeth, or spines,
or horns ; but something of the kind occasionally distin-
guishes them. In Phileurus, Oryctei,, and several other
Dynastidce, the first joint is armed at the apex externally
with a considerable mucro ; in the fore-leg of Dasytes
ater a similar process is prolonged into a crooked horn*.
But the most important appendages of the tarsi are the
cla>ws which almost universally arm their extremity, and
which appear clearly analogous to those of birds^ qua"
drupeds, &c., though probably differing as to their sub-
stance''. Some few, however, are without them; this, as
I lately observed, is the case with Phanceus with respect
to the four posterior legs ; the anterior ones of Vanessa
amongst the Lepidoptera^ and all those of Stylops and
many Acari L., are also without them : this is likewise
the case with the first pair of legs, or the second of the
pedipalps of Galeodes. In this genus these organs con-
sist of two joints •=. With respect to 7iumber they vary
in different tribes, but not so much as the calcaria:
these variations may likewise be represented by three
numbers. The most natural is txsoo in all the tarsi, exhi-
bited by the Predaceous beetles and the great majority;

2.2.1. are to be found in Hoplia, A7iisonyx, &c. '^;

1.2.2. in Belostoma; three in all the leojs in the Ara-

^ Plate XXVII. Fig. 26. tv". " See above, p. 396.

« L. Dufour Descr. desix Arachmdes. Annales, &c. 1820. 19.
"^ Plate XXVII. Fig. 31. is the posterior claw oi Hoplia.

EXTERNAL ANATOMY OF INSECTS. 691

neida;^ ; in Meloc^j Elate?; &c., each claw is double or
consisting of two, which makes Jour in each leg; and in
ixiAny Hippobosa'dfC there are six^; in Nepa and the
Myriapods there is only 07ie. In most insects, perliaps,
the claws are simple or undivided''; but in Galeruca,
Melolonthn subspinosa^^ &c., they are bifid at the apex; as
is the exterior claw of the four posterior legs in Chasmo-
diatxvi(\ Maa-aspis ^ M*^L., and of r/// in Melolonthn hor^
ticola ; in Serica brunnea M*^L. the claws are all cleft at
the extremity, but the internal tooth is broad, flat, and
obtuse S; in Melolontha vulgaris and Pelidnota punctata
M^L***, the claws are armed with an internal tooth near
the base'. In the Araneida:^ which have three claws, the
two external ones are furnished with several parallel
teeth, which the animal uses to keep separate the threads
of its web, and probably for other purposes "^ ; and some
Predaceous beetles, as Lebia and Cymindis^ have both
their claws similarly furnished '. These organs vary in
their relative proportions : thus, in Anoplognathus the
inner claw is much smaller than the other "*; and in Elater
sulcatiis, fuscipes, &c., it is represented by a mere bristle ;
in Hoplia, in the anterior tarsus it is not half the length
of the outer one"; in Areoda and Pelidnota M'^L. this
last is the smallest. They vary also in length — in Ryji-
chccnus^ Ascalaplius^ 8:c., they are very short ; in the La-
mellicorns, Galeodes, &c., very long ; and in Myrmelco7i

^ Plate XXIII. Fig. 14. " Plate XXVII. Fig. o2.

«= Ibid. Fig. 46. •• Ibid. Fig. 53, 54.

' Ibid. Fig. 49. f Ibid. Fig. .38.

* Ibid. Fig. 39. " This structure is not general in this genus.

' Plate XXVII. Fig. 40. "^ Plati. XXIII. Fig. 14.

> Plate XXVII. Fig. 4.3. " Ibid. Fig. 4?.

" Ibid. Fig. 48.

2 V 2

692 EXTERNAL ANATOMY OF INSECTS.

longer than the claw-joint. "With regard to their curva-
ture they generally form the segment of a circle ; in many
Asilidce they are crooked like the claws of the eagle ',
and the posterior one of the Hoplia is bent like a hook'';
they most commonly diverge from each other ; but in
the Riitelida;^ A7ioplognathidcE, &c., they are perfectly
parallel, and in the former often inflexed '^. With regard
to other appendages of the part we are treating of, if you
examine the stag-beetle and many other Lamellicorns,
you will find between the claws a minute but conspicuous
joint terminated by two bristles which seem to mimic
the ungula and its claws ; these parts are what are deno-
minated in the table the palmula, plantula, and pseudony-
chia: in the stag-beetle these are long''; in the Mclolon-
thidce short ^; and in many Cetoniadcc they resemble an
intermediate claw.

The most remarkable of the appendages of the tarsi ai'e
to be looked for on their under side or sole {solea), and
are the means by which numbers of insects can overcome
atmospheric pressure and walk against gravity. Many
of these have been fully described in a former let-
ter ^ ; but much that relates to them was there omitted,
which I shall now detail to you. Four kinds of pidvilli,
as I would call these appendages, are found in the sole
of insects, upon each of which I shall make a few remarks.

The^;^^ is a cushion or brush composed of very thickly
set hairs or short bristles : examples of this you will find
in the majority of Tetramerous and Trimerous beetles. In
Chrysomela^ Timarcha, &c., there is one of these cushions

^ Plate XXVII. Fig. 53. •> Ibid, Fig. 51.

<" Ibid. Fig. 47. •■ Ibid. Fig. 56. a-^J*.

• Ibid. Fig. 49. a^,p, f Voi,. II. p. .326—.

EXTERNAL ANATOMY OF INSECTS. G93

on each of the three first joints ; in Prionus, Liparus,
&c., there is a pair; and in Coccinella on the /wo first; in
others [Bnlaninus Nucwn, &c.) a pair only on the penul-
timate joint ; in Calandra Pahnarum, IViina barbirostris^
&c., that joint has an intire cushion ; in Eiirynottis mu-
ricatus K. =» the three first joints of the four anterior tarsi
are similarly circumstanced, but the cushions resemble
sponge*'.

The second kind of cushion is a vesicular membrane
capable of being inflated. This distinguishes the tarsi
of T7irips^i and many Acari L.''; likewise those of
Xeyios^; and also of many Orthoptera fully described on
a former occasion ^, though the fact of their capacity of
inflation has not been ascertained, belong to this sec-
tion.

The third kind of covering of the sole is when the
three or four first joints of the tarsus each terminate in
one or t'joo membranous lobes or appendages : of the first
description is Prioccra K., in which the lobes are invo-
lute s ; and of the second Hhipicera Latr. •>, in which
there is a pair on each joint, in the Brazil species set
with very fine hairs.

The Jcnirth and last kind are what may with the utmost
projoriety be denominated suckers, since their use as such
is clearly ascertained. These are not only to be found
in a large proportion of the Diptera, in some of which
there are i'voo of them, as in the Asilida ' ,• and in others

* Linn. Trans, xii. t. xxii. f.\. ^ For other instances of
this structure, see above, p. 336. "^ De Geer, iii. 7.

•' Ibid. vii. 84. Plate XXVII. Fi g. 60, 63.

' Ibid. Fig. 61. f Vol. II. p. 327—.

* Plate XXVII. Fig. 5I>. "^ Linn. Tram. xii. t. xxi.f. 3.
' Plate XXVII. Fig. 53.

694 EXTERNAL ANATOMY OV INSECTS.

three, as the Tahanida^ ; but also in many of the subse-
quent Orders: thus, in the Heteropterous i/(?7«?jw/^ra, in
Scutellera and Petitatoma, but not the Reduviadce, and
in the Neuropterous genus Nyin2')hes Leach there is a mi-
nute one under each claw. It is discoverable between the
claws in many HymeJioptera, as Apis '', Vespa, &c. But
the genus that exhibits to the curious Entomologist the
most singular and elaborate apparatus of this kind is
Dytiscus Latr, ; and the examination of the under side of
|he haiid of any male of this genus will almost compel the
most inattentive observer to glorify the wisdom and skill
of the Allfather so conspicuously manifested in the
structure of these complex organs. For this part in these,
instead of two or three pedunculate cups as in the in-
sects just mentioned, is composed of a vast number, some
large and some small. If you take a male specimen of
the common D. marginalis, you will find that the three
first joints of the hand are very much dilated, so as to
form a plate or shield nearly cii'cular, fringed all round
with stiffish hairs ; if you next examine the under side of
this plate with a good magnifier, you will discover at the
base, where it is united to the cubit, two circular cups,
the external one more than three times the size of the
ot)ier, with an umbilicated centre'^; besides these two
l^ger cups the rest of the shield is covered by a vast
pumber of minute ones of a similar construction*': the
Ijirger cups are nearly sessile, but the smaller are
elevated upon a tubular footstalk^; the three first joints
of the intermediate tarsi are also dilated, but not into an

' Plate XXVII. Fig. 54. P/iilos. Trans. 1816. t. xviii./. 9—11.
'■ PiA ri; XXVII. Fig. 55. t. ' Plate XV. Fig. 9. a.

