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EDITED BY

EDWARD B. POULTON, M.A, F.R.S.

HOPE PROFESSOR OF ZOOLOGY IN THE UNIVERSITY OF OXFORD

Orford
PRINTED FOR PRIVATE CIRCULATION

BY HORACE HART, PRINTER TO THE UNIVERSIi ¥

1897

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1502 1897

BDITED BY

EDWARD B’ POULTON, Wea JEG aS)

HOPE PROFESSOR OF ZOOLOGY IN THE UNIVERSITY OF OXFORD

Orford
PRINTED? FOR PRIVALE, CIREULATION

BY HORACE HART, PRINTER TO THE UNIVERSITY

1897

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PREEACGE

Ture Hope Department is not likely to contribute
largely to the preparation for examinations which is at
present the most conspicuous function of the University
and Colleges of Oxford. It is hoped that public lectures,
delivered from time to time, may act as some incentive
towards the study of natural history, and that, out of
the numerous subjects of the Final Honour School in
Animal Morphology, those few which can be appropriately
illustrated from the Hope Collections, may be usefully
expounded in short courses.

The chief duty of the Department must always be
the care and the proper arrangement and display of the
vast collection of insects of all orders which we owe in
the first place to the munificence of the Rev. Frederick
William Hope. From the discharge of this duty, if it
is to be discharged adequately, results must follow which,
it is claimed, give to the Department a meaning and
significance in the life of our ancient University. In the
present state of Zoological Science, it is impossible to make
use of existing knowledge in the careful study of a large
amount of material without adding to that knowledge.
Research after the various kinds of knowledge which have
been prized by mankind during successive ages was of
old the prominent function of the University; and
although obscured during the recent generations by

4 PREFACE

excessive devotion to the examination system, may still
be claimed as an academic duty and high privilege second
to no other in importance. And signs are not wanting
that the University of Oxford is in this respect tending
towards the ancient ideals, and, while unwilling to yield
any of the obvious advantages of modern educational
systems, is also inclined to encourage learning and original
research.

I therefore determined to follow the example of my
friend and colleague the Linacre Professor, and issue from
time to time volumes of Reports from the Department,
containing reprints of the various memoirs which have
been written in connexion with it. The present volume,
the first of the series of Hope Reports which I trust will
follow, is the outcome of four years’ work. During these
years much time and attention has been occupied in
obtaining increased space and warmth, as well as many
other improvements which the growth of the collections
had rendered necessary. It is therefore to be expected
that the succeeding volumes will appear at shorter intervals,
now that these improvements have been effected.

The lines of research which can be favourably pursued
in the Hope Department are, in addition to the investiga-
tion of insect form, function, and classification, those
general sides of Zoological Science for which insects
afford some of the best illustrations—such wide subjects
for instance as evolution, natural selection, variation, and
the numerous problems included in the phrase relation
to environment.

The memoirs dealing with these latter subjects, being
of more general interest, are placed first in the following
arrangement, and, while the works of each author are
kept together, those which deal with general subjects are
in each case placed first. Two memoirs, No. 6 and

PREFACE 5

No. 12, describe work which was done before June, 1893,
but publication itself took place after that date. In all
Other cases, as well as in a large part of No» 12, the
researches were conducted between June, 1893, and the
present date.

The Reports of the Department for the years 1895
and 1896 are included as Nos. 18 and 19. It is intended
to include the Reports of all future years in the forth-
coming volumes, so that a continuous account of the
progress of the Department will be registered.

This volume, and still more the volumes which will
follow, are the evidence that the Hope Department is
a centre of activity, and counts as one of the forces which
are doing important academic work in Oxford, even
though its part in teaching for examinations must be
a small one.

The Plate at the beginning of this volume represents
the makers of the Hope Department—the Rev. Frederick
William Hope, F.R.S., who presented his vast collections
and complete entomological library to the University,
founded the Chair, and continued until his death to
purchase fresh materials to add to those which he had
already given; Ellen Hope, his wife, who carried on the
work, purchasing and presenting many collections of
the utmost value, endowed the Keepership of Engraved
Portraits, the Collections, and Library, and added to the
endowment of the Chair; and John Obadiah Westwood,
the first Hope Professor, whose great name and fame
enriched the Hope Collections from all parts of the world,
who added largely to them from his own private collec-
tions, and described an immense number of species, the
types of which are among the most valued treasures of
the Department.

I have to thank Mr. Alfred Robinson, of the Museum,

6 PREFACE

for his skilful and careful work in preparing the design
which surrounds the three portraits. The insects repre-
sented were described and figured by Professor Westwood
in the ‘Thesaurus Entomologicus, and their types are in
the Hope Department. The uppermost insect is Euchrysia
eleptidea, from Adelaide (Plate X XVI) View Bom tie
‘Thesaurus’): that on the left side is Solenura telescopica,
from Java (Plate X XVI, Fig. 10). Both thesesmsect
are much enlarged, the originals being minute parasitic
Hymenoptera belonging to the Chalcididae. The butterfly
on the right side is Hesperia (Oxynetra) Zambesiaca, from
the Zambesi (Plate XX XIV, Fig. 9). It is of the natural
size. The left-hand beetle is Chlamydopsis duboulai, from
Australia (Plate III, Fig. 7), the right hand Zygaenodes
diopsideus, captured by Dr. A. R. Wallace at Sarawak,
Borneo (Plate V, Fig. 5). Both are represented many
times the natural size. ;

The portraits were reproduced from engravings of
Mr. and Mrs. Hope and a photograph of Professor
Westwood, all kindly lent for the purpose by Miss
Swann.

EDWARD B. POUEGORM
Hore DrerariMENT OF ZOoOLcGy,

Univrrsiry Museum, Oxrorp,
June 14, 1897.

CONTENDS: OF VOL 4

. Preface.

. A Naturalist’s contribution to the Discussion upon the Age of the Earth,
by Edward B. Poulton, Hope Professor. (The Presidential Address
to the Zoological Section of the British Association at Liverpool,
1896; from the ‘ Report of the Meeting.’)

. Theories of Evolution, by Edward B. Poulton. (Address in opening
a discussion at the Meeting of the Boston Society of Natural History,
Feb. 7, 1894; from the ‘Proceedings of the Society,’ vol. xxvi,

Pp. 371-)
. A Remarkable Anticipation of Modern Views on Evolution, by Edward
B. Poulton. (From ‘Science Progress,’ April, 1897.)

. On the Courtship of certain European Acridiidae, by Edward B.
Poulton. (From ‘Transactions of the Entomological Society of
London,’ 1896, p. 233-)

. The Experimental Proof that the Colours of certain Lepidopterous
Larvae are largely due to modified Plant Pigments derived from
food, by Edward B. Poulton. (From ‘Proceedings of the Royal
Society,’ 1893, vol. liv, p. 417.)

. On the sexes of Larvae emerging from the successively laid eggs of
Smerinthus populi, by Edward B. Poulton. (From ‘Transactions
of the Entomological Society of London,’ 1893, p, 451.)

. Mr. Merrifield’s Experiments in Temperature Variation as bearing on
' Theories of Heredity, by Frederick A. Dixey, M.A., M.D., F.E.S.,
Fellow of Wadham College, Oxford. (From ‘Transactions of the
Entomological Society of London,’ 1894, p. 439-)

. Remarks on Mr. Merrifield’s later researches, by Frederick A. Dixey.
(From ‘Proceedings of the Entomological Society of London,’ March,
1895.)

CONTENTS OF OL

Io.

18,

On the Relation of Mimetic Characters to the Original Form (Abstract),
by Frederick A. Dixey. (From ‘ Report of the Meeting of the British
Association at Oxford,’ 1894.)

. On the Relation of Mimetic Characters to the Original Form, by

Frederick A. Dixey. (From ‘Transactions of the Entomological
Society of London,’ 1896, p. 65.)

. On the Phylogeny of the Pierinae, by Frederick A. Dixey. (From

‘Transactions of the Entomological Society of London,’ 1894,
Pp: 249.)

. On Walker's American types of Lepidoptera in the Oxford University

Museum, by W. Schaus, F.Z.S. (From ‘Proceedings of the
Zoological Society of London,’ 1896, p 634.)

. The Habits and Respiratory Mechanism of Corystes cassivelaunus, by

W. Garstang, M.A., Fellow of Lincoln College, Oxford. (From
‘Journal of the Marine Biological Association, N.S., vol. iv,
No. 3, August, 1896.)

. The Function of Antero-lateral Denticulations of the Carapace in

Sand-burrowing Crabs, and the Systematic Features, Habits, and
Respiratory Phenomena of Portumnus nasutus (Latreille), by
W. Garstang. (From ‘Journal of the Marine Biological Association,’
N.S., vol. iv, No. 4, March, 1897.)

. The Morphology of the Mollusca, by W. Garstang. (From ‘Science

Progress,’ vol. v, March, 1896.)

. Report of the Hope Professor of Zoology for 1895. (From the

‘Oxford University Gazette.’)

Report of the Hope Professor of Zoology for 1896. (From the
‘ Oxford University Gazette.’)

DBrifish Associafion for fhe Rdvancement! of
Sctence.

LIVERPOOL, 1896.

ADDRESS

TO THE

ZOOLOGICAL SECTION

BY

Proressor E. B. POULTON, M.A., F.R.S., F.LS.,

PRESIDENT OF THE SECTION,

A NATURALIST’s CONTRIBUTION TO THE DISCUSSION UPON THE AGE OF
THE HARTH.

A very brief study of the proceedings of this Section in bygone years will show
that Presidents have exercised a very wide choice in the selection of subjects. At
the last Meeting of the Association in this city in 1870 the Biological Section had as
its President the late Professor Rolleston, a man whose remarkable personality
made a deep impression upon all who came under his influence, as I have the
strongest reason for remembering, inasmuch as he was my first teacher in zoology,
and I attended his lectures when but little over seventeen, His address was most
characteristic, glancing over a great variety of subjects, literary as well as scientific,
and abounding in quotations from several languages, living and dead. A very
different style of address was that delivered by the distinguished zoologist who
presided over the Meeting. Professor Huxley took as his subject ‘The History of
the Rise and Progress of a Single Biological Doctrine.’

Of these two types I selected the latter as my example, and especially desired
to’attempt the discussion, however inadequate, of some difficulty which confronts
the zoologist at the very outset, when he begins to reason from the facts around
him—a difficulty which is equally obvious and of equal moment to the highly
trained investigator and the man who is keenly interested in the results obtained
by others, but cannot himself lay claim to the position and authority of a skilled
observer—to the naturalist and to one who follows some other branch of know-
ledge, but is interested in the progress of a sister science.

Two such difficulties were alluded to by Lord Salisbury in his interesting presi-
dential address to the British Association at Oxford in 1894, when he spoke of
‘two of the strongest objections to the Darwinian explanation’ of evolution—viz.
the theory of natural selection—as appearing ‘ still to retain all their force.’ The
first of these objections was the insufliciency of the time during which the earth
has been in a habitable state, as calculated by Lord Kelvin and Professor Tait,
100 million years being conceded by the former, but only 10 million by the latter.
Lord Salisbury quite rightly stated that for the evolution of the organic world as
we know it by the slow process of natural selection at least many hundred
million years are required; whereas, ‘if the mathematicians are right, the biologists
cannot have what they demand. . . . The jelly-fish would have been dissipated in
steam long before he had had a chance of displaying the advantageous variation
which was to make him the ancestor of the human race.’

The second objection was that ‘ we cannot demonstrate the process of natural
selection in detail; we cannot even, with more or less ease, imagine it.’ ‘In
natural selection who is to supply the breeder’s place?’ ‘There would be nothing

D

9 | REPORT—1896.

but mere chance to secure that the advantageously varied bridegroom at one end
of the wood should meet the bride, who by a happy contingency had been advan-
tageously varied in the same direction at the same time at the other end of the
wood. It would be a mere chance if they ever knew of each other’s existence—a
still more unlikely chance that they should resist on both sides all temptations to
a less advantageous alliance. But unless they did so the new breed would never
even begin, let alone the question of its perpetuation after it had begun.’

Professor Huxley, in seconding the vote of thanks to the President, said that
he could imagine that certain parts of the address might raise a very good dis-
cussion in one of the Sections, and I have little doubt that he referred to these
criticisms and to this Section. When I had to face the duty of preparing this
address, I could find no subjects better than those provided by Lord Salisbury.

At first the second objection seemed to offer the more attractive subject. It
was clear that the theory of natural selection as held by Darwin was misconceived
by the speaker, and that the criticism was ill-aimed. Darwin and Wallace, from the
very first, considered that the minute differences which separate individuals were
of far more importance than the large single variations which occasionally arise—
Lord Salisbury’s advantageously varied bride and bridegroom at opposite ends of the
wood. In fact, after Fleeming Jenkins’s criticisms in the ‘ North British Review’
for June 1867, Darwin abandoned these large single variations altogether. Thus
he wrote in a letter to Wallace (February 2, 1869): ‘ I always thought individual
differences more important ; but I was blind, and thought single variations might
be preserved much oftener than I now see is possible or probable. I mentioned
this in my former note merely because I believed that you had come to a similar
conclusion, and I like much to be in accord with you.’? Hence we may infer that
the other great discoverer of natural selection had come to the same conclusion at
an even earlier date. But this fact removes the whole point from the criticism
I have just quoted. According to the Darwin-Wallace theory of natural selection,
individuals sufficiently advantageously varied to become the material for a fresh
advance when an advance became necessary, and at other times sufficient to main-
tain the ground previously gained—such individuals existed not only at the
opposite ends of the wood, but were common enough in every colony within its
confines. The mere fact that an individual had been able to reach the con-
dition of a possible bride or bridegroom would count for much. Few will dispute
that such individuals ‘have already successfully run the gauntlet of by far the
greatest dangers which beset the higher animals [and, it may be added, the lower .
animals also |—the dangers of youth. Natural selection has already pronounced a
satisfactory verdict upon the vast majority of animals which have reached
maturity.’ *

But the criticism retains much force when applied to another theory of evolution
by the selection of large and conspicuous variations, a theory which certain writers
have all along sought to add to or substitute for that of Darwm. Thus Huxley
from the very first considered that Darwin had burdened himself unnecessarily in
rejecting per saltum evolution so unreservedly. And recently this view has been
revived by Bateson’s work on variation and by the writings of Francis Galton. I
had at first intended to attempt a discussion of this view, together with Lord
Salisbury’s and other objections which may be urged against it ; but the more the
two were considered, the more pressing became the claims of the criticism alluded
to at first—the argument that the history of our planet does not allow sufficient
time for a process which all its advocates admit to be extremely slow in its
operation. I select this subject because of its transcendent importance in relation
to organic evolution, and because I hope to show that the naturalist has something
of weight to contribute to the controversy which has been waged intermittently
ever since Lord Kelvin’s paper ‘On Geological Time’ * appeared in 1868. It has
been urged by the great worker and teacher who occupied the Presidential Chair

1 Life and Letters, vol. iii. 2 Poulton, Colours of Animals, p. 308.

% See his letter to Darwin, November 23, 1859: Life and Letters, vol. ii.

4 Trans. Geol. Soc., Glasgow, vol. iii. See also ‘On the Age of the Sun’s Heat,’
Macmillan, March 1862: reprinted as Appendix to Thomson and Tait, Vatwral Philo-

TRANSACTIONS OF SECTION D. 3

of this Association when it last met in this city that biologists have no right to
take part in this discussion. In his Anniversary Address to the Geological So-
ciety in 1869 Huxley said: ‘ Biology takes her time from geology. ... If the
geological clock is wrong, all the naturalist will have to do is to modify his
notions of the rapidity of change accordingly.’ This contention is obviously true
as regards the time which has elapsed since the earliest fossiliferous rocks were laid
down. For the duration of the three great periods we must look to the geologist ;
but the question as to whether the whole of organic evolution is comprised within
these limits, or, if not, what proportion of it is so contained, is a question for the
naturalist. The naturalist alone can tell the geologist whether his estimate is sufli-
cient, or whether it must be multiplied by a small or by some unknown but cer-
tainly high figure, in order to account for the evolution of the earliest forms of
life known in the rocks, This, I submit, is a most important contribution to the
discussion.

Before proceeding further it is right to point out that obviously these argu-
ments will have no weight with those who do not believe that evolution is a
reality. But although the causes of evolution are greatly debated, it may be
assumed that there is no perceptible difference of opinion as to evolution itself, and
this common ground will bear the weight of all the zoological arguments we shall
consider to-day.

It will be of interest to consider first how the matter presented itself to
naturalists before the beginning of this controversy on the age of the habitable
earth. I will content myself with quotations from three great writers on biological
problems—men of extremely different types of mind, who yet agreed in their
conclusions on this subject.

In the original edition of the ‘ Origin of Species’ (1859), Darwin, arguing from
the presence of trilobites, Nautilus, Lingula, &c., in the earliest fossiliferous rocks,
comes to the following conclusion (pages 306, 307) : ‘Consequently, if my theory
be true, it is indisputable that before the lowest Silurian stratum was deposited
long periods elapsed, as long as, or probably far longer than, the whole interval
from the Silurian age to the present day; and that during these vast yet quite
unknown periods of time the world swarmed with living creatures.’

The depth of his conviction in the validity of this conclusion is seen in the fact
that the passage remains substantially the same in later editions, in which, how-
ever, Cambrian is substituted for Silurian, while the words ‘ yet quite unknown’
are omitted, as a concession, no doubt, to Lord Kelvin’s calculations, which he
then proceeds to discuss, admitting as possible a more rapid change in organic life,
induced by more violent physical changes.’

We know, however, that such concessions troubled him much, and that he
was really giving up what his judgment still approved. Thus he wrote to
Wallace on April 14, 1869: ‘Thomson’s views of the recent age of the world have
been for some time one of my sorest troubles... .’ And again, on July 12,
1871, alluding to Mivart’s criticisms. he says: ‘I can say nothing more about
missing links than what I have said. JI should rely much on pre-Silurian times ;
but then comes Sir W. Thomson, like an odious spectre.’

Huxley’s demands for time in order to account for pre-Cambrian evolution, as
he conceived it, were far more extensive. Although in 1869 he bade the
naturalist stand aside and take no part in the controversy, he had nevertheless
spoken as a naturalist in 1862, when, at the close of another Anniversary Address
to the same Society, he argued from the prevalence of persistent types ‘that any
admissible hypothesis of progressive modification must be compatible with per-
sistence without progression through indefinite periods;’ and then maintained
that ‘should such an hypothesis eventually be proved to be true . . . the conclusion
will inevitably present itself that the Palseozoic, Mesozoic, and Cainozoic faune

sophy, vol. i. part 2, second edition; and ‘On the Secular Cooling of the Earth,’
Royal Society of Edinburgh, 1862. 6th ed. 1872, p. 286.
D2

4, REPORT—1896.

and flora, taken together, bear somewhat the same proportion to the whole series
of living beings which have occupied this globe as the existing fauna and flora do
to them,’

Herbert Spencer, in his article on ‘Tllogical Geology’ in the ‘ Universal
Review ’ for July 1859,' uses these words: ‘ Only the last chapter of the earth’s
history has come down to us. The many previous chapters, stretching back to a
time immeasurably remote, have been burnt, and with them all the records of life
we may presume they contained.’ Indeed, so brief and unimportant does Herbert
Spencer consider this last chapter to have been that he is puzzled to account for
‘such evidences of progression as exist’; and finally concludes that they are of no
significance in relation to the doctrine of evolution, but probably represent the
succession of forms by which a newly upheaved land would be peopled. He
argues that the earliest immigrants would be the lower forms of animal and
vegetable life, and that these would be followed by an irregular succession of
lugher and higher forms, which ‘ would thus simulate the succession presented by
our own sedimentary series.’

We see, then, what these three great writers on evolution thought on this
subject: they were all convinced that the time during which the geologists con-
cluded that the fossiliferous rocks had been formed was utterly insufficient to
account for organic evolution.

Our object to-day is first to consider the objections raised by physicists against
the time demanded by the geologist, and still more against its multiplication by
the student of organic evolution ; secondly, to inquire whether the present state
of paleeontological and zoological knowledge increases or diminishes the weight of
the threefold opinion quoted above—an opinion formed on far more slender
evidence than that which is now availabie. And if we find this opinion sustained,
it must be considered to have a very important bearing upon the controversy.

The arguments of the physicists are three :—

First, the argument from the observed secular change in the length of the day
the most important element of which is due to tidal retardation. It has been
known for a very long time that the tides are slowly increasing the length of our
day. Huxiey explains the reason with his usual lucidity: ‘That this must be so
is obvious, if one considers, roughly, that the tides result from the pull which
the sun and the moon exert upon the sea, causing it to act as a sort of break upon
the solid earth.’ *

A liquid earth takes a shape which follows from its rate of revolution, and
from which, therefore, its rate of revolution can be calculated.

The liquid earth consolidated in the form it last assumed, and this shape has
persisted until now, and informs us of the rate of revolution at the time of con-
solidation. Comparing this with the present rate, and knowing the amount of
lengthening in a given time due to tidal friction, we can calculate the date of
consolidation as certainly less than 1000 million years ago.

This argument is fallacious, as many mathematicians have shown. The present
shape tells us nothing of the length of the day at the date of consolidation ; for
the earth, even when. solid, will alter its form when exposed for a long time to the
action of great forces. As Professor Perry said in a letter to Professor Parts
‘T know that solid rock is not like cobbler’s wax, but 1000 million years is a very
long time, and the forces are great.’ Furthermore, we know that the earth is always
altering its shape, and that whole coast-lines are slowly rising or falling, and that
this has been true, at any rate, during the formation of the stratified rocks.

This argument is dead and gone. Weare, indeed, tempted to wonder that the

' Reprinted in his Hssays, 1868, vol. i. pp. 324-376.

2 Anniv. Address to Geol. Soc. 1869. > Nature, Jan. 3, 1895.

* Tt must not be forgotten, however, that this argument and those which follow it
have done very good work in modifying the unreasonable demands of geologists a
quarter of a century ago.

¢
i

TRANSACTIONS OF SECTION D. 5

physicist, who was looking about for arguments by which to revise what he con-
ceived to be the hasty conclusions of the geologist as to the age of the earth,
should have exposed himself to such an obvious retort in basing his own con-
clusions as to its age on the assumption that the earth, which we know to be
always changing in shape, has been unable to alter its equatorial radius by a few
miles under the action of tremendous forces constantly tending to alter it, and
having 1000 million years in which to do the work.

With this flaw in the case it is hardly necessary to insist on our great uncer-
tainty as to the rate at which the tides are lengthening the day.

The spectacle presented by the geologist and biologist, deeply shocked at
Lord Kelvin’s extreme uniformitarianism in the domain of astronomy and cosmic
physics, is altogether too comforting to be passed by without remark; but in thus
indulging in a friendly tu qguoque, I am quite sure that I am speaking for every
member of this Section in saying that we are in no way behind the members of
Section A in our pride and admiration at the noble work which he has done for
science, and we are glad to take this opportunity of congratulating him on the
half-century of work and teaching—both equally fruitful—which has reached its
completion in the present year.

The second argument is based upon the cooling of the earth, and this is the
one brought forward and explained by Lord Salisbury in his Presidential Address.
It has been the argument on which perhaps the chief reliance has been placed, and
of which the data—so it was believed—were the least open to doubt.

‘On the Sunday during the meeting of the British Association at Leeds (1890),
I went for a walk with Professor Perry, and asked him to explain the physical
reasons for limiting the age of the earth to a period which the students of other
sciences considered to be very inadequate. He gave me an account of the data
on which Lord Kelvin relied in constructing this second argument, and expressed
the strong opinion that they were perfectly sound, while, as for the mathematics,
it might be taken for granted, he said, that they were entirely correct. He did
not attach much weight to the other arguments, which he regarded as merely
offering support to the second.

This little piece of personal history is of interest, inasmuch as Professor Perry
has now provided us with a satisfactory answer to the line of reasoning which so
fully satisfied him in 1890. And he was led to a critical examination of the sub-
ject by the attitude taken up by Lord Salisbury in 1894, Professor Perry was
not present at the meeting, but when he read the President’s address, and saw
how other conclusions were ruled out of court, how the only theory of evolution
which commands anything approaching universal assent was set on one side
because of certain assumptions as to the way in which the earth was believed to
have cooled, he was seized with a desire to sift these assumptions, and to inquire
whether they would bear the weight of such far-reaching conclusions. Before
giving the results of his examination, it is necessary to give a brief account of the
argument on which so much has been built.

Lord Kelvin assumed that the earth is a homogeneous mass of rock similar to
that with which we are familiar on the surface. Assuming, further, that the tem-
_ perature increases, on the average, 1° F. for every 50 feet of depth near the
surface everywhere, he concluded that the earth would have occupied not less
than twenty, nor more than four hundred, million years in reaching its present
condition from the time when it first began to consolidate and possessed a uniform
temperature of 7000° F.

If, in the statement of the argument, we substitute for the assumption of a
homogeneous earth an earth which conducts heat better internally than it does
toward the surface, Professor Perry, whose calculations have been verified by Mr. O.
Heaviside, finds that the time of cooling has to be lengthened to an extent which
depends upon the value assigned to the internal conducting power. If, for
instance, we assume that the deeper part of the earth conducts ten times as well
as the outer part, Lord Kelvin’s age would require to be multiplied by fifty-six.
Even if the conductivity be the same throughout, the increase of density in the

6 REPORT—1896.

deeper part, by augmenting the capacity for heat of unit volume, implies a longer
age than that conceded by Lord Kelvin. If the interior of the earth be fluid or
cantain fluid in a honeycomb structure, the rate at which heat can travel would
be immensely increased by convection currents, and the age would have to be
correspondingly lengthened. If, furthermore, such conditions, although not
obtaining now, did obtain in past times, they will have operated in the same
direction.

Professor Tait, in his letter to Professor Perry (published in ‘Nature’ of
January 3, 1895), takes the entirely indefensible position that the latter is bound
to prove the higher internal conductivity. The obligation is all on the other side,
and rests with those who have pressed their conclusions hard and carried them
far. These conclusions have been, as Darwin found them, one of our ‘ sorest
troubles’; but when it is admitted that there is just as much to be said for another
set of assumptions leading to entirely different conclusions, our troubles are at an
end, and we cease to be terrified by an array of symbols, however unintelligible to
us. It would seem that Professor Tait, without, as far as I can learn, publishing
any independent calculation of the age of the earth, has lent the weight of his
authority to a period of 10 million years, or half of Lord Kelvin’s minimum. But
in making this suggestion he apparently feels neither interest nor responsibility in
establishing the data of the calculations which he borrowed to obtain therefrom a
very ditferent result from that obtained by their author.

Professor Perry’s object was not to substitute a more correct age for that
obtained by Lord Kelvin, but rather to show that the data from which the true
age could be calculated are not really available. We obtain different results by
making different assumptions, and there is no sufficient evidence for accepting one
assumption rather than another. Nevertheless, there is some evidence which
indicates that the interior of the earth in all probability conducts better than the
surface. Its far higher density is consistent with the belief that it is rich in
metals, free or combined. Professor Schuster concludes that the internal electric
conductivity must be considerably greater than the external. Geologists have
argued from the amount of folding to which the crust has been subjected that
cooling must have taken place to a greater depth than 120 miles, as assumed in
Lord Kelvin’s argument. Professor Perry’s assumption would involve cooling to
a much greater depth.

Professor Perry’s conclusion that the age of the habitable earth is lengthened
by increased conductivity is the very reverse of that to which we should be led
by a superficial examination of the case. Professor Tait, indeed, in the letter
to which I have already alluded, has said: ‘ Why, then, drag in mathematics
at all, since it is absolutely obvious that the better conductor the interior in
comparison with the skin, the longer ago must it have been when the whole was
at 7000 F., the state of the skin being as at present?’ Professor Perry, in reply,
pointed out that one mathematician who had refuted the tidal retardation
argument 1 had assumed that the conditions described by Professor Tait would
have involved a shorter period of time. And it is probable that Lord Kelvin
thought the same; for he had assumed conditions which would give the result—
so he believed at the time—most acceptable to the geologist and _ biologist.
Professor Perry’s conclusion is very far from obvious, and without the mathematical
reasoning would not be arrived at by the vast majority of thinking men.

The ‘natural man’ without mathematics would say, so far from this being
‘absolutely obvious,’ it is quite clear that increased conductivity, favouring escape
of heat, would lead to more rapid cooling, and would make Lord Kelvin’s age even
shorter,

The argument can, however, be put clearly without mathematics, and, with
Professor Perry’s help, I am able to state it in a few words. Lord Kelvin’s
assumption of an earth resembling the surface rock in its relations to heat leads to
the present condition of things, namely, a surface gradient of 1° F. for every
50 feet, in 100,000,000 years, more or less. Deeper than 150 miles he imagines

1 Rev. M. H. Close in R. Dublin Soc., February 1878.

TRANSACTIONS OF SECTION D. Z

that there has been almost no cooling. If, however, we take one of the cases
put by Professor Perry, and assume that below a depth of four miles there is ten
times the conductivity, we find that after a period of 10,000,000,000 years the
gradient at the surface is still 1° F. for every 50 feet; but that we have to
descend to a depth of 1500 miles before we find the initial temperature of
7000° F. undiminished by cooling. In fact the earth, as a whole, has cooled
far more quickly than under Lord Kelvin’s conditions, the greater conductivity
enabling a far larger amount of the internal heat to escape; but im escaping it
has kept up the temperature gradient at the surface.

Lord Kelvin, replying to Professor Perry’s criticisms, quite admits that the age
at which he had arrived by the use of this argument may be insufficient. Thus,
he says, in his letter !: T thought my range from 20 millions to 400 millions was
reer wide enough, but it is quite possible that I should have put the superior
imit a good deal higher, perhaps 4,000 instead of 400.’

The third argument was suggested by Helmholtz, and depends on the life of
the sun. If the energy of the sun is due only to the mutual gravitation of its
parts, and if the sun is now of uniform density, ‘the amount of heat generated by
his contraction to his present volume would have been sufficient to last 18 million
years at his present rate of radiation.’* Lord Kelvin rejects the assumption of
uniform density, and is, in consequence of this change, able to offer a much higher
upward limit of 500 million years.

This argument also implies the strictest uniformitarianism as regards the sun.
We know that other suns may suddenly gain a great accession of energy, so that
their radiation is immensely increased. We only detect such changes when they
are large and sudden, but they prepare us to believe that smaller accessions may be
much more frequent, and perhaps a normal occurrence in the evolution of a sun.
Such accessions may have followed from the convergence of a stream of meteors.
Again, it is possible that the radiation of the sun may have been diminished
and his energy conserved by a solar atmosphere.

Newcomb has objected to these two possible modes by which the life of the
sun may have been greatly lengthened, that a lessening of the sun’s heat by under
a quarter would cause all the water on the earth to freeze, while an increase of much
over half would probably boil it all away. But such changes in the amount of
radiation received would follow from a greater distance from the sun of
154 per cent., and a greater proximity to him of 184 per cent., respectively.
Venus is inside the latter limit, and Mars outside the former, and yet it would be a
very large assumption to conclude that all the water in the former is steam, and
all inthe latter ice. Indeed, the existence of water and the melting of snow on Mars
are considered to be thoroughly well authenticated. It is further possible that in
a time of lessened solar radiation the earth may have possessed an atmosphere
which would retain a larger proportion of the sun’s heat ; and the internal heat of
the earth itself, great lakes of lava under a canopy of cloud for example, may have
played an important part in supplying warmth.

Again we have a greater age if there was more energy available than in
Helmholtz’s hypothesis. Lord Kelvin maintains that this is improbable because
of the slow rotation of the sun, but Perry has given reasons for an opposite
conclusion.

The collapse of the first argument of tidal retardation, and of the second of the
cooling of the earth, warn us to beware of a conclusion founded on the assumption
that the sun’s energy depends, and has ever depended, on a single source of which
we know the beginning and the end. It may be safely maintained that such a
conclusion has not that degree of certainty which justifies the followers of one
science in assuming that the conclusion of other sciences must be wrong, and in

disregarding the evidence brought forward by workers in other lines of research.

We must freely admit that this third argument has not yet fully shared the fate

1 Nature, January 3, 1895.
* Newcomb’s Popular Astronomy, p. 523.

8 REPORT—1896.

of the two other lines of reasoning. Indeed, Professor George Darwin, although
not feeling the force of these latter, agrees with Lord Kelvin in regarding 500
million years as the maximum life of the sun!

We may observe, too, that 500 million years is by no means to be despised: a
great deal may happen in such a period of time. Although I should be very sorry
to say that it is sufficient, it is a very different offer from Professor Tait’s
10 million.

In drawing up this account of the physical arguments, I owe almost everything
to Professor Perry for his articles in ‘ Nature’ (January 3 and April 18, 1895),
and his kindness in explaining any difficulties that arose. I have thought it right
to enter into these arguments in some detail, and to consume a considerable pro-
portion of our time in their discussion. This was imperatively necessary, because
they claimed to stand as barriers across our path, and, so long as they were admitted
to be impassable, any further pregress was out of the question. What I hope has
been an unbiassed examination has shown that, as barriers, they are more imposing
than effective; and we are free to proceed, and to look for the conclusions warranted
by our own evidence. In this matter we are at one with the geologists; for, as
has been already pointed out, we rely on them for an estimate of the time occupied
by the deposition of the stratified rocks, while they rely on us for a conclusion as to
how far this period is sufficient for the whole of organic evolution.

First, then, we must briefly consider the geological argument, and I cannot do
better than take the case as put by Sir Archibald Geikie in his Presidential Address
to this Association at Edinburgh in 1892.

Arguing from the amount of material removed from the land by denuding
agencies, and carried down to the sea by rivers, he showed that the time required
to reduce the height of the land by one foot varies, according to the activity of the
agencies at work, from 730 years to 6800 years. But this also supplies a measure
of the rate of deposition of rock; for the same material is laid down elsewhere,
and would of course add the same height of one foot to some other area equal in
size to that from which it was removed.

The next datum to be obtained is the total thickness of the stratified rocks
from the Cambrian system to the present day. ‘On a reasonable computation
these stratified masses, where most fully developed, attain a united thickness of
not less than 100,000 feet. If they were all laid down at the most rapid recorded
rate of denudation, they would require a period of seventy-three millions of years.
for their completion. If they were Jaid down at the slowest rate, they would
demand a period of not less than 680 millions.’

The argument that geological agencies acted much more vigorously in past
times he entirely refuted by pointing to the character of the deposits of which the
stratified series is composed. ‘ We can see no proof whatever, nor even any
evidence which suggests that on the whole the rate of waste and sedimentation
was more rapid during Mesozoic and Paleozoic time than it is to-day. Had there
been any marked difference in this rate from ancient to modern times, it would be
incredible that no clear proof of it should have been recorded in the crust of the
earth,’

It may therefore be inferred that the rate of deposition was no nearer the more
rapid than the slower of the rates recorded above, and, if so, the stratified rocks
would have been laid down in about 400 million years.

There are other arguments favouring the uniformity of conditions throughout
the time during which the stratified rocks were laid down, in addition to those
which are purely geological and depend upon the character of the rocks themselves.
eee more biological than geological, these arguments are best considered

ere.

The geological agency to which attention is chiefly directed by those who desire
to hurry up the phenomena of rock formation is that of the tides. But it seems

' British Association Reports, 1886, pp. 514-518,

TRANSACTIONS OF SECTION D. 9

certain that the tides were not sufficiently higher in Silurian times to prevent the
deposition of certain beds of great thickness under conditions as tranquil as any of
which we have evidence in the case of a formation extending over a large area,
From the character of the organic remains it is known that these beds were laid
down in the sea, and there are the strongest grounds for believing that they were
accumulated along shores and in fairly shallow water. The remains of extremely
delicate organisms are found in immense numbers, and over a very large area,
The recent discovery, in the Silurian system of America, of trilobites, with their
long delicate antennze perfectly preserved, proves that in one locality (Rome, New
York State) the tranquillity of deposition was quite as profound as in any locality
yet discovered on this side of the Atlantic.

There are, then, among the older Paleozoic rocks a set of deposits than which
Wwe can imagine none better calculated to test the force of the tides; and we find
that they supply evidence for exceptional tranquillity of conditions over a long
period of time.

There is other evidence of the permanence, throughout the time during which
the stratified rocks were deposited, of conditions not very dissimilar from those
which obtain to-day. Thus the attachments of marine organisms, which are per-
manently rooted to the bottom or on the shores, did not differ in strength from
those which we now find—an indication that the strains due to the movements
of the sea did not greatly differ in the past.

We have evidence of a somewhat similar kind to prove uniformity in the
movements of the air. The expanse of the wings of flying organisms certainly
does not differ in a direction which indicates any greater violence in the atmo-
spheric conditions. Before the birds had become dominant among the larger
flying organisms, their place was taken by the flying reptiles, the pterodactyls,
and before the appearance of these we know that, in Paleeozoic times, the insects
were of immense size, a dragon-fly from the Carboniferous rocks of France being
upwards of 2 feet in the expanse of its wings. As one group after another of
widely dissimilar organisms gained control of the air, each was in turn enabled to
increase to the size which was best suited to such an environment, but we find that
the limits which obtain to-day were not widely different in the past. And this is
evidence for the uniformity in the strains due to wind and storm no less than to
those due to gravity. Furthermore, the condition of the earth’s surface at present
shows us how extremely sensitive the flying organism is to an increase in the
_ former of these strains, when it occurs in proximity to the sea. Thus it is well
known that an unusually large proportion of the Madeiran beetles are wingless,
while those which require the power of flight possess it in a stronger degree than
on continental areas, This evolution in two directions is readily explained by the
destruction by drowning of the winged individuals of the species which can
manage to live without the power of flight, and of the less strongly winged indi-
viduals of those which need it. Species of the latter kind cannot live at all in the
far more stormy Kerguelen Land, and the whole of the insect fauna is wingless,

The size and strength of the trunks of fossil trees afford, as Professor George
Darwin has pointed out, evidence of uniformity in the strains due to the condition
of the atmosphere.

We can trace the prints of raindrops at various geological horizons, and in some
cases found in this country it is even said that the eastern side of the depressions
is the more deeply pitted, proving that the rain drove from the west, as the great
majority of our storms do to-day.

When, therefore, we are accused of uniformitarianism, as if it were an entirely
unproved assumption, we can at any rate point to a large body of positive evidence
which supports our contention, and the absence of any evidence against it.
Furthermore, the data on which we rely are likely to increase largely, as the result
of future work.

After this interpolation, chiefly of biological argument in support of the geolo-
gist, I cannot do better than bring the geological evidence to a close in the words
which conclude Sir Archibald Geikie’s address: ‘ After careful reflection on the
subject, I affirm that the geological record furnishes a mass of evidence which no

D3

10 REPORT— 1896. :

arguments drawn from other departments of Nature can explain away, and which,
it seems to me, cannot be satisfactorily interpreted save with an allowance of time
much beyond the narrow limits which recent physical speculation would concede.’

In his letter to Professor Perry,’ Lord Kelvin says :—

‘So far as underground heat alone is concerned, you are quite right that my
estimate was 100 million, and please remark * that that is all Geikie wants; but I
should be exceedingly frightened to meet him now with only 20 million in my
mouth.’

We have seen, however, that Geikie considered the rate of sedimentation to
be, on the whole, uniform with that which now obtains, and this would demand
a period of nearly 400 million years. He points out furthermore that the time
must be greatly increased on account of the breaks and interruptions which occur
in the series, so that we shall probably get as near an estimate as is possible from
the data which are available by taking 450 million as the time during which the
stratified rocks were formed.

Before leaving this part of the subject, I cannot refrain from suggesting a line
of enquiry which may very possibly furnish important data for checking the
estimates at present formed by geologists, and which, if the mechanical difficulties
can be overcome, is certain to lead to results of the greatest interest and importance,
Ever since the epoch-making voyage of the ‘Challenger,’ it has been known that
the floor of the deep oceans outside the shallow shelf which fringes the continental
areas is covered by a peculiar deposit formed entirely of meteoric and volcanic
dust, the waste of floating pumice, and the hard parts of animals living in the
ocean, Of these latter only the most resistant can escape the powerful solvent
agencies. Many observations prove that the accumulation of this deposit is
extremely slow. One indication of this is especially convincing: the teeth of sharks
and the most resistant part of the skeleton—the ear- bones—of whales are so thickly
spread over the surface that they are continually brought up in the dredge, while
sometimes a single haul will yield a large number of them. Imagine the count-
less generations of sharks and whales which must have succeeded each other in
order that these insignificant portions of them should be so thickly spread over
that vast area which forms the ocean floor. We have no reason to suppose that
sharks and whales die more frequently in the deep ocean than in the shallow
fringing seas; in fact, many observations point in the opposite direction, for
wounded and dying whales often enter shallow creeks and inlets, and not uncom-
monly become stranded. And yet these remains of sharks and whales, although
well known in the stratified rocks which were laid down in comparatively shallow
water and near coasts, are only found in certain beds, and then in far less abun-
dance than in the oceanic deposit. We can only explain this difference by supposing
that the latter accumulate with such almost infinite slowness as compared with
the continental deposits that these remains form an important and conspicuous
constituent of the one, while they are merely found here and there when looked
for embedded in the other. The rate of accumulation of all other constituents is
so slow as to leave a layer of teeth and ear-bones uncovered, or covered by so thin
a deposit that the dredge can collect them freely. Dr. John Murray calculates
that only a few inches of this deposit have accumulated since the Tertiary Period.
These most interesting facts prove furthermore that the great ocean basins and
continental areas have occupied the same relative positions since the formation of the
first stratified rocks; for no oceanic deposits are found anywhere in the latter. We
know the sources of the oceanic deposit, and it might be possible to form an esti-
mate, within wide limits, of its rate of accumulation. If it were possible to
ascertain its thickness by means of a boring, some conclusions as to the time which
has elapsed during the lifetime of certain species—perhaps even the lifetime of the
oceans themselves—might be arrived at. Lower down the remains of earlier
species would probably be found. The depth of this deposit and its character at
deeper levels are questions of overwhelming interest ; and perhaps even more so is

1 Nature, Jan. 3, 1895. 2 P. L. and A,, vol. ii. p. 87.

a a i

TRANSACTIONS OF SECTION D. ou
the question as to what lies beneath. Long before the ‘Challenger’ had proved
the persistence of oceanic and continental areas, Darwin, with extraordinary fore-
sight, and opposed by all other naturalists and geologists, including his revered
teacher, Lyell, had come to the same conclusion. His reasoning on the subject is
so convincing that it is remarkable that he made so few converts, and this is all
the more surprising since the arguments were published in the ‘ Origin of Species,
which in other respects produced so profound an effect. In speculating as to the
rocks in which the remains of the ancestors of the earliest known fossils may still
exist, he suggested that, although the existing relationship between the positions
of our present oceans and continental areas is of immense antiquity, there is no
reason for the belief that it has persisted for an indefinite period, but that at some
time long antecedent to the earliest known fossiliferous rocks ‘continents may
have existed where oceans are now spread out; and clear and open oceans may
have existed where our continents now stand.’ Not the least interesting result
would be the test of this hypothesis, which would probably be forthcoming as the
result of boring into the floor of a deep ocean ; for although, as Darwin pointed
out, it is likely enough that such rocks would be highly metamorphosed, yet it
might still be possible to ascertain whether they had at any time formed part of a
continental deposit, and perhaps to discover much more than this. Such an under-
taking might be carried out in conjunction with other investigations of the highest
interest, such as the attempt to obtain a record of the swing of a pendulum at the
bottom of the ocean.

We now come to the strictly biological part of our subject—to the inquiry as
to how much of the whole scheme of organic evolution has been worked out in
the time during which the fossiliferous rocks were formed, and how far, therefore,
the time required by the geologist is sufficient.

It is first necessary to consider Lord Kelvin’s suggestion that life may have
reached the earth on a meteorite—a suggestion which might be made the basis
of an attempt to rescue us from the dilemma in which we were placed by the
insufficiency of time for evolution. It might be argued that the evolution which
took place elsewhere may have been merely completed, in a comparatively brief
space of time, on our earth.

We Imow nothing of the origin of life here or elsewhere, and our only
attitude towards this or any other hypothesis on the subject is that of the
anxious inquirer for some particle of evidence. But a few brief considerations
will show<that no escape from the demands for time can be gained in this way.

_ Our argument does not deal with the time required for the origin of life, or
for the development of the lowest beings with which we are acquainted from the
first formed beings, of which we know nothing. Both these processes may have
required an immensity of time ; but as we know nothing whatever about them, aad
have as yet no prospect of acquiring any information, we are compelled to confine
ourselves to as much of the process of evolution as we can infer from the structure
of living and fossil forms—that is, as regards animals, to the development of the
‘simplest into the most complex Protozoa, the evolution of the Metazoa from the
Protozoa, and the branching of the former into its numerous Phyla, with all their
Classes, Orders, Families, Genera, and Species. But we shall find that this is

“quite enough to necessitate a very large increase in the time estimated by the
geologist.

The Protozoa, simple and complex, still exist upon the earth in countless

“species, together with the Metazoan Phyla. Descendants of forms which in their
day constituted the beginning of that scheme of evolution which | have defined
above, descendants, furthermore, of a large proportion of those forms which, age
after age, constituted the shifting phases of its onward progress, still exist, and in
a sufficiently unmodified condition to enable us to reconstruct, at any rate in
mere outline, the history of the past. Innumerable details and many phases of
supreme importance are ‘still hidden from us, some of them perhaps never to be
recovered. But this frank admission, and the eager and premature attempts to
expound too much, to go further than the evidence permits, must not be allowed

12 REPORT—1896.

to throw an undeserved suspicion upon conclusions which are sound and well
supported, upon the firm conviction of every zoologist that the general trend of
evolution has been, as I have stated it, that each of the Metazoan Phyla originated,
directly or indirectly, in the Protozoa.

The argument founded on the meteorite hypothesis would, however, require
that the process of evolution went backward on a scale as vast as that on which
it went forward, that certain descendants of some central type, coming to the earth
on a meteorite, gradually lost their Metazoan complexity and developed backward
into the Protozoa, throwing off the lower Metazoan Phyla on the way, while cer-
tain other descendants evolved all the higher Metazoan groups. Such a process
would shorten the period of evolution by half, but it need hardly be said that all
available evidence is entirely against it.

The only other assumption by means of which the meteorite hypothesis might
be used to shorten the time is even more wild and improbable. Thus it might be
supposed that the evolution which we believe to have taken place on this earth,
really took place elsewhere—at any rate as regards all its main lines—and that
samples of all the various phases, including the earliest and simplest, reached us
by a regular meteoric service, which was established at some time after the com-
pletion of the scheme of organic evolution. Hence the evidences which we study
would point to an evolution which occurred in some unknown world with an age
which even Professor Tait has no desire to limit.

If these wild assumptions be rejected, there remains the supposition that, if life
was brought by a meteorite, it was life no higher than that of the simplest Proto-
zoon—a supposition which leaves our argument intact. The alternative supposition,
that one or more of the Metazoan Phyla were introduced in this way while the
others were evolved from the terrestrial Protozoa, is hardly worth consideration.
In the first place, some evidence of a part in a common scheme of evolution is to
be found in every Phylum. In the second place, the gain would be small; the
arbitrary assumption would only affect the evidence of the time required for evolu-
tion derived from the particular Phylum or Phyla of supposed meteoric origin.

The meteoric hypothesis, then, can only affect our argument by making the

most improbable assumptions, for which, moreover, not a particle of evidence can
be brought forward.

We are therefore free to follow the biological evidence fearlessly. It is neces-
sary, in the first place, to expand somewhat the brief outline of the past history of
the animal kingdom, which has already been given. Since the appearance of the
‘Origin of Species,’ the zoologist, in making his classifications, has attempted as far
as possible to set forth a genealogical arrangement. Our purpose will be served by
an account of the main outlines of a recent classification, which has been framed
with a due consideration for all sides of zoological research, new and old, and
which has met with general approval. Professor Lankester divides the animal
kingdom into two grades, the higher of which, the Hnterozoa (Metazoa), were
derived from the lower, the Plastidozoa (Protozoa). Each of these grades is again
divided into two sub-grades, and each of these is again divided into Phyla, cor-
responding more or less to the older Sub-Kingdoms. Beginning from below, the most
primitive animals in existence are found in the seven Phyla of the lower Protozoan
sub-grade, the Gymnomyxa. Of these unfortunately only two, the Reticularia (Fora-
minifera) and Radiolaria, possess a structure which renders possible their preservation
in the rocks. The lowest and simplest of these Gymnomyxa represent the starting-
point of that scheme of organic evolution which we are considering to-day. The
higher order of Protozoan life, the sub-grade Corticata, contains three Phyla, no one
of which is available in the fossil state. They are, however, of great interest and |
importance to us as showing that the Protozoan type assumes a far higher organi-
sation on its way to evolve the more advanced grade of animal life. The first-
formed of these latter are contained in the two Phyla of the sub-grade Coelentera,
the Porifera or Sponges, and the Nematophora or Corals, Sea-Anemones, Hy-
drozoa and allied groups. Both of these Phyla are plentifully represented in the
fossil state. It is considered certain that the latter of these, the Nematophora,

TRANSACTIONS OF SECTION D. 13

gave rise to the higher sub-grade, the Ceelomata, or animals with a cceelom or
body-cavity surrounding the digestive tract. This latter includes all the remain-
ing species of animals in nine Phyla, five of which are found fossil—the Echino-
derma, Gephyrea, Mollusca, Appendiculata, and Vertebrata.

Before proceeding further, I wish to lay emphasis on the immense evolutionary
history which must have been passed through before the ancestor of one of the
higher of these nine Phyla came into being. Let us consider one or two examples,
since the establishment of this position is of the utmost importance for our argu-
ment. First, consider the past history of the Vertebrata,—of the common ancestor
of our Balanoglossus, Tunicates, Amphioxus, Lampreys, Fishes, Dipnoi, Amphibia,
Reptiles, Birds, and Mammals. Although zoologists differ very widely in their
opinions as to the affinities of this ancestral form, they all agree in maintaining
that it did not arise direct from the Nematophora in the lower sub-grade of
Metazoa, but that it was the product of a long history within the Coelomate sub-

rade. The question as to which of the other Coslomate Phyla it was associated
with will form the subject of one of our discussions at this meeting; and I will
therefore say no more upon this period of its evolution, except to point out that
the very question itself, ‘the ancestry of Vertebrates, only means a_ rela-
tively small part of the evolutionary history of the Vertebrate ancestor within
the Coelomate group. For when we have decided the question of the other
Ceelomate Phylum or Phyla to whick the ancestral Vertebrate belonged, there
remains of course the history of that Phylum or those Phyla earlier than the point
at which the Vertebrate diverged, right back to the origin of the Coelomata; while,
beyond and kelow, the wide gulf between this and the Ccelentera had to be
crossed, and then, probably after a long history as a Coelenterate, the widest and
most significant of all the morphological intervals—that between the lowest
Metazoon and the highest Protozoon—was traversed. But this was by no means
all. There remains the history within the higher Protozoan sub-grade, in the
interval from this to the lower, and within the lower sub-grade itself, until we
finally retrace our steps to the lowest and simplest forms. It is impossible to
suppose that all this history of change can have been otherwise than immensely
prolonged ; for it will be shown below that all the available evidence warrants the
belief that the changes during these earlier phases were at least as slow as
those which occurred later.

If we take the history of another of the higher Phyla, the Appendiculata, we
find that the evidence points in the same direction. The common ancestor of our
Rotifera, earthworms, leeches, Peripatus, centipedes, insects, Crustacea, spiders
and scorpions, and forms allied to all these, is generally admitted to have been
Cheetopod-like, and probably arose in relation to the beginnings of certain other
Ceelomata Phyla, such as the Gephyrea and perhaps Mollusca. At the origin of
the Coelomate sub-grade the common ancestor of all Coelomate Phyla is reached,
and its evolution has been already traced in the case of the Vertebrata.

What is likely to be the relation between the time required for the evolution
of the ancestor of a Coelomate Phylum and that required for the evolution, which
subsequently occurred, within the Phylum itself? The only indication of an
answer to this question is to be found in a study of the rate of evolution in the
lower parts of the animal kingdom as compared with that in the higher. Con-
trary, perhaps, to anticipation, we find that all the evidences of rapid evolution are
confined to the most advanced of the smaller groups within the highest Phyla,
and especially to the higher Classes of the Vertebrata. Such evidence as we have
strongly indicates the most remarkable persistence of the lower animal types. Thus
in the Class Imperforata of the Reticularia (Foraminifera) one of our existing
genera (Saccamina) occurs in the Carboniferous strata, another (Trochammina) in
the Permian, while a single new genus (Receptaculites) occurs in the Silurian and
Devonian. The evidence from the Class Perforata is much stronger, the exist-
ing genera Nodosaria, Dentalina, Textularia, Grammostomum, Valvulina, and
Nummulina all occurring in the Carboniferous, together with the new genera
Archeediscus (?) and Fusulina.

I omit reference to the much-disputed Eozoon from the Laurentian rocks far

14. REPORT—1896.

below the horizon, which for the purpose of this address I am considering as the
lowest fossiliferous stratum. We are looking forward to the new light which will
be thrown upon this form in the communication of its veteran defender, Sir
William Dawson, whom we are all glad to welcome.

Passing the Radiolaria, with delicate skeletons less suited for fossilisation, and
largely pelagic and therefore less likely to reach the strata laid down along the
fringes of the continental areas, the next Phylum which is found in a fossil state
is that of the Porifera, including the sponges, and divided into two Classes, the
Calcispongiz and Silicospongize. Although the fossilisation of sponges is in many
cases very incomplete, distinctly recognisable traces can be made out in a large
number of strata. From these we know that representatives of all the groups of
both Classes (except the Halisarcide, which have no hard parts) occurred in the
Silurian, Devonian, and Carboniferous systems. The whole Phylum isan example of”
long persistence with extremely little change. And the same is true ot the Nema-
tophora: new groups indeed come in, sometimes extremely rich in species, such as
the Palzozoic Rugose corals and Graptolites; but they existed side by side with
representatives of existing groups, and they are not in themselves primitive or
ancestral. A study of the immensely numerous fossil corals reveals no advance in
organisation, while researches into the structure of existing Aleyonaria and Hydro-
corallina have led to the interpretation of certain Palaeozoic forms which were pre-
viously obscure, and the conclusion that they find their place close beside the
living species.

All available evidence points to the extreme slowness of progressive evolu-
tionary changes in the Coelenterate Phyla, although the Protozoa, if we may judge
by the Reticularia (Foraminifera), are even more conservative.

When we consider later on the five Coelomate Phyla which occur fossil, we
shall find that the progressive changes were slower and indeed hardly appreciable
in the two lower and less complex Phyla, viz.: the Echinoderma, and Gephyrea,
as compared with the Mollusca, Appendiculata, and Vertebrata.

Within these latter Phyla we have evidence for the evolution of higher groups
presenting a more or less marked advance in organisation. And not only is the
rate of development more rapid in the highest Phyla of the animal kingdom, but
it appears to be most rapid when dealing with the highest animal tissue, the
central nervous system. The chief, and doubtless the most significant, difference
between the early Tertiary mammals and those which succeeded them, between the
Secondary and Tertiary reptiles, between man and the mammals most nearly
allied to him, is a difference in the size of the brain. In all these cases an enormous
increase in this, the dominant tissue of the body, has taken place in a time which,
geologically speaking, is very brief.

When glancing later on over the evolution which has taken place within
the Phyla, further details upon this subject will be given, although in this as in
other cases the time at our disposal demands that the exposition of evidence
must largely yield to an exposition of the conclusions which follow from its
study. And undoubtedly a study of all the available evidence points to the con-
clusion that in the lower grade, sub-grades, and Phyla of the animal kingdom
evolution has been extremely slow as compared with that in the higher. We do
not know the reason. It may be that this remarkable persistence through the
stratified series of deposits is due to an innate fixity of constitution which has
rigidly limited the power of variation; or, more probably perhaps, that the lower
members of the animal kingdom were, as they are now, more closely confined to
particular environments, with particular sets of conditions, with which they had to
cope, and, this being successfully accomplished, natural selection has done little
more than keep up a standard of organisation which was sufficient for their needs ;
while the higher and more aggressive forms ranging over many environments, and
always prone to encounter new sets of conditions, were compelled to undergo respon-
sive changes or to succumb. But whatever be the cause, the fact remains, and is of
importance for our argument. When the ancestor of one of the higher Phyla
was associated with the lower Phyla of the Coelomate sub-grade, when further
back it passed through a Coelenterate, a higher Protozoan, and finally a lower

TRANSACTIONS OF SECTION D. 15

Protozoan phase, we are led to believe that its evolution was probably very slow
as compared with the rate which it subsequently attained. But this conclusion is
of the utmost importance; for the history contained in the stratified rocks nowhere
reveals to us the origin of a Phylum. And this is not mere negative evidence, but
positive evidence of the most unmistakable character. All the five Ccelomate
Phyla which occur fossil appear low down in the Paleozoic rocks, in the Silurian
or Cambrian strata, and they are represented by forms which are very far from being
primitive, or, if primitive, are persistent types, such as Chiton, which are now
living. Thus Vertebrata are represented by fishes, both sharks and ganoids; the
Appendiculata by cockroaches, scorpions, Limulids, Trilobites, and many Crustacea ;
the Mollusca by Nautilus and numerous allied genera, by Dentalium, Chiton,
Pteropods, and many Gastropods and Lamellibranchs ; the Gephyrea by very
numerous Brachiopods, and many Polyzoa ; the Echinoderma by Crinoids, Cystoids,
Blastoids, Asteroids, Ophiuroids, and Echinoids. It is just conceivable, although,
as I believe, most improbable, that the Vertebrate Phylum originated at the time
when the earliest known fossiliferous rocks were laid down. It must be remem-
bered, however, that an enormous morphological interval separates the fishes which
appear in the Silurian strata from the lower branches, grades, and classes of the
Phylum in which Balanoglossus, the Ascidians, Amphioxus, and the Lampreys are
placed. The earliest Vertebrates to appear are, in fact, very advanced members of
the Phylum, and, from the point of view of anatomy, much nearer to man than tu
Ampftioxus. If, however, we grant the improbable contention that so highly
organised an animal as a shark could be evolved from the ancestral vertebrate in
the period which intervened between the earliest Cambrian strata and the Upper
Silurian, it is quite impossible to urge the same with regard to the other Phyla.
It has been shown above that when these appear in the Cambrian and Silurian,
they are flourishing in full force, while their numerous specialised forms are a
positive proof of a long antecedent history within the limits of the Phylum.

If, however, we assume for the moment that the Phyla began in the Cambrian,
the geologist’s estimate must still be increased considerably, and perhaps doubled,
in order to account for the evolution of the higher Phyla from forms as low as
many which are now known upon the earth ; unless, indeed, it is supposed, against
the weight of all such evidence as is available, that the evolutionary history in
these early times was comparatively rapid.

To recapitulate, if we represent the history of animal evolution by the form of
a tree, we find that the following growth took place in some age antecedent to the
earliest fossil records, before the establishment of the higher Phyla of the Animal,
Kingdom. The main trunk representing the lower Protozoa divided, originating
the higher Protozoa; the latter portion again divided, probably in a threefold man-
ner, originating the two lowest Metazoan Phyla, constituting the Ccelentera. The
branch representing the higher of these Phyla, the Nematophora. divided, origina-
ting the lower Coelomate Phyla, which again branched and originated the higher
Phyla. And, as has been shown above, the relatively ancestral line, at every
stage of this complex history, after originating some higher line, itself continued
down to the present day, throughout the whole series of fossiliferous rocks, with
but little change in its general characters, and practically nothing in the way of
progressive evolution. Evidences of marked advance are to be found alone in the
most advanced groups of the latest highest products—the Phyla formed by the
last of these divisions.

It may be asked how is it possible for the zoologist to feel so confident
as to the past history of the various animal groups. I have already explained
that he does not feel this confidence as regards the details of the history,
but as to its general jines. The evidence which leads to this conviction js
based upon the fact that animal structure and mode of cevelopment can be, and
have been, handed down from generation to generation from a period far more
remote than that which is represented by the earliest fossils; that fundamental
facts in structure and development may remain changeless amid endless changes of
a more general character; that especially favourable conditions have preserved

16 REPORT—1896.

ancestral forms comparatively unchanged. Working upon this material, com-
parative anatomy and embryology can reconstruct for us the general aspects of a
history which took place long before the Cambrian rocks were deposited. This
line of reasoning may appear very speculative and unsound, and it may easily
become so when pressed too far. But applied with due caution and reserve, it
may be trusted to supply us with an immense amount of valuable information
which cannot be obtained in any other way. Furthermore, it is capable of stand-
ing the very true and searching test supplied by the verification of predictions
made on its authority. Many facts taken together lead the zoologist to be-
lieve that A was descended from C through B; but if this be true, B should
possess certain characters which are not known to belong to it. Under the in-
spiration of hypothesis a more searching investigation is made, and the characters
are found, Again, that relatively small amount of the whole scheme of animal
evolution which is contained in the fossiliferous rocks has furnished abundant
confirmation of the validity of the zoologist’s method. The comparative anatomy
of the higher Vertebrate Classes leads the zoologist to believe that the toothless
beak and the fused caudal vertebree of a bird were not ancestral characters, but
were at some time derived from a condition more conformable to the general plan
of vertebrate construction, and especially to that of reptiles. Numerous secondary
fossils prove to us that the birds of that time possessed teeth and separate caudal
vertebrae, culminating in the long lizard-like tail of Archaeopteryx.

Prediction and confirmation of this kind, both zoological and paleontological,
have been going on ever since the historic point of view was adopted by the
naturalist as the outcome of Darwin’s teaching, and the zoologist may safely claim
that his method, confirmed by palzeontology so far as evidence is available, may be
extended beyond the period in which such evidence is to be found.

And now our last endeavour must be to obtain some conception of the amount
of evolution which has taken place within the higher Phyla of the Animal Kingdom
during the period in which the fossiliferous rocks were deposited. The evidence
must necessarily be considered very briefly, and we shall be compelled to omit the
Vertebrata altogether.

The Phylum Appendiculata is divided by Lankester into three branches, the
first containing the Rotifera, the second the Cheetopoda, the third the Arthropoda, Of
these the second is the oldest, and gave rise to the other two, or at any rate to
the Arthropoda, with which we are alone concerned, inasmuch as the fossil records
of the others are insufficient. The Arthropoda contain seven Classes, divided into
two grades, according to the presence or absence of antennee—the Ceratophora,
containing the Peripatoidea, the Myriapoda, and the Hexapoda (or insects); the
Acerata, containing the Crustacea, Arachnida, and two other classes (the Pantopoda
and Tardigrada) which we need not consider. The first Class of the antenna-
bearing group contains the single genus Peripatus—one of the most interesting
and ancestral of animals, as proved by its structure and development, and by its
immense geographical range. Ever since the researches of Moseley and Balfour,
extended more recently by those of Sedgwick, it has been recognised as one of the
most beautiful of the connecting links to be found amongst animals, uniting the
antenna-bearing Arthropods, of which it is the oldest member, with the Cheetopods.
Peripatus is a magnificent example of the far-reaching conclusions of zoology, and
of its superiority to paleontology as a guide in unravelling the tangled history of
animal evolution. Peripatus is alive to-day, and can be studied in all the details
of its structure and development ; it is infinitely more ancestral, and tells of a far
more remote past than any fossil Arthropod, although such fossils are well known
in all the older of the Paleozoic rocks. And yet Peripatus is not known as a
fossil. Peripatus has come down, with but little change, from a time, on a mode-
rate estimate, at least twice as remote, and probably many times as remote, as
the earliest known Cambrian fossil. The agencies which, it is believed, have
crushed and heated the Archean rocks so as to obliterate the traces of life which
they contained were powerless to efface this ancient type, for, although the passing
generations may have escaped record, the likeness of each was stamped on that

Se

TRANSACTIONS OF SECTION D. 17

which succeeded it, and has continued down to the present day. It is, of course,
a perfectly trite and obvious conclusion but not the less one to be wondered at, that
the force of heredity should thus far outlast the ebb and flow of terrestrial change
throughout the vast period over which the geologist is our guide.

If, however, the older Palseozoic rocks tell us nothing of the origin of the
antenna-bearing Arthropods, what do they tell us of the history of the Myriapod
and Hexapod Classes P

The Myriapods are well represented in Paleeozoic strata, two species being
found in the Devonian and no less than thirty-two in the Carboniferous. Although
placed in an Order (Archipolypoda) separate from those of living Myriapods, these
species are by no means primitive, and do not supply any information as to the
steps by which the Class arose. The imperfection of the record is well seen in the
traces of this Class ; for between the Carboniferous rocks and the Oligocene there
are no remains of undoubted Myriapods.

We now come to the consideration of insects, of which an adequate discussion
would occupy a great deal too much of your time. An immense number of species
are found in the Palzeozoic rocks, and these are considered by Scudder, the great
authority on fossil insects, to form an Order, the Paleeodictyoptera, distinct from any
of the existing Orders. ‘The latter, he believes, were evolved from the former in
Mesozoic times. These views do not appear to derive support from the wonderful
discoveries of M. Brongniart ' in the Upper Carboniferous of Commentry in the
Department of Allier in Central France. Concerning this marvellous assemblage of
species, arranged by their discoverer into 46 genera and 101 species, Scudder truly

says:
‘Our knowledge of Paleeozoic insects will have been increased three or four fold
at a single stroke..... No former contribution in this field can in any way

compare with it, nor even all former contributions taken together.’ *

When we remember that the group of fossil insects, of which so much can be
affirmed by so great an authority as Scudder, lived at one time and in a single
locality, we cannot escape the conclusion that the insect fauna of the habitable
earth during the whole Palseozoic period was of immense importance and variety.
Our knowledge of this single group of species is largely due to the accident that coal-
mining in Commentry is carried on in the open air.

Now, these abundant remains of insects, so far from upholding the view that
the existing orders had not been developed in Palzeozoic times, are all arranged by
Brongniart in four out of the nine Orders into which insects are usually divided,
viz. the Orthoptera, Neuroptera, Thysanoptera, and Homoptera. The importance
of the discovery is well seen in the Neuroptera, the whole known Palxozoic
fauna of this Order being divided into 45 genera and 99 species, of which 33
and 72 respectively have been found at Commentry.

Although the Carboniferous insects of Commentry are placed in new families,
some of them come wonderfully near those into which existing insects are classified,
and obviously form the precursors of these. This is true ofthe Blattide, Phasmide,
Acridiidee, and Locustide among the Orthoptera, the Perlide among the
Neuroptera, and the Fulgoride among the Homoptera. The differences which
separate these existing families from their Carboniferous ancestors are most
interesting and instructive. Thus the Carboniferous cockroaches possessed ovi-
positors, and probably laid their eggs one at a time, while ours are either vivi-
parous or lay their eggs in a capsule. The Protophasmidz resemble living species
in the form of the head, antenne, legs, and body; but while our species are either
wingless or, with the exception of the female Phyllide, have the anterior pair
reduced to tegmina, useless for flight, those of Palaeozoic times possessed four well-
developed wings. The forms representing locusts and grasshoppers (Palewacridiide)
possessed long slender antennz like the green grasshoppers (Locustide), from
which the Acridiidz are now distinguished by their short antenne. The diver-
gence and specialisation which is thus shown is amazingly small in amount. In

1 Charles Brongniart.—‘ Recherches pour servir 4 l’Histoire des Insectes fossiles

des temps primaires, précédées d’une Etude sur la nervation des ailes des Insectes.’
1894. 2 §. H. Scudder, Am. Jowrn. Soi., vol. xlvii. February 1894. Art, viii.

18 REPORT—1896.

the vast period between the Upper Carboniferous rocks and the present day the cock-
roaches have gained a rather different wing venation, and have succeeded in laying
their eggs in a manner rather more specialised than that of insects in general; the
stick insects and leaf insects have lost or reduced their wings, the grasshoppers
have shortened their antenne. These, however, are the insects which most closely
resemble the existing species ; let us turn to the forms which exhibit the greatest
differences. Many species have retained in the adult state characters which are
now confined to the larval stage of existence, such as the presence of tracheal gills
on the sides of the abdomen. In some, the two membranes of the wing were not
firmly fixed together, so that the blood could circulate freely between them. On
the other hand, they are not very firmly fixed together in existing insects. Another
important point was the condition of the three thoracic segments, which were quite
distinct and separate, instead of being fused as they are now in the imago stage.
This external difference probably also extended to the nervous system, so that the
thoracic ganglia were separate instead of concentrated. The most interesting
distinction, however, was the possession by many species of a pair of prothoracie
appendages much resembling miniature wings, and which especially suggest the
appearance assumed by the anterior pair (tegmina) in existing Phasmidee. ‘here
is some evidence in favour of the view that they were articulated, and they exhibit
what appears to be a trace of venation. Brongniart concludes that in still earlier
strata, insects with six wings will be discovered, or rather insects with six of the
tracheal gills sufficiently developed to serve as parachutes. Of these, the two
posterior pair developed into the wings as we know them, while the anterior pair
degenerated, some of the Carboniferous insects presenting us with a stage in
which degeneration had taken place but was not complete.

One very important character was, as I have already pointed out, the enormous
size reached by insects in this distant period. This was true of the whole known
fauna as compared with existing species, but it was especially the case with the
Protodonata, some of these giant dragon-flies measuring over two feet in the
expanse of the wings.

As regards the habits of life and metamorphoses, Brongniart concludes that
some species of Protoephemeridx, Protoperlide, &c., obtained their food in an
aquatic larval stage, and did not require it when mature. He concludes that
the Protodonata fed on other animals, like our dragon-flies; that the Paleeacridiides
were herbivorous like our locusts and grasshoppers. the Protolocustide herbivorous
and animal feeders like our green grasshoppers, the Paleoblattidze omnivorous
like our cockroaches. The Homoptera, too, had elongated sucking mouth-parts
like the existing species. It is known that in Carboniferous times there was a lake
with rivers entering it, at Commentry. From their great resemblance to living
forms of known habits, it is probable that the majority of these insects lived near
the water and their larve in it.

When we look at this most important piece of research as a whole, we cannot
fail to be struck with the small advance in insect structure which has taken place
since Carboniferous times. All the great questions of metamorphosis, and of the
structures peculiar to insects, appear to have been very much in the position
in which they are to-day. It is indeed probable enough that the Orders which
zoologists have always recognised as comparatively modern and specialised, such
as the Lepidoptera, Coleoptera, and Hymenoptera, had not come into existence.
But as regards the emergence of the Class from a single primitive group, as regards
its approximation towards the Myriapods, which lived at the same time, and of
both towards their ancestor Peripatus, we learn absolutely nothing. All we can
say is that there is evidence for the evolution of the most modern and specialised
members of the Class, and some slight progressive evolution in the rest. Such evo-
lution is of importance as giving us some vague conception of the rate at which the
process travels in this division of the Arthropoda. If we look upon development as
a series of paths which, by successively uniting, at length meet in a common point,
then some conception of the position of that distant centre may be gained by
measuring the angle of divergence and finding the number of unions which occur
in a given length. In this case, the amount of approximation and union shown in

TRANSACTIONS OF SECTION D. 19

the interval between the Carboniferous Period and the present day is relatively
so small that it would require to be multiplied many times before we could
expect the lines to meet in the common point, the ancestor of insects, to
say nothing of the far more distant past, in which the Tracheate Arthropods
met in an ancestor presenting many resemblances to Peripatus. But it must not
be forgotten that all this vast undefined period is required for the history of one of
the two grades of one of the three branches of the whole Phylum.

Turning now to the brief consideration of the second grade of Arthropods,
distinguished from the first grade by the absence of antenne, the Trilobites are
probably the nearest approach to an ancestral form met with in the fossil state.
Now that the possession of true antennee is certain, it is reasonable to suppose that
the Trilobites represent an early Class of the Aceratous branch which had not yet
become Aceratous. They are thus of the deepest interest in helping us to under-
stand the origin of the antennaless branch, not by the ancestral absence, but by the
loss of true antennz which formerly existed in the group. But the Trilobites did
not themselves originate the other Classes, at any rate during Paleozoic times.
They represent a large and dominant Class, presenting more of the characters of the
common ancestor than the other Classes; but the latter had diverged and had
become distinct long before the earliest fossiliferous rocks; for we find well-marked
representatives of the Crustacea in Cambrian, and of the Arachnida in Silurian
strata. The Trilobites, moreover, appear in the Cambrian with many distinct and
very different forms, contained in upwards of forty genera, so that we are clearly
very far from the origin of the group.

Of the lower group of Crustacea, the Entomostraca, the Cirripedes are repre-
sented by two genera in the Silurian, the Ostracodes by four genera in the Cambrian
and over twenty in the Silurian; of these latter, two genera (Cythere and Bairdia)
continue right through the fossiliferous series and exist at the present day.
Remains of Phyllopods are more scanty, but can be traced in the Devonian and
Carboniferous rocks. The early appearance of the Cirripedes is of especial interest,
inasmuch as the fixed condition of these forms in the mature state is certainly not
primitive, and yet, nevertheless, appears in the earliest representatives.

The higher group, the Malacostraca, are represented by many genera of Phyl-
locarida in the Silurian and Devonian, and two in the Cambrian. These also
afford a good example of the imperfection of the record, inasmuch as no traces of
the group are to be found between the Carboniferous and our existing fauna in
which it is represented by the genus Nebalia. The Phyllocarida are recognised as
the ancestors of the higher Malacostraca, and yet these latter already existed—
in small numbers, it is true—side by side with the Phyllocarida in the Devonian.
The evolution of the one into the other must have been much earlier. Here, as in
the Arthropoda, we have evidence of progressive evolution among the highest
groups of the Class, as we see in the comparatively late development of the Brachyura
as compared with the Macrura. We find no trace of the origin of the Class, or of
the larger groups into which it is divided, or, indeed, of the older among the small
groupings into families and genera.

Of the Arachnida, although some of the most wonderful examples of persistent
types are to be found in this class, but little can be said. Merely to state the
bare fact that three kinds of scorpion are found in the Silurian, two Pedipalpi,
eight scorpions, and two spiders in the Carboniferous, is sufficient to show that the
period computed by geologists must be immensely extended to account for the
development of this Class alone, inasmuch as it existed in a highly specialised
condition almost at the beginning of the fossiliferous series; while, as regards
so extraordinarily complex an animal as a scorpion, nothing apparent in the way of
progressive development has happened since. Professor Lankester has, however,
pointed out to me that the Silurian scorpion Paleeophonus possessed heavier limbs
than those of existing species, and this is a point in favour of an aquatic life like
that of its near relation, Limulus. If so, it is probable that it possessed external

1 For an account of the evolution of the Crustacea see the Presidential Addresses
to the Geological Society in 1895 and 1896 by Dr. Henry Woodward.

20 REPORT—1896.

gills, not yet inverted to form the lung-book. The Merostomata are of course a
Paleozoic group, and reach their highest known development at their first appear-

ance in the Silurian ; since then they have done nothing but disappear gradually, ©

leaving the single genus Limulus, unmodified since its first appearance in the
Trias, to represent them. It is impossible to find clearer evidence of the decline
rather than the rise of a group. No progressive development, but a gradual or
rapid extinction, and consequent reduction in the number of genera and species, is
a summary of the record of the fossiliferous rocks as regards this group and man

others, such as the Trilobites, the Brachiopods, and the Nautilide. All these .

groups begin with many forms in the oldest fossiliferous rocks, aud three of them
have left genera practically unchanged from their first appearance to the present
day. What must have been the time required to carry through the vast amount
of structural change implied in the origin of these persistent types and the groups
to which they belong—a period so extended that the interval between the oldest
Paleozoic rocks and the present day supplies no measurable unit ?

But I am digressing from the Appendiculate Phylum. We have seen that the
fossil record is unusually complete as regards two Classes in each grade of the
Arthropod branch, but that these Classes were well developed and flourishing in
Paleozoic times. The only evidence of progressive evolution is in the development
of the highest orders and families of the Classes. Of the origin of the Classes
nothing is told, and we can hardly escape the conclusion that for the development
of the Arthropod branches from a common Cheetopod-like ancestor, and for the
further development of the Classes of each branch, a period many times the length
of the fossiliferous series is required, judging from the insignificant amount of
development which has taken place during the formation of this series.

It is impossible to consider the other Coelomate Phyla as I have done the
Appendiculata. I can only briefly state the conclusions to which we are led.

As regards the Molluscan Phylum, the evidence is perhaps even stronger than
in the Appendiculata. Representatives of the whole of the Classes are, it is believed,
found in the Cambrian or Lower Silurian. The Pteropods are generally admitted
to be a recent modification of the Gastropods, and yet, if the fossils described in the
genera Conularia, Hyolithes, Pterotheca, &c. are true Pteropods, as they are
supposed to be, they occur in the Cambrian and Silurian strata, while the group
of Gastropods from which they almost certainly arose, the Bullide, are not known
before the Trias. Furthermore, the forms which ‘are clearly the oldest of the
Pteropods—Limacina and Spirialis—are not known before the beginning of the
Tertiary Period. Hither there is a mistake in the identification of the Paleozoic
fossils as Pteropods, or the record is even more incomplete than usual, and the
most specialised of all Molluscan groups had been formed before the date of the
earliest fossiliferous rocks. Even if this should hereafter be disproved, there can be
no doubt about the early appearance of the Molluscan Classes, and that it is the
irony of an incomplete record which places the Cephalopods and Gastropods in the
Cambrian and the far more ancestral Chiton no lower than the Silurian. Through-
out the fossiliferous series the older families of Gastropods and Lamellibranchs are
followed by numerous other families, which were doubtless derived from them ;
new and higher groups of Cephalopods were developed, and, with the older groups,
either persisted until the present time or became extinct. But in all this splitting
up of the Classes into groups of not widely different morphological value, there is
very little progressive modification, and, taking such changes in such a period as
our unit for the determination of the time which was necessary for the origin of
the Classes from a form like Chiton, we are led to the same conclusion as
that which followed from the consideration of the Appendiculata, viz. that

the fossiliferous series would have to be multiplied several times in order to

provide it.