' 'bid. b. ^ P/iilos. Trans. 1816. /. xx. /. 9, 13-15.

EXTEIINAI. ANATOMY OI INSECTS. 695

orbicular shield, ami thickly set with minute peduncu-
lated suckers*. The structure varies however in dif-
ferent species. Thus in D. Umhatus the shield is trian-
gular with the smaller suckers at the base, and two rows
of larger oblong ones, concave but not umbilicated, at the
apex ; in another Brazilian imdescribed species (Z). ob"
ova/us K. Ms.) the shield is oblong and quite covered
with suckers like those last mentioned; in D.sulcatus (Act-
litis Leach) almost the whole plate is occupied by a very
large sucker, above which, at some distance in the inner
side, are two smaller ones, while the extremity of the
shield is covered by minute ones elevated on long foot-
stalks: the central umbilicated elevation of the large one,
which nearly fills its cavity, is in this species beautifully
radiated. The male of Colymbctes transversalis has also
an orbicular shield, but the suckers are much less strongly
marked. The use of this organ has been before suffi-
ciently explained ^.

A few words will be necessary upon the folding of the
legs in repose. When insects walJc^ the thigh is usually
in an ascending position, rising above the horizontal line,
the tibia forming with it rather an obtuse angle, and the
tarsus nearly a right one with the tibia ; but in the My-
riapods, as far as I can unravel their swift many-footed
motions, these angles in walking do not take place ; iit
repose however, in many insects, the coxa forms an angle
with the thigh below the horizontal line and with the tibia
above it, and the tibia and tarsus continue in the same
liney and point downwards nearly vertically ; in others,
as in the Tetrameimis beedes, the last-mentioned joints

- PhUos. Trans. 1816. /. xx. /. 4, 1 1. " See above, p. 305—.

696 EXTERNAL ANATOMY OF INSECTS.

form an angle with each other and turn upwards, the tibia
having an external oblique cavity to permit this ; but the
insects most remarkable for packing close their legs are
those carnivorous genera Dermestes, Aiithrenus, Bi/rrhusy
&c. In the last-mentioned genus there are cavities in
the under side of the trunk, in each division of the
breast, and at the base of the abdomen, to receive the
legs when folded ; the coxce have also a cavity to receive
the base of the thigh. In the anterior- legs this last part
has a longitudinal one on its tipper side, and in the
four poste7-ior on the under ^ which receives the tibice,
which at the inner edge are straight, and at the outer
curvilinear, and the tarsi are turned up and received by
the concave part, on the anterior side of the Jirst pair
and the posterior side of the two last of the tibice, so as
to lie between it and the body : when the legs are close
packed, the animal looks almost as if it had none. I
have observed that when Dytisci repose on the water,
the posterior legs are turned up and laid over the elytra,
and curved towards the head.

vi. Pectines. I must next say a few words upon a re-
markable organ, which seems in some degree supplemen-
tary to the legs, by which the Creator has distinguished
the genus Scorpio, called from its parallel teeth, set in a
back, Xheiv pecten or comb^. This back consists of two
or more articulations, is attached by its anterior extremity
to the sides of the postei'ior piece of the mesostethium,
and is marked by a longitudinal furrow or channel. The
teeth, which vary in number in the different species, and

=> Plate XXVII. Fig. 50.

EXTERNAL ANATOMY OF INSECTS. 697

in tlie same species at different periods of its gi'owtli, are
usually ovato-lanceolate, or obtusangular, furnished on
their exterior ed^e with what appears to be a longitudi-
nal sucker, and supported between their bases, or at the
base, both within and without, by triangular, conical, or
subglobose pi'ops. With regard to the W5<f of these organs,
it has not been clearly ascertained. Amouroux states
that he has seen the animals use them as feet, and he con-
jectures that by them they may fix themselves and turn
upon tliem as on a pivot, when they have to make a re-
trograde movement*. M. Latreille, from their liaving
branchial pouches immediately under them, seems to
think that they are connected with respiration''. This
may be true ; but from the suckers just described, I am
uiclined to think with Amouroux, that they are useful to
the animal in its motions, and that like the suckers of the
Gecko, flies, &c., they enable it to support itself against
gravity and to climb perpendicular surfaces.

Whether the five obtriangular plates, elevated on a
pedicle, which are found arranged in a series on the un-
der side of each of the jointed coxiE of the posterior legs
in Galcodes, are at all analogous to the pectens of scor-
pions, has not been ascertained*^. M. Leon Dufour
watched them very attentively in one species ( G. intrepi-
dus), but he could observe no motion in them'*.

* Amouroux Inxeclcs Venbneux, 44.
'' Observations Nouvelles, &c. Mem. du Mus. viii. 1 77.
' .V. Diet, d'llisl. Kat. xii. 370.

'' Descr. de sic Arachnidcs, Sec. Ann ales Gen. ilcs Scicnc. Phys.
1820 11). /. Ixix./. T.d.

LETTER XXXVI.

EXTERNAL ANATOMY OF INSECTS

CONTINUED.
THE ABDOMEN, AND ITS PARTS.

The abdomen of insects, which we are next to consider,
is the third great section of the body, and is the seat of
the organs of generation, as well as of a principal part
of those connected with respiration. My remarks upon
it will be under the following heads : Its substance; ar-
ticulation with the trunk; composition; shape a?id pro-
portions; its appendages; and its clothing.

i. Substance. Under this head I may observe in ge-
neral, that where the abdomen is protected by hard elytra
or tegmina, as in most Coleoptera, and many Heteropte-
rous Hemiptera, the upper side is generally of a softer
and more flexible substance than the tmder, which from
its exposure requires a greater degree of hardness and
firmness to prevent its being injured. In some,^ — as the
Dynastidae and those beetles whose elytra are connate,
or as it were soldered together, the former is scarcely
more than membrane. In others of the above tribes,
nearly the tsohole of the back of whose abdomen, as in Sta-
phylinus; or only its anal extremity, as in Melolontha; or
its sides, as in Eygceus, &c., is not covered by the elytra

EXTERNAL ANATOMY OF INSECTS. 699

or teginiiia, that part, as was requisite for its protection,
is harder than the covered portion.

ii. Articulation ivit/i the tnink. Two distinct modes
ot" this articulation take place : — in the first the abdomen
is united to the trunk by the 'ii'hole diameter of its base,
without any appearance of incision ; in the other only a
small part of that diameter, with a very visible incision.
All the Orilers, except the majority of tlie Hi/meiioptera
and Diptera., and the Araneidde, belong to ih^Jirst of
these sections ; for in all these the aperture by which the
abdomen is suspended to the trunk, occupies the whole
of the base ; I say suspended, because, though in many
cases it inosculates in the posterior cavity of the latter
part, it does not in all, and the margins of the orifice are
united by ligament to those of that cavity. Indeed, in
the Coleoptcra and others that have a somewhat promi-
nent metaphragm ^, the trunk may with more pro-
priety be said to inosculate in the abdomen. With re-
gard to the second section, — those in which the orifice is
of less diameter than the base, occupying only a portion
of it, — it may be further subdivided into those whose ab-
domen is sessile, and those in which it is united to the
trunk by the intervention of a long or short 2)edicle or
footstalk : to the first of these subdivisions belong all
those Diptera that have an incision between the trunk
and abdomen — for many tribes of this Order, as the Ti-
pididte, AsilidiC, &c., belong rather to the^^rs^ section —
and the Ara7ieidcc; the abdomen, however, mail is merely
suspended, without any inosculation. To the second
subdivision belong all the Hymenoptera, except the Ten-

•' Anatom. Compar. i. 450.

700 EXTERNAL ANATOMY OF INSECTS.

thredinidcE and Siricida:, the abdomen of which is united
to the trunk by the whole diameter of its base ; these
may be further subdivided into those that have a veiy
short pedicle and those that have a long one ; but as
the mode of articulation in both these is the same,
there will be no necessity to consider them separately.
M. Cuvier has included the Diptera and Araneidce in
the same tribe with such Hymenoptera as have a petio-
late abdomen*; but as the manner in which the latter
articulates with the trunk is widely different from that of
the Diptera &c., I thought it best to consider them as
distinct; especially as in \\\q Diptera there is no tendency
to a pedicle, while only the above two tribes oiMymeno-
ptera are wholly without it. This learned author thus de-
scribes the articulation where the abdomen is connected
by a pedicle. " They have," says he, " a real solid arti-
culation, a kind of hinge in which the first segment is
emarginate above, and receives a saliant portion of the
trunk upon which , it moves ; this articulation is ren-
dered solid by elastic and powerful ligaments ; muscles
which have their attachment in the interior of the trunk
are inserted in this first segment, and determine the ex-
tent of its movement*." But this passage by no means
conveys an adequate idea of the singular mechanism by
which the Divi?ie Artificer has enabled these little crea-
tures to impart the necessary movements to an organ so
bulky compared with its very diminutive point of attach-
ment. As no author that has fallen in my way has ex-
amined the articulation of the abdomen with the trunk in
these Hymenoptera with the attention which it merits •*,

' Anatom. Compar. i. 4.51.

^ De Geer notices something of'thekind in Cimbcxfcmorata. ii.947.

KXTEIIN'AI. ANATOMV OF INSECTS. 701

I shall enlarge a little upon it You would be surprised,
and not without reason incredulous, were I seriously to
assert that those insects lift their weighty posteriors
by means of a rope and imlley ; yet something like this
really does take place, though not with all in a manner
equall}' striking. The point of articulation in the insects
in question, except in Evania^ is at the base of the meta-
thorax just above the posterior pair of legs: here you see
a small orifice, either insulated or connected by a narrow
opening with the larger one, when the abdomen is re-
moved, which in many instances, as in the common wasp,
is surmounted by another still smaller, through which,
if you examine it attentively, you will find there is trans-
mitted a flat and sometimes broadish ligament or rather
tendon, in which the levator muscles of the abdomen, at-
tached by their other end to the metaphragm^, terminate:
another minute orifice above the base of the pedicle af-
fords a point of attachment to the tendon, so as to give
it prize upon the abdomen. Here the upper orifice in
the trunk is the pulley [ttvchlea)^, the tendon is the
rope [funiculus) ^, and the abdomen is the weight to be
lifted. When the muscles contract, the tendon, running
over the edge of the aperture, is pulled in, and the part
just named is elevated ; and when they are relaxed the
tendon is let out, and it falls. Some little variation in
the structure takes place in different tribes : thus, in the

* It was omitted to be observed, when the supposed pneumatic
pouches in the genus Vespn were mentioned (see above, p. 585), that
they have also a very conspicuous metajjliragm, as probably have
most Ili/menoptcra, to whicli the muscles that move the wings are
attached.

'• Pi.ATK IX. Fig. 13. F is the tendon, G' the aperture in the
abdomen C, and a, the aperture in the trunk B.

702 EXTERNAL ANATOMY OF INSECTS.

Fot^micidiB, ScoUadUe, &c., instead of a separate orifice,
the part I call the pulley is merely an upper sinus of the
large orifice that receives the pedicle of the abdomen.
The shape of these orifices, both of the trunk and abdo-
men, varies in different genera : thus, in the bee it is tri-
ano-ular, with the vertex reversed ; and in the wasp the
upper one is circular, and the lower one transversely ob-
long ; but in all, the apertures of the trunk correspond
with those of the abdomen. In Evajiia, in which the
minute abdomen is inserted in the upper side of the me-
tathorax, there is scarcely any trace of this structure.
With regard to the articulation of the pedicle itself with
the lower orifice of the trunk, it appears simply sus-
pended, with little or no inosculation. I may observe
under this head, that though the abdomen in almost all
insects is wholly clear of the cavity of the trunk, yet in
some Phalangidce {Gonyleptes K.) it appears almost re-
tracted within it*.

iii. Composition. I shall next consider the segments
into which the abdomen is usually divided, their num-
ber, and other circumstances connected with them. In
the Hippohoscida;, Acaridce, Phalangidce, and Arajieidtje,
the part we are considering is not divided into segments,
though in some instances, as in Gonyleptes and the can-
criform Epeirce^, they are represented hy folds; but in
the great majority of insects it consists of several dorsal
and ventral pieces or segments, forming by their union
the annuli or rings into which it appears divided. The
number of these abdominal segments varies in different

^ Plate XV. Fig. 11. Linn. Trans, xii. t. xxii. ^16.
*■ Surely these Epeirce, of so different a habit from the rest, form
a distinct genus?

EXTERNAL ANATOMY OF INSECTS. 703

insects; I have noticed more than (wenf^/ such variations,
and probably there are many more. Before I give you
them in detail, I must first observe that the dorsal and
ventral segments, though sometimes they correspond in
nimiber, yet veiy often do not, the dorsal most com-
monly exceeding the ventral by a segment; in a few
cases however the reveise takes place. In the sexes also
there is frequently a difference in the number of seg-
ments, as has been before observed^. I shall express
the variations in question by two figures, the^rst repre-
senting the number of dorsal segments, and the second
the ventral — they usually only express the apparent seg-
ments: perhaps a very general examination and dissec-
tion might bring many of them nearer to a common
type.

1:1. Chelonus. 6:5. Nepa.

3:3. Chrysidce^. KHalictus ^.

4:2. Leucospis^. (Belostoma.

6:5. Syrphus. ^ CCurculioh.

5 : 6. Halictus ? . \ Cerambyx L.

=» See above, p. 339.

'' There is reason to suppose that in Chelonus and the C'hysidce
several segments are retracted witliin the abdomen, and if the cavity
of its under side in the latter be examined, it will be discovered that
the epigastriuin is divided in the middle into two pieces, and that both
the sides of this and the following segments are covered by three
narrow accessory plates, one to each, the last being the shortest.
De Geer (ii. 833.) describes Chrysis ignita as ]\a\'\ng four abdominal
rings ; but this is only in appearance, there being really only three.
This appearance is produced by the apex of the last dorsal segment
being more depressed and marked with several deep little excava-
tions that look like holes. In some species of Stilbum this segment
consists as it were of three ridges or steps.

'^^ In this genus the ventral segments are replaced by a long narrow
central plate, succeeded by a minute one.

704 EXTERNAL ANATOMY OF INSECTS.

7:6. Dijtiscus $. 9:7. Perga Leach ?.

7:7. Ammophila, Sic. 9:8. Perga S.

0 ^ iDytiscus S' 10:7. Locusta 'Lea.ch ?.
o : D. ^ "^

(Lncanus, &c. 10:8. <?.

8:7. Geol}upes hatr. 10:10. Mshna.

8:8. Pimpla. 11:7. Phasma.

8:10. Eucklora M-^L. =• ? 11:9. Chelifer.

8:13. Scutigera. 12:11. Thelyplwnus.

^\t>. Carabus Latr. Many: Mijriapoda.
9:6, Gymnoplmrus 111.

1 shall next explain the articulation of the segments
with each other, both that of the rings formed by the
union of the dorsal and ventral pieces, and that of those
pieces themselves. In general it may be stated with re-
spect to the former, that each ring is suspended by liga-
ment to that which precedes it; but this takes place in
three ways — in some the margins of the suspended rings
touch each other only, with little or no i7iosculatio?i ;
in others the dorsal segments only touch, and the base
of each ventral is covered more or less by the apex of
the preceding one ; and in others agam the base of the
whole ring, both above and below, is so covered, or
inosculates. The first kind here mentioned yoM will
find exemplified in Melolontha, Geotrupes, Muscat &c.;
the second in Scorpio ,- and the third in Staphylintis, the
Hymenopteray and many others. In the Coleoptera, says
M. Cuvier, speaking of the movements of the abdomen,
the rings onlji^ touch each other at the margin, and the

* In this genus the bed of the posterior coxae appears to consist
of two segments, which are beautifully fringed with parallel short
bristles.

EXTERNAL ANATOMY OF INSECTS. 705

movement is very limited ; whilst in the Hrjmenoptera
they are so many little hoops, which inosculate in each
other as the tubes of a telescope, one third only of
their extent often apj^earing uncovered". We see the
reason of this structure when we consider the calls they
have for greater powers of movement in this part in lay-
ing their eggs, and annoying their enemies and assail-
ants ; and also in the Staphylinidcc to enable them to
turn up their abdomen like a scorpion, both as a posture
of attack, and to fold their wings: in all cases, however,
as far as my observation goes, these animals, when they
want to lengthen this part, can disengage the rings from
almost all inosculation, so that no impediment remains
to any movement.

The articulation of the dorsal and ventral segments
with each other is next to be considered. In hilus
and some Centroti the ring appears to be formed of
a single piece, with scarcely any trace of the existence of
any such division ; it is however almost universal, and is
oi three descriptions; in the first the dorsal segments are
united to the ventral at the lateral margin or edge of the
abdomen; in the second it is above this margin, and in the
third helcmo it. You will find that in Fulgora and many
other Homopterous Hcmiptcra these segments unite at
the margin, as they do likewise in Cimex lertularms be-
longing to the other Hemipterous section ; but in the
rest of the Heteropterous tribes, the ventral segments
turn upwards, and their union with the dorsal is in the
back of the abdomen ; in these the Hemelytra and wings
only cover the dorsal segments, leaving the edge, formed

' Audlniu Campnr. i. 4;">1.
VOL. in. '2 z

706 EXTERNAL ANATOMY OF INSECTS.

of the ends of the ventral, uncovered. The LameUi-
corn beetles also, and many other Coleoptera, exhibit the
same structure. To the last description, in which the
dorsal segments turn down to meet the ventral, belong
the Lepidoptera, Locusta Leach; likewise Sirex, Chrysis,
and many other Hymenoptera. The articulation between
these segments is by means of an elastic membranous
ligament, which usually is not externally visible ; but in
many instances, in which the connecting ligament is of a
firmer substance, as in Scorpio, TJielyphonus, and Phrynus,
it is very conspicuous, and in the latter genus exhibits
many longitudinal folds, as it does likewise in Gryllo-
talpa, which must permit a vast extension of the abdo-
men. In this membrane, in some cases, as in Dynastes
M'^L., Melolontha, &c., the two or three first spiracles
are fixed ^. In the Hymenoptera and many other insects
the dorsal segments do not unite by their margin with the
ventral, but the end of each dorsal laps over that of the
corresponding ventral.