Of the Phylum Gephyrea, I will only mention the Brachiopods, which are
found in immense profusion in the early Paleozoic rocks and which have occupied
the subsequent time in becoming less dominant and important. So far from
helping us to clear up the mystery which surrounds the origin of the Class, the
earliest forms are quite as specialised as those living now, and, some of them (Lingula,

TRANSACTIONS OF SECTION D. 21

Discina) even generically identical. The demand for time to originate the group
is quite as grasping as that of the others we have been considering.

All the Classes of Echinoderma, except the Holothurians, which do not possess
a structure favourable for fossilisation, are found early in the Paleozoic rocks,
and many ofthem inthe Cambrian. Although these early forms are very different
from those which succeeded them in the later geological periods, they do not possess
a structure which can be recognised as in any way primitive or ancestral. The
Echinoderma are the most distinct and separate of all the Colomate Phyla,
and they were apparently equally distinct and separate at the beginning of the
fossiliferous series.

In concluding this imperfect attempt to deal with a very vast subject in a very
short time, I will remind you that we were led to conclude that the evolution of
the ancestor of each of the higher animal Phyla probably occupied a very long
period, perhaps as long as that required for the evolution which subsequently
oceurred within the Phylum. But the consideration of the higher Phyla
which occur fossil, except the Vertebrata, leads to the irresistible conclusion that
the whole period in which the fossiliferous rocks were laid down must be
multiplied several times for this later history alone. The period thus obtained
requires to be again increased, and perhaps doubled, for the earlier history.

In the preparation of the latter part of this address I have largely consulted
Zittel’s great work. I wish also to express my thanks to my friend Professor
Lankester, whom I have consulted on many of the details, as well as the general plan
which has been adopted.

PRINTED BY
SPOTTISWOODE AND CO., NEW-STREET SQUARE
LONDON

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THEORIES: OF EV OLURION:
BY EDWARD B. POULTON.?

In dealing with theories of evolution, I think that we shall all
be agreed that we may leave out of consideration the question of
the origin of life, and deal only with what has happened to life
after its appearance, however that may have taken place. On
this subject we shall probably most of us still agree with the
opinion of Darwin’, that we are not in a position to even speculate
or think upon that question, —that any speculation about it
is almost a waste of time. And this, I think, remains true in
spite of the magnificent results of the organic chemists in produ-
cing chemical bodies by synthesis, which before had been regarded

1 Read February 7, 1894.
2 In Life and letters.

Poulton. | 272 | May 16,

as capable of being made only in the laboratory of the living
body. Many of these can now certainly be produced, but that is
very different indeed from creating protoplasm endowed with life ;
and so far are we from achieving this by any chemical means, that
I think we may venture to dismiss all consideration of the ulti-
mate origin of life.

But granting the origin of living matter, these theories of evo-
lution which we are considering and hope to discuss to-night can
deal with it, and with their help we believe that we can account
for what has subsequently happened ; namely, the evolution of all
forms of life, animal and vegetable, upon the surface of the earth.

The first of these theories which I propose to discuss is the
well-known Darwin-Wallace theory of natural selection, with its
three factors.

First, individual variation, — the fact that individuals differ,
and that the differences are essential or inherent in the organism,
so that even if animals were brought up alike, we know they
would still be unlike, and so that, however much the offspring
may resemble their parents, they are never exactly like their
parents or exactly like each other. There is, then, first, indi-
vidual difference, one of the most essential facts in the organism.

Secondly, the fact of heredity,—the fact that these inherent
differences may be and are inherited. Although the hereditary
transmission of acquired differences is disputed, the transmission
of those that are inherent is certain. This stands before us as
one of the most obvious and certain of conclusions, equally proved
by the observation and experience of every one of us.

Thirdly, the fact that there must be a struggle for existence ;
that there are far more individuals born into the world in every
species, even the most slowly increasing, than can possibly survive
and reproduce.

These three factors must by logical necessity lead to a survival
of the fittest among individual variations. It does not require a
scientific mind to comprehend that, — to infer that some amount
of evolution must ensue from the co-operation of those three
factors, every one of which stands firm and undisputed. Among
all the advocates of rival theories which have been brought
forward to explain evolution, no one has ever ventured to attempt
to disprove any one of these three factors. They stand unchal-
lenged.

Bias

1894. | oye [ Poulton.

Qo

The politician, Henry Fawcett. saw, long before scientific
people themselves understood what Darwin meant by natural
selection, that logically some result must ensue from such co-op-
eration. Fawcett said that natural selection must produce evolu-
tion as surely as a round stone will roll further than a square one.
Some measure of evolution is simply the logical result of the
co-operation of these three undisputed, abundantly proved factors.

Now, some writers have thought to undermine the theory of
natural selection by arguing that the important and essential
factor of individual variation is not explained by the theory which
rests upon it. True, it is not; but for the theory of natural
selection, the explanation does not signify. So long as individual
variation is present, so long as it is hereditary, it does not signify
how it is produced. There are, indeed, many theories professing
to account for it; but biologists are not generally agreed as to the
manner in which it is produced. But so long as it is there, it is
available, and natural selection can make use of it.

It is interesting to note that, when Newton discovered the
principle of universal gravitation, some people maintained that he
had discovered nothing because he had not explained what gravity
itself was. Now after two hundred years we can safely assert
that universal gravitation stands out as one of the most trium-
phant discoveries of the human intellect ; and yet we, even now,
are just as much in the dark as to what gravitation itself is as
when Newton wrote. Exactly so it is with regard to individual
variation. So long as it is a fact essential to organic nature, that
one individual must be different from another, and so long as
these differences are hereditary, so long may natural selection
have abundant material for its work, even though it is unable to
explain how that individual difference is produced. I am very
far from undervaluing the interest of such an explanation; on the
contrary, I maintain that it forms one of the most interesting of
biological problems now before the scientific world, or likely to
be before it for many a day.

In fact, every successful attempt at scientific explanation only
interprets down to a certain level of causation ; and this is just as
true of universal gravitation and natural selection as it is of
smaller efforts. Down to a certain level of causation, natural
selection explains at any rate some part of organic evolution. A
more fundamental level would be to explain the factors upon

Poulton. | By Tial [May 16,

which natural selection itself depends; but because we have not
yet reached that lower level, we have no reason for doubting, as
some would believe, the complete efficiency, at its own level, of
the explanation we do happily possess.

The theory which stands in contrast with natural selection, and
which has been here supported more fully than in any other civi-
lized country, with the exception of France, is the theory we
usually attribute to Lamarck. Erasmus Darwin in England,
however, has the priority, in that he first brought forward the
principles which Lamarck more effectively supported. But to
Herbert Spencer belongs the chief credit, because he has taken
that part of the earlier theory which is acceptable to modern
biological thought, and upon this basis has formed his great
theory of evolution.

Lamarck believed in an innate tendency toward perfection in
animals. Now, that is a view which very few zoologists at the
present time, if any, would dare to sustain. In fact, an evolution
due to an innate principle of perfection is not very much removed
from the doctrine of special creation which preceded any theory
of evolution. Herbert Spencer, therefore, rejecting all those
elements of Lamarck, which the scientific world could not
possibly accept, has taken that which has commended itself to
science, and upon it has formed his great theory of evolution ; so
that the Lamarckian theory, as presented to the world to-day,
comes before it in Spencerian language and in the closest relation
to Spencerian thought. In saying this, however, I do not by any
means intend to be understood as supporting Spencer’s theories
or the views upon which he bases them.

The Lamarckian theory, then, upon which Spencer has based
his philosophy, is a theory of evolution dependent, not like
natural selection upon three factors, but upon two. It depends
first of all upon the effect wrought on the individual by that
which happens during its lifetime. Instead of depending on
those innate and essential differences upon which natural selection
rests, this theory depends on those changes which are caused
during the life of the individual,—the action of some external force
upon it, the effect of its own will, the changes produced by the
use and disuse of its own parts. The Lamarckian theory depends
in fact on all those changes in an individual which we now call its
acquired characters; that is, characters which the individual has

1894. ] 375 { Poulton.

come to possess but which were not potentially present at the
beginning of its separate life.

The first factor, therefore, is made up by changes that are
wrought in this way. The second factor is heredity, by which it
is supposed that these changes are transmitted ; and it is certainly
true that if such transmission is possible, some amount of evolu-
tion must result. You will all be prepared to admit that. if these
two factors represent facts, their co-operation must produce some
amount of evolution.

It is important to remember, however, that both factors are not
undisputed, as are the three factors of Darwinian evolution.
Although we all admit the existence of acquired characters as
the effect of external causes upon the individual during its life,
yet biologists are by no means agreed that these effects are
hereditary, and, if not, the acquired character ends with the
individual in which it arose, and, not being handed on, can never
become a character of “he species. It is impossible for those wh
hold the Lamarckian er Spencerian view to escape from this. If
it is true that such characters are transmitted, then the foundation
of the theory is secure ; but the transmission of acquired characters
is by no means proved. Herbert Spencer has preferred to occupy
himself in rearing a magnificent edifice upon this foundation,
rather than employ his acute intellect in testing its firmness and
security in every possible way.

So far as observation goes, all those characters which are
believed by many to owe their origin to the Lamarckian principle,
are present in the individual before the beginning of its active
life, before the operation of those causes which were believed
originally to account for the characters. According to the
Lamarckian theory such characters have already become heredi-
tary; and therefore it is of essential importance to the Lamarckian
to prove that acquired modifications can be and are transmitted.
Only in this way can he give good grounds for the opinion that
such characters, when they occur ready-made in the individual,
are to be explained by the action of external causes during the
lives of ancestors.

These are the two main theories of evolution. There are
several others, upon which I will dwell only for a moment because
these two alone command any very large amount of attention at
the present time.

Poulton. | 376 [May 16,

In the first place, Lamarck’s theory of the imnate tendency
towards progressive perfection in animals is not held in exactly
that form, but some zoologists in this and other countries believe
that they see evidence in the rise and fall of certain groups of
fossil animals for the existence of a tendency towards extinction,
or a tendency towards sudden growth, which les within the ani-
mal itself and is not determined by any external cause. That
is a very close approach to Lamarck’s original principle of an
innate tendency in one direction or another. I will not discuss
it at any length, because I think that this evening if we get
some idea and have some discussion on the merits of the two
main theories of evolution, that will be as much as we can expect.
I will only say with regard to the subject that arguments based
upon fossil remains are apt to be somewhat dangerous, because
we have, at least so far as the conditions of life are concerned,
so small an amount of evidence. In certain parts of Africa, for
instance, the presence of the tse-tse fly absolutely limits the
existence of some of the larger quadrupeds. Wherever that tly is,
the animal cannot exist. It is very possible that in future times
skeletons will be found in specially large numbers on the borders
of districts where the fly abounded, and any attempt to argue,
from the appearance of the skeletons themselves, as to the
causes of this great extinction will obviously be entirely false
and misleading. We have in the skeleton of an animal so smal.
an indication of the events of its life and the conditions of its
death, that itis, except in very rare cases, most unsafe to argue
as to the causes of its extinction.

Another theory of evolution is one which has been brought
forward by Professor Geddes of Scotland. He believes that there
is an innate tendency towards growth and towards that dissipa-
tion of matter which constitutes its reverse, — the anabolic and
katabolic tendencies, as he calls them. But that view, although
he argues it with much eloquence, has not been widely accepted,
and I think it will be generally admitted that it does not yet rest
on sufficient proof.

In addition to these, there are some who maintain the position
that there is an unknown cause of evolution. They believe that
these theories, although one or more of them may be of value,
are yet insufficient to account for organic evolution. Those who
take this line are of course logically bound to bring forward the

~~ ee

1894. | WA [ Poulton.

classes of facts with which no existing theory is, as they maintain,
competent to deal.

All we shall have time for to-night is briefly to compare natural
selection, the Darwinian interpretation of evolution, with the
Lamarckian theory. It is interesting to note that, although they
are so essentially distinct one from another, in earlier times these
two theories appear to have been entirely confused. Lamarckian
evolution, Spencerian evolution, appeals to the mind of man far
more strongly than Darwinian evolution. Any one of us, were
we to have created the organic world, would certainly have
created it according to Lamarck. We should have made evolu-
tion by use and disuse of parts, and not by natural selection.
However, we are not concerned with the sort of world that we
should have created. The question before us as scientific men
is not what might have happened, but what has happened.
Nature, as I have heard Prof. Michael Foster say, has a very
queer way of going by roundabout paths and refusing to take the
roads we should lay out for her ourselves, and which we look
upon as the most direct and obvious. The fact that the general
aspect of the Lamarckian theory commends itself to the human
mind affords no reason for Jooking upon it as the correct one, as
opposed to the Darwinian theory.

The Duke of Argyle, who is still strongly antagonistic to
natural selection, 2 few years ago wrote an article in the Nine-
teenth century called ‘‘The power of loose analogy.” By this
title he intended to imply that those who believe in natural selec-
tion have been led away by the specious character of the words
themselves. I suppose that the Duke feels himself bound to
account in some way or other for the fact that people believe in
natural selection, while he does not, and accordingly he suggests
that the seductive power of the title employed by Darwin has
misled the scientific mind into a belief in the process itself, —
only rare and subtle intellects like his own being proof against
such an allurement. Nafural: a word expressive of familiar
objects and processes always around us. Selection: a process
with which we are all familiar. In this way it seems reasonable
to the Duke of Argyie to suppose that men have been misled by
the seductive nature of the terms employed by Darwin. The
terms applied to processes familiar to every one, and therefore
every one accepted them at once, without inquiring what they

Poulton. |

isu)

78 [May 16,

really meant. This is, of Course, an explanation eminently satis-
factory to the single writer who was not to be convinced by ‘‘the
” But when we proceed to test this
ingenious suggestion, and look into the history of the times to
which it applies, when we read Darwin’s letters, we find that he
continually complains that people do not understand what he
means by natural selection, and he almost regrets having used
these words. He says more than once that he wishes he had
used Herbert Spencer’s term, the survival of the fittest, because his
own title, natural selection, is comprehended with such difficulty.

When we look to another class of evidence we find equally sure
ground for the conviction that natural selection was driven into
men’s minds with the very greatest difficulty, and by no means
with the ease which the Duke of Argyle assumes. It is very
interesting to consult the various skits written between twenty
and thirty years ago, and in which the writers supposed that they
were making fun of Darwin’s theory. If you willread them, you
will be struck by one very remarkable fact: their authors are all
making fun of Lamarck when they believe they are making fun
of Darwin.

[remember once seeing a picture in Punch, representing the
evolution of the power of flight by the human species. It repre-
sented a man standing upon the roof of a house and waving his
hands, which, in consequence of the use to which they were put
during his individual life, grew somewhat in size. Passing down
to the next generation, his son was found waving rather larger
hands, and the waving made them still larger. In the course of

power of loose analogy.

generations the descendants acquired large wings and flew down
from the roof of the house. That was supposed to be a parody
on evolution according to Darwin. I have called it a skit, but
you will see at once that you cannot get a better illustration of
Lamarckism. It és Lamarckism. It is not making fun of it; it
is a description of the process itself.

Then Lord Neaves wrote a song in which he attempted to
make great fun of Darwin’s theory. It was a very long song,
many verses of which were skits upon Lamarck, while supposed
to be skits upon Darwin.

“‘A deer with a neck that was longer by half
Than the rest of its family’s — try not to laugh —
By stretching and stretching became a giraffe,
Which nobody can deny.”

1894. ] 379 [ Poulton.

This is pure Lamarckism. The evolution was supposed to be
caused by stretching without any selection at all.

The best example of all, however, is given by Mr. Courthope,
in his ‘*Paradise of birds.” I commend his account of the evolu-
tion of birds and mammals to those who believe the Lamarckian
theory. He tells us there about the Ornithorhynchus, which he

commends as a very prudent beast :—

‘“‘For he saw in the distanee the strife for existence,

That should his grandchildren betide,

And resolved, as he could, for their ultimate good,
A remedy sure to provide;

With that, to prepare each descendant and heir
For a separate diet and clime,

He laid, as a test, four eggs in his nest,
But he only laid two at a time.

On the first he sat still, and kept using his bill,
That the head in his chicks might prevail ;

Her he hatched the next young, head downwards ihe slung
From the branches, to lengthen his tail.

Conceive how he watched till his chickens were hatched,
With what joy he perceived that each brood

Were unlike at the start, had their dwellings apart,
With distinct adaptations for food.

From the bill, in brief words, were developed the birds,
Unless the tame pigeons and ducks lie;

From the tail and hind legs in the second-laid eggs,
The apes and—Prof. Huxley.”

If we now turn to the skits on evolution written at the present
day we find they are very different. Miss May Kendall, in
writing her ‘‘Ballad of the Ichthyosaurus,” only a few years ago,
Says :—

‘““’er man was developed, our brother,
Weswam and we ducked and we dived,

And we dined as a rule on each other ;
What matter? The toughest survived.”

This is true natural selection. The authoress understood what
she was talking about. And even long ago, at the time when
those mistaken parodies were written, intended for Darwin and
really applying to Lamarck, we find an acute mind like that of
James Russell Lowell, in the Biglow papers, making fun of

Darwinian evolution :—

Poulton. ] 380 [ May 16,

“Some flossifers think thet a fakkilty’s granted

The minnit it’s proved to be thoroughly wanted,

Thet a change o’ demand makes a change o’ condition,
Aw thet everythin’ ’s nothin’ except by position;

Ez, fer instance, thet rubber-trees fust begun bearin’
Wen p’litikle conshunces come into wearin’,

Thet the fears of a monkey, whose holt chanced to fail,
Drawed the vertibry out to a prehensile tail.”

That is a most ingenious and interesting parody, making the
theory of natural selection apply to the individual instead of to
the species. The writer pretends to suppose that a quality is
gained in the course of the individual life, because of the individual
need ; whereas under natural selection it is gained in the course
of many generations by a need which is imperative enough to
cause the extinction of individuals without the quality, or with
it in a comparatively slight degree.

Another interesting question has been raised by Mr. Lloyd
Morgan, as to whether the phrase ‘‘natural elimination” would
not be a more correct one than ‘‘natural selection.” The process
is, of course, selection by and through elimination. The survival
of the fittest means the elimination of the unfittest.

The relation between selection and elimination has been put in a
very striking way by Mr. Samuel Butler, who says that according
to natural selection we are what we are, not by the successes of our
fathers and mothers, but by the failures of our uncles and aunts.
The question is, shall we dignify with the title of this important
cause of evolution those who have failed in the struggle, and do
not happen to be the ancestors of any living species, or those who
have succeeded in the struggle and are now abundantly repre-
sented by descendants? I think that ‘‘natural selection” forms
on the whole the best term for the process. It has the advantage,
also, of being the historic term proposed by Darwin.

Another important point in favor of ‘‘natural selection” as a
term, is that it suggests a parallelism or comparison with the
process of artificial selection. Yet another point is the fact that
you may find in the words themselves all the three factors
obviously suggested ; for selection would be impossible without
individual difference, and it would be useless unless these
differences were hereditary ; and, furthermore, selection implies
something which selects ; that is to say, the conditions of nature,

1894] 381 [Poulton.

the rate of increase with its result, the struggle for existence.
So that the three factors of natural selection are implied by the
very words themselves.

Now I want very briefly to bring forward the chief objec-
tions that have been urged against natural selection. In the
first place, if natural selection be true, all the varied characters
of animals and plants must prove to be useful to the possessor
in the struggle, or to have been useful at some time in its
history.

We are only required, however, to prove utility as regards
undoubted characters of the species, and these are hereditary,
and we must put on one side certain characters which are con-
fined to the individual in which they appear, For instance, if it
were proved that the Mollusca of any one river differed from
those of the same species in another river, but that the differences
were confined to the individuals in which they occurred, so that if
these Mollusca were placed when young in the second river, they
would come to resemble those which were proper to it, then we
should not be concerned with characters of the species at all.
The language spoken by a nation similarly is not a character of
the human species, for we know that a child of another nation
would acquire it perfectly together with the particular modes of
thought and expression tortuous or direct which are associated
with it. These results of environment are not characters of the
human species. The individuals of the human species come into
the world with a certain elasticity, a certain power of being
developed in various directions. But although the elasticity
itself is a character of the species, and is inherent, the particular
quality in which it may result when operated upon is certainly not
a specific character.

The more we work on the characters of animals in general, even
though we at first can see no utility, the more we come to admit
this principle, and to believe that either now or in some past
time, the characters have been useful. I can certainly say of
many characters which I have studied in some of my investiga-
tions, that at first they seemed tu be meaningless, but afterwards
appeared to be of much importance in the struggle for existence.
I think we may safely assume with regard to many characters of
which we can now see no explanation that by and by the explana-
tion will be forthcoming.

\

Poulton .] 382 [May 16.

Being unable to prove utility does not invalidate natural selec-
tion. If inutility could be proved for any large class of characters,
the theory would certainly be destroyed as a wide-reaching and
significant process. I do not think, however, that any such
evidence has been forthcoming. I shall be interested in the dis-
cussion which follows this paper to hear whether those who
believe in the Lamarckian theory have any such evidence to
produce, whether they can prove that any one great class of
characters has been useless in the past and remains useless in the
present.

Another class of objection has been urged long ago, and is still
urged to-day. Why do we not find in the paleontological series
the records of failures? Now, as regards the individuals of a
species we cannot expect to find any such evidence. What is
failure? Failure means, according to natural selection, the
failure to produce offspring. The individual which comes into
the world and dies young has failed. The individual which is
represented in the generations of the future has succeeded.
Natural selection has set its stamp upon that individual. But it
is impossible to say whether or not this is true of any particular
fossil. We have not got the facts before us by which we can
form any conclusions.

Furthermore, we know the struggle for existence is exces-
sively complicated. The skeleton alone, though of the highest
value in association with the rest of the organism, has been the
turning point in the struggle in a comparatively small number of
cases. When it has been the turning point in association with
other parts, these latter are absent. We have only a very small
part of the problem before us, and never can expect any more.

But while we cannot expect to find evidence of the survival of
the fittest among the individuals of a species, we may expect to
find it in the supplanting of classes by classes, of groups of
species by groups of species. Some of the facts which have been
brought forward as evidence in this direction do, to my mind,
very strongly support the theory of natural selection by paleonto-
logical evidence. Consider especially the case of the large
mammals preceding those which gave rise to the quadrupeds now
upon the earth. So far as we can judge of these huge forms by
\their skeletons, they appear to have possessed a bodily structure
\s well fitted to survive as that of many now living in the world;

1894. | 883 [ Poulton.

but they differed from these latter in that they had extremely
small brains. We can easily understand that inferiority of intel-
lect would cause them to be worsted by animals which were in
other respects no better endowed.

Exactly parallel is the relation of man and the apes. In bodily
structure the difference is insignificant. In the brain, however,
we meet an important and essential distinction. It would appear
‘here that natural selection has taken one particular part of the
organism of paramount importance in the struggle, and has
developed that rather than made a change along the whole line.

We see the same relationship in the gigantic reptiles of the
secondary period as compared with the mammals of the Tertiary.
The latter with their larger brains and higher intelligence were
able to supplant the former, just as they have in turn been sup-
planted by the still larger brained animals whose descendants now
people the earth. All this seems to me to afford very strong
support to the theory of natural selection.

Passing now to another class of objections: natural selection,
it is said, can never account for the beginnings of things. Until
an organ is raised to a useful level, selection can have nothing to
do with it. At first sight that is a serious objection, but it
suggests its own answer; viz., that an organ so rarely develops
ab initio. Organs are not formed anew in an animal, but they
are formed by the modification of pre-existing organs; so that,
instead of having one beginning for each organ, we have to push
the beginning further and further back, and find that a single
origin accounts for several successive organs, or at any rate
several functions instead of one.

The typical vertebrate has four limbs. These in fishes are
used for swimming, while in terrestrial forms the same limbs are
modified and used for walking. New organs are not introduced,
but the old are modified for a new purpose. When the terres-
trial form again becomes aquatic, the limb that was used for
terrestrial progression is modified back into a functional fin; and
again, when flight becomes necessary, the same organ is used for /
the new function. So that whatever the changes in the mode of
progression, we need no new organ at all; for the old organ |
used for the new purpose. It is very much easier to understar
how a useful level can be attained in that way than by org;
starting ab initio. But of course we must come down to a

Poulton. ] 384 [May 16,

beginning if we push our inquiries far enough. In attempting
this, we are carried: to those remote times in which the ancestors
of vertebrates arose. Upon these forms we can do no more than
speculate, but it is at any rate impossible to prove that four bud-
like projections from the body may not have been useful, from
their very beginning, to a slender worm-like animal in pushing
its way through mud or thick weeds. Dr. E. B. Tylor has told
me that he believes that the same thing holds with regard to
human weapons. He said that, in examining ancient weapons,
he was often struck with the fact that a weapon or implement
had ultimately turned out to be so very much more useful for a
new purpose rather than that for which it was originally formed.
Here, then, one origin apparently accounts for several forms of
implement.

Another objection raised against natural selection is that a
selective cause is never a true cause. Professor Cope means to
imply that when he speaks of the ‘‘Origin of the fittest.” But
Darwin’s argument on this point is perfectly sufficient. He says
that when a man drops iron into sulphuric acid, he does not
originate the chemical force that operates, but he may be fairly
said to make sulphate of iron. So natural selection does not
itself originate the factors upon which it depends, but it is so
essential to the result that it may be fairly looked upon as the
true cause (at that level of causation). In Galton’s work we
have a most complete inquiry into human variation and its inheri-
tance, and he shows us that such variation by itself, unguided by
selection, can never advance to anything. Even if you start with
ancestors who are remarkable for any intellectual or structural
feature, their descendants, although some of them may partake
of their parents’ peculiarities, sometimes even to an increased
extent, will ultimately return to the pattern of the race. There
is always a ‘‘recession towards mediocrity.” Hence, unguided
variation can never explain the ‘‘origin of the fittest.” Such a
view is entirely contradicted by the results of Galton’s researches.
Any marked change in the direction of fitness can only become a
character of the species by accumulation through many genera-
tions, and this can only take place by natural selection. Varia-
\ tion unguided by selection can never advance on the increase of
\ fitness present among the individuals of a single generation ; and
ce these improvements, if relatively marked, can never become

EE ————

1894. ] 585 { Poulton.

a character of the species without selection, but by recession will
tend to be lost in the subsequent generations.

I have briefly touched on some of the chief difficulties which
are advanced against natural selection. I now propose to devote
the remaining part of my time to the difficulties which seem to
me to apply to the Lamarckian theory.

Lamarckian evolution, as I have mentioned before, depends
upon acquired characters. A good deal of misconception has
arisen from this use of the word ‘‘acquired.” An acquired char-
acter has sometimes been interpreted to mean any character that
an animal has come to possess; hence, inherent and acquired
characters have been confused. The word ‘‘acquired,” as used
by biologists, must be understood to have a limited and special
application, meaning only those characters which have been pro-
duced in the organism by the incidence of external forces, or by
the action of its own forces, use and disuse of parts, and so on,
during its life. Weismann has suggested the term ‘*blastogenic”’
for characters potentially present in the germ at the very beginning
of life, and ‘‘somatogenic” for those which appear afterwards and
are not potentially present in the germ. Here blastogenic is the
equivalent of inherent, and somatogenic of acquired.

Some years ago I suggested that the terms ‘‘centripetal” and
“centrifugal” might be employed to express this acquired differ-
ence, acquired characters being centripetal, because they are
impressed upon the body or one of its parts from without ; inherent
characters being centrifugal, because, arising from within, due to
the essential nature of the organism itself, in the course of devel-
opment they come to appear, as it were, on the surface as visible
features.

When we now consider the transmission of acquired characters,
upon which the Lamarckian theory certainly depends, we are led
first of all to inquire whether it is possible to frame a theory of
heredity within which such transmission can be included. If, for
instance, there is a change in the brain of an animal, owing to
the exercise of some part of it, how can such.a change in the
brain-cell be transferred to the germ-cells of the animal, so as to
be transmitted to its offspring? It may be objected, if you can
prove that such transmission does take place it is no matter
how it takes place. Quite true, if the evidence is sufticient and
indisputable. But we must remember that the amount of evi-

PROCEEDINGS B. S. N. H. VOL. XXVI. 25 AUG. 1894.

Poulton. | 8386 | May 16,

dence required in order that there may be sufficient, depends upon
the probability or improbability of the thing to be proved. This
view is extremely well put by Professor Huxley in his memoir of
Hume, where he says that if any one came to him and stated that
he had seen a piebald horse in Piccadilly he weuld be prepared to
believe it; that he might require confirmatory evidence if the
statement were that a zebra had been seen; but that if even the
friend in whom he trusted told him he had seen a centaur trotting
down that eminent thoroughfare, he should emphatically disbelieve
it, and that nothing short of a monograph on the anatomy of the
centaur by a comparative anatomist of the stamp of Johannes
Miiller would convince him that the observation was correct. We
are compelled to admit that the amount of evidence we require
does to a great extent depend upon the inherent probability or
improbability of the conclusion to be sustained. If it appears to
us to be almost impossible to conceive of a mechanism whereby
an acquired character can be transmitted from the outlying parts
of the organism to its germ-cells, then we have every reason for
scrutinizing most carefully any evidence that is alleged to prove
such transmission.

Let me first of all give you a concrete example which is fre-
quently brought forward by those who believe in the Lamarckian
theory in this country, and have chiefly studied the skeletons of
Mammalia. They say the joint of an animal possesses just the
sort of shape that would be produced by the motion of the joint
itself, and they urge that the joint as we see it has arisen from
the hereditary effects of that motion. They look upon this as a
very satisfactory explanation, because they consider it to be so
obvious and fundamental. You do not require anything further,
selection is unnecessary and even the individual variation—so
mysterious a factor of the Darwinian theory—is here entirely
explained.

But is the interpretation valid? In the first place, it is clear
that such an hypothesis can never afford a wide or general explana-
tion. There are a great many parts of the animal body which
are not modified in their use. You cannot thus explain the
growth of hair, or the color upon the surface of the organism.
For these and other useful but passive structures, the Lamarckian
interpretation will not hold at all. Hence we may divide the
organism into two sections, to one of which the Lamarckian

1894.| 387 [| Poulton,

theory might be held to apply, and to the other the Darwinian
alone.

But upholders of the Darwinian theory consider that it applies
to the other section as well. They point out, that while the
form of the joint is the sort of form that would be produced by
the motion, such a form is the only one which admits of con-
venient motion, that motion has been essential to the life of the
organism, that alert and rapid movements have been a necessity
in the struggle for existence, and that any form which would
prevent or clog the movements would be at once destroyed by
the operation of natural selection. Natural selection they hold
to be competent to explain these parts which the Lamarckians
also claim to explain, while it offers the only explanation of the
other parts.

If we suppose that Lamarckian evolution in part explains the
actively used organs, and Darwinian evolution in part, we should
expect that modification would take place more quickly in that
section of the organism where the two principles were at work
than in the other section where only one principle—the Dar-
winian—can play a part. But there is no evidence of such
especially rapid evolution. It seems to me that we are in a
position to use the old principle of cutting off superfluous causes.
No unnecessary cause should ever be introduced into an explana-
tion, and if Lamarckism, untenable in the one section, is super-
fluous in the other, it should be removed, unless there is very
clear evidence proving that it has been at work.

Furthermore, in certain cases, such as the protective attitudes
and appearances assumed by many animals, we meet with clear
evidence that the two kinds of parts—those that are effected by
their use and those that are not affected—have undergone develop-
ment together, suggesting strongly that their evolution has been
under the direction of one set of forces, and not of two sets
which have little in common.

Having now brought forward certain general objections to the
Lamarckian position, let me take exception to one or two special
cases.

Certain animals, such as lobsters and crabs, have the power of
very readily parting with some of the most important of their
members. The large claws are easily thrown off, and this may
be of great advantage in the struggle of life, because when an

Poulton. | 388 [ May 16,

individual is attacked by an enemy and seized by the claw, it has
a chance of escaping. In the case of the lobster, the dismembered
claw may not let go of the enemy although the enemy may
let go of the claw. The claw may take charge of the enemy
while the lobster escapes.

Now that isa very interesting adaptation. We find the claw
so formed that it can be thrown off, but even when thrown off it
continues to be of much use to the organism, Its nervous and
muscular mechanism is so arranged that mutilation actually
stimulates it to contract, and it continues to hold the enemy. In
the case of certain crabs, the dismembered claws keep snapping
and jumping about. The same is true of the tails of many lizards,
which, when thrown off, will jump about in the most active way,
distracting the attention of the enemy, while the lizard makes its
escape. Here, too, mutilation stimulates the nervous and
muscular mechanism in tail and claw.

In these cases of actively used parts of the organism the
Lamarckian interpretation is absolutely at fault. You cannot
apply it. It is impossible to explain upon the theory of the
transmitted effects of use and disuse. No activity manifested by
the tail after it has ceased to be part of the lizard can ever be
transmitted. Not only that, but all development undergone by
the tail from the effects of use and disuse, etc., up to the time of
its severance, is also lost to the individual, and cannot be
hereditary. And so with the claw. The large claw is the most
important appendage of the lobster, and yet it is probable that
most lobsters lose it many times and grow a new one. We have
here a very specialized organ with very remarkable functions
continuing in ever an increased degree after severance from the
animal; all this is readily explained by the Darwinian theory, but
cannot be explained by the Lamarckian.

The same inadequacy of the Lamarckian theory is forced upon
us when we look a little more deeply into the nature of the
process which is supposed to occur. The Lamarckians attempt to
explain joints and some other structures by the effects of stress
and pressure, but when we look into the matter a little, we find
that the explanation is not so complete as it is supposed to be.

For instance, it has been believed in this country by many
distinguished biologists that the complex shape of mammalian
teeth is due to pressure produced by mastication. As the pressure

1894. | 389 [ Poulton®

has been applied to the tooth, so has the tooth grown. But
would pressure produce such an effect upon a tooth? That is
certainly not our experience. Pressure and friction have an
unfortunate way of wearing a hole in the tooth, rather than
causing it to grow an elevation. As a matter of fact we know
that the shape of teeth is predetermined long before they are cut
in the soft dental matrix beneath the gum. It is not a question
of the transmission of acquired characters, but the supposed
transmission of a character which the parent cannot by any means
acquire. ‘Teeth, so far as they react to pressure or friction can
only react by wearing away. With regard to the joint, we are
told by some Lamarckian writers, that pressure and friction pro-
duce the reverse effect and wear away cavities rather than cause
new growth.

I was reading a most interesting paper by Dr. Wortman of
New York, the other day, attempting to explain the occurrence
of a furrow in a joint, owing to the pressure of a corresponding
ridge. The pressure of the ridge, it was said, produces a furrow
in the opposite side of the joint. It seems to me that in this we
are going a little beyond what physiology and histology teach us.
It seems to me to be a blind appeal to mechanical forces unsup-
ported by any adequate investigation of the physiology and _ his-
tology of the tissues concerned. Is it likely that a bone would
react to intermittent pressure by producing a furrow? It is far
more probable that the reverse effect would tend to be produced.

I will only ask one more question with regard to this matter of
use and disuse, and that is, why, if you are going to explain any
of these parts by pressure and friction, should the process be
stopped when a useful level is reached? If the pressure does
cause such effects and they are hereditary, how are they prevented
from increasing beyond all bound in the course of generations ?
Why should pressure on teeth cease to produce further growth,
when the tubercle has reached its proper height? It seems to me
that the fact that all these shapes of bones and teeth just reach
and stay at an adaptive level is the strongest evidence that they
are not produced by the operation of mechanical forces, but by
natural selection. -

We now pass to the consideration of indirect evidence: that it
would be impossible to explain evolution without the Lamarckian

theory.

Poulton. | 390 [May 16,

Time will permit me to deal with only one class of characters,
and that is associated with the nervous system and manifested as
instinct. These instinctive actions are generally thought to be
the strongest evidence in favor of Lamarckian evolution. It has
been argued that we cannot explain the instinctive action of
animals — the wonderful instincts which are due, as we know, to
modifications of the nervous system, — except by supposing that
animals have intelligently modified their actions in consequence
of experience and observation, and that the result has then been
transmitted and has become the non-intelligent instinct of their
offspring. If we had no other explanation of instinctive action,
such an interpretation would constitute a strong support to the
Lamarckian theory.

I do not, however, believe that this is the only, or, indeed, the
correct explanation of instinct. In considering this question, we
must distinguish between the instinct manifested by many of the
higher invertebrate animals and much that we are apt to call the
instinct of the vertebrates. A great many actions which are put
down to instinct in the higher vertebrates, such as birds and
mammals, are not instinctive at all, but merely the result of
observation during the life of the individual. We see an example
of this in the action of the seal which, as Nansen tells us, took up
a position on the outer ice-floes to escape the dangers of the polar
bear, and afterwards incurred this very danger on the inner floes
to avoid the greater peril from the hunter. This is a clear case
of reasoning from the results of observation, and no instinctive
avoidance of danger. So also with a bird which flies away if you
have a gun in your hand, but allows you to come near when you
have a walking-stick. This is the result of reason and not merely
instinct; and we must carefully distinguish between a lesson
learned by the individual, however well learned and easily
repeated it may be, and a true instinctive action which was never
learned at all but sprang fully formed into existence. Such true
instincts certainly occur in the higher vertebrates, such as the act
of sucking performed so perfectly without any education or
practice by the newly born mammal. In the lower animals such
true instincts are relatively far more numerous and play a most
prominent part in the life of the individual. In these cases of
true instinct I would suggest that we are dealing with actions
which have never been intelligent at any time in the past history

1894. | 391 [ Poulton.

of the species, and which have been due to the operation of
natural selection upon the nervous system. Certain cases which
are most strongly held to be the outcome of the transmission of
gained experience and the acquired results of practice certainly
cannot be explained in this way.

For instance, how upon any such hypothesis can you explain
the wonderful structure of the cocoon spun by the larva of an
insect? The view would be, [ suppose, that the ancestral larva
spun a cocoon which was not much of a success and was in con-
sequence attacked by enemies; that the larva observed these
attacks, and accordingly improved its cocoon. But that is not
the way in which the struggle for existence is waged with insects.
If the larva failed, it failed, and that would be the end of the
matter. It has no chance of improvement ; it has no opportunity
of learning by experience. Its only chance of survival is to avoid
experience of foes altogether ; experience is the most dangerous
thing in the world to an edible insect. This becomes still more
obvious when we remember that failure or success is almost always
determined long after the cocoon is made. The caterpillar perhaps
spins the cocoon in autumn, but the real stress of competition will
come in winter, when insect-eating animals are pressed hard with
hunger and search high and low for food. But the caterpillar by
this time is a chrysalis and of course hasno opportunity of improv-
ing the cocoon. The selective test is applied long after the opera-
tion has been performed, and when there is no possibility of gaining
by experience. We are thrown back, then, solely upon natural
selection, which acts on the nervous system of the caterpillar,
and thus compels it to make the cocoon in a certain way. In
other words, those caterpillars which are impelled by their
nervous system to make ill-formed, conspicuous cocoons have no
chance of living, and in future stages producing offspring.
Hence, the selection caused by the keen sight of foes first raises
and then maintains at a high level the standard of cocoon-
making.

This contention as to the uselessness and danger of experience
applies to the whole of those smaller defenceless animals which
have no chance of fighting with their enemies or of escaping
when once they have been detected.

Another special kind of instinct has been greatly relied on
by Romanes as evidence for the Lamarckian theory of transmitted

Poulton. | 392, [May 16,

experience. Certain Hymenoptera allied to wasps possess an
instinct which leads them to sting larvae and store them up in
their nests as food for their young. It is generally believed that
the larva is stung in the central part of the nervous system so
that it can no longer struggle. I say ‘‘generally believed”
because it has been pointed out to me by so distinguished an
observer as Dr. Peckham of Milwaukee, that certain facts are
opposed to the generally received account. It is to be hoped
that the observations which are chiefly due to Fabre will be
repeated and tested as minutely as possible. The prey is stored
up in the mud-tube or burrow of the hymenopteron, and keeps
perfectly fresh because it is alive, although completely paralyzed.
Larvae stored up in this way appear to live much longer than
those which, in the full possession of their faculties, are deprived
of food.

Now this is a very wonderful instinct, and it has been argued
that here is a case which cannot be explained except on
Lamarckian lines. I maintain, on the contrary, that it is a case
which cannot by any possibility be explained on Lamarckian
lines.

The wasp-like insect has no opportunity of learning by experience
because it can never know whether the larva stored up is a failure
ora success. If the larva had not been stung, or, accepting the
received accounts, had been stung in the wrong place, it would
struggle and perhaps kill the young grub; or dying of starvation
it might dry up and be useless as food. But the hymenopteron
never goes back to inquire. It makes all the difference to the
young grubs whether the food provided for them is in an appro-
priate condition or not, but it makes no difference whatever to the
parent insect. The latter seals up the chamber in which its eggs
have been laid and never opens it again; it has no chance of not-
ing the failure or success of the food it has provided. It is clearly
a case like that of the cocoon which cannot be explained on the
Lamarckian theory and must be explained on the Darwinian.
And this latter interpretation is easy : those insects which possessed
the nervous mechanism impelling them to provide food in an ap-
propriate condition gave to their offspring the opportunity of sur-
viving and inheriting the same instinct. While others, impelled
to perform less efficient actions, were thereby cut off from any
representation in the next generation.

1894. | 393 | Poulton.

If the origin of wonderful and complex examples of instinct
such as these cannot be explained by the Lamarckian theory but
readily by the Darwinian, why should not natural selection also
offer an adequate explanation of all other cases?

[ have already taken up a great deal too much of your time.
[much hope to have the opportunity to-night of hearing many
stronger arguments in favor of the Lamarckian theory than it has
been my opportunity to hear hitherto.

Note.— In revising the short-hand transcript for publication, I
have not made any changes which alter the character of the ad-
dress. It remains the record of a spoken address, the sequence
and continuity of which were maintained by the use of brief notes.
I have not verified the quoted opinions and words of others, and
there are probably verbal errors. I believe, however, that in
every case the true meaning of the author has been presagved.
—E. B. Pourron. Oxford, May 21, 1894. te

Me

vd

SERA fi
teat

owe WARKABLE ANTICIPATION OF MODERN
VIEWS ON EVOLUTION.

HE great pioneer of modern anthropological and
ethnological research—James Cowles Prichard, was
born at Ross, in Herefordshire, 11th February, 1786.
The following brief account of his life is taken from Pro-
fessor E. B. Tylor’s article in the Fiucyclopedia Britannica
(1885, vol. xix., pp. 722, 723). Prichard was brought up
as a member of the Society of Friends, to which body his
parents belonged. He joined the medical profession, taking
his Doctor's degree at Edinburgh, ‘“ afterwards reading for a
year at Trinity College, Cambridge, whence, joining the
Church of England, he migrated to St. John’s College,
Oxford, afterwards entering as a gentleman commoner at
Trinity College, Oxford, but seeking no degree in either
University. In 1810 he settled at Bristol as a physician.”
Among his many great achievements in anthropology was
the proof ‘‘ that the Celtic nations are allied by language with
the Slavonian, German, and Pelasgian (Greek and Latin),
thus forming a fourth European branch of the Asiatic stock
(which would now be called Indo-European or Aryan)”.
His treatise on the subject, entitled ‘“Zastern Origin of the
Celtic Nations,” appeared in 1831. ‘It is remarkable that
the essay by Adolphe Pictet, De ?Affinité des Langues
Celtigues avec le Sanscrit, which was crowned by the
French Academy and made its author’s reputation, should
have been published in 1837 in evident ignorance of the
earlier and in some respects stricter investigations of
Prichard.”

Although Prichard’s memory is much honoured, it
appears that in one important respect he has not hitherto
received his due. My friend Professor Meldola lately
drew my attention to a section of the second volume of
Researches into the Physical Historyof Mankind (2nd edition,
1826) which, as he pointed out, anticipated in the clearest
manner the arguments which have been recently advanced

2 SCIENCE PROGRESS:

by Professor Weismann in favour of the non-transmission
of acquired characters. The deep significance of the
passages in question had been observed by Dr. Maurice
Davis, J.P., who brought them under the notice of his son-
in-law, Professor Meldola.

In response to Professor Meldola’s invitation to prepare
an account of this most interesting contribution to the
history of evolution, I read the work carefully and soon
found that other important ideas are anticipated in it.

Thus, Prichard apprehended with perfect clearness that
domesticated races of animals and plants have been pro-
duced by the selection of man and not by favourable sur-
roundings, careful training or cultivation. He believed
in the possibility of organic evolution and supported it by
excellent arguments which still have the strongest weight
to-day. He even recognised the operation of natural
selection although he assigned to it a subordinate 7dd..
The most important anticipation is, however, the masterly
discussion on the transmission of acquired characters,
a discussion in which the distinction between acquired
and inherent or congenital characters is clearly drawn, and
many of the most difficult cases are fully argued out, the
conclusions reached being those independently arrived at
by Professor Weismann over half a century later.

It is very remarkable that all this should have passed,
as I believe, unnoticed. The neglect can only be explained
by supposing that this particular edition was never consulted,
but that Darwin and others always went to later editions of
the same work. I shall be able to show that Prichard was
not very confident in the strength of his own conclusions
and, so far as I have consulted his later editions and works,
I find reason for the belief that his convictions weakened still
further. Indeed strong indications of uncertainty are to
be found in the second edition itself, although they are con-
fined to the later sections, and do not appear in close
proximity to the important conclusions which they never-
theless affect.

It is certain that if Darwin had read this second edition
he would have given Prichard a high place in the account

BeiceE MA RICE ANEICIPALTION, ERC. 3

of the history of evolution which appears in the introduc-
tion to all later editions of the Ovzgzn. So too would
my friend, Professor Osborn, have given high honour to
Prichard in his interesting work, /vom the Greeks to Dar-
win. It is an anomaly that such works as the Vestzges
should attract attention, while Prichard’s keen insight,
sound judgment, and balanced reasoning on many aspects
of organic evolution should remain unknown.

I am very far from maintaining that these most in-
teresting anticipations in any way diminish the credit of
those recent writers who have treated the same subjects in
greater detail and of course independently. The interest
evoked by Dr. Davis’ discovery in the literature of evolu-
tion is mainly due to the work of those recent authors by
whom the whole subject has been brought into the light of
day, and the attention of every intellectual man and woman
has been compelled.

The limits of space oblige me immediately to proceed,
after this too brief introduction, with a detailed statement of
Prichard’s arguments and conclusions, which will be found
to justify, in the fullest manner, all that I have said in his
praise.

It has already been said that the arguments referred to
are found in the Aesearches into the Physical Flistory of
Mankind, vol. ii. (London, 2nd edition, 1826). They are
included in the seven sections of the first chapter of Book
ip: 525), which is-entitled’a “General Survey /oljthe
Causes which have Produced Varieties in the Human
Species, with Remarks on the Origin of Nations and on

the Diversity of Languages”. The first chapter treats
““Of the Causes which have Given Rise to Varieties in the
Human Species”. In the first section of the first chapter

the author admits that it is fruitless to seek for a complete
explanation of the causes which have produced the varieties
which are witnessed in the human species. “The origin
of the varieties in the breed is enveloped in the same
obscurity which still hangs over every question relating to
the theory of propagation.”

The opinion that the different shades of colour met

4 SCIENCE PROGRESS.

with in various races are caused by climatic changes and by
varying intensity in the rays of the sun, is then considered,
and a great many ancient and modern exponents of this
view are quoted. After reproducing a long passage from
sutton, the hypotheses of the Rev. Dr S_,S. Smaithon
New Jersey are described. These deal not only with the
‘gradation in the complexion nearly in proportion to the

latitude, ...” but also with the influence which heat
exerts upon the secretion of bile. In consequence of heat
eine bile... is augmented. 20.) Vhisiliquonemgesweme
complexion. ...” -** Bile, exposed’ to the sunvancramare

known to change its colour to black—black is, therefore, the
tropical hue.” This latter and the very similar views of
Blumenbach are, however, dismissed by Prichard as ‘‘ with-
out foundation” ; while as to the former suggestion of Dr.
Smith, together with that of Buffon and the older writers, he
observes that the principal observations on which it is based
are correct. ‘‘It is certain that the majority of black races
of men are inhabitants of the intertropical regions, and that
most of the light-coloured nations are to be found in cold
or temperate climates.” But although he admits the fact,
he maintains that it is capable of ‘‘a different interpretation
from that which modern writers have in general adopted”.
Me similarly admits that the skin of a European is
darkened by the sun, and continues: “ It seems, at first, not
very improbable that individuals darkened by exposure to
heat in southern climates, may have an offspring of deeper
colour in consequence, and if this effect increases in every
generation it may be thought sufficient, in a long course of
ages, to produce a black colour of the deepest tint”. But this
view does not by any means commend itself to him; for he
continues ‘that this notion, however, is altogether incorrect,
I venture to conclude from the following considerations :—

“1, The progeny of individuals, embrowned by exposure
to the sun, is born with the original complexion, and not with
the acquired hue of the parents.” Furthermore, he points
out that white and black races moved respectively to
tropical and temperate climates have retained their original
colour for ages. The second consideration which leads him

Apne MARKADLE ANTICIPATION, BIC. 5

to reject the above-mentioned conclusion is very significant,
and I give it in his own words (p. 532) :—

“2. The supposition is contrary to a general law of the
animal economy, according to which, acquired varieties are
not transmitted from parents to their offspring, but terminate
in the generation in which they have taken their rise.”

The succeeding two sections are allotted to the con-
siderations contained in paragraphs 1 and 2.

Section ii. (p. 532) is headed “Instances Showing the
Permanency of Complexion in Different Races”. ‘The cases
in which races have completely changed in colour after
removal to a different climate he explains by a mixture of
breed ; and points out that “it is easy to find examples of
an opposite tendency, and to show that the original hue
Mas been preserved .... hus he brings forward@mme
instances of the descendants of English colonists in the
West Indies and Spanish in South America who “remain
as fair as their European ancestors,’ when there has been

no intermarriage with other races. ‘That this assertion
is correct, | am convinced,” he says, ‘‘by the results of re-
peated inquiries.” In the East the same results are found,

although the migration of white races into hot climates took
place at far earlier dates. Thus amongst other examples
he mentions that of the “white or Jerusalem Jews” who
are believed to have migrated to the Malabar coast in the
year 490 A.D., and whose living descendants are ‘‘said to
resemble the European Jews in features and in com-
plexion ”.

The converse ‘‘experiment of transplanting black races
into northern climates” has not been carried on for so long
a period, but Dr. Prichard points out that ‘several genera-
tions have produced little or no alteration in the complexion
of Negroes in the United States and in other temperate
climates”. It is indeed stated that ‘the domestic Negroes
who are protected from the heat of the sun by more clothing,
and who pass their time in sheltered houses, are of a darker
complexion than the slaves who labour half naked in the
fields”.

Section iii. This most significant and remarkable part

6 SCIENCE PROGRESS.

of the work is headed (p. 536), “Laws of the Animal
Economy in Regard to the Hereditary Transmission of
Peculiarities of Structure”; the brief title at the head of the
pages runs ‘‘ Laws of Nature in Hereditary Transmission ”.
This discussion, which forestalls by more than half a century
the considerations and conclusions of recent writers and
especially of Professor Weismann, is opened by the state-
ment that physiological writers have often inquired ‘‘ what
peculiarities of structure are liable to be transmitted by
parents to their offspring, and what terminate with the
individual without affecting the race. Perhaps the following
remark,” the author goes on to say, ‘‘may afford the solution
of this inquiry ”.

I must now quote without any omission the succeeding
two paragraphs in which the two classes of characters—
inherent and acquired—are defined, as fully and clearly
as they have ever been, and the opinion is strongly ex-
pressed that the former are transmissible, the latter non-
transmissible by heredity :—

“Tt appears to be a general fact, that all connate varieties
of structure, or peculiarities which are congenital, or which
form a part of the natural constitution impressed on an
individual from his birth, or rather from the commencement
of his organization, whether they happen to descend to him
from a long inheritance, or to spring up for the first time in
his own person—for this is perhaps altogether indifferent—
are apt to re-appear in his offspring. It may be said, in
other words, that the organization of the offspring is always
modelled according to the type of the original structure of
the parent.

“On the other hand, changes produced by external
causes in the appearance or constitution of the individual
are temporary, and, in general, acquired characters are
transient ; they terminate with the individual, and have no
influence on the progeny.”

At this point the author adds a most interesting foot-
note in which he tells us (p. 537) that ‘this distinction,
which has not been pointed out by any former writer on
physiological subjects, was first suggested to me in conversa-

A REMARKABLE ANTICIPATION, ETC. 7

tion many years ago by Mr. Benjamin Grainger, of Derby”.
It would be of high interest to ascertain something more
about Mr. Grainger and to find out whether he ever
published on his own account. It is however probable,
from the other pregnant ideas contained in Dr. Prichard’s
work, that the clear expression, apt illustration, and ad-
mirable discussion of these principles are entirely original.

He then proceeds to illustrate the first proposition
“that all original or connate peculiarities of body are
hereditary”; first instancing the well-known “ porcupine
family, in which a remarkable peculiarity of the [human]
skin was transmitted through three successive generations,”
and the facts which prove the hereditary nature of com-
plexion, as shown in section ii. Supernumerary and
abnormally thickened digits are then brought forward and
proved by many examples to be markedly hereditary ; as
also ‘‘a singular thickness of the upper lip, in the Imperial
house of Austria,” introduced it is believed ‘‘ many centuries
ago... by an intermarriage with the ancient house of
Jagellon”.

The last examples of such connate characters are especi-
ally significant. ‘The same observation equally applies to
those minute varieties of organization, which give rise to
peculiarities of habit or temperament, and predispose to a
variety of morbid affections, as deafness, scrofulous com-
plaints, and the whole catalogue of disorders in the nervous
system. Even those singular peculiarities termed idio-
syncrasies are often hereditary, as in the instance of a
remarkable susceptibility of the action of particular medi-
cines, such as mercury.”

With regard to the second proposition ‘that acquired
peculiarities, or characters impressed by adventitious circum-
stances, and not arising in the spontaneous development of
the bodily structure, are never transmitted ... ” he re-
marks, as it has often been insisted upon since, that the
conclusion ‘“‘is more difficult to establish than the foregoing

., since the proofs must needs be of a negative kind.
But,” he continues, ‘‘there is no want of evidence of this
description.” And he again insists, as if he could not put it

8 SCIENCE PROGRESS. —

too clearly and emphatically: ‘It seems to be the law of
the animal economy, that the organization of the offspring,
which as we have seen follows the type ‘given by the
natural and original structure of the parent, is unaffected
by any change the latter may have undergone, and un-
influenced by any new state it may have acquired”.

He then discusses the examples which are supposed to
support the opposite conclusion, first mentioning the statement
‘that dogs and cats, the tails of which had been cut off, some-
times produce young ones which have a natural defect of the
same part. It is taken for granted that these appearances
are connected together in the relation of cause and effect,
and therefore afford a proof that acquired peculiarities are
hereditary.” The author argues that cases of this kind are
accidental, and he points out that such defect of parts is apt to
occur in every species ;—in man as wellas in animals. He
points to the vast experiment due to “our caprice” in muti-
lating the ears and tails of domestic animals, and to the
effects of surgical operations upon man. What remarkable
results would be witnessed if such changes were hereditary !

Professor Weismann was first led to the same conclusion
as Dr. Prichard by constructing a theory of heredity which
seemed to him to explain the facts and observations better
than any which had been previously proposed. But the
theory did not include any mechanism by which the trans-
mission of acquired characters could take place. Professor
Weismann, believing that his theory was in the main right,
began to inquire for the evidence on which the belief in
such transmission is based, and as soon as he commenced
his inquiries the evidence broke down in every direction.

With Prichard it was otherwise, for the existing theories
seem to have been against him. Thus he argues that his
opponents ‘‘seem to have derived their opinion rather from
some conjectural theory of generation, than from any facts
which have appeared well established” ; and he goes on to
contend that we know so little “that we are not authorized
to reason from any hypothesis on this subject”.

He next deals with the statement “that after mutilation
or other artificial change has been repeated through many

A REMARKABLE ANTICIPATION, ELC. 9

generations, a sort of habit may be acquired, by which the
new state becomes as it were natural, and may thus modify
the race”. To this he replies that the evidence of such
habit could only be obtained by diminishing the mutilation
in progressive generations and comparing the result; whereas
in all such cases the violence committed and the resulting
injuries are continued unabated. “If, however, an expert-
ment be wanting to prove that repetition effects no difference
in the results,” he points to the practice of circumcision
which has gone on for some thousands of years without
producing any hereditary change.

Prichard argues that such non-tranmission is beneficial,
in fact he contends ‘that all the laws of nature, or the
general plans which we trace through the organized
world, tend uniformly to produce beneficial effects, though
particular evils are sometimes contingent upon their opera-
tion”. With regard to this instance he points out that, if such
transmission took place, both man and animals would prac-
tically become more and more ‘ mutilated and defective ”.

The author next proceeds to consider the effects of
disease, introducing the subject in the following paragraph :
“we cannot discern any essential circumstance in which
changes produced by art or by casual injury differ from
those which are effected by other external causes. We
should therefore suppose from analogy that the latter are
not more communicable to posterity than the former, and
this presumption is confirmed when we inquire into facts.”

He points out that the constitutional effects of many
diseases (“small-pox, measles, scarlatina, whooping-cough”),
rendering those who have suffered from them more or less
immune, are never hereditary. Without attempting to
explain in what the change consists, he rightly claims it as
“a permanent state of the constitution, which lasts as long
as the individual. . . . Those imperceptible modifications in
the bodily structure which render the constitution incapable
of being acted upon by certain morbid poisons are governed
by the same law, as far as regards hereditary descent, as
the observable changes of form which are induced by art or
accident.”

10 SCIENCE PROGRESS.

At this point the writer intercalates another clear state-
ment of the essential distinction between inherent hereditary
and acquired non-hereditary characters. The statement is
so admirable that I quote it in full.

“We may remark in general that each individual being,
through the animal and vegetable worlds, has certain laws
of organization impressed upon its original germ; according
to which the future development of its structure is destined
to take place. These inbred or spontaneous tendencies,
governing the future evolution of the bodily fabric, cause it
to assume certain qualities of form and texture at different
periods of growth. From these predispositions are derived
the characteristic differences, and the peculiarities of indi-
vidual beings. Now it appears that such spontaneous
tendencies are alone hereditary, and that whatever changes
of organization are superinduced by external circumstances,
and are foreign to the character of structure impressed upon
the original stamina, cease with the individual, and have no
immtence on the race,

“Yet this law of hereditary conformation exists with a
certain latitude or sphere of variety, but whatever varieties
are produced in the race, have their beginning in the original
structure of some particular ovum or germ, and not in any
qualities superinduced by external causes in the progress of
its development.”

These sentences might well have been written to-day,
to sum up the results of all our observations on such
subjects. These results have been summed up at greater
length and in more technical language, but I venture to
think that Dr. Prichard’s statement contains everything that
is valuable and essential in every later attempt. It will be
observed that Weismann’s conception of inherent characters
as blastogenic, acquired as somatogenic, stands out clear
and distinct; furthermore, that the source of individual
difference is traced to the germ.

After these general statements he returns to the question
of disease and discusses predisposition. He points out that
medical writers have generally believed that any predisposi-
tion to disease may arise in any constitution if subjected to

A REMARKABLE ANTICIPATION, ETC. LE

the appropriate causes; “that . . . the gouty diathesis, for
example, may be acquired by long habits of intemperance,
and transmitted to posterity,’ and so also with other ill
effects witnessed in the children of dissolute parents. If
this be so, Prichard admits that “we have a clear: proof
of the hereditary nature of acquired states of the constitu-
tion ”’.

Against such a view he contends that any particular
disease can only follow when there exists “a preparation,
laid in the first place by nature, in the original stamina and
habit of the body”; and he points out that the same hurtful
cause may produce quite distinct diseases. Thus “ intempe-
rate living . . . is commonly said to bring on, in one person,
a predisposition to gout, in another to diseases of the liver,
or of the stomach, or of the brain. Now since the difference
is not in the external causes, it must be in the natural
peculiarities of the constitutions on which they act. These,
therefore, are previously fitted by original organization to
take on them one form of morbid affection rather than
another. It is then clear that the predisposition is laid by
natural or congenital structure, in the first instance.” Indi-
viduals differ in particular organs; the exciting causes of
disease bring out the weaknesses which previously existed
and might otherwise have remained unknown. Such de-
fects “being a part of the original bodily structure” are
hereditary. ‘‘ The first individual who exposes himself to
the morbid causes, first betrays the peculiar defect of his
race, and is thus erroneously supposed to lay the foundation
fon it”

Syphilis, which appears to be an exception, he explains
by ‘‘a peculiar mode of infection. . . . This is evidently a
phoenomenon of a very different kind from the similarity of
structure which the laws of nature have ordained between
parents and their offspring.”

Hence he infers ‘that the phoenomena of predisposition
to diseases, rather confirms than invalidates the general
observations before laid down, and we may be allowed to
conclude, that no acquired varieties of constitution become

hereditary, or in any manner affect the race”. | bats
ys y | ence aaa SON

12 SCIENCE (PROGRESS.

The preservation of complexion after a race has migrated
to a very different climate conforms to the general law.
Although the parents may alter greatly “the adventitious
colour has no influence on the offspring ”.

Hence in looking for the causes of varieties of mankind
we must not ‘direct our attention to the class of external
powers which produce changes on individuals in their own
persons, but to those more important causes, which acting on
the parents, so influence them that they produce an offspring
endowed with certain peculiar characters, which characters,
according to the law of nature, become hereditary, and thus
modify the race”.

The sentence I have last quoted concludes the section
and very naturally introduces section iv., entitled, ‘‘ Theory
of the Origin of Varieties” (p. 548).

This section opens with a sentence which might well
have been written by Darwin: “ Varieties of form or
colour, as they spring up in any race, are commonly called
accidental, a term only expressive of our ignorance as to
the causes which give rise to them”. — On the other hand—
“how, by what influence, and tx what manner” they are
produced, “we shall perhaps never be able to ascertain”.

Examples of new varieties which have sprung up within
tlle experience of. man are then given: the “ porcupine?
and six-fingered man, albinos and variations in colour. He
next describes the sudden origin of the ancon or otter
breed of sheep, quoting from Col. Humphries in the
Philosophical Transactions for 1813 (part 1.).

Prichard favours the view that when the offspring does
not exhibit a new variety but follows the main lines of its
race or breed, it is apt to be influenced by the father rather
than the mother ; and he quotes a number of statements and
opinions believed to favour this view ; and finally alludes to
the celebrated cross between the mare and the male quagga
in which it was confidently believed that so great an effect was
produced on the former that her later offspring, although
begotten by a stallion, were influenced in the direction of
the quagga (telegony).

The mother, on the other hand, was believed to be in

A REMARKABLE ANTICIPATION, ETC. 13

the main responsible for the new varieties which arise from
time to time. This opinion Prichard considered to be
probably well grounded; and the conclusion that size and
stature chiefly depend on the mother he also thought to be
well established. Hence we see that his judgment and
penetration were not always proof against popular convic-
tions insufficiently sustained by evidence. These strange
views about the relative importance of the two parents
seem to have disappeared, and only traces of them are to
be found in the popular beliefs of the day.

The author dismisses the extreme cases of the supposed
effect of the mother’s imagination upon the unborn child as
manifestly absurd; but looks with some favour upon the
opinion, also held by Erasmus Darwin whom he quotes,
that the future offspring may be effected by the imagination
of the parent at the moment of conception. In proof of
the ancient origin of this belief he alludes to Jacob's ex-
periments upon the flocks of Laban.

When, however, Prichard comes to reconsider all his
suggested causes of variation he is dissatisfied with them
and admits that “the circumstances—are of a more per-
manent nature,” and that it is often ‘‘impossible to discover
any peculiar circumstance in the condition of the mother”.
This leads him to consider the similar instances among
domestic animals and among plants and at this point he
anticipates in a truly remarkable manner Darwin's general
conclusions as to the origin of our domestic breeds.

“Tt is generally supposed,” he says on page 557, “that
cultivation is the most productive cause of varieties in the
kind, both in the animal and vegetable kingdom. But it
may be questioned, does cultivation actually give rise to
entirely new varieties, or does it only foster and propagate
those which have sprung up naturally, or as it is termed
accidentally ?

‘In this latter way the influence of art is very impor-
tant in constituting breeds, as of cattle, dogs, horses. The
artificial process consists in a careful selection of those in-
dividual animals which happen to be possessed, in a greater
degree than the generality, of any particular characters

14 SCIENCE PROGRESS.

which it is desirable to perpetuate. These are kept for
the propagation of the stock, and a repeated attention is
paid to the same circumstances, till, the effect continually
increasing, a particular figure, colour, proportion of limbs,
or any other attainable quality, is established in the race,
and the uniformity of the breed is afterwards maintained by
removing from it any new variety which may casually spring
up in it.”

The main result of Darwin’s indefatigable labours on
the formation of domestic races could not be more ac-
curately summarised than in these words published in 1826.

Prichard expresses himself as uncertain whether do-
mestic animals are more prone to vary than others, but
considers that the artificial conditions may in all prob-
ability ‘‘occasion deviations in their progeny”.

The influence of climate seemed to him the most im-
portant of all causes of race-formation—so important in fact
that he discusses its examples under a separate section, while
the adaptation of races, animal and human, to their climates
form the subjects of the concluding sections vi. and vit.

The examples of the effect of climate are brought
forward in section v. (p. 558), entitled, ‘Instances of
Variety in the Breed, Arising from the Operation of Exter-
nal, Chiefly of Local Causes”. The first instance is that of
the swine of Cuba which are said to be twice the size of the
parent breed. He then instances the peculiar and uniform
colour of the cattle and horses ‘descended from the
variegated domestic breeds” which have become wild in
South America, and the common bear which differs in
colour in various European localities.

When the races of several distinct species resemble
each other in a single locality it is fairly maintained that
some special local influence may be strongly inferred.
Thus it is stated that the Angora breeds of rabbits, goats,
and cats are remarkable for their long fine silky hair and
white colour. ‘These characters . . . indicate a common
cause, which must be some peculiarity in the circumstances
under which these animals exist in the climate and situa-
tion occupied by them.”

A REMARKABLE ANTICIPATION, ETC. 15

Then follow many other examples—the blackness which
characterises both men and animals in Malabar and
Guinea, the whiteness of Polar animals, the height of Pata-
gonian man, the differences which separate the English race
in America and the West Indian Islands from that in the
parent country, and the negroes of America from those of
Africa.

The section concludes in a significant paragraph in
which the author suggests that perhaps some of these local
varieties may be specially adapted to ‘the circumstances of
the countries in which the deviation has taken rise,” and
he finally concludes by introducing the succeeding section
in these words: “It may indeed be inquired, whether the
deviations in general, which appear to follow a change of
climate, are not founded on a law of the animal economy,
which gives rise to an alteration in the breed calculated to
fit the race for its new abode” (page 566).

The sixth section (p. 567) is headed ‘Adaptation of
Certain Breeds to Particular Local Circumstances”. In this
section we are provided with numerous instances of the
adaptation of races to their environments. Blumenbach’s
opinion in favour of the multiple origin of the dog is quoted
at some length. Considering the undoubted adaptation of
many breeds for certain ends this naturalist concludes: ‘I
can scarcely persuade myself to look upon this as a mere
accidental consequence of degeneration, and not rather as
an intentional contrivance of the wise Creator”. To this
Prichard replies that such a remark “suggests the inquiry
whether the degeneration or variation of animals is in fact
a mere accidental phenomenon ...”. We should note
that degeneration is here used in the sense of departure
from ancestral type, and not implying, as it does in our time,
any degradation or simplification of structure.

Then follows a paragraph most significant of modern
views of organic evolution and the kind of evidence on
which the modern naturalist relies. The remarkable
‘double relation” which individual species bear on the
one hand to their special localities, and on the other to the
group to which they belong, is first pointed out, and main-

16 SCIENCE PROGRESS.

tained to be characteristic of the vegetable kingdom as well
as the animal. Thus the species of a family or genus are
often distributed round a centre ‘‘ which seems to be the
principal focus or favourite seat of the tribe,” from which
the branches diverge in various directions. The particular
species, when compared, can be referred to ‘one type of
organization”. The slighter differences between them
“seem to lose themselves in the sameness of form be-
longing to the genus, and even suggest a suspicion that
they all proceeded from one original. The phznomena
of resemblance must have had their sufficient reason as
well as those of diversity.” He then inquires whether the
explanation is to be found in the action of ‘some slight
modification in the productive causes” which stamped the
genus at its first appearance “ with all these specific diversi-
ties”; or whether on the other hand a uniform genus was
first created which ‘afterwards became diversified by the
influence of external agents”. He concludes that the
former of these alternatives is more strongly indicated by
the knowledge of his time.

‘Whichever of these suppositions may be true in point
of fact, the separation of families and genera into particular
species, and the distribution of these species to particular
habitations, according to their physical properties, is evi-
dently a part of the provision of nature for replenishing
the earth with organized inhabitants, placed everywhere
according to the congruity of soils and temperatures,
with their structure and habitudes.

“ But why is it to be supposed that the influence of this
law of adaptation has stopped here? Is it not probable
that the varieties which spring up within the limits of
particular species, are further adaptations of structure to
the circumstances under which the tribe is destined to exist ?
Varieties branch out from the common form of a species,
just as the forms of species deviate from the common type
of a genus. Why should the one class of phenomena be
without end or utility, a mere effect of contingency or
chance, more than the other ?

“There are indeed many instances in which we can

A REMARKABLE ANTICIPATION, ETC. 17

perceive an advantage in the varieties of form, and an
adaptation of particular breeds to external circumstances.”
He then gives numerous examples—the small active cattle
and horses which are found in mountainous countries, the
larger forms which flourish on fertile plains; the various
breeds of the hog which are believed to hold “a particular
relation to the localities in which they are placed”; the
change of a thick fleece into a thin coat when certain breeds
of sheep are transported to the tropics. ‘On considering
these and analogous phenomena, we can scarcely avoid con-
cluding that the variation of animals proceeds according to
certain laws, by which the structure is adapted to the
necessity of local circumstances.”

This statement looks at first sight very much like
natural selection. It is clear however that the writer held
a view similar to that which has been termed “self-
adaptation” by some modern writers, viz., that external
influences act on the organism in such a manner as to
evoke directly a favourable response.

Examples of similar adaptation are then found among the
races of man. The skin of black races is considered to be
a protection against the effect of heat; the native African
races can multiply in localities where a white population
cannot maintain its numbers, while negroes are unable to
establish themselves in northern latitudes. From these and
many other instances, it appears that ‘“‘in mankind, as in
some other races, particular varieties are adapted by consti-
tution and physical peculiarities to particular local situations”.

The section finally concludes with the following para-
graph: “ These remarks, if they are well founded, serve to
illustrate the doctrine of variation, or deviation, in the races
of animals in general, and they seem to lead us to the con-
clusion, that this is not merely an accidental phenomenon,
but a part of the provision of nature for furnishing to each
region an appropriate stock of inhabitants, or for modifying
the structure and constitution of species, in such a way as
to produce races fitted for each mode and condition of
existence. A great part of this plan of local adaptation
appears to have been accomplished by the original modifi-

18 SCIENCE PROGKE SS:

cation of a genus into a variety of species. It has been
further continued, and the same end promoted, by the rami-
fication of a species into several varieties.”

The seventh and last section (p. 575) of this part of the
work treats ‘“‘Of the Relation of Particular Varieties of the
Human Species to Climates”.

Prichard evidently thought that adaptation of races to
climate is especially characteristic of the human species, and
must be admitted to hold in certain instances whatever be
thought of his hypothesis that “the varieties in the species
of animals proceed from a principle in nature, modifying
the structure and constitution of races, and adapting them
to the physical circumstances under which these races may
bewecstined tomexist ~ ‘We considers that the ais:
tribution of the races of men bears ‘‘a certain relation to
climates,” and gives a broad sketch of the geographical
arrangement of races in support of this opinion. At the
conclusion, after inquiring how it is that ‘‘these varieties
are developed and preserved in connection with particular
climates and differences of local situation,” he gives the
following very significant answer : ‘‘ One cause which tends
to maintain this relation is obvious. Individuals and families,
and even whole colonies, perish and disappear in climates
for which they are, by peculiarity of constitution, not
adapted. Of this fact proofs have been already mentioned.”
We have here the undoubted recognition of natural selec-
tion, and it is remarkable that a man of such penetration
who recognised fully that domestic breeds are due to man’s
selection, should not have seen in this principle. a larger
importance and have extended it to the relations of species
to each other as well as to their physical environment.
Great as Prichard was he did not appreciate the most
pressing part of the “struggle for existence”.

Prichard furthermore considers it probable that there
are local influences which “‘promote the appearance of
those varieties which are best suited to them, or tend to
give rise to their production in the breed”. He freely
admits that this conclusion conflicts with his contention in
section ii, that the colour of a race is not permanently

He REMARKABLE ANTICIPATION, ETC. 19

affected by a change of climate, and, he might have added,
conflicts equally strongly with his argument in section iii.,
that acquired characters are not transmitted. However, he
is so fascinated by the view of a local influence directly pro-
ducing adaptation that he throws over much that he had
previously argued for in a most convincing manner. Thus
he suggests that races of men when removed into another
climate may not change because they are defended from the
local influences by living in houses, adhering to their old
foods, etc., also that the facts about the black and white
Jews of Cochin, from which he argued in section ii. that
climate produces no permanent effect on the race, may be
insufficiently known.

It is strange that one who reasoned so acutely in section
ii. did not seem to see that the following view if proved to be
true would undermine the whole of the argument : “ It may
however be true, that particular varieties, once established
in the stock, and transmitted for many generations, though
originally resulting in a certain degree from the influence of
local causes, will nevertheless continue permanent, even
long after the race has been removed from the climate in
which they originated ”.

In spite of this logical flaw, which is in itself of much
interest, inasmuch as it probably explains the suppression
of Prichard’s original views in later works, sufficient has
been said to prove that the author was one of the most
remarkable and clear-sighted of the predecessors of Darwin

and Wallace.
E- By Pourron

X.) Ou the Courtship of certain Huropean Acridiute.
By Professor Kpwarp B. Pourron, M.A., F.R.S.,
¥’..8., ete. oe

[Read April 1st, 1896. ]

THe extraordinarily fine and hot weather in Switzerland
at the end of August and beginning of September last
year (1895), was very favourable for the observations
which are here recorded. I was then staying at the
Weisshorn Hotel, high above Vissoye, in the Val
d’Anniviers, 7690 feet in elevation. Certain species of
Acridiide were excessively abundant in the immediate
neighbourhood of the hotel, species moreover which
afforded examples of very different methods of courtship.

In working at this subject I received the greatest
assistance from my two friends, Mr. F. Jenkinson and
Mr. F. V. Dickins: their keen powers of observation
enabled me to add many new facts of much interest, and
also afforded valuable confirmation upon the most diffi-
cult points. Mr. Jenkinson observed with me for hours
together on several occasions, so that we were able to
compare our impressions as we received them.

Dr. Sharp has kindly identified the species for me,
comparing my specimens with a Brunner collection at
Cambridge.

The object of this enquiry was to make out the
methods employed by the males in the courtship of the
females, and especially the part played by stridulation.
Dr. Sharp, in the Cambridge Natural History (Vol. v.,
p. 286), insists on the insufficiency of observations on this
point, and I therefore hope that this work has not been in
vain. The following observations suggest that the true
significance of the latter is tc be found in its use during
courtship. In only a single species of those observed,
Stethophyma fuscum, did the males commonly stridulate
without reference to the females, and merely in rivalry
with each other. In all the other sound-producing species
the power seemed, almost without exception, to be

TRANS. ENT. SOC. LOND. 1896.—PaRT 1. (JONE.) 16

234 Professor Edward B. Poulton on the

exercised with direct reference to females, or in rivalry
to other males in the presence of a female. In the case
of Psophus stridulus, true stridulation was only observed
when the close proximity of a female had evidently
thrown the male into a state of excitement.

The following considerations also support the same
conclusions. In Pezotettix pedestris, both sexes have
rudimentary wings and the male never makes any audible
sound. Nevertheless, when he is seated on the back of
the female attempting to pair, and during coitus itself,
he continually moves his third legs alternately as if
in stridulation. 1 believe that this movement is a vestige
of an ancient and long-lost power of producing sound.
Although stridulation is usually produced by a symmetrical
movement of the third legs, it will be shown that this is
not the case with Stenobothrus elegans. ‘There is there-
fore no objection to be raised against this character of
the movement in Pezotettiz. Another view, and that
held by my friend, the learned Orthopterist, Henri de
Saussure, is that sound is really produced, only we cannot
hear it. He holds that the sound is merely the outward
expression of the elated feelings of the male Pezotettiz.

Dr. Sharp, too, considers from the presence in
apparently dumb species of well-developed tympana—
and this is their condition in Pezotettic—<that the
Orthoptera provided with acoustic organs, and which we
consider dumb, are not really so, but produce sounds we
cannot hear, and do so in some manner unknown to us”’
(Cambridge Natural History, Vol. v., 287). On the
other hand, it may be urged that the perception of vibra-
tion by means of tympana may be of great value in the
life of an organism, even if the organism were incapable
of producing sounds, and that it may be retained for
some more general use when its original special function
has ceased to exist.

But in any case this movement of Pezotettix is con-
ducted with an apparatus homologous with that by which
sound is produced in other Acridiide, and yet one in
which the special sound-producing structures are absent.
The tegmina are too short to be brought into their usual
relation with the femora, and the ridge on the inner face
of the latter is without the “musical beads,” although
strongly chitinized and prominent as though it had pre-
viously possessed significance in this respect.

Courtship of certain European Acridiide. 235

Further evidence in support of this explanation is to
be found in the fact that Pezotettiv makes the movement
when he has succeeded in capturing the female and when
pairmg has actually begun. In the other species ob-
served the normal arrangement was for the male to
stridulate apparently to charm or please the female before
leaping on her; stridulation after this occurring only in
certain special cases (one observation on Stenobothrus
hemorrhoidalis, and one on Stethophyma fuscwm, im
which it is to be explained as an answer to another
very persistent male).

If, however, as I suppose, the movements of Pezotettia
are merely vestigial, we can quite understand their asso-
ciation in the nervous system with those stronger nervous
impulses which are concerned with the successful issue
of courtship, rather than with the impulses concerned
with courtship itself. According to this view the
functional stridulation is associated with anticipation
while the vestigial stridulation is only evoked by realiza-
tion. It should be added that it is quite possible that
these movements of the male Pezotettiv may have a
stimulating or perhaps merely a soothing effect on the
female.