Dorsal segmejits^. I shall next notice the segments
seriatim, in the order of their occurrence, beginning
with the dorsal ones. The most remarkable circumstance
with respect to these that occurs to my recollection takes
place in the Cancroid spiders [Epeira cancriformis, acu-
leata, &c.), in which the back of the abdomen is formed
by a plate, in some extended in a transverse direction
{E. ca7icriformis\ in others in a longitudinal one {E.
acideata), of a much harder substance than the under
side and quite flat, set with strong sharp spines, in the
former species apparently moveable, and terminating be-

-^ Plate VIII. Fig. 9. A', B' . ^ Ibid. Fig. 5. A".

EXTERNAL AXAro.MY OF INSECTS. 707

hind in a piece resembling in some measure the scutellum
of tlie Stratijomidcc and similarly armed with a pair of
spines * : in E. aculeata the sides of the abdomen, un-
der the plate, have a number of longitudinal folds like
those of P/injnus. In Ctyptocerus, a genus of ants pecu-
liar to South America, the Jirst segment, not reckoning
the pedicle, forms almost the whole back of the abdomen,
and the three last are so minute as scarcely to be distin-
guishable. Nothing very remarkable is exhibited by the
other segments, except that in Trichius the penultimate
is the largest; in some Staphylinidcc (S. splendens) and
Brachini ( B. melanocephalus) it is emarginate, and in the
former tribe also often terminating in a white membrane.
T^\iQ dorsal segment most worthy of notice is the last, which
is called \he podex ; for though in general it is a minute
piece, often retracted within the abdomen and invisible,
as in many Dipt era, yet sometimes it is the most con-
spicuous of the dorsal segments. It is most commonly
triangular, and usually deflexed and forming an angle
with a horizontal line; but in Clytra, Chlamys, and
Oryctes, it is inflexed ; in many Lamellicorns it is nearly
vertical. In Tettigonia F., many other Hcmiopterous
Hemiptera, and some Hymenoptera (Ciinbex), its sides
turn down and become ventral ; on its lower side it has
in these a longitudinal cavity which receives the oviposi-
tor in repose''. In many other insects it unites with the
last ventral segment, the hypopygimn, to form a tube
for that organ, as you will find in Callidium violacewn^,
many Muscidcs^ and Thelyphoims. As to its termination
the podex is sometimes bifid, Blatta ,- bipartite, Ranatra ;

' Pr.ATE XV. Fig. 10. '' Reaum. v. t. xvii./. 14 f/.a.

*•" Linn. Tratix. v. t.xu.f. 1.5.

2 ■/. 2

708 EXTERNAL ANATOMY OF INSECTS.

mucronate, Sirex; acuminate, Melolontha vulgaris, Tri-
chius hemipterus. Generally this part is flat ; but the disk
is elevated or gibbous in Ori/ctes and some other La-
mellicoms. In the majority of the Coleoptera Order it
is quite covered by the wings and elytra ; but in many of
the last-mentioned tribe, and sometimes the penultimate
segment also, it is not covered by them*. In some in-
sects the piece we are considering appears to consist of
two segments; in the male of Locusta morhillosa the
whole podex is rhomboidal, but it is formed by two tri-
angular pieces which articulate with each other; tliis
structure permits the more easy elevation of the terminal
one for the extrusion of the feces.

Ventral Segments ^. We are now to turn our atten-
tion to the ventral segments of the abdomen. The first
of them is what is called the epigastrium'^ in the table.
This part, according to M. Chabrier, is of considerable
importance to the animal in flight, as, by its pressure
against the trunk, not only regulating the movements of
the abdomen, but as, in his opinion, contributing to push
forward the trunk ^ in the descent of the animal. It is
remarkable only in the Coleoptera and Heteropterous
Hemiptera, to which my observations upon it will be
confined. It may be stated as usually consisting of two
articulations, that nearest the trunk being narrow, and in
the Predaceous beetles '', as also in Scutellera, Pentatoma,

* Daldorf (^5ia/ic Sodetifs Trans, vii.) has divided Geotrupes into
two families, one with the podex covered (G. vernalu, &c.) which he
calls modestly the other with it uncovered (G. stercorarius, &c.) which
he calls obscoeni. ^ Plate VIII. E .

' Ibid. n. d Sur le Vol des Ins. c. I Addend. 299.

' In Dytiscus marginalis the upper side of the margin of the Hy-
pochondna is curiously cut into transverse corrugations.

EXTERNAL ANATOMY OF INSECTS. 709

&c., interrupted in the middle =•. In many LamelUconis
this joint is concealed under the posterior coxcv, and with
the anterior part ot" the second forms a hollow cavity for
their reception ; this last joint is what is properly the
Epigastrium, the former, especially when distinct, being
called in the table the Hypochondria. In Sagra and
Brcntus the cj)igaslrium is particularly conspicuous for
its size, in die former occupying half, and in the latter
nearly two-thirds of the under side of the abdomen; but
in general it is distinguished from the remaining segments
only by the central mucro or point that terminates it
towards the trunk'', and which is received by a sinus of
the 7netasternum ; this point is generally minute and tri-
angular, but in Sagra it is large and rounded at the
extremity, and in Calandra it terminates nearly in a
transverse line somewhat waving. It is most remarkable,
liowever, in some species of the Heteropterous genus
Edessa F. ; for in E. nigripes and affinities it is a sharp
sterniform conical horn, which passing between the four
posterior legs covers the end of the prommcis. In fact,
this part appears a kind of abdominal sternum. In the
Cetoniadcs, Sic, \he Hypochondria unite before this mucro,
and form a ridge which articulates with it, and dips
towards the abdominal cavity ; in Scolytus the epigas-
trium is much elevated from the rest of the ventral seg-
ments, so that the under side of the .abdomen appears as
if it were suddenly cut off, wlience Herbst's awkward
though not inexpressive name, Ekkoptogaster -, this part
in this genus has something of a posterior mucro.

The intermediate ventral segments exhibiting no very

' Plate VIII. Fig. 6. C . * Ibid. B' .

710 EXTERNAL ANA'IOMY OF INSECTS.

remarkable peculiarities, I shall pass them without fur-
ther notice, and call your attention to the last, which is
opposed to the podex, and which I have named the hy-
popygium^. Though usually a single small piece, in
Edessa and many Pent atom ce it consists o^ several plates;
and in Trichius it is very large : it is mostly i?itire, but
in the male Dytisci it is cleft; in Lamia ocellata trilobed ;
in Edessa tripartite; in Centrotus Taurus it is boat-
shaped and hollowed out to receive the stalk of the ovi-
positor. It is also generally in the same line with the
body, but in Xenos it is turned up and bent inwards''.

iv. Shape. With regard to shajje, in some Orders the
abdomen varies considerably; but the most general form
is one that approaches to trigonal, so that a transverse
section will be a triangle,- with the vertex more or less
obtuse, and the base more or less convex; some tendency
to this form will often be found even in those insects whose
abdomen appears almost as flat as a leaf, as in many
Aradi. In the hive-bee the transverse section is almost
an equilateral triangle; in Belostoma grandis the disk of
the under side of the part in question is longitudinally
elevated into a trigonal ridge, the section of which is an
equilateral triangle, the sides being quite flat. In gene-
ral, in the vertical section of an abdomen, the vertex of
the triangle points dwsotitsoards, but in Libellula F. it
points upwards. In Blatta this section is nearly lanceo-
late ; in Staphylinus olens it is a segment of a circle with
the convex side downwards ; in ^shna F. with that side
upwards; and in Agrioji the section is circular. In
Copris, Ateuchus, &c., the abdomen is very short and

^ Plate VIII. L'. ^ Linn. Trans, xi. t. ix./. 15. b.

EXTERNAL ANATOMY OF INSECTS. 711

thick ; in Staphylinus slender and long; in Aradus^ Nepa,
&c., depressed and flat; compressed in Ophion and
Evania ; conical in Ciclijoxis; rhonihoidal in many
Mantes : boat-shaped in many Z/j/^^Z; fusiform in various
Papilionidcc ; lanceolate in some Ichneumonidce^ falcate
in others ; nearly round in Diapria pnrpurascens ; ovate
in Lyrops ; elliptical in Andrena-, oblong in many X?//o-
copcc ; heart-shaped in the naked Euglossa; ; triangular
in Di/tisctcs; gibbous in Plata; and vaulted in Chrysis.
At its base it is truncated in Sirex ; retuse in most bees ;
forming the segment of a circle in Andrena; in general
sessile, but in the majority of Hymenoptera^ as has been
already observed, terminating in a pedicle. The pedicle
is very short in the Andrenidce and Apidcc ,- long in the
Sphccida: : thick in the Formicidcc ; slender in Evania;
fusiform mPelecinus; clavate in Ammophila; campann-
late in many Vespida; ; nodose in Myrmica^ ; squami-
gerous in Formica^ : it sometimes also consists of two
joints, as in Ammophila and many Vespidic. As to
margin, some have none, as Centrotus ; in others, as
Dytiscus, it is very narrow ; in others again, wide and
flat, as in the NepidcV; in Staphylinus, &c., it is distin-
guishable only on the upper side of the abdomen ; in
Locusta Leach only on the under side, though mostly
intire ; it is serrated in Blatta, sinuated in Acanthia pa-
radoxa, and crenated in Cerceris.

v. Proportions. These vary greatly in the different
tribes ; in some the abdomen is long and slender, as in
Locusta, and Staphylinus ; disproportionably so in a re-
markable degree in some Agrionida from South America,

» Plate IX. Fig. 18. /'. " Ibid. Fu,. 17. //'.

712 EXTERNAL ANATOMY OF INSECTS.

as A. lineare, &c. ^ ; in others it is extremely short and
thick, as in Copris, &c.; a mere appendage in Evania;
it is shorter than the elytra in Ti'ox ; of the same length
in most beetles ; longer in Melolontha, Uister; &c. ; dis-
proportionably so in Staphylinus: though usually of the
same width with the trunk, in many Mantidce it is much
wider''; and more slender in the Libellulina, Myrmc-
leon, &c.

vi. Arms and Appendages'^. These are various ; and
maybe considered under the following heads : processes;
organs of resph'ation, tnoiiofi and prehension; weapons;
and other anal apj)endages the use of which is unknown.

1. Processes. Under this term I include all promi-
nences of whatever kind, whether tubercles, teeth, spities,
or horns, that arm any part of the abdomen. Many of
these are sexual characters, and have been sufficiently
described in a former letter'*; I need not therefore detain
you long on this head. Of the fii'st kind is a remarkable
elevation that distinguishes the second ventral segment
ofScoli/tus Destructor [Ips Scolytus Marsh.) or of a species
allied to it^; in S. pygnueiis {I. midtistriatus Marsh.) the
same segment is armed by a flat horizontal tooth or horn ;
in an Aradus from Brazil, before alluded to ^ {A. lami
natus K. MS.), the margin of the abdomen is surrounded
by eight flat subquadrangular laminae; in another species
figured by Stoll?, it is cut out into bays by a number of

^ Rcemer. Genera, &c. /. xxiv./. 4. '' Stoll SjKctr. t. vii.

"= Plate XV. Fig. 10-23. <^ See above, p.339— .

^ This tubercle I find only in a specimen from Sweden, sent to me
by Major Gyllenhal, but not in any British one I possess. In this spe-
cimen the declivity before mentioned (see above, p. 70.9.) is observa-
ble in the first segment, but in the others it is formed by the second.

f See above, p. 617. ^ Pnnaises, t. xiii. /. 84.

EXTERNAL ANATOMY OF INSECTS. 713

denticuliited teeth ; and in Acanthia paradoxa by long
spinose lobes'. In Edcssa F., another genus of bugs,
the abdomen usually terminates in four strong sharp
dentiform spines, the intermediate ones being the short-
est, and in some the inorgi?i is also armed with spines'';
occasionally the anal spines are very long^. In addition
to the ventral horns before mentioned that distinguish
the sexes of some insects''; the males of the genus Conops,
a two-winged fly, have, on the antepenultimate ventral
segment, a singular process, varying in length and shape
in the different species, standing nearly at right angles
with the belly, convex towards the trunk, and concave
towards the anus. De Geer supposes that with the anal
extremity this forms a forceps with which this fly seizes
the other sex ^.

2. Organs of rcspiratioji ^. I shall defer my account
of the spiracles, and other external respiratory organs,
till I come to treat of the system of respiration in insects,
when every thing connected with that subject will be
most properly discussed ; but there are certain appear-
ances in some insects, which at first sight seem to par-
take of the same character, but which being really inde-
pendent of that vital function, may here have their place.
If you examine the abdomen of the mole-cricket ( G/3///0-
talpa vulgaris), you will easily discover the true spiracles
in the folds of the pidmonariiim, which separates the back
of that part from the belly ; if you next inspect the five
intermediate segments of the latter, you will discover
on each nearer the base a pair of oblique little chan-

" Stoll Pnnaues, t. xiii. /. 101. *• Ibid. t. xvii./. 1 1 7.

*• Ibid. t. xxxvi./. 253. '' See above, p. 339—.

' De Gccr, vi. 260. /. xv./. 8. d. ' Plati; XXIX.

714 EXTERNAL ANATOMY OF INSECTS.

nels, which precisely resemble closed spiracles. These
may be denominated false or blind spiracles. Again, if
you examine the pupa of any Scutellera or Pentatoma,
in which tribe the true spiracles are ventral, you will
discover, placed in a square on the two or three interme-
diate dorsal segments, four or six elevated points resem-
bling spiracles, but not perforated, connected often by
corrugations in the skin or crust'; in the larvae also of
some Reduvii the first minute dorsal segriient, at each
lateral extremity, has a similar elevation with a central
umbilicus precisely resembling a spiracle, but still not
perforated : another instance of false spiracles in this sec-
tion of the Hemiptera, is furnished by Aradus laminatus
before mentioned, in the perfect insect; between the
spiracle and the margin of each ventral segment is a
white round callus, with a dark point resembling a
perforation on its exterior side, and terminating inter-
nally in a channel covered by membrane leading to the
disk of the segment, so that the whole in shape resem-
bles a tobacco-pipe^. A number of similar callosities
with a central impression, but without any channel, va-
riously disposed, are also to be found in another bug,
Rhimichus compressipes K.*^ In the Homopterous sec-
tion of this Order, a series of impressed points, which
may be easily mistaken for spiracles, are to be discovered
on both sides of the abdomen, at the margin in Centrotus,
in which the real spiracles are quite concealed.

In spiders, as we learn from Treviranus, the open ve7i-
tral spiracles of the scorpion are replaced by pseudo-

" Plate XXIX. Fig. 22. is part of the back of the abdomen of the
pupa of a Pentaloma. « the pseudo-spiracle, b the connecting corru-
gations, " Ibid, Fig. 24. a. ' Ibid. Fig. 2/. a.

EXTERNAL ANATOMY OF INSECTS. 715

spiracles ; tliese in Epeira Diadema are three pair of small
black points : on the back of the abdomen also are four
pair, but in some species there are only tisco^ : the most re-
markable, however, are exhibited bv the cancriform spi-
ders before noticed'': \n Epeira cancriformis, in the plate
which covers the abdomen, they are dark red spots with
an elevated rim and centre *= exactly resembling spiracles,
except that they are not perforated ; there are twenty-
four of them, twenty arranged round the margin, and
four in a square in the disk.

3. Organs of motion. In a former letter you were
told that several insects are enabled to leap by means
of orgaris in their abdomen ; I shall now describe such
of them as require further elucidation. I then said that
Podnra and Sminthums, two apterous genera, take their
leaps by means of an imalfork'^. In the former genus
the fork consists of a single piece attached to the under
side of the anus, and terminating in a pair of long slender
sharp processes which articulate with it and form the
fork or saltatorious instrument ^. In Sminthums the tines,
as they may be called, of the fork do not articulate with
the base, but are of the same piece and consist of two
joints, the terminal one being flat and obtuse *^. Machilis
to the anal fork adds eight pair of ventral linear springs
{Elastes), which are covered with hair or scales, and ter-
minate in a bristle or two. I have on a former occasion
mentioned the natatorious laminae with which the anus

* Treviranus. Arachnid. 23 — . i* See above, p. 702, 706.

'• Plate XXIX. Fic. 26. represents one of them.

•^ Vol. H. p. .319— .

« Plate XV. Fig. 14. M". DeGeer, vii. t.i'uf. 5, 10,21.

f Ibid./, iii. /.4, 14.