The comparison between Pezotettiv and the other
species supports in another way these conclusions as
to the essential significance of stridulation in courtship.
In the latter kinds, so far as they were sufficiently
observed, the female was treated with considerable cere-
mony; in Gomphocerus a peculiar attitude was assumed,
movement of some of the appendages of the head was
made, ard the female was in some cases patted or stroked,
in addition to the most assiduous stridulation. The latter
was never omitted in any species in which we could detect
any sound. But the little male of Pezotettix, being appa-
rently without any power of charming the female, behaves
in a manner entirely different from any of the others
described below. He lies in wait, leaps on the female,
and captures her unawares. ‘hen, when he is firmly
seated, the male attempts to charm her by nibbling with
his mandibles, and perhaps by the effect of the alternate
movement of his third legs.

The general impression left by the whole of the obser-
vations recorded below was favourable to the theory of
sexual selection, and to the view that the stridulating

236 Professor Edward B. Poulton on the

apparatus has been evolved by the agency of this
principle rather than by that of natural selection.

Others may draw opposite conclusions from the same
observations, which I therefore set forth by themselves,
apart from general theoretical considerations. I believe
that the observations themselves are correct, and that the
uncertain points are stated with due caution.

PEZOTETTIX PEDESTRIS.

Avaust 29, 1§95.—I watched a pair of Pezolettix
pedestris continuously for about an hour and a quarter,
viz., from about 2.50 p.m. to 3.45. ‘The day was fine and
the sun powerful, and this had been the case for many
days previous to the 29th.

When first observed, the male was seated on the back
of the female, the anterior legs being clasped round her
prothorax, but every now and then one of them was
passed round her head and sometimes even over the eye.
''wice the female was seen to raise her leg and sweep the
male’s leg off her face. The male’s second pair of legs
apparently clasped the posterior part of her first
abdominal segment, fitting im between the femora of
the female’s third pair of legs and her body. The male’s
third pair of legs were not used for maintaining his
position, but were held either horizontally or inclining
upwards posteriorly, the tibiz forming an acute angele
with the femora, and the tarsus being raised so as to form
an acute angle with the tibie. Jor nearly the whole of
the time of observation the male’s third legs were jerked
up and down alternately, the strokes not succeeding each
other very rapidly. No audible sound was produced.
No corresponding movement was seen on the part of the
female.

Jn attempting to copulate, the male let himself down,
sometimes on one side and sometimes on the other, suffi-
ciently far to bring the extremity of the abdomen below
that of the female. The terminal segments of the male’s
abdomen were then turned upwards and inwards towards
the external generative aperture of the female, with which
the everted male organs were brought into contact. No
movement of the corresponding female parts was seen,
but contractions of the whole abdomen occasionally took

Courtship of certain Huropean Acridtide. 237

place. In the above-described attitude the hold of the
male appeared to be very precarious, and it seemed that
he would have been shaken off by a comparatively slight
movement on the part of the female.

During the second half of the period of observation, the
male made more frequent and vigorous attempts, and I
noticed that from time to time he gently nibbled the
female with his mandibles in the dorsal and upper part of
the lateral thoracic regions. ‘The female, however,
appeared to be entirely indifferent to his attentions ; and
sometimes when the male was making the most energetic
attempts she would calmly begin to eat the leat of a
plant. On two occasions she finished, or nearly finished,
a small leaf, and many times nibbled parts of leaves.
Although she seemed to prefer the green leaves, she
sometimes ate portions of brown ones. Five times the
female ejected feces; once I thought the male did so,
but it may merely have been getting rid of some foreign
particle which had accidentally adhered. In the case of
the female there was no doubt.

Although the female did not attempt to get rid of the
male, she showed her indifference to his presence not
only in the manner already described, but by walking and
hopping about, often at the most inconvenient times, B 3y

3.49 copulation had not commenced, and I could wait
no longer. Both insects were then captured for
identification.

All the observations recorded above were made quite
close to the insects. By keeping as still as possible,
and moving very gently when it was necessary to
follow them, it was easy to bring the eyes within six or
eight inches of the insects without disturbing them
at all.

Avuaust 30.—I saw many of the same species in copula
beside the upper road, or rather path, leading from the
Weisshorn Hotel to Zinal. ‘The terminal seg rments of the
male’s abdomen are turned upwards, in the position indi-
cated by the attempts already described. ‘I'he alternate
movements of the third legs continue from time to time
during coitus: in one case (which may have been the
beginning of copulation) a female was seen to stretch out
the third legs from time to time, and make a rapid
shivering movement. With the above exception, the
female hopped and walked about freely during the pro-

238 Professor Edward B. Poulton on the

cess, the male being apparently firmly seated on her
back.

Avcust 31.—A pair were found in copula in the Alpine
garden close to the Weisshorn Hotel. The female was
seen to eat freely, and once to void excreta, while the
male was actively moving his third legs. This observa-
tion was confirmed by F. Jenkinson. ‘These remarkable
alternate movements of the male’s third legs during
coitus were also seen by F. Jenkinson and me in a very
large number of cases at other times. In a single case
observed by F. Jenkinson on August 31, the male’s legs
were at one time rapidly vibrated laterally, being moved
simultaneously and not alternately, as in the usual move-
ment. This perhaps corresponds to the shivering move-
ment seen by me in the female on August 30th.

SepremBer 1.—This latter observation was confirmed
by me in the Alpine garden. In this case the beginning
of the act was seen. The male appeared to be much
excited, and the shivering movement occurred from time
to time, just before and after the beginning of the act.
The female, which possessed only one leg of the third
pair, was quite motionless throughout. At the com-
mencement of the act she expelled feeces, which were
moist and quite different from the dry ejecta seen on
other occasions. In this and the complete passivity of
the female there is probable evidence that she was much
influenced by the act. This passive appearance was
entirely distinct from the indifference manifested in so
many of the cases previously observed, in which, how-
ever, the act had either not begun, or was probably far
advanced. Shortly after coitus the pair remained motion-
less for a considerable time.

SEPTEMBER 2.—Up to this date the events immediately
preceding pairing, and the pairing itself had been observed
with care, but there was no evidence to show how the
male became seated on the back of the female. I was
very anxious to find out how this occurred, and whether
there was any preliminary courtship by stridulation or
otherwise, although the species had never been heard to
stridulate. At this date, F. Jenkinson observed, and I
was able to confirm, that the males leap upon the females
when they come within a distance of about three inches,
but apparently do not notice them at a much greater
distance. Their attention appears to be directed to the

Courtship of certain Huropean Acridiide. 239

female by its movement, and they then leap with the
greatest accuracy F. Jenkinson obtained these results
by inducing captured females to leap from his hand in
the direction of a male. On one occasion he saw a male
approach and leap upon another male, probably mistaking
it for a female ; there was a tussle, in which one appeared
to try to bite the other. It thus appeared evident that
there is no preliminary courtship of any kind, but that
the male takes the female by surprise, and leaps upon her
before she is aware of his presence. ‘his conclusion was
abundantly confirmed Jater on.

SepremBer 3.—F’. Jenkinson and I observed a pair on
the grassy slopes below the Bella Tola. The male had
lost one of the legs of the third pair, and the female had
one of them apparently injured. The male was seated on
the back of the female, and was energetically attempting
to copulate much too far forward in the middle ventral line.
We watched his continual attempts for about fifteen
mivutes, at the end of which period he was no nearer to
success than at the beginning. This failure, when the
female was evidently ready, and kept opening the gene-
rative orifice, may have been due to the absence of the
leg. Although this limb is not used to hold firmly, the
absence of it may have affected his balance. At any
rate no failure of this kind was seen on any other
occasion.

Later on, about the middle of the day, we came to a
flat piece of ground covered with scanty grass, at the
bottom of the zigzags by which the Bella Tola is ascended.
The strong sun and the position of the ground made the
place extremely hot, and as both sexes of the Pezotettix
were very abundant, it appeared a good opportunity for
observing the pairing habits. The males were often
seated on stones, or other slight eminences; thus placed,
and with the head and anterior part of the body raised,
they were in a very favourable position to see and leap
upon any female which approached within three inches,
or sometimes even a greater distance. If the leap isa
failure, the male at once begins an active pursuit, leap-
ing more quickly and further than the female. In this
way it often happens that he loses sight of the latter, or,
is brought nearer to another female, whom he at once
attempts to capture. One main cause of failure in the
‘pursuit is that the male has very little, if any, power of

24.0 Professor Edward B. Poulton on the

seeing a female between his leaps, unless his attention has
been directed to her by the movement of the leap itself.
Hence the pauses, often greatly prolonged, between the
successive leaps frequently lead to the escape of the

female. Furthermore, the leaps made by the male, when
lying in wait for the female, were much better aimed
than those made in pursuit. Tt is probable that in the
former case he takes very careful aim; for he turns his
head and anteunie in the exact direction of the female,
and pauses before leaping, often making a slight rocking
movement of the anterior part of the body. Occasionally
this movement was seen in the female also,

When the male leaps upon her unawares, as I have
described, the female almost invariably tries to throw
him off, and generally succeeds. If, however, she failed
in the first attempt, in most cases she yielded forthwith,
and, probably asa result of these favourable conditions as
regards temperature, pairing was effected in a very short
time, sometimes even in a few seconds.

In one instance a male leaped upon a female and was
thrown off; the female was then driven round, so that in
a few minutes she again came within the range of his
leap. ‘The second time he was successful, securing a
firm hold, and beginning to nibble the female with his
mandibles. All resistance ceased, and pairing took place
in a few minutes.

Very occasionally the alternate strokes, but only once
or twice repeated, of the male’s third legs were seen when
the opposite sexes were near together. i believe, too,
that the same movement was made by the female, though
still more rarely. One female, when near to a male,
seemed to be excited, and raised her third legs, which
quivered from time to time. Any such indications were
very rare in the female. In nearly all cases she was taken
by surprise, and only yielded when very firmly held.

The female must be influenced in some way by the
male holding her and caressing her with his mandibles ;
for his position, when attempting to copulate, is very
precarious, and he could be easily shaken off. It appeared,
however, that the males did not begin to make any such
attempts until the females had ceased to resist.

In one single instance the female did not yield,
although very “firmly held; but it is probable that she
was immature, or injured, or in some way unfit for pair-

Courtship of certain European Acridiidx. 241

ing, as the male finally left her of his own accord. This
observation was made by both of us, and was of great
-interest. When we first saw them, the male was firmly
holding the female, but she kept struggling violently,
and trying to kick him off with her powerful third legs.
On at least three separate occasions the pair rolled over,
and remained in this position, with the male beneath,
for about half a minute. At such times the female was
unable to stregele at all successfully, and it seemed
possible that the male, when he was nearly unseated,
caused the pair to roll over; we could not, however, be
sure of this. Ultimately the male leaped off voluntarily,
as I have already stated. One side of the dorsal surface
of an abdominal segment was wounded in the female, but
as the injury did not appear to be fresh, it is not probable
that the male caused it.

In one or two cases the female, and once the male,
expelled feeces just before or during copulation. The
feeces were of the character already described, and not in
the usual dry state. '

In no single case was any preliminary courtship wit-
nessed in this species. There was no stridulation, no
display of colour or attitude. It was entirely a question
of capture, the females being almost invariably, at any
rate at first, unwilling prisoners, although occasionally
they showed indications of excitement in the presence of
a male.

It is highly probable that pairing takes place many
times in this species, and even more than once with the
same male.

There was an extremely high proportion of individuals
in coitu, even allowing for the fact that their habit of
freely jumping about renders them much more con-
spicuous than the unpaired males and females. The
proportion was far higher than that of any other
Orthopterous insect cbserved during this visit to Switzer-
land; it is possible, however, that the principal pairing
time of other species is earlier in the year.

GOMPHOCERUS SIBERICUS (var.).

This form was excessively abundant round the Weisshorn
Hotel, no other species approaching it in numbers. On
one occasion, after heavy rain, I’. Jenkinson saw immense

242 Professor Hdward B. Poulton on the

numbers of them lying in the path apparently
dead ; but after the sun had warmed them they all re-
covered.

Aveusr 30.—At this date I had a good opportunity of
watching the habits of the males in the presence of a
female. About a mile from the hotel, along the upper
road to Zinal, at about 11 a.m., I came upona spot which,
on account of its aspect and slope, had not long been
warmed by the sur, so that the insects were only just
beginning to bestir themselves. Here was alittle group of
this species—two males and a female—-probably close to
the place in which they had passed the night. ‘lhe female
was resting quietly on a small piece of rock, slightly
moving her abdomen, probably in relation to respiration.
Later on she drew each antenna beneath the first leg of
the same side, or perhaps drew the leg over the antenna.
It is probable that this movement is intended to wipe off
the dew. ‘The males often did the same, and the female
rubbed its eye, probably for the same purpose. This
explanation is all the more probable because I did not
see these movements at any time when the heat of the sun
was sufficient to have dispersed the dew ; although the
species was carefully observed on many occasions. One
male, standing by the female, was stridulating when I came
up ; the other was behind motionless. These three insects
were extremely shy, although this was by no means the
case at other times when individuals of this species were
watched in the heat of the day. Although I approached
so that my shadow was behind me, and very gently, the
male beside the female was alarmed at each slight rustle
or movement, raising himself on his legs and erecting
his antennx, apparently thoroughly on the alert. ‘Then
when I kept perfectly still he resumed his former position
and depressed the antenne towards the female, both of
whose antenne were also generally depressed. He did
not continue to stridulate, but, after remaining almost
motionless for some ten minutes, except for cleaning his
antennz now and then, turned his back on the female and
apparently began eating the heather. In a few seconds
the other male stridulated once or twice: the effect on
the first male was instantaneous ; he stridulated for a
second or two and then walked back to the female,
depressed one antennze towards her and patted her on the
thorax with oue of the first pair of legs. After all this

Courtship of certain European Acridiide. — 248

attention she made no apparent movement, and the other
male did not make any further advances. The active
male then walked away and met another female,
stridulated beside her until she also walked off. Another
male close at hand stridulated, and the active one
immediately replied, although in this case no female was
near.

These observations illustrate the habits of the species
in courtship, the males, as Mr. F. V. Dickins also pointed
out to me, always running after the females and never
jumping, although both sexes jump very actively when
disturbed. The use of stridulation as one of the tactics
of courtship was clearly seen, the rivalry between the
tivo males near the female being particularly interesting.
‘he same occasion gave rise to the other method of
courtship, viz., patting the female. The position of the
male’s antenne suggested attention to any movement the
female might make, or to anything she might do.

These notes also illustrate the immense abundance of
the species, the active male had only to walk two or three
inches away from the group of three in order to come
across another female and male.

I think that, in observations of this kind, it will be
useful to watch the species under many different conditions,
especially as regards temperature. In the hottest places
courtship is most energetic, and we have the most
favourable opportunity for seeing the whole process
carried through to completion, as in the case of
Pezotettix already described ; but when the temperature
is lower, and especially when the warmth of the sun has
only just roused the insects into activity, many interest- .
ine details may be witnessed which are often passed over
or hurried through in times of greater energy,

In spite of the excessive abundance of the species and
the almost constant attention of the males to the females,
wu successful termination to courtship was witnessed in no
single instance, and only two or three pairs were seen 1n
coitu. One of these was found on August 29th, a little»
below the hotel. The male, unlike the Pezofettix, was
unable to retain his hold, and when the female jumped,
as she did freely, he was dragged along on his back, and
retained this position for a considerable time in the
intervals between two successive jumps. It is probable
that with this species, the pairing season was nearly over ;

244, Professor Edward B. Poulton on the

and this conclusion is supported by the fact that the
females were often seen engaged in oviposition.

Aueust 51.—Jenkinson and I watched several females
ovipositing in the loose earth on a very hot slope just
outside the hotel, and in the beds of the little Alpine
garden. ‘The female thrusts her abdomen deeply into the
earth and remains in this position for some minutes. On
two occasions a female, after withdrawing her abdomen,
was seen to rake the ground vigorously with her third
legs, and, in one case, witnessed by Jenkinson, she
steadied herself by holding a plant stem with her
mandibles. We several times dug up the earth and
searched for the eggs, but without success. At this date
I found another pair of this species in coitu, on the path
just below the hotel.

Gomphocerus sibericus appears to be a very general
feeder, and its extraordinary abundance in the immediate
proximity of the hotel was probably due to the presence
of horses’ and mules’ dung, and other refuse upon which
they fed. Every patch of dung upon the path was
surrounded by dozens of individuals.

Auausr 31.—F. Jenkinson and I watched the males pur-
suing the females near the hotel. It often happened that
when a male came up to a female he extended the max-
illary and labial palpi towards her, and raised himself on
his legs in a very characteristic and remarkable attitude.
At other times these movements occurred at a later stage
of courtship. ‘The movement of the palpi stronely sug-
gested their use as organs of sense. When the female
ran away, as she generally did, the male pursued, always
trying to get in front of the female and thus stop her.
The male ran faster than the female, and altered his
direction so as to approach the female almost at right
angles to the course she was pursuing. After the pre-
liminaries of courtship—pursuit, stridulation, attitude,
and movement of the palpi—the male, standing beside
and close to the female, tries to jump on her, making a
curious short chirp as he does so. ‘lhe attempts were,
however, always unsuccessful in the cases observed by us.
Stridulation is in this species of definite length, and ends
in two or three short chirps; in most cases the male then
instantly approaches still nearer and tries to jump on the
female with the short chirp already described.

Neither Jenkinson nor I can remember the exact

Courtship of certain Huropean Acridiide. 245

order in which the male went through the various phases
of courtship. Itis probable that the order varied greatly,
and that some of the phases were often omitted.

SerremMBer 2.—On this and many other occasions the
males were often seen to leave the female they were
pursuing and, apparently without knowing it, to follow
some other female they accidentally came upon in the
course of the pursuit. A male pursuing a female was
once seen to approach and jump at the male of Pezo-
tettiv, having apparently mistaken it for the female.

SEPTEMBER 3.—On the grassy slopes below the Bella
Tola, a male observed by F. Jenkinson and me was
greatly excited by the pair of Pezotettix already described
as attempting, but unable to copulate. He stood in the
characteristic attitude, walked round them, and finally
stood in front and stridulated for the usual length of
time and with the usual ending, he then advanced as if
to jump, but before doing so became satisfied that he had
made a mistake, and walked away. It was evident that
he had mistaken the pair for the female of his own species.

Just below the zigzags up the Bella lola we saw a
male which, standing by a female, repeated the stridula-
tion four times with the usual conclusion on each occasion,
and then after all this attention let her walk away unper-
ceived. This and the other facts already described seem
to show that the males were very unobservant. In this
respect their behaviour was very different from that of
Pezotettiz, and from the very alert member of their own
species observed on August 30.

No hight was thrown upon the function of the remark-
able dilated tibize of the first legs of the male. ‘The
whole tibia, swollen into the shape of a pear, with the
tarsus articulated to its broader end, presented a most
curious appearance in the characteristic attitudes assumed
during courtship. On the underside of this dilated mass,
which js approximately circular in transverse section, two
rows of hairs are seen. Although the hairs are smaller,
and the rows more widely separated, both evidently cor-
respond to those which are found beneath the unmodified
tibize of the other legs.

Although we observed the habits of this species on
many other occasions, neither F. Jenkinson nor I had
ever seen the pairing accomplished. I therefore asked
Mr. F. V. Dickins if he would consent to watch through

246 Professor Edward B. Poulton on the

a very hot afternoon. This he very kindly did, and
although unsuccessful in this respect, he made many
interesting observations which I give in his own words :—

“On the 4th September, 1895, I watched the courting
habits of some grasshoppers on the knoll immediately
behind the Weisshorn Hotel.

‘At first I made my observations on the west slope,
but there was a cool wind blowing, and the insects were
neither numerous nor lively. Casting about I discovered
on the south-east slope a particular hollow away from
the wind, in the full glare of the sun, and focussing the
heat-reflections from the hillock-slopes around it. Here
the grasshoppers abounded and were very lively; I
watched them for about two hours.

““T noticed that the males, marked by swellings on
their first legs, were much more mobile than the females,
the latter were mostly extremely passive and had to be
chased and caught up by the males. There was a good
deal of this chasing which was very amusing to watch.
Sometimes the female, as if bothered, would remain
quiet for a time and allow the male to come up to her.
He appeared to stroke her with his antennz, but I could
not distinctly see what parts of her body he thus specially
caressed. The insects never seemed to leap unless
alarmed ; I thought that perhaps leaping was not an
ordinary mode of progression. J saw no male clasp or
leap upon any female; they chased and chased, threw up
the game, started a fresh pursuit, equally bootless, and
so went on, tireless. I was not fortunate enough to see
any accowplement. When the male was alongside the
female, in many cases, the insect assumed a strained atti-
tude, the anterior part of the body being raised high, and
the terminal segments curved upwards so that the dorsal
line was concave antero-posteriorly. Very often a curious
little click was heard, I thought, usually as the chase
ended in the pair suddenly standing still by each other.
One might suppose that it was a chirp of triumph. I
have no doubt it was made by the male.

“ One rather curious situation in this active little
drama is worth noting. <A female alighted or rather ran
up on my boot and sat quite still in the hot rays of
the sun. She sat so still that the idea struck me I might
try to caress her a. little myself. I accordingly looked
round for a slender flexible grass stem or dried haulm,

Courtship of certain Huropean Acridiide. 2A7

and having found one gently touched her with the plant
extremity. She did not stir, and I became bolder; I
rubbed her body on either side and also the inside of the
coxe and antenne. She was still unmoved, except that
a slight rigidity seemed to supervene, and the abdominal
extremity curved slightly upwards. Gently tickling this
part the curve rose and the rigidity seemed more marked.
I now stroked heras gently as I could, and she permitted
this exireme familiarity without resentment. Lastly, I
took her softly up and laid her in the palm of my hand.
Turning her from side to side she seemed quite content
and did not exhibit a flutter or atremor. I continued
my caressings for ten minutes or a quarter of an hour,
and then laid her in a warm spot and watched her for
another quarter of an hour. She did not move, although
she was alive enough. Was she hypnotized ?”’

This last interesting observation suggests that very
marked effects may be produced by the patting which I
witnessed on August 30th, and by the mbbling in the
case of Pezotettiv. In this latter species, indeed, the
effect produced on a female after her first unsuccessful
attempts to throw off the male, appeared to be very
much like that induced by Mr. Dickins in the female of
Gomphocerus.

SYETHOPHYMA FUSCUM.

This magnificent species was very abundant in thie
open grassy spaces between the trees at the water-
courses some few hundred feet below the hotel, and also
in certain places on the slopes far below the Bella Tola.
The stridulation was far more characteristic than that of
any other species observed: first three (sometimes two)
strokes of the third legs across the tegmina, then a rapid
vibration of the former against the latter for a few
seconds. ‘The result is three piercing sounds in rapid
succession, and then a prolonged rustle. The rivalry
between the males and their replies one to another were
very evident, but their relations to the female were only
witnessed once or twice.

Avcust 31.—This species was observed by the water-
courses. Many females were seen but never attended
by males on this occasion. I came across a pair of males
in the grass fighting in a very clumsy mauner: they lay

948 Professor Edward B. Poulton on the

side by side, pushing and kicking at each other, and
stridulating alternately. One male had lost one of the
third pair of legs, perhaps in an earlier part of the
fight, but if so it must have been somewhere else, as I
searched for the leg in vain. In spite of its mutilation
it replied with its single leg to every stridulation made
by the other, and these replies seemed especially irri-
tating to the uninjured male for it kicked more vigor-
ously than ever, and once made a determined but unsuc-
cessful effort to bite the end of the other’s abdomen. The
fight was already raging when I began to observe. After
I had watched it for several minutes the uninjured male
gave up and went away. It is possible that the fight
may have begun by one male leaping on the other in
mistake for a female, but it is more likely that it arose
in a quarrel over one female. This view derives some
support from the following observation.

SepreMBer 2.—At a certain spot on the slopes below
the Bella Tola the species was very common, and several
pairs were seen in coitu. ‘lhe female is larger and
duller in colour than the males, and her wings are much
smaller and probably useless for flight.

In the case of one pair in which copulation had
evidently only just taken place, the female was seen to
expel feces: another male was lying beside the pair
evidently trying to copulate with the female, continually
stretching his abdomen towards her with partial eversion
of the organs. He also stridulated from time to time,
and I feel almost sure, although I cannot speak with
certainty on this point, that the copulating male replied
on each occasion. In a few minutes the unsuccessful
male went away. I have suggested that the fight may
have begun in some such contest, but probably before
either male had succeeded in pairing. I cannot now
remember whether the stridulation during the fight and
on the occasion last described was similar to that which is
characteristic of the species at other times. I am con-
fident that no new sound was introduced, but cannot be
sure as to whether both movements were made with
their usual relation to each other.

Sepremper 7.—F. Jenkinson saw two males of this
species drawn together from a distance of several yards
apparently as the result of stridulating alternately.
When at length they met, they seemed much excited,

Courtship of certain European Acridiide. 249

but soon separated without fighting. Perhaps the fight
which I witnessed may have begun in this way.

STENOBOTHRUS (?) ELEGANS.

A beautiful little species which Dr. Sharp doubtfully
identifies as Stenobothrus elegans, was often seen, although
not abundant, below the hotel. The males in stridu-
lating, do not, like the two last mentioned species, move
the third legs symmetrically, but one follows the other.
Probably in consequence of this the sound swells and
diminishes rhythmically, presenting a remarkable likeness
to that made by a fly caught in a spider’s web. Con-
sidering its very small volume, this high and piercing
sound can be heard for a great distance.

STENOBOTHRUS H#MORRHOIDALIS.

After I left, F. Jenkinson observed a very small kind
which is almost certainly to be identified as the above
named species. Mr. Jenkinson has kindly given me the
following notes :—

“SEPTEMBER 9.—About 5 p.m. I found a very small
brown male, with the dorsal surface of the abdomen of a
reddish-orange colour. He was very assiduous in his
attentions to a green female with white V-shaped marks
on the side of the thorax. He generally kept close to
her, but was never obtrusive in his attentions, relying
apparently on the effect of his stridulation. This was
made with both legs simultaneously, generally very low,
but sometimes louder, a rapid uniform trill, rather like
the note of the lesser whitethroat. Sometimes she gave
him the slip, and they were as much as eight inches
apart, and out of sight of each other; but he continued
at short intervals his stridulation, and somehow,
apparently by accident, they came across each other
again, and the male posted himself in close attendance
as before. The female was generally nibbling at blades
of grass. If the male touched her, she seemed to repel
him by raising one of the third pair of legs. At 6°45
the sun was setting, and I had to go, so I boxed them
both. The male was perhaps just beginning to relax his
euergy.

“SeprTeMBER 7.—Below Weisshorn Hotel. A male
was stridulating and following a female, and was more

TRANS. ENT. SOC. LOND. 1896.—parr 11. (JUNE Ist.) 17

250 Professor Edward B. Poulton on the

successful in finding her again than any other species I
have observed. At 5°30 the male jumped on the
posterior part of the female’s body, his legs round her
tegmina. In this position he continued to stridulate
although at rare intervals (he did so at 5°50). The
female carrying the male shifted backwards moving her
abdomen. She seemed to have some difficulty in expelling
feeces, and this was apparently the cause of the movement.
The male stridulated, and then at 6:0, without having
copulated, he quitted the female, stridulated, and went
away.”

PSoPHUS STRIDULUS.

The large black males were common just below the
hotel, and on some slopes below the Bella Tola, where
Stethophyma fuscum abounded. Their red under wings
were very conspicuous when flying, the characteristic
rattling sound still further attracting attention to them.
The larger brown, toad-like females; with smaller wings,
are probably unable to fly.

I never saw the sexes together; but after I had left,
F. Jenkinson kindly sent me the following notes :—

“* SepreMBER 5.—When the male finds himself near a
female, he utters a double ‘ twitter’ (once a twitter and
then a trill), and moves excitedly. In one case I saw
him leap on the back of a female, but presently he left
her of his own accord.

“ At 3 p.m. I came across a pair in coitu, but the male
disengaged himself by vigorous movements of the third
legs. They remained for a long time within two inches
of each other, but nothing happened. I made the female
jump away, caught her, and put her in the male’s way.
He at once became excited, and twittered, but the female
escaped. This occurred more than once, when I lost
her.

«‘ A male, disturbed as 1 came home (about 6:45 p.m.,
when the sun was setting), hopped vigorously, but did
not open his wings.” ‘This latter observation is of inte-
rest, because the males always took to flight, when dis-
turbed, on other occasions.

“ SepreMBer 7.—On placing the female near the male,
he became excited, and made a twittermg sound with
his legs. The female, in moving off, showed the red

a i

Courtship of certain European Acridiidex. 251

under wings, but evenin the open path, the male seemed
to lose her at once. In another case, when the female
came near, the male jumped right away.”

It is noteworthy that most of the observations upon
the last-named two species were made late in the after-
noon, when the sun was losing its power.

CHDIPODA C@RULESCENS.

Thad long wished to study the courtship of these
beautiful insects, but there were none round the Weiss-
horn Hotel. Lower, at San Luc (5390 feet), they began
to appear, and still lower, at Vissoye (4006 feet), and all
along the main valley road, they were excessively abun-
dant. They are always difficult to observe, because they
haunt places where the combination of direct heat with
that reflected from rocks or bare slopes, is almost un-
bearable. I had no time to observe them until we had
come down to Fribourg.

SEPTEMBER 9.—T'hese insects were very abundant in a
large gravel pit, just outside the gate of the town, on the
road to La Roche. There is little doubt that they be-
longed to the above-named species. They were very lively,
continually flitting about over the bare earthand gravel.
They are very shy, and it is necessary to keep perfectly
still in the intolerable heat, in order to watch their habits.
I noticed that the males move their third legs as if in
stridulation, but that no audible sound was emitted.
There is an apparent lack of intention and effort about
their movement which suggested that the habit is pro-
bably only a vestige, and possesses no other significance.
The legs were raised, and seemed to be allowed to drop
by their own weight. Furthermore, these strokes were
not repeated at regular intervals, but quite irregularly,
and often singly. In this case I did not secure any
material, and therefore cannot speak with any confidence ;
but I anticipate that the legs will be found to be without
the sound-producing structures.

A female remained motionless on the ground near to
me. She was much larger than the males, and the ex-
posed surface of her body and wings was of a redder
brown. ‘The males were extremely acute in detecting
her presence, although she made no movement, and
looked exactly like a part of the ground. Whenever a

252 ~=Prof. E. B. Poulton on Huropean Acridiide.

male perceived her, he instantly approached without any
preliminary courtship, leaped upon her back, remained a
few seconds, and then voluntarily left her. The female
did not make any apparent movement, although I saw
quite half-a-dozen males leap upon her in the course of
afew minutes. The males never met near her, and I
saw no signs of any fighting. I could not tell whether
there was any actual pairing, but it is improbable that
this could have occurred in so short a time. It is likely
that the males found that she was in some way unfit for
pairing, and then left her. I have already implied that
there was no special display of the beautiful blue under
wings for the benefit of the female.

I trust that I may be able to make further observations
upon these beautiful and interesting insects at some later
date.

_ [From the Procerepines or THE Royat Society, Vou. 54.]

“The Experimental Proof that the Colours of certain Lepido-
pterous Larve are largely due to modified Plant Pigments
derived from Food.” By Epwarp B. PouuTon, M.A,, F.R.S.
Received May 12,—Read June 8, 1893.

[PLATES 3 AND 4. ]

In a paper printed in the ‘ Proceedings of the Royal Society’ for
1885 (pp. 269—315), I brought forward many reasons for regarding
certain elements of the colouring of Lepidopterous larve as modified
chlorophyll derived from the food plant. For this altered pigment
the name metachlorophyll was suggested (loc. cit., p.270). Many
other observations, subsequently made, supported the same conclu-
sion; but it was not until the summer of last year (1892) that I was
able successfully to carry out the critical experiment, viz., selecting a
species of larva which normally eats green leaves, to feed it from the
ege upon parts of the plant from which all colouring matter is
absent.

This experiment was carried out in the following manner :—

A captured female of Tryphaena pronuba laid many hundreds of
egos in a chip box. The first larve began to appear September 7,
1893. On this and the subsequent dates, the larve intended for the
purposes of these experiments were arranged in three sets, fed re-
spectively upon—(1) the yellow etiolated leaves from the central part
of the heart of the cabbage, (2) the white mid-ribs of such leaves
from which the yellow blade was carefully removed with scissors,
(3) the deep green external leaves of the same plant.

In all other essential respects the conditions of the three sets were
the same. All were kept in the dark to prevent the change of the
etiolin into chlorophyll. They were only exposed to light during the
times necessary for comparison and feeding, and these are indicated
below. A few were kept in glass cylinders standing on plates, the
majority being confined in white earthenware pots covered at first
with white muslin, but subsequently with glass sheets. Eventually
all were kept in pots.

It is clear that the only essential difference between the conditions
of the sets was the fact that the food of the first contained etiolin but

b

—

418 Mr. E.B. Poulton. Experimental Proof that the Colours

no chlorophyll, while the food of the second contained only a little
etiolin, and that so situated (around the fibrovascular bundles and
buried deeply in the substance of the mid-ribs) that the larve could
not make use of it, while the food of the third contained abundant
chlorophyll.

It is evident that any constant difference between the larval colours
in the three sets followed from these differences in the food supplied
them ; and, unless there are reasons for believing that the differences
were due to pathological change, and thus an indirect result of the
food, we must held that they are a direct result, and that important
elements of the larval colouring are dependent on the existence of some
modification of pigments derived from their food.

The course of the experiment will now be described in a tabular
form.

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of certain Larvee are due to Pigments derived from Food. 425

Before discussing the conclusions, it will be best to consider the
possible effect of certain conditions incidental to the experiments.

Darkness.—The almost continuous darkness probably affected the
colours of the larve in (1) and (3), as they became mature. The
adult larve of 7’. pronuba are sometimes bright green; and some of
the larve, hatched from the batch of eggs which supplied these ex-
periments, reared by Miss L. J. Gould in the light and with green
surroundings, remained a distinct, although dark, green until
maturity, quite unlike any of those referred to above.

Although it is thus probable that the larve are sensitive, like so
many others, to the colour and degree of illumination of their sur-
roundings, the results of these experiments are not affected in any
essential respect ; for there was abundant opportunity for comparison
before the changes referred to had taken place (e.g., October 10),
and when the majority of the larve in (1) and (3) were green (see
Plate 3, fig. 1). Furthermore it is also evident that the comparison
was equally valid after the change had taken place, inasmuch as the
brown ground colour, no less than the green, is shown to be due to a
modified plant pigment.

Nutritive Value of Pigmentless Food.—The extremely slow growth
of the larvee fed upon the white mid-ribs, and the death of all except
one of them in an early stage, may be looked upon as an argument
that they were in a pathological condition, one result being the in-
ability to form a certain kind of pigment. Such an interpretation
would, of course, upset the conclusions I have arrived at.

On the other hand, it may be urged that the single larva in (2)
which survived until it was advanced in the last stage was certainly
not pathological, and yet was unable to form the pigments in question.
Although it grew very slowly in early youth, it began to be con-
spicuous by its size on November 2, and from this date it grew
rapidly and fed largely (see Plate 4, figs. 1 and 2); judged by all
standards, it was perfectly healthy. Furthermore, everyoue who
breeds larvee knows that they are subject to diseases of various kinds,
and yet, so far as | am aware, the complete inability to form certain
classes of pigment has not been recognised as a symptom. Moreover,
the larvee fed on the thick succulent etiolated leaves (1) grew far more
rapidly then those fed on green leaves (8). This species hybernates
in the larval state, and, as is usually the case in such species, the
rate of growth is extremely irregular. Many of the larvee reared by
Miss Gould, and single larvee fed upon green leaves by me, lagged far
behind the others and yet remained healthy.

I believe that the retarding effect of the mid-ribs was not due to the
absence of plant pigments, but to the rapid drying and oxidation of
the cut surfaces (left by the removal of the rest of the leaf) and the
inability of the young larve to get sufficient food from other parts,

426 Mr. E. B. Poulton. Experimental Proof that the Colours

where the tough cuticle could not be easily penetrated by their small
weak mandibles. The larger larve do not experience the same
difficulty.

Tt will be well, however, to repeat the experiment with other larvae,
some of which may be expected to have greater powers of endurance.
I would suggest Mamestra brassice and Phlogophora meticulosa as
suitable for the purpose. Freshly cut mid-ribs might be offered
every day or perhaps twice a day.

Conclusions from the Haperiments.—Assuming that the results ob-
tained in Experiment (2) are not pathological, and I believe that
this assumption is justified, it follows that etiolin (1), no less than
chlorophyll (8), can be transformed into a larval colouring matter,
which may be either green or brown, and is so disposed as to form a
ground colour.

The fact that brown pigments may be thus formed is new. In my
previous paper (‘Roy. Soc. Proc.,’ 1885, pp. 269 et seq.) I gave
reasons for the conclusion that the green pigments are derived from
plants, but argued that brown pigments are proper to the larva.
This still remains true in many cases. Thus the green larve of
Amphidasis betularia, investigated in 1892, are coloured by derived
pigments contained in the superficial fat, while the brown larve are
coloured by true pigment contained in the epidermic cells (‘ Trans,
Ent. Soc. Lond.,’ 1892, pp. 357—359), so that the green fat which lies
beneath is concealed. The intensely opaque and dark larvee of many
other Geometre are probably similarly coloured by true pigments in
the cuticle or epidermis. But the brown ground colour of many
Noctua larve will probably be found to be due, like that of 7. pronuba,
to modified plant pigments.

A comparison of the larve fed on pigmentless food (Plate 3, fig. 2,
Plate 4, figs. 1—3) with those fed upon etiolated leaves (Plate 3,
fig. 1) and the similar larve fed upon green leaves, proves that both
green and brown ground colours are modified plant pigments. When
the larvee fed on etiolin were being compared on October 10, one of
them became irritated and expelled a drop of fluid from its mouth.
This fluid was of a faintly blwish-green colour. This observation
suggests that the change of etiolin into a soluble green pigment takes
place in the digestive tract. Chlorophyll similarly becomes soluble
and forms a green solution (turning brown on exposure) in the di-
gestive tract of larve. It is possible that the brown ground colour
of the larve is also a result of oxidation: at any rate, it is a change
in the direction of greater stability ; for I have shown that the colours
of certain brown larve, evidently coloured like those of 7’. pronuba,
are far more persistent after preservation than those of the green
varieties of the same species (‘ Roy. Soc. Proc.,’ 1885, pp. 275, 276).

Although the brown ground colour, probably situated in this

of certain Larvae are due to Pigments derived from Food. 427

species in the epidermic cells, is thus derived, there is an abundant
deposit of true pigment in the form of spots and patches in the
superficial cuticle. This was as distinct in the larve of (2) as in
those fed upon etiolin or chlorophyll; but, the ground colour of the
former being white instead of green or brown, it produced a greyish
effect (Plate 4, figs. 1—3). The opaque, white stripes in the sub-
dorsal and spiracular regions are also probably due to true pigment
situated in this case in the epidermic cells, and are equally conspicuous
in the larvee fed on pigmentless food (Plate 4, fig. 2).