716 EXTERNAL ANATOMY OF INSECTS.

of the larva ofAgrion and of some Diptera is furnished* ;
the same part in that of Dytiscus ends in a pair of taper-
ing organs, fringed on each side like the hind-legs of the
imago'', which doubtless assist it in swimming; those
respiratory foliaceous laminae which so singularly di-
stinguish the abdomen of the larvae of Ephemera, like the
legs of the Branchiopod Crustacea, are probably used in
some degree as fins, and aid their motions in the water *=.
Under this head may also be mentioned the many-jointed
bristles that form the long tails'* of the fly that proceeds
from these larvae, whose interesting history I long since
enlarged upon ; for when they fly the two lateral ones
diverge from the central one, and perhaps perform the
same office as the tail feathers {rectrices) of birds. These
bristles are also to be found in Machilis^, and probably,
as its leaps are almost as long as Jiights, for a similar
purpose, to steady their motion. I may here lastly state
that I once saw a Cryptophagus {Corticaria Marsh.), but
I forgot to note the species, walking upon my window,
which when it wanted to turn fixed itself to the glass by
an inflated anal vesicle, and so accomplished its purpose.
4. Organs of Prehension^ . The abdominal organs of
prehension are various ; but as the great body of them ar§
connected with the sexual intercourse of insects, I shall
not consider them till I come to treat on that subject.
The only remarkable one that is common to both sexes
is that of the earwig, which is too well known to every
child to call for any long description. The external or-

" See above, p. 154. ^ Plate XVIII. Fig. h.a.

' Plate XXIX. Fig. 3, 4. De Geer, ii. t. xvil. /. 12. and i. xviii.
/ 2. '• Ibid. /. xvi./.8— 13.

" Plate XV. Fig. 16. S" . f Ibid. Fig. 13. L".

1 XTEUNAI, ANATOMY OI' INSFXTS. 717

gans of oviposition I shall also describe hereafter, and
hkewise those of sccretio7i that have not already been
noticed.

5. Weapons. As the sfi figs o^ some Hi/meriopf era are
analogous to the ovipositors of the majority of that Order,
I shall consider them both together when I treat of the
sexual organs of insects; but there is one, and that a tre-
mendous one, not connected with those organs, which
may be noticed here. I mean the sting of the scorpion.
There appears to be some analogy between the poisonous
fimgs of one tribe of the Ophidian reptiles', the mandi-
bulae of spiders*', the second pair of pedipalps, or the
fangs of the Scolopendridcc '^, and the organ in question ^ ;
but the last possesses this peculiarity, that it is placed at
the opposite extremity of the body, where it is preceded
by a long jointed tail, which properly speaking is merely a
continuation of the abdomen, since the spinal marrow, the
intestinal canal, and the pseudocardia, are extended into it ^.
Providence might have a double view in thus contracting
the dimensions of this part of the abdomen ; in the first
place, the animal is by this enabled to turn its tail over its
back preparatory to its inflicting a wound, and in the se-
cond, perhaps, this formation favours the sublimation of
the venom, the long tail acting as an alembic for that
purpose. This machine consists of six angular joints in-
cluding the sting, the last but one being the longest, and
the last inflated, as it were, at the base, and terminating
in a sharp subulato-conical point which curves down-

=> Philoft. Trans. 1818. /. xxii.

'" A". Did. (rilist. Xat.u. 275—. Hoole's Leeuwenh. i, t. W.f. 19. \.

-^ Leeuwenh. Epist. 17- Octobr. 1687. /• 10. C.

^ Hoole's Leeuwenh. i. /. v./. 12, 13. ' Treviramis, Arach. 4.

718 EXTERNAL ANATOMY OF INSECTS.

wards, and has an orifice in a channel at the end on each
side. Treviranus could not discover these orifices in the
sting of Scofjno europceus ^ ,- they may however be readily
seen if viewed with a sufficiently high power, though not
under a common pocket microscope. Whether the very
slender, many-jointed, real tail of the remarkable genus
Thelyphonus is used in any respect as a 'weapoji, has
not been ascertained : it is a filiform hairy organ consist-
ing in some specimens of more than twenty joints, the
first being very much larger than the rest**.

6. Appendages'^. We are lastly to advert to those
appendages of the abdomen of which the use is not at
present discovered. These are the styles {styli) of the
Staphylinid^e ; the leaflets (foliola) of the Libellulina;
the floret [Jlosadus) of the FidgorcC; the cerci of the
Blattidce and Gryllina-, and the threads {Jila) of Ma-
chilis : but having nothing important to add concerning
them, the definitions of those terms will give you a suf-
ficiently clear idea of them'*. As they are common to
both sexes, if their use is connected with the sexual in-
tercourse, it must be similar to that which Treviranus
ascribes to the pectens of scorpions, they must be in-
struments of excitement.

And now, after this long discourse on the External
Anatomy and structure of these little beings, you may
think perhaps at first that the subject is exhausted ; and

* Treviranus, i<Ai sM^r. 14.

'• In my specimen including the first joint there are twenty, and
some seem to have been broken off. In Roemer's figure {Genera,
t. xxix. f. 11.) there are only ten. Perhaps they vary in number ac-
cording to the age of the animal.

' Plate XV. Fig. 13, 16, 17. " See above, p. 391 — .

EXTERNA!. ANATOMY OF INSFXTS. 719

that I must have discovered and described every part
and every variation of every part of the criist of an insect.
But when you go on to reflect what a comparatively
small number of these creatures have fallen imder my
examination, and in those, after all my laborious and
painful researches, from my limited faculties and other
imperfections of our common nature, how much will
probably have eluded my notice, you may conclude that
thousands of facts still remain concealed to reward the
patient assiduity of future investigators. Such are the
immensity and variety of the works of the Creator in
this department, that it would require a long life, and
fill volumes upon volumes, to discover and give a de-
scription of all the peculiarities of structure of the insects
that are already known ; and could all that exist * be so
studied and explained in full detail, the library that the
Calif Omar ordered to be burned at Alexandria could
scarcely have contained more books than would be re-
quired to receive the results. But " who is sufficient
for these things''?" This is a question that the most able
and most experienced physiologist must often feel dis-
posed to put to himself when, lost in the intricate laby-
rinth of the works of his Maker, he sees all things ar-
ranged, " wheel within wheel," in an order that he can
only jpartialli) unravel, instead of tracing the " regular
confusion" through all its windings. But glimpses of
light, and points of irradiation, here and there discover
to \\vci\ fragments, of the truth of things, and such vestiges

» I have heard it stated upon good authority that 40,000 species
of insects are already known, as preserved in collections. How great,
then, must be the number existing in this whole globe !

" 2 Cor. ii. 16.

720 EXTERNAL ANATOMY OF INSECTS.

of the grand system of the Deity, as enable him in some
degree to appreciate, and dispose him humbly to adore
that Wisdom, Power, and Goodness, that at first
created and now sustains in its full beauty and harmony

the WONDROUS WHOLE.

I am, &c.

END OF THE THIRD VOLUME.

Printed by Richard Taylor,
Shoe- Lane, London.

#

FUte^Pl.

r/.u.- /'u.

EXPLANATION OF THE PLATES'

PLATE VI."

FIG.

1 . Head of Mylabrix. Upper side, or face.
2. — Under side, or su/t/'acr.

3. Trophi of Dytiscus. Six pieces.

4. Head of Loc?w<rt. Face.

5. • Front view, to exhibit the mouth.

6. Trophi of ditto. »Spue« pieces.

7. Head of Cicada. Face.

8. Scutellera. Subfoce.

9. Trophi, or promusc is of Hemiptera. Three pieces.

10. Head of yK5/j«flf. Face.

11. ' ■ Front view.

12. Trophi of ditto. Seven pieces.

13. or antlia oi Lcpidopter a. Fo?<r pieces.

14-. of Panorpa. Three pieces.

PLATE VIL^

1. Head and trophi of PAr^ganea L. Face.
2. fespa Crabro. Ditto.

3. Trophi oi' Bombns.

4. Head of Tabanus L. Face.

5. Trophi or ;;ro6o5Cis of ditto. (Reaum.)
6. Bombylius'K

7. Head of Oxypteruvi . Face.

' Recourse must be had to the synoptical table of the nomencl-.i-
ture of the parts of the external crust of Insects (Vol. III. p. 354j for
the explanation of the reference letters not here ijiven.

" Vol. I. p. 3!)4-. III. p. 355-, 394-. IV. p^ 305—.

' Ibid. " Probably e' is resolvable into two pieces.

VOL. 711. 3 A

722 EXPLANATION OF THE PLATES.

FIG.

8. He^d of Piilex, with its antennae and trophi, or rostrulum.

Side view.
9. Araneidce, with the trunk.

10. Trophi of ditto.

11. Head of Scolopendra morsitans. Subface.

12. . — Front view, to show the

mouth.

13. Trophi of ditto.

!|4«. Pharynx of Pentatonia. (Savigny.)

PLATE VIII.'