In certain parts of the body the cuticle is of relatively greater thick-
ness—the head, prothoracic dorsal plate, supra-anal plate, true legs,
and parts of the claspers. In these situations, therefore, the com-
bination of a deeply-placed ground colour composed of derived pig-
ments with a superficially placed true pigment would not necessarily
produce the same effect as in the other parts of the body where the
cuticle is much thinner; for the derived pigments would tend to be
hidden. In these parts, therefore, both ground colour and markings are
cuticular, while both are composed of true pigment of such a tint as to
harmonise with the effect produced by the combination of two
distinct elements in other parts of the body. Hence these parts
remained normal in the larve of Experiment (2), resembling the
brown larvee of the other experiments, and serving to show what the
colour of the rest of the body would have been if the plant pigments
had been present in the food (Plate 4, fig. 3).*

Some indication was afforded in the course of these experiments
that the power of converting the plant-pigments into metachlorophyll
may be lost in larve which have been fed from the egg for a con-
siderable time upon pigmentless food. Thus the larve of Experiment
(2) remained pale when fed upon leaves which caused those of Ex-
periment (1) to become brown or green. At the same time it must
be remembered that these particular larve were certainly unhealthy,
and died soon after the change of food. I hope to repeat this experi-
ment upon healthy larve. I have already shown that many larvee
which are normally found upon a variety of food plants will starve
rather than eat certain of them when they have been fed upon the
others from the egg (‘ Ent. Soc. Lond. Trans.,’ 1887, pp. 312—3814).
It is possible that a somewhat analogous “ gastric education” may
take place as regards the digestive action upon plant pigments. But
confirmatory experiments, specially directed to test the conclusion,
are much wanted.

* [This argument appears to be valid in the case of the older larvx of this species
and probably many others. There are, however, many instances in which the
derived pigments are distinctly visible through an extremely thick cuticle (e.g., in
the head of larve of the genus Smerinthus). The distribution of the derived pig-
ments has not been investigated in this case.—October 15, 1893. ]

428 Mr. E. B. Poulton. Hxperimental Proof that the Colours

It is of great interest that the etiolin should be as effective as
chlorophyll in the production of larval colours. It is, however, prob-
able that the difference between etiolin and chlorophyll is, chemically,
extremely small, while both appear to undergo similar changes in the
larval digestive tract, yielding a substance which becomes dark
coloured on exposure to air, probably by oxidation. Thus of the two
heaps of feeces represented in Plate 3, fig. 1, that to the left had been
exposed to the air for some hours, and was dark brown, while that to
the right was fresh and of a pale-yellow tint. A cut midrib darkens
on exposure quite independently of the plant pigments as may be
seen in the same figure; but the tint is different, and the depth of
shade far less than in the feces containing abundant etiolin. The
feeces of the larve fed on pigmentless food similarly darkened far
less rapidly and to a much less extent than those of the others.

Although the results of these experiments are, I believe, completely
successful in establishing the conclusion they were intended to test,
it must be admitted that they point to the beginning of an investiga-
tion rather than its end. We now know that certain larval colours
are dependent on the existence of modified plant pigments, and this
naturally leads to an enquiry into the nature and causes of the
processes by which chlorophyll and etiolin are converted in the
animal body into a comparatively stable green or brown substance
far removed from its original position in the digestive tract, and
situated so as to form an important element in the effective colouring
of the individual.

DESCRIPTION OF PLATES 3 AND 4.
Plate 3.

Hig. 1.—A group of five larve of Tryphena pronuba in the 4th
stage, natural size. These larve had been fed entirely upon the
etiolated leaves of cabbage. They had hatched September 7 and
8 (1893) and were painted October 10. Nearly all the shades of
colour observed in the larve at this stage are represented in the
figure, four being various shades of green, and one brown. It is clear
from the figure that the larve can form a deep green colouring matter
from etiolated leaves. There was, in fact, no difference in this
respect between them and larvee fed on green leaves.

The marked contrast in colour between the green larve and the
leaf is some indication of the change which the etiolin has undergone
in the larval body. The dark marks along the sides are due to
superficially placed true pigment, which is formed independently of
any coloured substance in the food plant.

Two heaps of feeces are represented in the figure: that to the right

Poulton. Proc. Roy. Soc. Vol.54. PLZ

Natural Size :

x2

PJ Bayzand ninx. ith. Werner &Winter, Frankfort 7M.

Poulton. Proc. Roy. Soc. Vol.5%. P14.

Natural Size

Natural Size

of certain Larve are due to Pigments derived from Food. 429

fresh, and pale yellow in colour; that to the left exposed to the air
for some hours, and dark brown.

Fig. 2.—A group of three larve, of the same species, in the 2nd
stage, twice the natural size. These larvee had been fed entirely upon
the white mid-ribs of cabbage leaves. They had hatched September
8, and were painted October 11. While the larve represented in
fig. 1 were rather larger than those fed on green leaves, these are
much smaller. The colour is white, and maggot-like, the faint
greyish appearance being due to superficial true pigment. Except
upon the head, there is not a trace of either the green or the brown
ground colour invariably found in the larve of this species under
normal conditions. Furthermore, these larve are uniform in appear-
ance, although the normal larve are extremely variable.

A comparison between figs. 1 and 2 proves that the brown or green
ground colour of the species is due to some modification of etiolin
(or chlorophyll in the case of normal larve), unless indeed the results
are to be explained as pathological—an interpretation opposed to the
facts represented in the figures on Plate 4.

Plate 4.

Fig. 1.—Out of about fifty larvee which hatched September 8, and
were fed on white mid-ribs, a single one began to be conspicuous
by its size on November 2, and from this time it grew rapidly, and
was evidently quite healthy, although all the others were dead by
‘November 21. On December 2 it was painted (natural size) in
two positions, being in the 4th stage. The ground colour remained
white or cream-coloured ; the grey effect being caused by superficial
true pigment, which is seen to be especially marked upon the brown
head, claspers, thoracic legs, prothoracic, and supra-anal plates, and
upon the dark subdorsal semilunar marks.

Fig. 2.—The last skin was changed by December 18, and, on the
29th, the larva was again painted of the natural size, when advanced
in the last stage. The ground colour remained the same, but an
increase in the true pigment caused the larva to become a darker
shade of grey. A row of supra-spiracular dark markings also made
their appearance. The white subdorsal line and, perhaps, the spira-
cular line were evidently due to some cause of colour (probably pig-
mentary) distinct from that on which the pale ground colour of the
general body surface depended.

Fig. 3.—At the same date the head and anterior segments were
painted, x 4 diameters. In those parts where the cuticle is thickened,
the head, prothoracic plate, and thoracic legs, a brown ground colour
(as well as the black spots and patches) is developed from true pig-
ment in the cuticle itself, Hence these parts remain normal when

430 On the Colours of certain Lepidopterous Larve.

the larves are fed upon leaves without chlorophyll or etiolin. But
over the general surface of the body the cuticle is very thin, and
only contains the black spots and patches of true pigment, while the
brown or green ground colour, derived from plant pigments, is sub-
cuticular in position. Hence in a larva fed on pigmentless parts of
leaves, represented in fig. 3, this latter ground colour is replaced by
a creamy tint which is due to the uncoloured tissues of the body,
especially the fat, and to the contents of the digestive tract. This
creamy ground colour, combined with the spots of true pigment in
the cuticle, produces the general greyish appearance of these larve.

The posterior segments of the larva, painted at the same date,
x 4 diameters, are also represented in the figure, indicating that the
thickened cuticle of the supra-anal plate (which possessed a sharper
outline than that represented in the figure) contains both brown
eround colour and black spots of true pigment, while the general
surface presents the combination of a white ground colour and dark
spots, conferring a grey appearance.

i iow) ae ee “ge ;
ao ae + ; f

tee, 7 ir

.

t

; LONDON:
HARRISON AND SONS, PRINTERS IN ORDINARY TO HER MAIEST

ST, MARTIN’S LANE.

(¢ 45h)

(| XXIV? On the sexes of larve emerging from the succes-
sively laid eggs of Smerinthus populi. By Epwarp
B. Poutton, M.A., F.R.S., F.L.S., &c., Hope Pro-
fessor of Zoology in the University of Oxford.

[Read November 8th, 1893. |

My friend and former pupil, Mr. R. C. L. Perkins, once
told me that he had sometimes noticed that a pair of
Sphinx larvee found in the same stage of growth, in close
proximity upon the same tree, and presumably hatched
from a pair of eggs laid by the same parent, produce
moths of different sexes. He inferred that this arrange-
ment facilitated pairing, and he was led to wonder
whether there is a regular alternation of sex in the
successive offspring.

On the other hand, it appeared quite possible that the
cases which he had observed were exceptional, and that
the succession is irregular, or that it is such as to
facilitate intercrossing rather than frequent pairing be-
tween closely related individuals. This latter view is
suggested as a probable one by the numerous adaptations
by which wide intercrossing is favoured in other depart-
ments of organic nature, and by the following direct
evidence. Mr. W. Hatchett Jackson and Mr. O. H.
Latter have observed that the pupe obtained from diffe-
rent batches of larve of Vanessa io ‘‘ were principally,
but not entirely, of one or of the other sex.” * It is
generally admitted that the separate colonies of Vanessa
larvee are, at any rate as a rule, hatched from different
batches of eggs. Such an observation, if confirmed, is
to be interpreted by one of two suppositions. We
must either suppose that the whole mass of eggs of
each female Vanessa produces a great preponderance of
one and the same sex (males in some individuals and
females in others), or that different batches of eggs laid

* Trans. Linn. Soc. Lond., vol. v., 1890, p. 156.
TRANS. ENT. SOC. LOND. 1893.—PaRT Iv. (DE@.)

452 Prof. E. B. Poulton on the sexes of

by the same individual produce now a preponderance of
one sex, and now of another. Hither of these alterna-
tives would appear strongly to favour intercrossing. The
following observations, so far as they go, tend to support
the latter alternative.

A pair of Smerinthus populi were found in coitw in an
Oxford garden, between 10 and 11 a.m., on May 25th,
1893. They were carefully removed, and remained
together until 8.40 p.m. The attempt was made to
observe the order in which the eggs were laid, and to
rear the larve separately, the sexes being determined
in the pupal state. The results are most concisely shown
in a tabular statement.

Number and |Sexes produced.

Date. | order of eggs M=male ; Observations.
laid. r=female.
May 25. | 44 eggs laid, 15 u 1 missing (unknown whether
order unnoted. 28 F the egg hatched). 1 male and

1 female moth emerged in the
hot summer of 1893. 1 male
pupa was deformed and dead.

May 26. | 47 eggs laid. — All these eggs, the order of
which had been carefully noted,
hatched during my absence
from home, and the larve were

lost.
May 27. | 34 eggs laid. 4 missing; 1 larva died. 1
The order of female moth emerged 1893. 1
the first 22 un- 9M male pupa was deformed and
noted. 8F dead, and another rather de-
formed.
2d 00 oe — Larva died small (probably
3rd stage).
24 M Pupa rather deformed.
25 F
26 M
27 S Go HE
28 - M
29 M
30 M
31 F
32 1
38) oc M
34 M Moth emerged 1893.

Total 17m, 11¥F

larve of Smerinthus popult.

453

Date.

May 28.

May 29.

May 30.

May 31.

June l.

Number and
order of eggs
laid.

28 eggs laid,
order shown
below.

Hm OO bo re

8 eggs laid,
order unnoted.

14 eggs laid.
order unnoted.

7 eggs laid,
order unnoted.

3 eggs laid,
order unnoted.

‘Sexes produced.
M=male;
r=female.

BR HH HHS BEER

Total 13m, 13F

4m
2F

Observations.

Moth emerged 1893.

Larva died in 3rd or 4th stage,
owing to accident to branch of
food-plant.

Larva died in 3rd or 4th stage.

1 missing; 1 larva died. 1
male moth emerged 1893. 1
male pupa dead and deformed,
and 1 very small and rather de-
formed.

3 larve died.

1 egg did not hatch.

454 Prof. E. B. Poulton on the sexes of

Number and (Sexes produced.
Date. | order of eggs M=male ; Observations.
laid. r= female.
June 2. 7 eggs laid,
order shown
below.

1 F

2 -» M

3 . EF

erin tee F

5 Larva hatched, but died very
small,

6 Did not hatch. Probably no
development took place; egg
blackened.

Gite stot eter wecktsih eee oer Ditto. ditto.

Total lm, 3¥F
June 3. 1 egg laid. —— Larva did not hatch, but was

apparently fully formed in the
egg.

The total number of eggs laid on each successive day
forms an interesting curve rising to a maximum on the
second day and declining very rapidly on the fifth.

The most striking result shown in these tables is the
remarkable change in the proportion of the sexes on
different days. Thus on May 25th there were nearly
twice as many females as males, on May 27th over
50 per cent. more males, while on May 28th the numbers
were equal. It is possible that this change in proportion
may follow some biological law, especially when con-
sidered in connection with Mr. Jackson’s and Mr. Latter’s
above-mentioned observations. Itis at any rate enough
to suggest further observation. At present, however, as
Tlearn from Mr. Francis Galton, to whom I have sub-
mitted the figures, the numbers are not large enough to
warrant any such conclusion.

With regard to the succession of the sexes in a series
of individuals (May 27th, 28th, and June 2nd), the
arrangement does not appear to differ from that of black
and white balls drawn successively out of a bag con-
taining equal numbers of each. But here, too, wider
observations are required. The arrangement in little
groups of the same sex may possibly be adapted to
favour cross-fertilisation. But even in drawing pairs of

| otetietiestiicainnah someone oa ae oe

larve of Smerinthus popult. 455

black and white balls, two of the same colour will be
drawn together twice as frequently as those of different
colours. In future observations of a sluggish species
like Smerinthus populi, it would be desirable to track the
moth as it lays little groups of eggs on different leaves,
and to rear such groups separately. We must not
altogether put aside the remote possibility that the
parent may possess some power of controlling the sex
of her offspring.

Six moths emerged in the hot summer of 1893 ; three
of these were males and three females. The eggs from
which these individuals were hatched were scattered
through the successional series, and were not peculiar
to any part of it, and the same appears to be true of the
deaths of larvee and deformity of pupe.

Failures to hatch, however, are confined to the end of
the series, unless some of the ‘‘missing”’ larve are to
be explained in this way. ‘This tendency is especially
clearly seen on the last two days, and yet the very last
ego laid contained a well-formed larva which was unable
to hatch.

Even the small number of larval deaths which took
place are chiefly to be accounted for by the conditions of
the experiment. Thus, considering only the eggs laid
during May (and omitting the later eggs because of the
frequent failure to hatch), we find out of 40 larve reared
in separate sleeves (23 to 34 on May 27th, and the 28 on
May 28th) only two deaths occurred, not including the
manifestly accidental death of the fourth larva on May
28th. On the other hand, out of 95 larve reared in
eroups of from 3 to 8 (usually 7) in number, 11 larve
died or were missing. From this it may be inferred that
larvee are in some way injured by being reared in groups
with a much greater relative proximity than in nature.
I have also found.this to be true of S. ocellatus ; for,
when groups of more than 10 or 12 small larve were
enclosed in sleeves of moderate size, it was always found
that the numbers became reduced to a maximum of
about a dozen, and often much lower; whereas groups
of smaller numbers were frequently maintained without
any deaths.

The list as a whole strongly impresses upon us the
comparative rarity of death from internal causes (in-
cluding disease), and the overwhelming importance of

456 Sexes of larve of Smerinthus populi.

the struggle with highly organised enemies in deter-
mining the vast amount of destruction which occurs
among these animals in the natural state.

The unfortunate loss of the 47 larve of May 26th
served to show that the period of development within
the ege is extremely uniform. The eges laid on May
25th had been properly enclosed, and I thought I was safe
in leaving the others for a day. On my return every
one of the eggs laid on the 26th had hatched, and the
larvee had escaped; while not a single larva had emerged
from any egg laid at a later date.

Six of the male pups were deformed, but not one of
the females.

The total number of eggs laid was 198, and subsequent
dissection revealed a single egg in the body of the
parent moth. From these eggs 68 female and 59 male
pupe were obtained.

The results afford no support to the opinion that the
sex of insects can be determined by external conditions
during larval life. With conditions of very complete
uniformity, the proportions of the sexes—68 females to
59 males—appear to be normal. It may be admitted
that the larger female larve require more food, chiefly
to prepare for the amount of material to be stored up in
the ova. It would not therefore be at all surprising if
the female larvee were starved before the males when a
minimum of food was supplied. The consequent emer-
gence of a number of males would in no way support the
view that a scanty diet ‘“‘determines” this sex. It is
probable that some writers on this subject have mistaken
favouring for determining conditions.

There was no tendency towards the predominance of
males in the last-laid eggs, and therefore no indication
that this sex may be determined by exhaustion (in itself
most improbable) of the spermatozoa.

Oe ae a io

@ 12 Ty

‘

( XVIV Mr. Merrifield’s Experiments in Temperature-
Variation as bearing on Theories of Heredity. By
Freperick A. Dixey, M.A., M.D., F.E.S., Fellow of
Wadham College, Oxford.

[Read March 14th, 1894.]

Tue results of Mr. Merrifield’s experiments on the varia-
tions produced in butterflies by the exposure of the pupa
to different conditions of temperature, are in themselves
of great interest. But the interest becomes enhanced
when it is recognized that many of the new features
which make their appearance under these conditions are
identical with those occurring normally in other species
more or less closely allied to the subjects of experiment ;
that in not a few instances the disturbance of natural
temperature-conditions appears to have caused reversion
to an earlier stage in the phylogenetic history of the
species; and further, that the ancestral features thus
revived seem to vary with the nature of the disturbance.

Examples of these phenomena, from a previous series
of experiments, were given in Trans. Ent. Soc. Lond.
1893, p. 55, and were commented on by me (Ibid. p. 69).
The latest results obtained by Mr. Merrifield, besides
confirming many of tbe former, furnish further instances
of the same nature, as follows :—

I. VANESSA ATALANTA.
A. Warmed.

(1) The occurrence of red scales in the dark ground-
colour between the middle of the scarlet band and the
large white costal spot c. This is an approach to the
condition in V. huntera and V. myrinna, and more
remotely to that in Grapta and Argynnis. A correspond-
ing feature is seer in V. io, which in this respect is
more ancestral than V. atalanta.

(2) The tendency towards the formation of a scattered
ring of red scales round the spots 8 and y of Series D.

TRANS. ENT. soc. LOND. 1894.—parT 1. (SEPT.)

440 Dr. F, A. Dixey on Mr. Merrifield’s Experiments

This again recalls a common condition in V. myrinna and
V. huntera.

(3) The appearance of a new red spot on the under-
side of the forewing, just below the stem of the median
nervure before bifurcation. ‘This represents a pale patch
of various shades in V. callirrhoe, V. myrinna, V. huntera,
V. cardui, ete.

(4) The appearance of another red spot on the under-
side of the forewing, just below the first median nervule.
This represents a patch visible on both surfaces of JV.
callirrhoe, and fully developed in all the species nearly
allied to V. cardut.

(5) The tendency towards resolution of the inner
margin of the red band, as in J. callirrhoe.

(6) The suffusion of the dark ground colour with
golden brown, also as in /. callirrhoe.

Of these, Nos. (1) (2) and (3) are points now
observed for the first time; while (4) (5) and (6) are
confirmations of previous results. (See a former paper

by the author in Trans. Ent. Soc. Lond. 1893, p. 70.)

B. Cooled.

(1) Much substitution of lavender or metallic blue-
green scales for black. This points to the ancestral
condition seen in the females and parts of the males in
many species of Argynnis, e.g., A. paphia, var. valesina,
A. sagana 2, A. niphe 3 and ¢, and A. diana ?.

(2) The presence of minute patches of bluish scales
near the margin of the dark ground-colour in the hind-
wing, indicating the blue centres of the almost com-
pletely merged Series I11.—an ancient feature of Vanessa
and Grapta.

(3) The marked increase of marginal blue, especially
about the anal angle of the hindwing. This appears to
represent the condition seen in Argynnis niphe, and
ultimately to point back to the primitive Argynnid
colouring of A. valesina and A. diana ¢.

These are all confirmations of former results.

II. Vanessa 10.

In this species, warming tends to revive, in the fore-
wing, a series of dark spots (II), occurring normally in

—————— SC

in Temperature- Variation. 44.1

Araschnia levana. Cooling tends in the first place to
separate certain constituents of the ocellus, and when
carried to a high extent has the remarkable effect of
causing an unmistakable resolution of the ocellus in the
forewing, the appearance finally produced being that of
the ordinary Vanessa character in a comparatively un-
modified form. It is interesting to see how completely
these cooled specimens bear out the views which I ven-
tured to express, some years ago, on the origin and
constitution of this ocellus (Trans. Hnt. Soc. Lond.,
1390, pp: 99, 100, pl. i., fig. 12). The ocellus of the
hindwing is also affected in the same direction.

III. Vanessa POLYCHLOROS.

Cooling tends to produce several features which
appear to be ancestral. The chief of these are (1) the
pupilling with black of the spots of Series D in the fore-
wing; (2) the occasional indication of Series III. in the
hindwing; and (3) the tendency towards the formation
of a new dark spot between II.8 and III.8. These
points approximate towards the condition in Grapta.

IV. Grapra C-ALBUM.

In both broods cooling tends to induce or increase a
darkness of ground-colour; this being undoubtedly an
ancestral character.*

Tn all cases of this kind the obvious question occurs—
are we to consider these phenomena as true instances of
reversion, or is it merely that like causes have produced
de novo a like effect in descendant and ancestor? ‘The
latter explanation may account for some of the facts, but,
I think, not for all. It may perhaps give the reason for
a general diffusion of bluish scales, or for a change of the
ground-colour from black to brown, but it is scarcely
adequate to explain the special formation of a definite
pattern, as of Series III. with its blue centres in JV.
atalanta, or the reduction of the ocellus in JV. io to the
primitive Vanessa condition. Without raising the vexed
question of sexual selection, we may yet affirm that

* The observations on the three last species are new ; those on
V. atalanta, as has been seen, are partly new and partly old. On
the whole subject of the ancestral markings in Argynnis and
Vanessa, see the author’s paper in Trans. Ent. Soc. Lond., 1890.

442 Dr. F. A. Dixey on Mr. Merrifield’s Experiments

among the features induced or revived by altered tem-
perature-conditions, there is at least a residuum which
must have owed its first origin to causes other than the
direct action of temperature on the organism. Nor,
again, are these to be considered as cases of ‘‘ arrested
development”; for the stages reproduced are stages in
the phylogeny of the species, not in the ontogeny of the
individual.

If, then, these revived features are really ancestral,
how is their revival to be accounted for? The whole
subject of reversion abounds with difficulty. An expla-
nation commonly offered is that the characters last
developed in the history of a species, or of an individual,
are less stable than those that have a longer history
behind them, and that have become firmly established
under the operation of a long-continued process of
heredity. Any disturbance—such as an exceptional con-
dition of temperature—of the normal course of growth,
may therefore be expected to act in the first place on the
newer and less stable features, interfering with their
usual line of development, and shaking back the species
as it were to an earlier and more firmly-founded stage
of its development—just as in an earthquake the freshly-
built wing of a house, where the mortar was not yet dry,
might fall and leave the older portions standing. Such
an explanation, however, is in itself at best but partial,
for it gives no real reason why the newer features should
be less stable than the old; and indeed it comes to little
more than restating the difficulty in another form.

The two attempts to find a more definite explanation
of reversion which may be said at present to hold the
field, are those which pass respectively under the names
of Darwin and Weismann. If the Darwinian assumption
of centripetal “ gemmules” be granted, the commonest
case of reversion, that namely which results from hybridi-
zation, especially between recently-established species, is
capable of explanation under the hypothesis of pan-
genesis. But it may be questioned whether pangenesis
as stated by Darwin is capable of accounting for such
cases as the present, inasmuch as in them the condition of
full maturity is almost reached before the introduction of
the modifying disturbance. Although the ovum from which
the individual has originated may under the Darwinian
hypothesis have contained numerous gemmules of an

in Temperature-Variation. 4.43

ancestral type, which though usually dormant might
under certain circumstances become active in the onto-
genetic process, it would yet seem a legitimate conclusion
from the hypothesis, that the introduction of any cause
analogous to hybridization in its action on the developing
organism must belong to a far earlier stage in the onto-
geny than the beginning of the pupal condition ; it must
belong, in fact, to the stage of fertilization of the ovum.
There are, however, a few facts on record, such as the
assumption of ancestral characters by an old hen (Darwin,
« Animals and Plants under Domestication,” 1868, vol. 11.,
p. 04), and the appearance of an earlier vertebrate con-
dition in limbs of Amphibia reproduced after amputation
(Lbid., u., p. 15), which seem in some respects analogous
to the present instances,as being apparently cases in which
a disturbance of normal conditions at a comparatively
late ontogenetic stage has im some way led to reversion
in the course of the individual growth. ‘These cases are
regarded by Darwin as not incompatible with pangenesis,
though not fully explained by it.

If, on the other hand, we postulate with Weismann the
existence of “ids”? and ‘‘ determinants,’? endowed with
the nature and properties that he supposes, the instances
that we are considering become more explicable. For
according to this theory every feature in the structure of
the individual organism is the result of a “ struggle of the
ids” in ontogeny, the final character of each histological
unit being fixed at the moment of the liberation of its
proper determinants by the disintegration of the “ids.”
The competition between the carriers of heredity, many of
which must under the theory be ancestral in character, so
far from being confined to the ovum, is being waged
throughout the entire ontogeny, and is renewed at every
successive stage of development. ‘This being the case, it
is to be expected that any external influence, such as
temperature, on coming into force at any given stage,
should be able to exert an effect upon the struggle pro-
ceeding at that particular time between determinants
which are just beginning to play their parts in the onto-
geny, and should in consequence be able to modify pro
tanto the resulting adult organism. It would be, more-
over, natural to expect the different determinants to be
affected by different temperatures, nor would it be sur-
prising to find that temperature-conditions, which are

444 Dr. I. A. Dixey on Mr. Merrifield’s Experiments

ex hypothest diverse from those normal to the species,
should favour one or other set of ancestral determinants
at the expense of those more proper to the species. This
would explain why the effect of heat differs from that of
cold, though both lead to reversion.

bere is, however, one fact which shows that the above
explanation is not entirely adequate—the fact, namely, of
the hereditary transmissibility of certain temperature
modifications, as determined in the case of Polyommatus
phleas by Weismann himself (‘‘ The Germ-Plasm,” 1893,
p. 399). This phenomenon admits of a ready explanation
under the theory of pangenesis ; the point that pangenesis
fails to explain is the reversionary character of the original
change, unless, indeed, we suppose a “struggle of gem-
mules,” analogous to the “ struggle of determinants,” and
continued, like the latter, throughout the ontogeny; in
which struggle certain conditions favour the ancestral
rather than the modern gemmules. But just as the
theory of pangenesis seems to require some such addition
as that suggested, so also, under the rival hypothesis, it
seems necessary to supplement the explanation above
given with another supposition already propounded by
Weismann, namely, that the temperature-conditions are
capable, in some cases, of actually altering the consti-
tution of unexhausted determinants wherever they occur,
even in the germ plasm of the ovum itself.

Tam myself inclined to think that, granting Weismann’s
general theory of heredity, the more special cases of
reversion are to be chiefly explained, as above, by tie
critical influence of the temperature-conditions on the
struggle of the determinants, rather than by an intrinsic
effect on the determinants themselves. The latter may
account for such cases as a general lightening or darken-
ing of the ground-colour, as in Weismann’s P. phleas,
which strictly speaking are not really but only acci-
dentally reversionary ; it will not, however, account in
my opinion for the special ancestral marks shown by
Mr. Merrifield’s V. atalanta and V. io.

The point is capable of verification. If it be true that
there is a selective influence which is exerted upon the
actual struggle of the determinants, that influence would
find a different expression in the adult according to the
particular stage in the ontogeny at which the influence
was applied, as it would affect those determinants only

in Temperature- Variation. 445

between which at that time the struggle was being
waged.* If, on the other hand, there is no such influ-
ence, but the effect is entirely a direct one and modifies
the individual determinant, then all the as yet unex-
hausted determinants that are capable of reacting to this
particular disturbance would be affected in some degree ;
though no doubt, as Weismann supposes, to a greater
extent if they had reached the point of disintegration than
otherwise.

Again, it seems to me to be of great importance to
ascertain if possible which of these modifications are
transmissible to descendants. If all the modifications,
including those which I have supposed to be produced
in the first way, can be shown to be hereditarily trans-
missible, this would amount to a demonstration that the
second explanation is adequate ; and the first may then
be abandoned as unnecessary. Should only some be
inheritable, the presumption would be in favour of the
co-existence of both modes of action; moreover, the
greater the number of non-transmissible variations that
can be produced, the more will the case be strengthened
against pangenesis, and in favour of the “ centrifugal”
theory.

I am anxious to see, if possible, the results of breeding
experiments on specimens like these for yet another
reason. It seems to me that by comparative experi-
ments, with and without artificial selection, on such
variations as may be transmissible, a measure might be
obtained of the relative importance of selection and the
mere action of external influences in the transformation
of a species. I think, too, that no better group for such
experiments as these of Mr. Merrifield’s could be selected
than the Vanessas. For, in the first place, it is only
among poikilothermic animals that the direct effects of
temperature can be fully studied ; then among these the
Lepidoptera are pre-eminent for the extremely delicate
register of variation afforded by their wings ; and, lastly,

* The fact that in V. polychloros forcing invariably tends to pro-
duce a certain effect, whether preceded by warming or cooling ;
while refrigeration brings about another definite effect, whether
followed or not by forcing, seems so far favourable to this hypo-
thesis. See above, p. 452.

446 Dr. F. A. Dixey on Temperature-Variation.

among the Lepidoptera the Vanessas belong to an
assemblage the phylogeny of which may claim to be at
any rate partially known.* It is hardly necessary to point
out how much service may be rendered to researches of
this kind by the careful working out of the true internal
affinities of Lepidopterous groups. In proportion as their
phylogeny is placed on a secure basis, we shall be able to
pronounce with confidence on the real character, whether
reversionary or not, of these remarkable variations ; and
shall accordingly be able to estimate at its proper value
the evidence they bring towards the solution of the great
problem of Heredity.

* See the author’s paper already referred to, in Trans. Ent.
Soc. Lond., 1890, p. 89.

EXTRACTED FROM THE PROCEEDINGS

OF THE

ENTOMOLOGICAL SOCIETY OF LONDON

Of 20th March, 1895.

Mr. F. Merrifield exhibited some Limenitis sibylla, the
pup of which had been subjected to extreme temperatures.
A temperature of 85° to 90° was fatal to most; in those
which survived the black ground-colour is pale and freckled,
and there is some increase in the reddish scales near the apex
of the forewings and the anal angle of the hindwings ; and on
the underside the orange-brown ground-colour is increased in
area and is much lighter and more orange in its colouring.
The pupz endured cold better than heat. Icing from 8 to 40
days, followed by a normal temperature for 12 to 14 days,
produced no sensible alteration of markings or colouring, but
an exposure to a temperature of about 48° for 22 days and
up to 86 days caused a sprinkling of the white band with
black scales ; the most sensitive part in this respect is in the
hindwings, the interspace between the costa and the next
nervure ; here it is so dense as to turn the white to a dull
grey. On the underside this cooling caused a slight increase
in the area and intensity of some of the darker parts, but
this was counteracted by a tendency to suffusion and
spreading of any white parts. He thought that this species
would bear a longer exposure to a low temperature than he
had ventured on trying. He also showed a long series of
Vanessa C-album, the larvee of which had been kindly sent him,
in May last, by Mr. Allan Nesbitt of Llandogo, Monmouth-
shire. Though subjected to more severe cold and for longer
periods than those experimented on in 1893, as recorded in the

Transactions for that year, they showed no very considerable
increase in the results obtained. Some, however, showed a
substantial increase of the area and intensity of the dark
parts and a darkening of the light parts, besides the
occasional appearance of a few blue or lavender scales in
places where, according to Dr. Dixey, they had a special
significance. Mr. Merrifield stated that Dr. Standfuss had
published some temperature experiments on this species which,
as he had found, had shown itself not so sensitive to pupal
temperature as some other species of Vanessa had proved them-
selves to be. Unexpectedly he (Mr. Merrifield) had found the
species to be distinctly more intolerant of cold and less
intolerant of heat than is L. sibylla. Experiments on a few
pupe of Vanessa cardui in 1894, showed this insect to be
extremely sensitive in its colouring and markings to both
high and low temperatures; this was quite in accordance
with the experience of Dr. Standfuss, who had described the
great results obtained by his experiments with this species.
Dr. Dixey said that Mr. Merrifield had kindly given him the
opportunity of carefully examining the specimens exhibited that
evening. With regard to the specimens of L. sibylla, he should
prefer to reserve his remarks for another occasion, but in the
fine series of V. C-album he noticed many individuals as to which
he might say at once that they seemed to bear out in a most
interesting way the conclusions arrived at from former experi-
ments, conducted both by Mr. Merrifield and by Dr. Standfuss,
with other species. They showed evident marks of reversion,
and these marks were again of so special a kind as to pre-
clude the supposition that they were the direct result of changes
of temperature. The most remarkable of these features, 7.e.,
the well-developed condition of Series III., and the presence of
blue points in the dark patches composing it, might be seen
in a conspicuous form in the Chinese species Vanessa (Grapta)
C-aureum, which insect was for many reasons to be considered
as one of the oldest surviving representatives of the Vanessid
group. There could, then, be little doubt that in this
instance, as in so many others, Mr. Merrifield had succeeded,
by the introduction of altered conditions, in producing a
reversion to a more ancestral form than that normally
assumed by the species. The more these instances ac-

cumulated, the more they seemed to him to strengthen the
conclusion that the altered temperature-conditions were
capable of acting as a stimulus to which each organism would
respond according to its own pre-arranged constitution, and
that it was only in comparatively rare cases that the new
conditions operated as the causa efficiens of the change. (See
Weismann’s Romanes’ Lecture, 1894.) Even in such an
instance as that of P. phlwas, it was, perhaps, too much to
assume that the darkening of the scales was the direct result
of a high temperature, for in other cases the same temperature-
conditions led to the opposite result. If we pushed the matter
further and proceeded to ask what was the nature of the
pre-arrangement of material which enabled different species,
during growth, to respond in a different manner to the same
stimulus, and in many cases to respond by reverting to an
earlier phylogenetic stage, we found ourselves at once on
very debatable ground. It might, however, safely be borne in
mind that under either of the two leading theories of heredity
—the centripetal and centrifugal—it was perfectly con-
ceivable that a competition took place during the growth of
every organism between various elementary constituents—
call them what we please—the greater number of which were
destined to take no part in the somatic structure of the adult
organism, though they might still be transmitted in a latent
condition, through the germinal material, to succeeding
generations. To the revival into efficient activity, under
exceptional conditions, of some of these usually latent
‘determinants ’”’ or ‘‘ gemmules,’’ he was inclined to attribute
such remarkable instances of atavism as those now exhibited
by Mr. Merrifield.

Mr. Barrett said he was interested to find that one of the
forced forms of L. sibylla was similar to a specimen he had
seen which had emerged from the pupa during a thunder-
storm.

Mr. F. W. Frohawk, in connection with Mr. Merrifield’s
paper, exhibited a series of 200 specimens of V. C-albwn
bred from one female taken in Herefordshire, in April, 1894.
The series consisted of 105 males and 95 females, and
included 41 specimens of the hght form, and 159 of the
dark form.

Professor Meldola, in proposing a vote of thanks to
Mr. Merrifield, Dr. Dixey, and Mr. Frohawk, said that he
was glad to think that the subject of Seasonal Dimorphism,
which had been first investigated systematically by Weis-
mann, was receiving so much attention in this country. He
was of opinion that the results hitherto arrived at were quite
in harmony with Weismann’s theory of reversion to the
glacial form and all the evidence recently accumulated by
the excellent observations of Mr. Merrifield and others went
to confirm this view as opposed to that of the direct action
of temperature as a modifying influence.

Mr. Merrifield, Mr. Barrett, and Dr. Dixey took part in
the further discussion which ensued.

On the Relation of, Mimetic Characters to the Original Form.
By F?*A. Dixey, M.A., M.D., Fellow of Wadham
College, Oxford.

(Abstract.)

An objection that has been often brought against the
theory of mimicry, as enunciated by Bates and accepted
by Darwin, is the difficulty of imagining the first stages
in the production of a mimetic pattern. Fritz Miiller*
endeavoured to meet this objection by alleging that mimicry
chiefly originated between forms that already bore consider-
able resemblance to each other. The main instance (that
of Leptalis melia) on which he relied in order to prove his
point was not well chosen, for there is reason to think that
he was in error both in considering that this species repre-
sented the ancestral form of Leftalis and in supposing that
it was not protected by mimicry. Nevertheless his conten-
tion is sound in so far as it emphasises the fact that the
process of mimetic assimilation depends rather on the de-
velopment of old than on the starting of new features.

An illustration of this principle is afforded by a com-
parison of the non-mimetic butterflies Previs locusta and
P. thaloe with the mimetic species of the closely allied genus
Mylothris, and with Heliconius numata, which serves as the
model for the latter; all these forms inhabiting the same part
of the neotropical region. An almost perfect transition can be
traced on the undersides from the non-mimetic species of
Pieris through M. lypera 3, M. lorena 3, M. pyrrha 3, M.
lorena 2, to M. pyrrha Q, this last butterfly being a very close
copy of Helicomius numata. The whole series shows (1) that a
practically perfect mimetic pattern can be evolved by gradual
and easy stages without any violence or abruptness of
change; (2) that it 1s not necessary that the forms between
which mimicry originates should possess considerable initial
resemblance ; (3) that so small a beginning as the basal red

* Jenaisch. Zeitschr., vol. x., 1876.

a

patches on the underside of the hind-wing of many Pierines
gives sufficient material for the assimilative process to work
upon.

The feebler development of the mimetic pattern in the
males of this group calls for some explanation. No doubt
the females stand in greater need of protection, but does
there exist any active check on the fuller assumption of
mimetic patterns by the males? The retention of the
original white by the latter sex has been in similar instances
attributed to female choice; Mr. Wallace on the other hand
thinks it due to the difference of habits in the two sexes, the
females alone flying in company with the mimicked Heliconi.
But this leaves unexplained the presence of a partial mimetic
pattern in the male. The probability is that although on
the wing it may be advantageous rather than otherwise
to the male, as Mr. Wallace thinks, to be taken for an
ordinary white butterfly, yet when the insect is at rest, and
settled with the wings erect, any Heliconine resemblance
would be to some extent protective; and the whole aspect of
these males, the underside alone of which shows any mimetic
features, is the resultant of these two divergent tendencies.
The mimetic features of the male cannot be regarded as a
mere incidental result of the more complete transformation
of the female, because in many species of other groups the
female is completely mimetic while the male shows no ap-
proach whatever to a mimetic change; moreover there is a
species of Hesperocharis (H. hirvlanda) in which not only the
male but both sexes show a partial mimetic pattern no
further advanced than that of M. lorena 3 or M. pyrrha 6.
It is difficult to believe that in this case the pattern is not in
some degree protective.