1. Prothorax of L?/c«niW. a. Apex. b. Base, c d. Sides.

a. Disk.

2. Antepectus of ditto.

3. Alitrunk of ditto. Upper side. a. A piece between the

metathorax and metaphragm.

4. Under side.

5. Abdomen. Upper side, or tergum.

6. - Under side, or venter.

7. Antepectus of Hydrophilus piceus.

8. Alitrunk of ditto. Under side, to show the metasternum.

9. Abdomen of Dynastes Aloeus, to show the dorsal and

ventral spiracles.

10. Prothorax of Zocws^rt. a. Apex. b. Base. cc. Sides.

11. Antepectus of ditto, to show the prosternum.

12. Alitrunk of ditto. Upper side.
13. Under side.

14. ■ Lateral view. Vol. III. p, 4-8.

15. Abdomen of ditto. Lateral view.

16. Alitrunk of Cicada Latr. Upper side.

17. '——— — ^ Underside, a. The piece in the

9 corresponding to the drum-covers of the (J.
18,, Abdomen, and part of postpectus of ^ ditto. Under
,_^^e, to show the drums. Vol, II. p. 405 — .

Vol. III. p. 367-r-, 529—. IV. p. 326—.

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EXPLANATION OF THE PLATES. 723

FIO.

19. Abdomen, and part of postpectus of ^. Lateral view,

with the covers removed to show the machinery.

20. Alitrunk. Upper side. Peutaloma.

PLATE IX. »

1. Alitrimk of Cossus ligiiiperda. Upper side.

2. Part of ditto, to show the mesophragm.

3. ■ Under side.

4-. Fditagm oi Lepidoptera. Upper and under sides. Vol. IIL
p. 368, 539.

5. Tegula; of ditto. Tivo species. Vol, IIL p, 378.

6. Prothorax of JEshna. a. The base elevated and forming

an obtuse angle with the rest.

7. Alitrunk of ditto. Upper side. a. Two elevated areas

of the posterior parts of the collar, strengthened by a
marginal ridge and denticles, internally connected by
an elastic ligament, apparently to aid and sustain the
powerful action of the wing-muscles.

8. ■ Lateral view. a. A piece by which
the mid-leg is connected with the scapular. Vol. III.
p. 48, 565.

9. Part of the abdomen of Libellida^
10. Trunk of Semblis F, Upper side.

IL Alitrunk of Vespa Crahro. Upper side, a. Aperture in

the trunk for the passage of the ligament that elevates

the abdomen.
J2. Lateral view of ditto.
13. posterior part of ditto, and of the base of

the abdomen, to show the above apparatus, a. The

aperture. Vol. III. p. 701.
14'. Head and part of the manitrunk of Tenthredo L. to show

the membrane a. representing the prothorax. Vol. IIL

p. 550—.

" Vol. III. p. 367—, 529—. IV, p. 326-.
3a2

724 EXPLANATION OF THE PLATJPS.

FIG. Oil

15. Alitrunk of Xi/7%</m. Upper side. ,d lafosirA ob

16. Lateral view. J 0)9 )^^^i^■sf

17. Part of truok and abdomen of Formica, to* show' the

squama. Vol. III. p. 389. 3.
1 8, of Myrmicai to show the no-
dus. Vol. III. p. 389. 4.

19. Alitrunk oi Musca. Upper side. a. Alula or winglet.

20. Metathorax of ditto.

21. Alitrunk of ditto. Lateral view.

22. Abdomen of ditto. Venter.

PLATE. X.^

N.B. In this plate the red points out the costal, and the
yellotjo the anal areas, the intermediate being unco-

^««^^^- .-tiaaa .r

1^. Elytra, a. Base. b. Shoulder, c. Lateral margin,
d. Apex.

2. Tegmina. Blatta. i^v^^^^^^f^X^Sfiln^a .0 1

3. Hemelytra. Pentatoma J^^^T'^' ' " .yif^n^sS Jf

4. Wing. Coleoptera. a. An insulated nervuttt:- ' Vi>S.l Ilii

p. 625.

5. — — — Dermaptera.

6. Lepidoptera.

g. u_^ Hymenoptera. TenthreaoLi. -./^ <>

9. ■ Bombus. , ,,

10. Under wing. Hymenoptera. 'RVBiO i^

11. ^ _ Proctotrupes. \^^^-^ )^

12. — — — Diptera. Tipula. , rj -^

13. Psychoda. Vol. IIL p. 645.

14. '— Musca. a b. Two areolets be-
tween the costal and mediastinal nervures. c. Areolet
between the mediastinal and postcostal nervures.

Vol. II. p. 347—. HI. p. 372—, 595-.

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EXPLANATION Or TIIK Pf.ATES.

72.'5

d. Areolet between the postcostal nnd subcostal ncr-
vures. e. Open areolet. Vol. III. p. 634.
Under wing. Diptcra. Sfrati/otnis. ab. The two arco-
lets between the costal and postcostal nervurcs ; the
mediastinal being nearly obsolete, c. Middle areolets
crowned by a small one, d,

PLATE XL" Antenna.

FIG.

FIG.

1. Setaceous.

13. Distichous,

2. Capillary.

14. Pectinate.

3. Filiform.

15. Duplicato-pectinate.

4, Incrassate.

16. Ciliate.

a. Fusiform.

17. Flabellate.

6. Prismatic.

18. Ramose.

7. Ensiform,

19. Furcate.

8. Falciform.

20. Auriculatc. a. The auricle.

9. Moniliform.

21. Palmate.

10. Dentate.

22. Irregular.

11. Serrate.

23. Perfoliate.

12. Imbricate.

PLATE XII. Antenna.

FIG.

1. Capillaceous.

2. Mucronate.

3. Uncinate.

4. Clavate.

5. Nodose, or Biclavate.

6. Convolute.

7. Geniculate.

8. Capitate with a tunicate

knob.

FIG.

9. Capitate with a solid
knob.

10. Capitate with a perfo-

liate knob.

11. Filiform.

12. Globiferous.

13. Connate.
14.-

/"ISetige
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rous.

Vol.. III. p. 366, 510— IV. p. .iie-

726

EXPLANATION OF THE PLATES.

FIG.

16. Subulate.

''\ Filate, simple.
18./ ^

19. Filate, compound.

a. Joints.

20. Filate.

21. Aristate. Setarious,

a. Bristle.

22. Aristate. Plumate.

a. Bristle.

FIG.

23.

24.
25.
26.

27.
28.

Stupeous. Vol. III.

p. 6i6.
Plumose.

Scopiferous. a. Brush.
Barbate.
Verticillate.
Inflated.
29. Auriculate. a. Auricle.

PLATE XIII. »

1. Unguiculate feeler. Gonyleptes. a. Claw.

2. Securiform ditto. Cychrus. a. Terminal joint,

3. Inflated ditto. Araneid^ $. a. ditto.

4. Lunulate ditto. Oxyporiis. a. ditto.

5. Dentate mandible. Megachile.

6. Suctorious ditto. Larva of Dytiscus. a. Aperture,

7. Prosthecate ditto, Staphijliniis. Vol. III. pp, 356, 439.

8. Trophi of Curcidio L.

9. Pedunculate eyes. Diopsis.

10. Compound ditto. Muscidce.

11. Conglomerate ditto, luius.

12. Rostrate head. Balaninus.

13. Capistrate ditto. Nitidula.

14. Clypeate ditto. Copris.

15. Lychnidiate ditto, Fidgora.

16. Buccate ditto. Myops. a. The inflated part.

17. Cruciate prothorax. Loaista.

18. Cucullate and alate ditto. Tingis.

19. Subulate elytra, Sitaris.

20. Ampliate ditto, Lycus.

a. Footstalk.
Vol. III. p. 494. 3.
Ibid, p, 494. 2.

Vol, IV p. 307. iii. iv, 309. b, 310. d, 313. viii, .328, 334,

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EXPLANATION OF THE PLATES. 727

PLATE XIV. ^

FIG.

1. Ideal wing, to exemplify painting. Vol. IV. p. 286 — .

a. Anterior or exterior margin, b. Interior ditto.
c. Posterior ditto, d. Humeral angle, e. Scutellar
ditto, f. Posterior ditto, g. Anal ditto, a. Articulate
Jciscia, or band, b. Macular ditto, c d. Sesquialterous
ditto, dc. Sesquitertious ditto, f. Dimidiate ditto.
g. Abbreviate ditto, h. Pyramidate ditto, i. Super-
cilium. k. Hastate pupil. /• Compound eyelet or
ocellus, in. Nictitant ditto, n. Simple ditto, o. An-
nulet, p. Bipupillate eyelet, q. Sesquialterous ditto.
r. Double ditto, s. Caudate wing. t. Pupil, u. Iris.
V. Atmosphere.

2. Reversed wings. Gastrophaca.
'i. Digitate ditto. Pterodactylus .
V. Falcate ditto. Attacus.

5. Saltatorious leg, with loricate thigli. Locusta.

6. Natatorious ditto, Dytiscus.

7. Ambulatorious ditto. Lucanus.
S. Prehensorious ditto. Gonyleptcs.

PLATE XV. ••

1 . Laminate coxa. Haliplus.

2. Alate tibia. Lygceus phyllopus , a. The appendage.

3. Clypeate ditto. Crabro S- ^- ^'^^ clypeus. Vol. III.

p. 334-.

4. Dolabriform ditto. Curculio maritimus E.B.

5. Fossorious leg, with palmate tibia. Clivina. Vol II.

p. 365,

6, ■ with digitate ditto. Gryllotalpa. Ibid.

p. 366.

7. Chelate feeler. Scorpio.

8. Scutate tarsus. Hydrophilus picetis $. Vol, III. p. 336,

9. Patellate ditto. Dytiscus marginalis $. a. Cups, Ibid,

p. 336, 694—.

» Vol. IV. p. 286—, 3.38, 345—. ' Ibid. p. 345-, .350-.

728 EXPLANATION OF THE PLATES.

FIG.

10. Obumbrate abdomen. Epeira cancriformis.

11. Retracted ditto. Gonylqotes.

12. Cheliferous tail. Panorpa (J.

13. Flosculiferous ditto. Fulgora.

14. Saltatorious ditto. Podura.

15. Folioliferous ditto. Mshna.

16. Cauduliferous, and filiferous ditto. MachUis

17. Styliferous ditto. Staphylinus.

18. Unciferous ovipositor. Locusta.

19. Ensate ditto. Acrida.

20. Navicular ditto. Cicada.

21. Serrulate ditto. Tenth redo L.

22. Telescopiform ditto. Chrysis,

23. Anal apparatus of Blatta.

PLATE XVI. »

1 . Extricated ovipositor. Pimpla, Two pieces.

2. Telescopiform ditto. Stomoxys calcitrans? {"R-ezum.)

3. (Estrus. (Ibid.) Vol. I. p. 150.

4. Semicomplete pupa, Cicada.

5. Subsemicomplete ditto. Libelltda. a. Mask. Vol. III.

p. 125—.

6. Incomplete ditto. Hydrophilu.s. (Lyonnet.)

7. ■. A/yn»e/eo7z emerging from its cocoon.
(Reaum.)

8. — — — — Vcspa vtdgaris.

9. Chironomus plumosus. (Reaum.)

a b. Respiratory plumes.
1 0. Obtected pupa. Apatura Iris.
11. Vajiessa UrticcB. a. Head-case with

tivo points.
12. Gonepteryx Rhamni. a. Head-case with

one point.

' Vol. IV. p. 351. ii. III. Letter XXXII. Voi. I. p. 05—.

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EXPLANATION OF THE PLATES. 721>

FIG.

13. Obtected pupa. Sphitix Ligustri. a. The tongue-case.
h. The eye-case. c. The trunk-case. d. First segment
of the abdomen, e. The adminicula. J'. The mucro,
or point of tl>e tail. Vol. III. p. 549 — .

l-t. Hairy obtected pupa of Lariajascelina.

PLATE XVII. ^

1. Coarctate pupa. CEstrns hcvmorrhaidalis. (Rcaum.)

2. Utratyomis chamcpleon. (Ibid.) a. Tlie

pupa as formed within the skin of the larva.

4'. Oviform body which many pupa: of Diptera at first as-
sume under the skin of the larva. (Ibid.) Vol. III.
p. 235.

3. The same when the parts begin to show themselves.
(Ibid.)

5. Cocoon of Saturnia pavonia. a. Pupa. b. Threads that

close the orifice. Vol. III. p. 217, 279.

6. Loose and irregular ditto, of Ardia villica. Ibid. p. 220.
7- Boatshaped ditto, of Tortrix prasinana. Ibid. p. 221.

8. Network ditto, attached to the stalk of a plant.

9. Ditto, imitating the scales of fish. (Reaum.) Vol. I.

p. 462.

10. Spiral case of Trichopterous larva, formed of pieces of
'■ leaf. (De Geer.)

11. Grate spun by these larvae to prevent ingress. (Ibid.)

V^ol. II. p. 264.

12. Chilopodimorphous larva of Mclolontha vulgaris. Vol.

III. p. 163.

13. Araneidiform ? ditto of Cicindela campestris. Ibid. 152,

163.

Mm^y PLATE XVIIL "

1. Anopluriuiorphous larva. Chrysomeln Populi. n. Osvin-
ieria, orsceiit organs. Vol. II. p. 245. HI. p. 163, 166.

• U6i iupr. " Vor,. III. Letter XXXL

vol. iir. 3 b

730 EXPLANATION OF THE PLATES.
FIG.

2. Anoplurimorphous larva. Cassida. a. The fecifork co-

vered with excrement. Vol. IV. p. 353. 5.

3. Helminthimorphous or vermiform ditto o? Balaninus Nu-

cum. Vol. III. p. 163.

4. Chilognathimorphous ditto of £/a/er /Seg-efwrn. a, c. Spi-

racles.

5. Decapodimorphous ditto o^Dytiscus marginalis. Vol. III.

p. 165.

6. Chilopodimorphous ditto of Staphylinus? a. Anal pro-

leg.

7. Amphipodimorphous ditto of Acrida. Vol. III. p. 165.

8. Larva of Zelus.

9. Helminthimorphous ditto. Apis mellifica. (Reaum.)

10. Larva of Sirex.

11. - Tenthredo L. (Reaum.) a. 6 legs. L 16 pro-
legs.

12. ' ■— Sphinx, a. 6 legs. 6. lOprolegs. c. Anal horn.

1 3. Spinose ditto of Vanessa lo.

PLATE XIX. ^

1. haxva, of Papilio Machaon. a. Its retractile osmaterium

emerging from its neck. Vol. II. p. 244 — . III.
p. 148.

2. Larva of Cerura Vinula. a. Its anal mastigia. Vol. III.

p. 151.

3. Onisciform ditto of Thecla Rubi.

4. Larva of Stauropus Fagi. (Rosel.) Vol. III. p. 133.

note ■*.

5. . ■ Notodonta ziczac. (Reaum.)

6. i Laria fascelina. a. Pencil of hairs, b. Ver-

ricules of ditto, c. Fascicule of ditto. Vol. IV. p. 277.
3, 5, 7.

7. of one of the Geometers in their attitude of

surveying.

• Vol. III. Letter XXXI.

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EXPLANATION OF THE FLATES. 7^1

FIG,

8. Arancidiform larva of iVyrw;f/('o«. (Reaum.)

9. Larva of Culex pipiens. (lleaum.) a. Tail. b. Respi-

ratory apparatus.

10. of C/iiro)iomiis plumosus. (Reaum.) a. Respira-
tor}' organs.

11. of a Voliicella inhabiting the nests of humble-bees.

(Reaum.) a. Anal radii.

12. of Elophiliis pcndulus. (Reaum.) «. Respiratory

tubes.

13. of Stratyomis Chamceleon. (Swamm.) a. Plumes

\ of respiratory orifice.

PLATE XX. *

1. Larva of a Musca.

2. an (Estrus.

3. Egg of Vanessa Urticce. (Sepp.)

4'. Hipparchia Pilosellce. (Ibid.)

5. ■ ■ — Hyperanthus. (Ibid.)

6. Geometra Cratcegata. (Ibid.)

7. Pier is Brassicce. (Ibid.)

8. ■ Hipparchia jEgeria. (Ibid.)

9. • Ourapteryx Sambucaria. (Ibid.)

10. • Nociua nupta. (Ibid.)

11. ■ — Fraxini. (Ibid.)

12. Geometra prunaria . (Ibid.)

13. ■ ■ armillata. (Ibid.)

14. Lasiocampa neustria. (Reaum.)

15. Hipparchia Jurtina. (Sepp.)

16. Pentatorna. a. Bow-shaped spring, by which

the operculum is thrown off. Vol. III. p. 104.

17. Apis mellifica. (Reaum.)

18. — — ^ Culex pipiens. (Ibid.) a. Summit.

19. Scatophaga. (Ibid.) a a. Auricles.

* Ubi supr. and Letter XXX.

732 EXPLANATION OF THE PLATES.

FIG.

20. Necklace of eggs. Vol. III. p. 67. '

21. Egg of Tipula oleracea. (Reaum.)

22. Ophion luteum. (De Geer.) Vol. IV. p. 213 — .

23. - Nepa cinerea. (Swamm.)

24'. Jelly, wifh a necklace of eggs running in a spiral direc-
tion from end to end, taken out of the water.
25. Jelly of more consistence, enveloping the eggs oi Phry-
Vol III. p. 68.

Printed by Richard Taylor,
Shoe-Lane, London.

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