Red basal spots like those of the mimicking Pierines are in
some cases found in the mimicked Heliconi ; this is especially
the case in those that form models for the Pierine genera
Euterpe and Pereute. ‘These spots are too widespread in the
Pierine subfamily to have arisen from imitation of the
Heliconii ; their presence in the latter is probably due to
‘reciprocal mimicry” between distasteful forms, as sug-
gested by the author in Trans. Ent. Soc. Lond., 1894,

pa2o8-

3

A curious case of a mimetic assemblage is afforded by the
Pierines Euterpe critias and E. bellona, together with their
respective models Papilio zacynthus and the Helicon of the
thelxiope group. The Papilio and the Heliconit have no close
resemblance to each other; but appear to be held together,
as it were, by the intermediate Pierines. If the Helicon are
considered as the models for the whole group, the question
arises why E. critias should copy a mimic (P. zacynthus), and
not a very good one, instead of the original distasteful model
(Heliconius). It is more probable that here also we have an
instance of an “inedible association”’; this conclusion being
strengthened by the fact that a certain amount of ‘‘ give and
take”, or ‘‘ reciprocal mimicry’, seems to have occurred not
only between the Heliconii and the Pierines, but also between
the Pierines and the Papilio.

The paper was illustrated by coloured drawings of the
species referred to.

August, 1894.

[From the British Association
Reports, 1894.|

OXSGormy)

( III, On the Relation of Mimetic Patterns to the Original
Form.* By Freperick A. Drxzy, M.A., M.D.,
F.E.S., Fellow of Wadham College, Oxford.

[Read Feb. 5th, 1896.]
Piwrns: Dey) an Ve

I, ae Grapuat Growrs or A Mimertic PArrerN.

Iris now many years ago that Fritz Miller published
an answer to those opponents of the theory of mimicry
who made much of the difficulty of accounting for the
first advances towards the formation of a mimetic
pattern.t In the course of this communication he
pointed out (as indeed Darwin had done before him)
that mimicker and mimicked might, in many instances,
be reasonably supposed to have started, not from a
position of wide divergence from each other, but rather
with the possession of some feature or features, common
to them both, which should give material ready to hand
for the assimilative process to work upon. ‘The chief
instance relied on by Fritz Miiller in support of his
contention was the well-known mimetic genus of
Pierine butterflies known as Leptalis or Dismorphia.t
The black and yellow Leptalis (Dismorphia) melia,
according to him, was to be regarded as representing
the primitive type of coloration of the genus; and
although it did not itself mimic any other form, it never-
theless showed independently so much of the character-
istic Heliconine colours and arrangement of pattern,
that the complete Heliconine aspect presented by many
of its near relatives could be derived from it with com-
paratively shght modification.

* A preliminary abstract of the present paper has appeared in
the British Association Reports for 1894.

+ ‘‘Einige Worte tiber Leptalis,” Jenaisch. Zeitschr., vol. x.,
1876, p. 1.

t The old genus Dismorphia has been divided by Messrs.
Godman & Salvin into Dismorphia, Pseudopieris, Enantia, and
Acmepteron, Biol. Centr.-Amer., Rhopal. II., p. 174. Dr. Butler
further distinguishes Moschoneura, Cist. Entom., Pt. iii.

TRANS. ENT. SOC. LOND. 1896.—ParT 1. (MARCH.) 5

66 Dr, F. A. Dixey on the Relation of

The instance chosen by Fritz Miiller was unfortunate.
A wider view of Pierine affinities than he had the oppor-
tunity of taking would no doubt have led him to the
conclusion that, after all, the original Leptalis probably
was a white or white and black butterfly, and not a black
and yellow or black and orange insect like Leptalis
(Dismorphia) melia. Moreover, the position that D. melia
is not a mimic can hardly be sustained. It bears a very
considerable resemblance to D. ewmara, which is itself
an almost exact copy of Actinote pellenea ; Actinote being
the neotropical representative of the well-known inedible
genus Acrea. There is little room to doubt that D. melia,
so far from preserving the primitive Leptalis type, has
diverged to some distance therefrom under the influence
of mimicry.

But although Fritz Miiller’s principal instance does
not appear to me to be strong enough to bear the weight
of argument that he rests upon it, there cannot be much
question that his contention in the main is_ perfectly
sound ; and that, as a general principle, the process of
mimetic assimilation depends rather on the development
of old, than on the starting of new features, either of
pattern or of colour.

In order to illustrate this principle, I have prepared the
series of figures shown in Plates IIT. and IV., Figs. 1-12.
These represent an array of facts that I venture to think
are in many respects of great interest.

Fig. 1 shows the underside of the male of one of the
ordinary neotropical non-mimetic Pierines*, a true Pieris
as that genus is restricted by Dr. Butler—P. locusta of
Felder. The chief points to be observed are in the
hindwing. ‘They are (1), the spots or patches of bright
red which are found at the base of the precostal, median
and internal spaces respectively (Fig. 1, a, c,d); (2) a
well-defined yellow streak (e) occupying the costal space ;
(3) a pale central area (f'), in many specimens yellowish,
occupying the region of the cell and the adjacent portion
of the wing, especially towards the internal border ;
(4) a dark shade (h, 7) on the anal and costal sides
respectively of the pale central area. The present
species happens to be a rather heavily coloured member
of its group, but in other species of the same genus

* See below, p. 72, note.

Mimetic Patterns to the Original Form. 67

Pieris we get a great lightening of the general tone of
colour, without however losing the essential features now
referred to. In P. phaloe for instance, also a non-
mimetic Pieris from the same neotropical region, we have
as it were an attenuated and washed-out version of the
scheme of marking seen on the hindwing of P. locusta.
Here (Fig. 2) are visible the same basal red patches,
though now confined to the precostal and internal spaces ;
the same pale costal streak and central area, now in most
specimens white rather than yellow; and on either side
of the latter the same two dark shades, now reduced to
a pair of brownish streaks. From either of these types
to the well-known Heliconine form here represented by
Heliconius numata (Fig. 11), seems a sufficiently long
step; nor is it at first sight apparent that there is any-
thing in common between the former and the latter
schemes of coloration. Nevertheless, while it will be
allowed on the one hand that the female of Mylothris
pyrrha (Figs. 9, 10) presents a very good imitation of
H. numata, it can be shown on the other hand that this
last-named Pierine owes its mimetic features to a simple
development of characters already possessed by the
other Pierine forms just spoken of, to which it is closely
allied.

In order to make this apparent, it will be necessary to
refer to some of the other neotropical species of the
same genus Mylothris. This interesting lttle group,
comprising besides M. pyrria the closely related M.
malenka, M. lypera, and M. lorena, has been more than
once spoken of by Mr. Wallace* as affording an instance
of mimetic females associated with males of the ordinary
white type of Pierine coloration. It is quite true that
all the males throughout the group exhibit on their upper
surfaces nothing but the ordmary white character; Mr.
Wallace, however, does not mention the curious fact
that the same males universally show on the under
surface, though in varying degrees, an approach towards
the Heliconine pattern that is so completely imitated
by their mates. These partially developed features on
the under surface of the males enable us to trace the
history of the growth of the mimetic pattern.

Let us take the underside of the male of Mylothris

© “ Tropical Nature,” 1878, p. 204 ; “ Darwinism,” 1889, p. 271.

68 Dr. F. A. Dixey on the Relation of

lypera (Fig. 3), and compare it with that of Pieris locusta.
There is no difficulty in identifying the principal markings
as before enumerated. ‘The yellow costal streak and
central area (e, f) and the anterior and posterior dark
shades (h, 7) are present in M. lypera as in P. locusta, all
occupying the same relative positions; the precostal red
however has disappeared, and the internal and median
touches of the same colour have united and prolonged them-
selves into a triangular streak reaching about a third of
the way across the wing (cd). A small dark area (4),
which in P.locusta lies immediately posterior to the internal
red patch, has in M. lypera extended itself in the same
direction with the extension of the patch, and has, beyond
the outer extremity of the latter, united with the anterior
dark area (i) in such a way as to completely surround the
red patch with a distinct region of black. All the areas
somewhat vaguely indicated in P. locusta have in M.
lypera acquired a distinct and definite character with
sharply-marked, clear-cut borders. There is no doubt
of the homology of the markings in the two cases, nor
does the change from one to the other deserve to be
called either violent or abrupt.

The underside of the male of MW. lorena (Fig. 4) takes
us astep onward. Here are exactly the same features,
but with a further development along the same lines.
The red patch has now become a definite streak reaching
half-way across the wing, but still bears the same rela-
tion to the anterior dark area. ‘The costal streak and
central area have undergone a similar elongation, and in
this instance are much paler in colour. The whole aspect
perhaps recalls that of P. phaloe rather than that of P.
locusta, and the correspondence with the former insect
is still further borne out by the presence of a diagonal
dark streak (k) in the forewing, part of which is indicated
in P. phaloe, uniting the costal with the posterior or
outer margin.

The general streakiness of the male of M. lorena is
preserved or enhanced in the male of M. pyrrha (Fig. 5).
There is in this case no diagonal dark band crossing the
forewing, but the red streak of the hindwing acquires
additional distinctness and importance, while the banded
appearance is further increased by a slight change in the
disposition of the enveloping black.

As far as the hindwing is concerned, we have now

Mimetic Patterns to the Original form. 69

all but reached the complete mimetic condition of
M. pyrrha 2 (Figs. 9,10). The only thing still wanting
is an infusion of more or less brownish red into the pale
yellow or orange of the costal and central streaks. It is
observable that even in the female J. pyrrha the assi-
milation between the old red of the basal patch and the
new red of the costal and central areas is not quite per-
fect, the former always retaining on the under surface a
more vigorous and decided tint than the latter (see
Bie. Oye, cd, WE

With regard to the forewing, there is no doubt a con-
siderable interval between the male and female of
M. pyrrha. An inspection, however, of the female of
M. lorena and M. malenka (Figs. 6, 7, 8), enables us to
see how it may be bridged over. Comparing the sexes
of M. lorena (Figs. 4, 6, 7), we find that their patterns
are identical in the main features, though the female has
an additional dark streak in the forewing (l) running
parallel with the inner border. ‘The central pale area of
the hindwing has also in the female almost or entirely
disappeared from the lower surface, while the other
spaces on both wings which in the male are white or
very pale yellow, assume inthe female a deeper yellow,
warming towards the base of the wig to an orange or
brownish red. ‘These changes, comparatively slight as
they are, are sufficient to give the temale M. lorena, a
decidedly Heliconine aspect. They point out, moreover,
the manner in which the still more completely Heliconine
facies of M. malenkw ¢ (Fig. 8) and M. pyrrha
(Figs. 9, 10) may grow naturally out of the Pierine
materials already noticed. A very close comparison of
M. pyrrha with H. numata (Figs. 10, 11) will indeed
show that the correspondence of markings is not abso-
lutely perfect in every particular; nevertheless, the
general effect is marvellously alike, and if assisted by
similarity in habits and mode of flight, must be amply
sufficient for all practical purposes of protection to the
Mylothris.

Looking at this series as a whole, and bearing in mind
that it would be possible to include other forms * which
would render the gradation still easier than is shown

* For example, P. marana and M. lypera 92.

70 Dr. F. A. Dixey on the Relation of

here, we cannot, I think, feel any doubt that it is suff-
cient to demonstrate the possibility of the formation of a
practically perfect mimetic pattern from the crdinary
form of a quite distinct type, without any violent or
abrupt changes of design. It does not, indeed, lend any
support to the view that mimicry can only originate
between forms that already possess considerable and
obvious resemblance to one another, nor does it coun-
tenance the opinion that mimetic changes are effected
per saltum. What the series of forms here figured does
show is that, granted a beginning however small, such as
the basal red touches in the normal Pierines, an elaborate
and practically perfect mimetic pattern may be evolved
therefrom by simple and easy stages.

II. Sexuat DimorpHism In Mimetic Forms.

There remains, in regard to the foregoing series, a
question of great interest ; namely, what is the meaning
of the diversity between the sexes in these more or less
completely mimetic forms? Why should the one sex
have advanced so much further along the mimetic path
than the other? It is no doubt the case that the females
stand in greater need of protection than the males, but
to say this still leaves several questions unanswered.
Are we right in regarding the male patterns as perpetu-
ating stages through which the other sex has also
passed in order to reach its present state of mimetic
completeness, or are we to suppose that the selection by
enemies has affected only the female sex, and that the
patterns seen on the males are merely an incidental result
of heredity, being, in fact, a secondary version of the
female pattern transmitted in a weaker form? In either
case, what has checked the further development of
mimicry in the male? Is this imperfect development
simply a passive result of the absence of necessity for
change, or is there some active force at work preventing a
further modification ? It is well known that an explana-
tion of a somewhat similar case has been sought in the
p:inciple of sexual selection ; the females, it was suggested,
as the more conservative sex, preferring in their mates the
ancestral type of coloration of the group.* Mr. Wallace,

* Belt, “ Naturalist in Nicaragua,” Ed. 1888, p. 385.

>

Mimetic Patterns to the Original Form. (al

on the other hand, points out that in the Pierine group
before us the habits of the two sexes are different; that
whereas the females haunt the forest glades in company
with the Heliconii, the males congregate and fly m the
open with other species of white butterflies, among whom
a reddish or brownish insect would be especially con-
spicuous, and would be very liable to experimental
tasting.* This fact would seem to supply an active check
on the development of the pattern in the male, but it
still leaves undetermined the meaning of so much of
the Heliconine colouring as does exist, and of this
Mr. Wallace has offered no explanation.

I am myself inclined to think that however much it
may be to the advantage of these male forms to be taken
under some circumstances for white butterflies of the
ordinary kind, yet there must be times and occasions—
probably while the insect is at rest and settled—when
the partial mimicry of the underside comes into play, and
tends to afford protection. An instance in support of
this view exists in Hesperocharis hirlanda (Fig. 12).
This insect, like the males of those that have just been
considered, is on the upper surface an ordinary white
butterfly of the usual kind; the lower surface, however,
presents an incipient mimetic pattern of a like degree of
development with those of Mylothris lorena g and
M. pyrrha 6. This can be no feeble reflection of a
mimetic pattern complete in the female, for the sexes of
H. hirlanda hardly differ; moreover H. hirlanda, with
one or two other forms probably not specifically distinct
from it, is the only species of its genus which shows any
approach towards a mimetic coloration. The mimicry,
slight as it is, must therefore, it would seem, be of some
service, as otherwise it would in this case be meaning-
less; and if this be so with H. hirlanda, it is reasonable
to suppose that whatever amount of protection such an
approach to the Heliconine pattern confers, is also shared
by the males of Mylothris.

A further point of interest that arises in connection
with H. hirlanda is this—that a mimetic effect which
generally resembles that of M. pyrrha &, is here reached
by different means. Hesperocharis, like Mylothris, starts
no doubt from a regular Pierine form, such as that

* “Tropical Nature,” 1878, p. 205.

ia Dr. F. A. Dixey on the Relation of

exhibited by P. phaloe; but whereas in Mylothris the
main red streak of the hindwing arises from the internal
and median basal red, and js central (Fig. 5, cd), in
Hesperocharis it results from a development of the pre-
costal and costal red patches, and occupies the correspond-
ing regions of the wing (Fig. 12, a, b). The precostal
red is undeveloped in Mylothris, and the median red is
undeveloped in JLesperocharis. One result of this
is that in the latter form the relative position of the main
yellow and red streaks is reversed; notwithstanding
which the general resemblance to Mylothris is consider-
able, and the difference would very probably remain
undetected by many insectivorous animals. ‘The present
point has already been noticed by me elsewhere.* I draw
attention to it here simply because it affords another
illustration of the gradual growth of mimetic patterns
from an original non-mimetic form. +t

III. Recrrprocat Mimicry Between IneprsteE Forms.

In the previous communication to the Entomological
Society{ of which I have already made mention, I drew
attention to certain facts which I am now able to illustrate
by Pl. V., Figs. 13 and 14, representing the undersides of
a Pierine (Pereute leucodiosime) and a Heliconius (H. mel-
pomene) respectively. Both Heliconius and Perewte are,
it will be seen, furnished with basal red spots, and this is
the case with very many of the Heliconw and their

* Trans. Ent. Soc. Lond., 1894, p. 286.

+ Throughout the foregoing remarks, P. phaloe and P. locusta g,
have been spoken of as non-mimetic forms. This is undoubtedly
the case with P. phaloe, but it is perhaps possible that even in ©
P. locusta @, the underside of the hindwing may have (especially
in darkly-coloured individuals) a certain mimetic value. The
underside of the hindwing in P. locusta, P. cinerea and some
others resembles that of Heliconius melpomene and other protected
species in giving the general idea of a dark wing-area with yellow
costal or precostal streak and basal red spots. The forewing of
P. locusta contains a large surface of white, but this would be
partly or wholly concealed in the resting position. It is true also
that the yellow streak and red patches do not occupy exactly
corresponding positions in the Pierts and the Heliconius ; but there
is abundant evidence to show that while affinity displays great
respect for the exact position on the wing of any given feature
of the pattern, mimicry to a large extent disregards this, and aims
rather at a general similarity of effect. See the instance of
Hesperocharis hirlanda above, and see also below, p. 74, note.

ft Trans, Ent. Soc. Lond., 1894, pp. 296, etc

Mimetie Patterns to the Original Form. 73

Pierine imitators. What is the meaning of this coinci-
dence? The first answer that suggests itself is that it is
simply an ordinary case of mimicry ; the red spots belong
originally to the Heliconius, and the Pierine has acquired
similar spots in order to complete the mimetic picture.
‘wo facts, however, militate against this supposition.
The first is that these red patches, so far from being
confined to the mimicking Pierines, are found to have
a very wide distribution throughout the whole Pierine
subfamily, existing not only, as we have seen, in non-
mimetic neotropical forms such as Pieris locusta and
P. phaloe, but in numerous old-world genera as well,
reaching a great development in the Indian and Austra-
lian Delias, and having even left a relic in the common
white butterflies of our own country. It would be extra-
vagant to suppose that these widespread characters owe
their origin simply to the necessity for mimicking certain
South American Heliconii. Moreover, as I have else-
where shown, such an origin for the old-world forms as
this hypothesis would involve is at variance with what is
known of Pierine phylogeny. The second fact is that
although several Heliconii which are not the subjects of
mimicry show marks of the kind, yet they are most con-
stant, most distinct and most Pierine-like in species of
Heliconius that serve as models. ‘There must, it would
seem, be a relation between the two forms which is not
entirely due to mimicry by the Pierine. Are we then to
say that the Heliconius is the mimic and the Pierine the
model? ‘This would appear to be going against all
received ideas on the subject, and to be negatived by ali
that is known of the inedible qualities of Heliconius and
of the ancestral coloration of the Pierines ; nevertheless,
with respect to the particular marks in question I believe
that it comes near to the true expression of the fact, and
I would suggest that the key to the difficulty is to be
found in the following considerations.

It has been well shown by Fritz Miiller,* whose con-
clusions have been followed and amplified by Meldola and
Poulton, that there exist two kinds of mimetic associa-
tions—in one of which an edible form shelters itself by
resemblance to another form well known to be inedible,
this being the aspect of mimicry first detected and
explained by Bates; while in the other a group is
constituted all of whose members are inedible, and join

* “ Kosmos,” 1879, p. 100.

74 Dr. F. A. Dixey on the Relation of

forces, so to speak, in order to share the dangers of
experimental tasting. Jn the first kind it is obvious that
the only imitation must be by the unprotected of the
protected form ; there is no force tending in the converse
direction. But in the second kind it does not seem to
have been sufficiently noticed that, especially if the
numbers of the associated species are approximately
equal, there may fairly be expected to arise a kind of
give-and-take arrangement, in consequence of which two
or more inedible forms may hasten the assimilative
process by imitating each other. ‘This is my reading of
the case beforeus. There are some independent grounds*
for thinking that the mimicking Pierines in this par-
ticular group of instances are not, as has been generally
assumed, edible. It is therefore not unreasonable to
suppose that being distasteful, like the associated
Heliconii, and forming with them a company for mutual
protection, they have both taken from and bestowed on
them characteristic features of pattern—both sides, in
fact, having undergone what I some time since ventured
to call reciprocal mimicry.” I have elsewhere given more
detailed reasons in support of this view ; I reintroduce it
here for the sake of illustrating it from those Pierine marks
that have been specially under consideration.

* E.g., (1) the abundance of some of the mimetic species of the
same or of a closely allied genus, as Pereute charops and Euterpe
tereas (testified to by Messrs. Godman and Salvin and by Fritz
Miller respectively) ; and (2) the fact that the nearest old-world
representatives of the same group, 7.e., the members of the genus
Delias, have all the characteristics of insects protected by a
disagreeable taste or odour.

+ It may perhaps be objected that the resemblance between such
forms as are represented in Figs. 13, 14 is not sufficiently close
to warrant the supposition of mutual protection between them.
To this it may be replied, that (1) the colour of the diagonal band
of the forewing is probably in the living Heliconius much nearer
to that of the Perewte than appears in the figure, which was taken
from a specimen that had been for some years in the Hope collec-
tion. It is well known that the reds in Heliconius and Acrea are
especially apt to fade on keeping. (2) ‘he resemblance may be
enhanced by attitude, the figures having been drawn without any
particular attention to this. (3) The brightly coloured basal marks,
though occupying different relative positions in the two insects,
convey the same general idea of a gently-curving, slender, white or
vellow streak (belonging to the forewing in the Pereute and the
hindwing in the Helzconius), beset near its base with isolated spots
of vivid red, and traversing a black or dark-brown area of wing
close to the body.

Mimetic Patterns to the Original Form. 75

The same argument will apply to features similar to
the above which may be seen in certain Papilionine,
Nymphaline, Erycinide, and even in some moths.
And I may say in passing that Fritz Miiller’s principle
here referred to appears to me to be of much wider
application than has been hitherto supposed. There
exist several large groups more or less uniform in their
scheme of coloration, though heterogeneous in their
affinities, which it seems almost certain will in the main
turn out to be cases of ‘‘inedible associations,” each
one possibly including a few instances of true mimicry
within its borders. In deciding on the actual nature
of such resemblances, it may be borne in mind that
‘reciprocal mimicry ” constitutes good evidence of the
distastefulness of all the forms between which it can be
shown to occur, while the abundance or scarcity of a
mimetic insect is also a valuable test of its edibility.

IV. Divercent Memsers or AN INEDIBLE Group.

The last set of figures (Pl. V., Figs. 15-18) discloses a re-
markable state of things, which is of interest both in its
bearing on what has been advanced in the preceding sec-
tion, and also as providing a further illustration of the im-
portance of small changes. The Papilio represented in
Fig. 15 (P. zacynthus ¢) is undoubtedly the model for the
Pierine shown in Fig. 16 (H. tereas). These two insects
form one of Bates’s original instances of mimicry. But
beside the latter we have another Huterpe, viz., H. bellona
(Fig. 17), whose markings are, without doubt, homologous
with those of its congener. LH. bellona however, though
so closely resembling H. tereas the mimic of P. zacynthus,
itself copies, not the Papilio, but the members of a group
of Heliconius of which H. erato (Fig. 18) is a good
example. ‘he bright yellow patch on the forewing of
the Heliconius is very well imitated by the Pierine, and
on the hindwing of the latter the crimson patch of
E. tereas, etc , has been modified into a series of scarlet
stripes; these being a palpable attempt to reproduce
the radiating chestnut streaks of H. erato or one of its
congeners. It is curious to see what slight modifications
between the two species of Huterpe enable them to

76 Dr. F. A. Dixey on the Relation of

imitate two such distinct insects as the Papilio and the
TTeliconiws*

The addition of these two forms, viz., Muterpe bellona
ard Heliconius erato, the former of which was perhaps
not known to Bates, evidently complicates the “ mimicry ”
question. Js the resemblance between the Heliconius
and the Papilio, which certainly exists though it is not
very close, accidental? But for the intermediate Pierine
forms we should perhaps not have suspected any special
relation between them. On the other hand, is the Heli-
conius the general model for all the rest? If so,
P. zacynthus becomes a mimic instead of a model; while
its own imitator, H. tereas, is in the curious position of
mimicking a mimic, instead of going straight to the
fountain-head, 7.e., the Heliconius.

In my opinion, the most satisfactory way of accounting
for these complicated relations is the supposition that
here we have another instance of a mimetic assemblage
of the second kind—an ‘‘inedible association.” he
two extreme forms, viz., the Papilio and the Heliconius,
which by themselves might perhaps not be sufficiently
near one another to be mutually protective to any very
great extent, are held together, as it were, within the
limits of an inedible mimetic group, by the welding power
of the intermediate Huterpes.t It is of interest in con-
nection with what has been already advanced as to reci-
procal mimicry, or the give-and-take system, in associa-
tions of this kind, that the Papilio, the Heliconius and
both Pierines are furnished on the underside with basal
red spots.

V. Conciusron.

It cannot, I think, be doubted that the remarkable
facts touched upon in the present paper raise points of
fresh interest in the great question of mimicry. The
leading and binding idea in all that I have said has been

* The Heliconine pattern is still further developed in the female,
and on the under surface of the male of LH. bellona, than on the
upper surface of the latter sex as represented in Fig. 17.

+ The series could be rendered still more complete by the
insertion of I. critias and EH. beliona 9, on the Papilio and
Heliconius sides respectively of Euterpe bellona ¢.

Mimetic Patterns to the Original Form. 77

my conviction, formed after much deliberation, of the
gradual and natural character of these complicated
changes, and of the absence of any violent or arbitrary
element in their process of development. Whether
the explanations here suggested are true and adequate,
can in most instances only be decided by observation in
the field; and it is much to be desired that travellers and
residents in countries where these and similar phenomena
occur should carefully record all facts relating to the
habits, postures, modes and times of flight, prevalence,
seasonal occurrence and exact distribution of the various
species that come under their observation.

There is also need of such experimental evidence as to
the means of defence adopted by these forms as can only
be satisfactorily obtained in the midst of their natural
surroundings. Meanwhile, it must suffice to point out
the conclusion towards which the only facts available
appear to lead, while the actual verification by observa-
tion and experiment must perforce be left to those whose
opportunities enable them to apply these final tests to the
subjects of enquiry.

My best thanks are due to Prof. Poulton, F.R.S., for
much encouragement and many facilities for work. ‘he
figures were drawn, by his permission, from specimens in
the Hope Collection at Oxford.

Dr. F. A. Dixey on the Relation of

List or SPECIES MENTIONED.

PIERINZ.

Pereute leucodrosime, Koll.
Euterpe tereas, Godt.

» erttias, Feld.

» bellona, Cram.
Mylothris pyrrha, Fabr.

a lorena, Hew.
Hs lypera, Koll.
Ne malenka, Hew.

Hesperocharis hirlanda, Stoll.
Pieris locusta, Feld.
» phaloe, Godt.
», marana, Doubl.
» cinerea, Hew.
Dismorphia melia, Godt.
Ss eumara, Doubl.

PAPILIONIN#.
Papilio zacynthus, Fabr.

ACRAINE,
Actinote pellenea, Hiibn.

HELICONINE.
Heliconius melpomene, Linn.
us erato, Linn.
- numata, Cram.

Mimetic Patterns to the Original Form. 79

ExpLaNaTion oF Puatss III., IV., & Y.

Puate III.

Fig. 1. Pieris locusta g, underside.
2. P. phaloe 9, 5
3. Mylothris lypera g, 5,
4. M. lorena ¢, re
5. M. pyrrha 2, 3
6. M. lorena @, _
PLATE IY.
Fic. 7. Mylothris lorena 2, upperside.
8. M. malenka 9, a

9. M. pyrrha 2, underside.
10. M. pyrrha 2, upperside.
11. Heliconius numata, upperside.
12. Hesperocharis hirlanda, underside.

PuaTE V.
Fig. 13. Pereute leucodrosime, underside.
14. Heliconius melpomene, a
15. Papilio zacynthus 9 , upperside.
16. Euterpe tereas, :
17. EH. bellona 6, 5
18. Heliconius eruto, 5

IN ALL THE FIGURES
a, precostal red patch on the base of the hindwing underside,

b, costal 3 ” ” ”
c, median “ e < ra
d, internal ” ” ” ”

e, costal light streak.

f, central pale area.

i, anterior dark shades.

h, posterior dark shade.

k, diagonal dark bar of forewing.

1, dark bar of forewing parallel to inner margin.

Wass . f)
we i aii phew th ns te,
|

© Saba inlets, i ae.

pS En giles ie ont eae
or Gain de a % aie, vs

| nee earn! at ' ‘pha he ie

in ae ne ay pi Aaeme ey AL i os
7 aphid by Ber hced aN, ary “7

ng ¥ -

ean

: aa

ca

a

Ptey us

locust «

Pp , eO
vers pha lo« :

ee
wader Le

Mylothyr LS by pe ra

Uaroer

side

Mylothrtis lorena «

ume de

-st, Newman iP orru

IV.

rrna

1
hour Loreen

Arey, 5 Way, | ny 12 )
1 POQAFCS. 77. SOC. LOTue 1S9¢ d

srpe terect:

(249°)

(1x) On the Phylogeny of the Pierine, as illustrated by
their Wing-markings and Geographical Distri-
bution. By Freverick A. Dixey, M.A., M.D.,
F.ELS., Fellow of Wadham College, Oxford,

[Read February 7th, 1894.]
PrAtss, TET. TV.,, V.

TABLE OF CoNTENTS.

Page
I. INTRODUCTORY . : : F : : 249
II, THE WING-MARKINGS . f 5 Spe
1. The submarginal series of Shae souls 14202
2, The dark marginal area or spots 5 1 202
3. The light series between 1 and 2 : 5 AGS)
4. The discoidal spots. : 7 269
5. The markings on the mndoreiie of the
hindwing : ; > Bee
a. The yellow precodtall str oat : . 218
b. The pinkish basal patch . ‘ - 282
c. The red basal areas . . ; 280
III. PHYLOGENETIC CONCLUSIONS . - 5 the)
x The evidence of the Wing- Haisiaes. 5 Pxsis)
. The evidence of Distribution . : » 322
BV, woke OF SPECIES MENTIONED . 3 : pepsi)

I. Iyrropuctory.

In the present paper my object has been to apply to
the study of the subfamily Pierinx the methods which I
used in investigating the phylogenetic relations of another
group of Lepidoptera, as recorded in a former communi-
cation to this Society.* I have in the first place
endeavoured to work out the homology of the various

* “On the Phylogenetic Significance of the Wing-markings in
certain genera of the Nymphalide,” Trans. Ent. Soc. Lond., 1890.

TRANS. ENT. SOC. LOND. 1894,.—partT U1. (JUNE). R

250 Dr. Frederick A. Dixey on the

markings to be found throughout the group, and have
then attempted to state the phylogenetic conclusions to
which this evidence appears to lead. Though my
principal aim has been the elucidation of the Pierine
wing-markings, which so far as | am aware have never
before been systematically studied from this point of
view, I have not ignored those other features that are
usually known as “ structural” ; and I have also tried to
estimate the bearing upon phylogenetic questions of the
facts relating to the present distribution of the Pierinx
in space. ‘lhe serious limitations under which anyone
who wishes to construct a phylogeny for such a group as
this must necessarily labour have been elsewhere acknow-
ledged; it is of course manifest that little or no help
can be expected from embryological or paleontological
sources. ‘There are, however, many compensating features
to be reckoned on the other side; and in view of certain
comments that have at times been passed on previous
work of this kind, I may perhaps be allowed to quote a
few sentences from the writings of one of our leading
naturalists, which seem to me to state the special ad-
vantages afforded by these and similar researches with
a force and cogency that it would not be easy to gainsay.
After pointing out the pre-eminent value of the Diurnal
Lepidoptera to the student of distribution and variation,
the writer I refer to proceeds as follows—‘‘ But besides
their abundance, their universal distribution, and the great
attention that has been paid to them, these insects have
other qualities that especially adapt them to elucidate the
branches of inquiry already alluded to. These are the
immense development and peculiar structure of the wings,
which not only vary in form more than those of any other
insects, but offer on both surfaces an endless variety of
pattern, colouring, and texture. . . . This delicately
painted surface acts as a register of the minutest differ-
ences of organization,—a shade of colour, an additional
streak or spot, a slight modification of outline continually
recurring with the greatest regularity and fixity, while the
body and all its other members exhibit no appreciable
change. The wings of butterflies, as Mr. Bates has well
put it,* ‘serve as a tablet on which Nature writes the

* See “The Naturalist on the Amazons,” 2nd edit., p. 412.

Phylogeny of the Pierinee. 251

story of the modifications of species’; they enable us to
perceive changes that would otherwise be uncertain and
difficult of observation, and exhibit to us on an enlarged
scale the effects of the climatal and other physical con-
ditions which influence more or less profoundly the
organization of every living thing.’* Whether any par-
ticular investigator is or is not competent to undertake
this kind of research may be open to question, but I think
that the study itself needs no further vindication than
these words of Mr. Wallace.

In treating of the details of the wing-markings I have
tried to be intelligible and explicit, even at the cost of
being somewhat lengthy. I have, however, been obliged
to content myself with selected examples; a complete
treatment would run to a vast length, and in most cases
the lines here laid down may be easily applied to the
insects not mentioned in this paper. Some of the iden-
tifications of markings may at first sight seem startling ;
for instance, that of the straight orange-coloured line
crossing the disc of the wings in Dercas with the series of
black spots in the females of Ganoris ; but I believe that
in every such case it will be found that the homology can
be certainly traced, step by step. It is hardly necessary
to poimt out the importance of being on one’s guard
against the misleading suggestions of merely superficial
resemblances, and also of giving due weight to the
disturbing influence of mimicry. The details of this
latter process, when minutely examined ina favour-
able group such as the Pierinx, are seen to be of so
complicated and interesting a character, that I may
hope to be excused for having treated of some of
these details with considerable fulness, and even for
having ventured to introduce a new term in order to
distinguish a special case of the phenomenon known as
“ Convergence.” >

The generic names employed in this paper are those
of Mr. Butler in his well-known “ Revision” (Cistula
Entomologica, vol. i., 1870, p. 383), supplemented by sub-
sequent memoirs from the hand of the same author, and

* “On the Papilionide of the Malayan Region,” Trans. ‘Linn,
Soc., xxv., p. 1 (1866).
+ See page 298.

D252, Dr. Frederick A. Dixey on the

by the arrangement at present adopted in the National
Collection under his charge. I confess that {[ am not
always in agreement with this arrangement, but the
importance of a definite and accessible standard is obvious,
and no better one could be found for my purpose. Hven
if the genera are not in every instance distinguished by
characters of real ‘‘ generic value,” they are usually
natural groups, and in most cases of great convenience in
practice. The list of genera and species which I have
appended may be found useful as indicating the exact
insects which are mentioned in the course of the paper,
and also as giving an idea of the scope and contents of
those genera whose names may still be somewhat un-
familiar. A paper of this kind is not the place in which
to introduce changes of nomenclature or to discuss
questions of synonymy ; and as regards classification I
have done no more than throw out a few suggestions
which, perhaps, may one day be taken up.

Il. Tse W1NG-MARKINGS.
1, The submarginal series of dark spots.

Comparing together the three species of the subfamily
Pierine that are commonest in this country, viz., Ganoris
brassice, G. rape, and G. napi, we find that the females
of all three resemble one another in the possession of a
series of black spots on the upper surface of the forewing.
One of these spots (Fig. 16, 8 8) occurs between the
second and third median nervules ; another (ibid., S 10),
between the first median nervule and the submedian
nervure ; and the third (ibid., S 11) between the
submedian nervure and the inner margin of the wing.
The latter spot, which varies considerably in the amount
of its development, takes the form of a streak nearly
parallel with the inner margin. In the males, this series
of spots is evanescent. ‘The whole series is normally
absent in G. brassice 6, and in some specimens of
G. rapes, and G. napi d ; the males of the two latter
species, however, generally have the spot between the
second and third median nervule more or less developed,
though the other two are not present. Turning to the
underside of the wing in these species, we find the first
two spots usually present in both males and females;

Phylogeny of the Pierimee. 253

the third is but faintly visible in the female, and in the
male not visible at all. These three spots are all that
can be seen in ordinary specimens of G. brassice, rape,
and napi ; but in some specimens of G. napi, and less
distinctly in some of G. rapx, the series is continued
towards the anterior border of the wing by a fourth spot
placed just behind the junction of the third and fourth
subcostal nervules, and traversed by the first discoidal.
The spots that have now been referred to can be seen in a
very well-marked form in G. gliciria.

These indications of a submarginal series of black
markings become more pronounced in Synechloe daplidice.
Here, in the female, a submarginal row exists in easily
recognisable form, three of the constituent spots of
which are clearly homologous with those already des-
cribed in G. napi, rape, and brassice (Fig. 15).
In this region of the wing nearly every interspace be-
tween nervules contains a spot; the spots tending to
become confluent, especiaily towards the costal margin.
There is generally no spot between the first and second
median nervules, and often none between the submedian
nervure andthe inner margin of the wing. In the male,
the anterior portion of the series is distinct enough, the
large spot, however, between the submedian nervure and
first median nervule is absent from the upper surface,
though regularly present beneath. The female S. daplidice
also shows a continuation of the same series on the
hindwing, well-marked at the costa, but usually becoming
less plain as the anal angle is approached. In the male
S. daplidice, one term of the series is generally all that 1s
present in the hindwing’; and turning back to G. brassice,
rape, and napi, we find the same spot invariably
present on the upper, and often on the lower surface of
the costa in the hindwing of both sexes (Figs. 15, 16,
8S 14—18).

Other species of the genus Synchloe present the same
submarginal series in greater completeness. S. eallidice® ,
for instance, has the whole series well developed on the
forewing, and in most specimens on the hindwing also.
A comparison with S. daplidice will show that the series
is really homologous in the two cases, and will, moreover,
demonstrate that in S. callidice the smallest spot of the
series belongs to the interspace between the first and
second median nervules, which in NS. daplidice is usually

254. Dr. Frederick A. Dixey on the

not furnished with a spot at all; and that the largest and
best-marked member of the group, namely that between
the second and third median nervules, corresponds with
the spot which we saw to be most persistent in the males
of G. brassice, rape, and napt. This spot, moreover, as
well as the next most persistent (that between the
first median and submedian), is usually picked out with
black on the underside of both S. callidice and S. daplidice,
where the markings corresponding to those of the upper
surface are, as a rule, chiefly composed of green or yellow
scales with but small admixture of black. The hindwing
of NS. callidice 2 shows a continuation of the series;
though here the markings as they approach the inner
margin tend to assume the appearance of chevrons rather
than of spots, which tendency is still more marked on the
underside.

The South American genus Tatochila presents the
same series on both fore and hindwings, the females as a
rule most completely (as in 7’. autodice). The male of 7’.
theodice, however, exhibits the whole series quite plainly ;
and in both of these species the markings in question
tend to assume the form of a line of chevrons, the apices
of which point towards the margin of the wing, instead of
towards the base, as in NS. callidice.

I+propose to distinguish this series of spots as 5
(for Submarginal), numbering the constituent markings
according to the interspaces they respectively occupy.
Tn all the forms as yet mentioned the full number of
marginal interspaces, from the costal nervure to the anal
angle, is in the forewing 11, in the hindwing 8. Another
space may be reckoned in the hindwing, that, namely,
between the costal margin and the costal nervure. The
corresponding space in the forewing is exceedingly narrow,
and never carries a separate spot. We may take then
the number of spaces potentially containing spots as I1
and 9 in the fore and hindwing respectively, and may
designate all possible terms of the series as 5 1—20,
beginning at the costa of the forewing. None of the
species above referred to exhibits the whole range of spots
from 1 to 20 in a discrete condition, some being generally
absent and others fused ; the series may, however, be seen
complete on the upper surface of the forewing and lower
surface of the hindwing in many specimens of Callidryas
philea and C. thalestris 2 (Fig. 22,8 1—11).

Phylogeny of the Pierinee. 255

In certain genera (Hronia, Huchloe, etc.), the presence
of a fifth subcostal nervule eves rise to an additional
interspace in the forewing; this, however, causes no
difficulty, inasmuch as the extra interspace so formed is
never occupied by a distinct spot. If necessary, the
additional subcostal interspace may be referred to as
5a; by which plan we shall avoid throwing the number-
ing out of correspondence with that adopted in the other
genera (see Fig. 23). In those genera (Pereute, Delias,
etc.) which possess only three subcostal nervules in the
forewing, I shall for convenience consider S 4 as
absent.

Having identified the series S in the species named,
we shall find no difficulty with the remaining members of
the genera Synchloe and Tatochila, all of which possess it
in a condition of greater or less development. In all these
cases, if the sexes differ, the female invariably presents
the series in greater completeness ; though such of the
spots as are present in the male are sometimes more
distinct. Thus in SW. hellica 2, the whole range occurs
with the exception of S 9 (this being also the spot
which is regularly small or absent in VN. callidice and
S. daplidice 2), and the spots show a great tendency to
fuse into a submarginal band, especially towards the
costa of the forewing. In the male, however, all are
absent from the hindwing, and S 9—11 also from the
forewing; 8 8 is distinct; S 7 hardly visible; and S 2-5
are fused into a single spot which is more distinct than the
corresponding patch in the female.

The same submarginal series can be traced with equal
certainty in the genus Belenois. Here again the series
is as a rule more complete in the females, while the
individual spots are more distinct in the males. This can
be well seen for example in B. mesentina (Fig. 15), where
the males show a submarginal band on the forewing which
can without difficulty be resolved into a series of five spots,
representing S 2—3,5,6, 7 and 8. On the upper surface
of the females the spots show a greater tendency to fuse
with one another, and with the dark area of the apex and
hindmargin ; they are nevertheless in most specimens
recognizable on the upper surface, and nearly always
fairly distinct beneath. Much the same is the case with
the submarginal series on the hindwing; this is constantly
present in a distinct form on the under surface of both

256 Dr. Frederick A. Dixey on the

sexes, and also to a variable extent on the upper surface
of the male. The whole range (except the last member,
S 20) occurs constantly on the upper surface in the
female, but shows a strong tendency to fuse with the
dark marginal band of the wing. In both male and
female of this species the conspicuous and persistent spot
S 8 occupies a prominent position, being pushed back as
it were towards the centre of the wing, and so causing an
indentation in the submarginal row. In B. severina the
series is generally less well-marked than in B. mesentina,
being to a great extent fused with the dark marginal
band; 8 10 and 11, however, which are absent in the
latter insect, are mostly visible in B. severina 9.
B. calypso is noticeable as having the present series
particularly well-marked on the underside of the hind-
wing ; in the female it is also well in view on the upper
surface. Pinacopteryx larima, again, has the series well
developed on the hindwing, and recalls some species of
Synchloe and Ganoris by the prominence given to 8 8, 10,
and 11. In several species of Belenois, as for instance
B. teutonia ? and B. coronea, the fusion of the spots of
series S with one another and with the dark apical and
marginal area is almost or quite complete. (See B.
peristhene, Fig. 14).

The genera Appias, Catophaga, and Hiposcritia pre-
sent us in many of their members with the same series,
more or less developed. In H. lalage, for instance, 8
1—9 are fairly well marked on the forewing (most
distinctly on the underside); while some spots of the
series are also in most cases visible on the hindwing.
In the greater number of species, however, the series
is so fused with the dark apical and marginal area as
to be hardly distinguishable (as in O. zamboanga?), or 1s
altogether obsolete (as in most specimens of A. nero).
It is noticeable that the spot S 8, to which I have before
drawn attention, is usually the last to disappear from the
forewing; and that in many cases where § no longer
exists aS a separately recognizable series, the place of S
8 is indicated by a prominent projection inwards of the
fused marginal area (Figs. 9,10, 11). The underside of
the hindwing often retains traces of the submarginal
series when the upper surface of one or both wings has
entirely lost them (C. lankapwra ? and some specimens of
A. nero).

Phylogeny of the Pierine. 257

In the genus Delias the same assemblage of spots
meets us again, though scarcely in a very definite form.
The well known D. ewcharis (Fig. 5) shows the series on
both surfaces of each wing, the spots being to a great
extent merged with one another; the band formed by
their fusion is nevertheless quite distinct, and its in-
dentations correspond with the usual disposition of the
spots on the wing in those species where they exist in a
more discrete condition. ‘The series is also visible in D.
hyparete (underside) ; and the same range of markings is
present as a sinuous band in the Australian D. aganippe
(best seen in the female, and on the underside); in Jess
distinct form in D. harpalyce, and still recognizable,
though now almost completely merged, in the closely
allied D. nigrina. A comparison of the upper surface of
the wings of the last named insects with those of other
species of the genus Delias, such as D. belladonna (Fig. 4),
D. pasithoe, and D. thisbe, serves to suggest the manner
in which the submarginal series (in common with other
features) may have arisen—namely, as a survival of an
original dark ground-colour, which has become broken
up, first into irregular bands and finally into spots, by
the appearance and gradual enlargement of touches of
a lighter colour in the spaces between the nervules.
Further reference will be made to this point when other
markings, whose history appears to be similar to that of
the present series, come under consideration.

Metaporia agathon (Fig. 7) presents the series in
much the same condition as D. eucharis, the band is,
however, somewhat thicker and less defined. It is easy
to trace the same feature through many species of the
genera Pontia and Huphina; thus in P. soracta it is met
with in the hindwing as a series of faintly-developed
acute-augled chevrons, pointing outwards (as in Tato-
chila). In the forewing, S 3, 5—9 are easily visible. It
is noticeable that S 8 is in this insect exceptionally
small ; it retains, however, its usual tendency to break the ©
line of the series by advancing further than the others
towards the centre of the wing. In Pontia crategi the
whole series has vanished ; but in Huphina coronis, H.
phryne (Fig. 8) and others, it is well marked; the most
persistent spots being, as in other genera, 8 6, 8 and 10;
and the same general differences between the sexes, in
relation to the series, being observable here as in Synchloe

258 Dr. Frederick A. Dixey on the

and Ganoris. Indications of the series, more or less pro-
nounced, can also be seen in H. timnatha, H. aspasia,
H. judith, H. nama, and other species.

The strong resemblance to WDelias belladonna borne
by Prioneris thestylis is very probably due to mimicry,
as suggested by Wallace (“ Pieride of the Indian and
Australian Regions,” Trans. Ent. Soc. Lond., 5rd series,
iv., pp. 309, 383). But from the presence of traces of the
submarginal series in other species of Prioneris (as in P.
autothisbe and P. clemanthe), it seems likely that it is
rather the retention than the origin of the submarginal
series in P. thestylis that is attributable to this cause.
Material for the production of a likeness of D. belladonna
was no doubt already to hand in the existence of an
homologous series of markings in both insects. Other
species of Prioneris, not having the same reason for
keeping close to the original design, have strayed away
more or less widely from it.

Mr. Wallace has also pointed out the agreement in
some respects between Delias and the South American
genus Huterpe (ibid., p. 344). If, with Mr. Butler, we
divide Swainson’s genus Huterpe into Pereute, Leodonta,
Catasticta and Huterpe proper, we shall find that while
all the normally coloured species of the group are
demonstrably linked with one another and with Delias
by their general system of marking and scheme of
coloration, two of the genera (Pereute and Leodonta)
further suggest a near relationship with Delias by the
peculiarities of their neuration; there being in these
instances only three instead of four subcostal nervules
in the forewing (Butler, “ Revision of the Genera of
the Subfamily Pierine,’ Cistula HEntomologica, vol. 1,
1870, pp. 39, 40, ete). The appearance of several
species of this group of genera (notably Huterpe tereas)
has been profoundly altered by mimicry; but putting
aside such forms as these, we shall find no difficulty
in tracing a common pattern throughout most of the
remaining members of the group. ‘This pattern is not
dissimilar from that which characterizes those species of
Delias which we have seen to be probably the older
(e.g., D. belladonna, D. pasithoe and D. thisbe). To this
part of the subject I shall return later, at present it will
be sufficient to point out the distinct presence of the
submarginal series S in such examples as Catasticta

Phylogeny of the Pierinee. 259

nimbice, C. anaitis, C. bithys, and to a less degree in
Leodonta dysoni and SL. tellane. The close resemblance
between the remarkable Pierine Huchewra socialis and
C. bithys, in respect of the marking of the upper
surface, may warrant us in identifying the corresponding
portion of the wing in the former insect with the sub-
marginal row S undoubtedly present in the latter
(Bias. 1; 2).

The series S having now been traced through several
genera, until it, so to speak, loses itself in such gene-
ralised, and apparently primitive forms as those pre-
sented by Delias belladonna, Catasticta bithys and Hu-
cheira socialis, it will be advisable to return to the genus
Synchloe, and seek thereabouts for a new starting-point
from which to pursue the same series through its
developments in a fresh assemblage of genera which
have not at present been noticed. Such a starting-
point may be found in a comparison of S. daplidice 9°
with the female of almost any species of the genus
Colias. A short examination will show that the same
submarginal series exists in the latter genus. A good
species for the purpose is C. hyale (Fig. 20), in which
both sexes exhibit the series distinctly. The consti-
tuent spots broaden out towards the costa and tend to
become fused with one another and with the black patch
at the apex. ‘I'his tendency is carried further in many
species of Colias, particularly in the males, where, as in
C. edusa, marginal and submarginal markings are fused
together into a deep dark border. The females, how-
ever, preserve the spots of the submarginal series in a
more discrete condition. In most species of Colias S is
well developed on the under surface, the component
spots being usually black on the forewing, and on the
hindwing orange or pinkish. Ina few species, such as
C. phicomone and C. paleno, the series is obscured or
absent. Meganostoma, which resembles Colias so closely
in other respects, shows also the submarginal series on
the under surface; usually as a row of somewhat faint
pinkish dots, which are clearly identical with S in
Colics.

Through Meganostoma the passage is easy to Gonep-
terye and Amynthia. In G. rhamni and G. cleopatra no
vestige of S is to be seen on the upper surface ; on the
lower surface, however, of many of the males and most

260 Dr. Frederick A. Dixey on the

of the females, it 1s visible in the hindwing, and near
the apex of the forewing, as a series of minute brownish
dots; similar to, but as a rule even smaller than, those
of Meganostoma. Rhodocera leachiana and Amynthia
meerula show exactly the same feature, the spots being
dark brown or black, and a vestige of the series
is present in A. clorinde. In the closely-allied genus
Dereas, 5 is curiously modified into a brown or orange
streak passing in an almost straight direction from the
apex of the forewing to the anal angle of the hindwing.
In D. wallichii, 8 8 is large and prominent; but the
remainder of the series is scarcely visible on the upper
surface, though easily recognisable below.

In the genera Callidryas, Catopsilia, and their alles,
the extent to which § is developed varies within wide
limits. Callidryas philea 9 has already been noticed as
presenting, on the upper surface of the forewing, in many
specimens, a complete set from’ S 1 to $ 11 (Fig. 22). In
this, as in other species of the genera named, it is usually
S 7 and not S 8 that breaks the line by advancing towards
the centre of the wing. The series is not usually continued
on the upper surface of the hindwing, but both wings show
it tolerably well below. S is well developed on the upper
surface of Catopsilia flava ¢ (Fig. 21), and is visible to
a variable extent on both surfaces (except the upper
surface of the male) in C. catilla, Aphrissa godartiana,
and others. In some of these insects 5 on the under
surface forms part of the characteristic brown or pink-
ish mottling of the wing; in others, as the male of C.
phlegeus, it is almost or quite reduced to the condition
of minute pink spots, like those of the genus Gonepterya.
It is worth noticing that on the underside of Phebis
trite, S takes in the forewing the form of a straight
streak, not unlike that in Dercas lycorias, leading diago-
nally across the wing. On the hindwing a similar streak
appears, which, however, does not represent 5 as the
apparently corresponding streak in Dercas undoubtedly
does, but is at least partly developed from another
system of spots which will be noticed later. Attentive
examination will disclose the existence of traces of the
true S between the streak in question and the hind
border of the wing.

In Hebomoia the series is always at least partly visible
on the forewings, and often on the hindwings as well.

Phylogeny of the Pierinee. 261

The component spots are usually large and distinct, as
may be especially well seen in H. glaucippe 9 (Fig. 19).
The same insect also shows the series tolerably well on
the under surface, where it is in other members of the
genus, as a rule, somewhat lost in the general mottling
of the wing.

S is often well seen on the underside of species be-
longing to the genus [vias, where it assumes a condition
very like that which obtains in Colias. In I. marianne
it is especially well developed, and the component spots
on the hindwing are often furnished with pale centres.
Some members of the series are frequently also visible
on the upper surface, as in J. marianne 9, where 8 6—9
are conspicuous (Fig. 18).

The genera Teracolus, Swains., Idmais, Boisd., and
Callosune, Doubl., are united by Mr. Butler as Teracolus.
In most of the species included under this head, the
series now being discussed is distinctly visible, especially
in the female and on the under surface. Good examples
of the series are furnished by 7. danae and T. etrida.
In 7. eucharis $ it has mostly vanished from the upper
surface; S 8, however, remains, as in so many other
instances, and is, moreover, in this insect often reinforced
by the presence of 5 13 and 14, which spots have been
also seen to persist in our common species of Ganoris.
The female of 7. regina possesses § in a well-developed
condition on both surfaces, S 10 being especially con-
spicuous. ‘The same series is visible to a less degree in
the female of 7. cone. The males of both species show
indications of S on the lower surface, but none on the
upper. ‘The series may also be seen in a well-developed
state in 7’. hewitsonii and T. amata (Fig. 17).

In EHuchloe the series has almost disappeared. A relic,
however, persists near the apex of the forewing in some
species, best seen, perhaps, in H. tagis, H. ausonia, and
HE. hyantis ; while HE. reakirtii @ shows 8 on the upper
side of the forewing very distinctly; S 8 indenting the
line as in the genus Synchloe. A comparison of the
under surface of the hindwing in H. cardamines and
EH. ewpheno with the somewhat similar system of marking
in S. daplidice suggests also the probability that part of
the green mottling in Huchloe represents the submarginal
series. ‘I'he same series is certainly visible on the upper
surface of the hindwing in some specimens of FH. lucilla °.

262 Dr. Frederick A. Dixey on the

Certain species of Nepheronia—for example, N. jodea
? and N. valeria ?—show the series S in a form that
strongly recalls the condition of the same series in
Metaporia agathon. In both Nepheronia and KHronia,
however, S is very apt to be merged, especially on the
upper surface, with the dark marginal area. The female
of H. leda (Fig. 23) shows the first few spots of the
series on the upper side of the forewing in a condition
resembling that in some species of Callidryas, which
resemblance applies also to the lower surface, where S
occurs in a modified form on both wings, traces of the
same series being likewise visible in the male.

Summary.—Most of the members of the subfamily
Pierine possess, in a greater or less state of develop-
ment, a submarginal series of dark spots. The genera
Synchloe, Belenois, Tatochila, and some species of Colias,
amongst others, present the series in a fair state of
completeness. In other members of Colias, and in
several genera such as Ivias, Hebomoia, and Teracolus, the
series is often less distinguishable, owing either to fusion
of its constituent spots with each other and with the
dark marginal area, or to suppression of some of their
number. Relics of the series remain in Ganoris, Huchloe,
and other genera, being especially persistent in the
female sex; in Gonepteryz, Dercas, Callidryas, Phebis,
Catopsilia, and other allied genera, the series often
undergoes curious modifications. The aspect of the
series in such genera as Pontia, Huphina, Metaporia, and
Nepheronia, suggests its development from portions of
the original ground-colour left (by the formation and sub-
sequent fusion of lighter patches in a dark or dusky area)
as a dark band following the contour of the wing; and,
finally, by an extension of the process, as a submarginal
chain of spots. The possibility of such a mode of origin
is well illustrated by the condition of the wings in many
species of the Eastern genera Prioneris and Delias, and
the Western Leodonta, Catasticta, and Hucheira.

2. The dark marginal area or spots.

In nearly all our common Pierinw we find a dark
patch at the apex of the forewing; better marked, as a
rule, in the females than in the males. In G. brassicx

Phylogeny of the Pierine. 263

it is large and crescent-shaped, extending for some
distance along both costa and outer margin of the wing.
In G. rape ? it is not as a rule prolonged very far on
the outer margin, but it still reaches some way along the
costa. In the male of the same insect it is generally
small, and confined to the actual region of the tip. In
neither of these species is there much indication of
resolution, except that in most specimens of G. brassicex,
especially in the females, the hinder arm of the dark
crescent shows an irregularity due to the massing of
black scales about the marginal terminations of the
nervules. But in G.napi (Fig. 16) resolution is generally
well marked; and it becomes evident that the dark
crescentic or triangular area of the tip is really formed
by the fusion of the anterior members of the series §,
which we have just been considering, with another
series, which may be called M, occupying the actual
margin of the wing, and consisting, in its fully resolved
condition, of a row of dark spots, each of which is
traversed by the peripheral portion of one of the ner-
vules. It is noticeable that in this species the black
marginal spots are often found extended, especially in
the female, in the form of a powdering of dark scales
along the course of the nervules towards the base of
the wing.

Turning to S. daplidice (Fig. 15), we find the consti-
tuent elements of the apical patch still better shown
than in G. nap. The marginal and submarginal series
are always distinct, being separated from one another by
portions of the general white colour of the wing, which
take the form of a row of white spots on the dark apex,
usually four in number. Either of these two species
serves well to illustrate an important difference between
the spots of the two series, S and M. The spots of the
former series occupy, as we have seen, the interspaces
between nervules; and when fusion between adjacent
members of the series takes place, it does so by an
extension of dark scales across a nervule. On the other
hand, each of the spots of the latter series is centred,
not in an interspace, but around the peripheral portion
of a nervule or nervure. Thus the spots of the two
series tend to alternate with one another, though this
effect is to some extent interfered with by the frequent
fusion of some of the spots with others of the same

264 Dr. Frederick A. Dixey on the

series. It is further noticeable that in both of these
insects the marginal series M is usually continued in the
form of a row of dots smaller than those helping to
constitute the apical patch, but still distinct, along the
outer border of both fore and hindwing. In 8. daplidice
? (Fig. 15), the submarginal series being also distinctly
present on the hindwing, the alternate arrangement of
the two series is in this situation very apparent. The
constituent spots of series M may be numbered for con-
venience, in the forewing 1—11, in the hindwing 12—20,
one being counted for each nervure or nervule that
reaches the margin; and the same allowance may be
made as was suggested in the case of S for the occa-
sional suppression of a fourth or addition of a fifth
subcostal nervule (see p. 255).

Many examples of the occurrence of this marginal
series can be found among the near allies of the species
just named, and in all of them there is a tendency
towards the formation of a dark apical patch by the
union near the tip of the forewing with the anterior
members of the submarginal group 8. In G. gliciria
many members of the series are usually present, often
tending in the females to form by fusion a broad mar-
ginal band in both fore and hindwing. Other species of
the genus Synchloe besides S. daplidice present M in a
fairly well-developed condition. It is usually conspicu-
ous in the female S. callidice, S. protodice and SW. hellica,
and to a less extent in the males of the same insects ;
where it clings longest, as in the common species of
Ganoris, to the region of the tip. Tatochila autodice and
T'. theodice show M in very nearly the same condition as
the species of Synchloe last named.

Turning to the genus Colias, we find that the mar-
ginal series has undergone some modification. In the
males it is often completely fused with the submarginal
series, the two together forming a broad outer band to
the wing, as in CU. edusa 6. ‘I'he same may also take
place in the female, as in C. palwno; but m most cases
the two series, S and M, are in the female more or less
distinct, being marked off from one another by areas of
ground colour which take the form of a row of light-
coloured spots, not unlike those present in many species
of Synchloe (see p. 263). In some instances, as in
CU. hyale and C. phicomone, this description applies also

Phylogeny of the Pierinee. 265

to the males. Most species show a strong tendency for
the spots 8 8 and M 8—9, and, in a less degree, 8 10
and M 10—11, to become fused with one another by the
obliteration of the separating patches of pale ground
colour, ‘T'he individual members of series M are usually
more distinct from one another on the hind than on the
forewing. Not infrequently they are fused into a com-
plete band in both. On the lower surface M is in this
genus rarely if ever visible; thus offering a strong con-
trast to 8.

In Meganostoma the fusion of M with S is usually
complete on the forewing; the females, however, of some
species show traces of a separation ; a few patches of the
yellow ground-colour, like those in the females of many
species of Colias, appearing in the midst of the dark
border. In some forms, as M. philippa ?, these light
patches become much enlarged, and the two series S and
M are as distinct from one another as in any species of
Colias. M. cesonia usually shows the spots well on the
upper surface of the hindwing; and in most species of
this genus, M is often visible beneath as a row of minute
pinkish dots on the terminations of the nervules at the
margin.

In Gonepteryx, Rhodocera, Amynthia, and Dercas, the
series is not as a rule strongly developed. G. rhamni
usually shows on both surfaces a row of marginal dots,
dark red or brown above and pinker beneath, at the
outer extremities of the nervules, which are undoubtedly
relics of M. These are best marked at the tip of tho
forewing, where they often tend to run into a thin con-
tinuous marginal line, and are generally more apparent
in the female. The apical band is more strongly accen-
tuated in Rhodocera leachiana, especially in the female,
in which sex also M is often found on the hindwing in a
fairly developed condition. ‘T'races only of the series are
visible in the species of Amynthia; but in Dercas M is
reinforced by the anterior portion of §S, and helps with it
to form a conspicuous dark area at the region of
the tip.

The condition of M in Hebomoia needs no special
remark, except that on the under surface its separate
existence appears to be sacrificed to the exigencies of
the protective pattern.

In Callidryas, Metura, Phebis, Aphrissa, and Catop-

TRANS. ENT. SOC. LOND, 1894.—parT 11, (JUNE.) 8

266 Dr. Frederick A. Dixey on the

stlia, the development of M varies. Most of the species,
however, show the usual tendency of M to expand into
an apical patch, either with or without reinforcement
from S. The members of the series are generally
reduced on the lower surface of the hindwing to a row
of marginal dots; and the great characteristic of the
present series, namely that it belongs to the nervules,
and not, like the former one, to the interspaces, is kept
up throughout. On the upper surface of Catopsilia
flava 2 (Fig. 21), M and § are both well developed, and
their relation to one another closely resembles that
which obtains in Colias.

The same series is often present in the genera Ivias
and Teracolus ; being, as usual, most constant in the
females, and most prominent on the upper surface. It
appears occasionally as a chain of spots, as in the hind-
wing of many specimens of J’. ione ?, and some of
T. regina, but more often as a simple marginal band, as
in J. marianne (Fig. 18). This band may be com-
pletely fused with S, as in the hindwing of 1’. phisadia,
or partially so, as in 7’. amata. A plain marginal band,
in the forewing expanding at the tip and more or less
indented opposite the branching of the median nervure,
in the hindwing sometimes breaking into a chain of
spots, is also the usual condition of M in the genus
Tervas.

In Nepheronia and EHronia M is generally present as
a well-developed marginal band sometimes more or less
fused with 8, and often sending dark prolongations
inwards along the course of the nervules. In some
species, however, as N. thalassina and EH. leda, it is
mostly confined to the apical region; in the latter
indeed it is absent from the hindwing of the male
altogether, and barely visible on that of the female
(Fig. 23). The series in Huchloe is generally recogniz-
able as a row of dots, sometimes fused at the apex with
the anterior members of §; but often, as in H. tagis and
H. ausonia, preserving its independent existence.

The condition of M in the genera Metaporia and
Huphina recalls that in Nepheronia; the constituent spots
being generally fused into a marginal band from which
dark offshoots run inwards, accompanying the course of
the nervules. A similar description will apply to Pontia,
though in this genus the dark markings are often greatly

Phylogeny of the Pierine. 267

reduced. P. soracta, however, shows M with sufficient
distinctness ; and even in P. crategi M itself is in some
instances visible, while the dark prolongations along the
course of the nervules is a well-known and conspicuous
feature.

Delias and Prioneris help to show us what is in all
probability the earliest condition of the present as well
as of the former series. The upper surface of both fore
and hindwing in the female of D. eucharis presents once
more the familiar pattern of Metaporia agathon and
Nepheronia gea ?. thas already been pointed out that
there is an easy passage from this system of marking
to that which we find in D. belladonna, D. pasithoe, and
several other species; while the same features are un-
doubtedly visible with but slight modification in the
American genera Huterpe, Catasticta, Leodonta, and
Hucheira (see p. 258). A comparison of the insects just
named, to which may be added Prioneris thestylis and
other species of the same genus, can hardly fail to suggest
the probability of the origin of both M and 8 as portions
of the original dark ground-colour marked off from one
another with gradually increasing distinctness by the ap-
pearance, enlargement, and confluence of whitish patches
in the interspaces between nervules. The alternate
character of the two series S and M, when broken
up into spots, is seen to be a consequence of the shape
and position of the original dusky white touches that
first brmg them into view. ‘These touches may be seen
for example in D. belladonna (Fig. 4) to be divisible into
two sets, which we may call marginal and basal, both
occupying the central areas of the interspaces. Between
the two setsis included the portion of ground colour cor-
- responding to 8, the constituent spots of which, when iso-
lated, will necessarily have their centres in the interspaces.
But the marginal set of light marks tends to reach by
tapering extremities to the edge of the wing (see Fig. 5) ;
so that the interposed marginal patches of unaltered
ground colour, forming the first beginnings of M, are of
necessity focussed round points in the nervules an d not
in the interspaces. And when in consequence of the
further development and fusion of the white or pale
markings, the marginal relics of dark ground colour
become reduced to a row of isolated dark spots, these
spots are, as we have already seen in S. daplidice (p. 263)

“268 Dr. Frederick A. Dixey on the

and other cases, always traversed by the peripheral
portion of a nervule or nervure. This fact is well
exemplified by M. agathina, M. poppea, and several
other species of Mylothris (Fig. 12).

The invasion of white, which is already considerable in
D. eucharis 2, becomes still more predominant in the
male of the same insect, where, however, the original
ground-colour still persists, not only m the series S and
M, but also in the form of the dark streaks accompanying
the nervures and nervules, a feature which we have seen
to be common in many other genera, especially Pontia,
Huphina, Metaporia, and Nepheronia.

Without leaving the genus Delias we can find several
examples where the intrusive white has ousted the whole
of the original ground-colour, except at the margins and
apex. ‘This is the case for instance in D. descombeswé ,
D. agostina $, D. coeneus ,and D. momea. In most of
these species the dark marginal area is plainly composed
of S and M inamore or less complete state of fusion,
and it is noticeable here as elsewhere that the female
almost invariably retains a larger proportion of the
original ground-colour than the male.

Many species of belenois resemble the last mentioned
species of Delias in the tendency towards fusion of the
marginal and submarginal series. DB. peristhene (Fig. 14)
is exceedingly like DL. momea in this respect, and in B.
teutonia 2 and B. coronea the fusion is still more com-
plete. But m very many species of Belenois and
Pinacopteryx, S and M are plainly distinguishable from
one another; and in some, as in B. calypso (as also in
Pinacopteryx capricornus), the resolution of both into a row
of dots is complete. ‘The formation of a series of rings
along the margin of the hindwing (as in Synchloe calli-
dice 2, S. protodice 2, etc.), by the union of the horns
of the crescents or chevrons belonging to series 8 with
the spots of series M, is a noticeable feature on both
surfaces of many specimens of B. mesentina 8 (see
Fig. 13); and the identity of the whole arrangement of
the submarginal and marginal series in Belenois with that
in Synchloe becomes perfectly evident on a comparison of
B. mesentina with S. johnstonw or S. hellica.

In Appias the two series when present are not sharply
marked off from one another. In some species, however,
S has almost or quite disappeared, and M may persist

Phylogeny of the Pierine. 269

alone as a marginal band, showing more or less ten-
dency towards resolution (Appias lyncida $, A. celes-
tina 6, etc.).

Suwmmary.—tThe present, like the preceding series, is
thus seen to be a relic of the original dark ground-colour.
It is intercepted between the margin of the wing and
a series of pale touches (best seen in certain species of
Delias and Catasticta) that making their appearance in
the submarginal region of the interspaces, more or less
isolate, indent and divide up the dark marginal area. It
may eventually disappear altogether (as in some speci-
mens of G. rape ¢), but usually persists on the forewing,
at least, in the region of the apex. When present, it
shows great variation in the extent to which it is resolved
into separate spots, and also in the amount of fusion it
undergoes with the neighbouring series 8S. As a general
rule it is, like the last-named series, more constantly
present in the female sex, and more completely resolved
in the male. |

3. The light series between 1 and 2.

The region of pale ground-colour included between
the two dark-coloured series S and M, becomes of
necessity more sharply defined and circumscribed as the
constituents of each dark series become fused together
into bands instead of remaining as rows of spots. The
tendency so often seen of the two dark series to become
partially fused with one another, by the extension
between them of dark lines following the course of the
nervules, leads, when carried far enough, to the splitting
up of the included pale area into a series of pale spots,
which sometimes attain a very distinct and definite
character, especially at the apex of the forewing. These
pale spots have already been incidentally noticed during
the discussion of the two series between which they lhe ;
it will not be necessary to do more in this place than to
suggest that, for the purpose of separate reference, the
letter I should be taken to represent the whole series,
the possible constituents being numbered {—20, in corre-
spondence with the dark spots of series S which bound
them on the inner aspect. (See Figs. 1, 2, 5, 21, etc.)

A. The discoidal spots.
In none of our three common species of Ganoris does

270 Dr. Frederick A. Dixey on the

there exist a true discoidal spot.. The nearest approach
is to be found in G. napi, where the disco-cellulars of the
forewing, together with the other nervules, are in many
specimens accompanied by a sprinkling of black scales ;
which in some instances are sufficiently numerous in this
particular region to give almost the appearance of a
black discoidal spot or patch. This may be best seen in
specimens of (. bryonix, but dusky specimens of the
ordinary G. napi will sometimes show the tendency
almost equally well. The same tendency is carried a
little further in TVatochila autodice, while T’. theodice
shows the corresponding marks in a condition of strong
development, with a slight indication of a similar feature
on the hindwing as well. Passing to the genus Synchloe,
we find the discoidal spot invariably present, at least in
the forewing; and in most species large and distinct,
especially in the females. SS. daplidice (Fig. 15) has the
spot well developed on both surfaces; on the lower sur-
face it is more or less shaded with green. The same is
the case with the somewhat smaller discoidal spot in
S. callidice. Another example of a large and conspicuous
discoidal spot is furnished by 8S. hellica.

In Colias, a discoidal spot is nearly always present on
each surface of both fore and hindwings. On the upper
surface of the latter it is sometimes independently
present and sometimes only shows through from
beneath ; but it is seldom absent altogether. ‘The spot
on the forewing is in this genus, as in Synchloe, usually
dark brown or black. It may be ringed or pupilled with
orange; in the former case the orange is of a deeper
shade than the general ground-colour. Hxamples of
this may be seen in CO. meadii, CO. cunninghamii, and
others. In C. fieldit and C. edusina the discoidal spot in
the forewing is unusually large; in no species of Colias,
however, does it overpass the boundaries of the sub-
costal nervure in front and the third median nervule
behind. It may be very small, as in C. barbara; or
entirely absent, as in some specimens of C. paleno and
C’. pelidne. On the lower surface it is often centred with
white or silver. On the upper surface of the hindwing,
the spot when present is not dark, but varies in different
species from the palest yellow to a full orange. It is
distinguished from the general surface of the wing either
by its different shade of yellow or orange (as in C. hyale)

Phylogeny of the Pierinze. 271

or by its freedom from admixture with the darker scales
that often give the hindwing in this genus a compara-
tively dusky appearance (as in some specimens of C.
edusa). In many species a small companion is visible
in the interspace between the second subcostal and dis-
coidal nervure. On the under surface the discoidal spot
is much more distinct. Its centre is silvery white, and
it is usually encircled with a brown or orange ring,
which in some species is sharply marked off both
internally and externally by thin marginal lines of a
darker colour. The companion reproduces the discoidal
spot on a smaller scale. It always occupies an inter-
space, whereas the chief discoidal spot is situated upon
the second disco-cellular nervule. (Fig. 20, D 4.)

No doubt is likely to arise as to the identity of the
discoidal spot in Synchloe with that in Colias so far as
the forewing is concerned. The chief difference between
them is that in the former genus the spot is less sharply
defined and less regular in outline ; moreover in Synchloe
it frequently reaches forward to the costa, and it may
extend backward to the space between the first and
second median nervule; whereas in Colias, as we have
seen, it does not pass the limits set by the subcostal
nervure and the third median nervule. But there can be
no reasonable question that the spots are homologous in
the two cases; and a comparison of the two genera
further suggests the probability that in Synchloe we
have an older, in Colias a newer and more specialised
form of the marking. This conclusion accords with
what has been already said about the marginal and sub-
marginal series of markings, which in Colias, especially
in the males, have departed somewhat further from the
original type than in Synchloe; and it will be seen to
receive further confirmation from what is to follow.
With regard to the discoidal spot on the hindwing,
although it is perhaps not at first sight clear that the
markings in the two genera are really homologous, it is
nevertheless quite possible, on an attentive examination
of allied forms, to trace the steps by which the passage
from one to the other is effected. In the hindwing of
many species of Synchloe there is no indication of a
discoidal spot at all; in others, however, a definite
aggregation of black scales is visible about the disco-
cellular nervules. In some species, suchas S. protodice 9°,

272 Dr. Frederick A. Dixey on the

the nervules, though surrounded with black scales, are
themselves covered with white, or (on the underside) pale
yellow scales; a light-coloured centre being thus provided
for the dark discoidal patch. In the genus J'atochila
this light-coloured centre acquires greater importance.
On the under surface of 7’. autodice the white scales are
seen not only covering the disco-cellular nervules, but
also intruding some way upon the yellow of the general
surface; in this species, however, the pale patch thus
formed has no dark border. But there can be little
doubt, on a comparison of 7’. autodice with Colias paleno,
that the whitish area surrounding the second disco-
cellular nervule in the one is homologous with the silvery
patch in the corresponding region of the other; while
the identity of the discoidal marks in Tatochila with
those in Synchloe, and of the same marks in C. palxeno
with those in other species of Colias, is a matter of
certainty. The brown ring surrounding the silvery
pupil on the under surface of most species of Colias is
indicated in C. paleno, where its general appearance
points to the probability of its origin from the dark
scales that have already been noticed as gathering about
the region of the disco-cellular nervules in Synchloe.
In C. palzno itself, however, the central pale patch (as in
T'atochila) becomes far more prominent than the sur-
rounding dark border. An examination of the discoidal
spot on the underside of the hindwing in Gonepteryx
rhamnt Q and Amynthia merula will disclose the same
general arrangement of a pale area traversed by the
second disco-cellular nervule, and surrounded by a ring of
darker scales, that we have already seen to be character-
istic of the spot in other genera. In these insects, how-
ever, as in Lhodocera leachiana, the spots, though clearly
identical with those in Colias, are in a lower state of
development and specialization. Turning again to the
discoidal spots on the forewing, we may at first sight
hesitate to identify the bright orange spots in G. rhamnt
or G. cleopatra with the black spots or patches in
Synchloe and Colias. But in Amynthia clorinde we have
what is unmistakably an intermediate form of the spot, in
which the vivid orange of the one closely encircles the
deep brown or black of the other, and from which either
the Gonepteryx or Colias type of spot might be easily
derived. Much the same is the case with I’. leachiana ;

Phylogeny of the Pierinee. 273

but in this insect the black markedly predominates.
The discoidal spot in the forewing of R. leachiana is also
noticeable as having a small companion, of similar
character but with a greater proportion of orange, in
the root of the interspace between the subcostal and the
first discoidal nervure.

The discoidal spots in Dercas, when present, corre-
spond closely with those in the genera just named. The
spot on the forewing of D. lycorias is like that im
G. rhamni ; it is, however, less compact, and surrounds
both disco-cellular nervules instead of the second only,
as in the latter insect. The spot on the upper surface of
the hindwing is scarcely visible, but those on both wings
beneath nearly resemble the corresponding marks in
Rf. leachiana. On the underside of D. wallichii the
marks are of the same character, but reduced in size ;
from the upper surface they are almost or quite
absent.

In Meganostoma the discoidal spots, both above and
beneath, so closely correspond with those in Colias as to
call for no special remark. In Callidryas, Metura, Pheebis,
Aphrissa, and Catopsilia, they present also the same
general appearance. On the upper surface of the hind-
wing, the discoidal spot is seen as a rule faintly or not at
all; but on the forewing there is often a well-marked
dark patch, enclosing either the second disco-cellular,
as usually in Catopsilia thawruma and C. catilla 2,
or both disco-cellulars, as in Aphrissa godartiana ?. On
the underside the form of a silvery circular patch,
surrounded by a pinkish or brownish ring, is almost
universally kept up. ‘There is in some species (as in
Callidryas philea) a tendency for the discoidal spot in
the forewing to divide into two parts, one for each disco-
cellular nervule ; while in the hindwing the small com-
panion which has been already noticed in Colias is nearly
always present in the interspace between the discoidal
and subcostal nervures. One or two species (as C.
florella 2) possess a second companion within the cell.
The present series, when fully resolved, seems thus to
consist of five spots, two belonging to the two disco-
cellular nervules in the forewing, the third belonging to
the interspace between the subcostal and _ discoidal
nervures in the hindwing, the fourth to the second
disco-cellular nervule, and the fifth to the discoidal cell,

274 Dr. Frederick A. Dixey on the

also in the hindwing. I propose to designate the system
as D 1—5.*

The last-named genera exhibit a good deal of varia-
tion in the size of the constituent spots of D, and
also in the breadth of the encircling darker ring. In
C. catilla ¢, the latter, spreading widely out from the
silver centres, and being reinforced in the hindwing
by a similar development from certain of the spots of
series $, forms a conspicuous dark red patch on the
under surface of both primaries and secondaries. A
similar tendency is seen in many specimens of Callidryas
thalestris and other members of that genus. In all these
cases the border of the discoidal spots on the under
surface is assimilated in colour to the general character
of the darker mottlings that form the prevailing feature
of the wing-pattern. It is interesting to observe, in the
case of Phebis trite, that the straight diagonal streak
already referred to (p. 260) as crossing the under surface
of the hindwing is made up of elements belonging to
both series $8 and D, as follows: The part between the
two subcostal nervules is 8S 14; that between the sub-
costal and discoidal is D3; the next, where the streak
intersects the second disco-cellular, is D 4; it then skips
a space, and reappears between the median and sub-
median nervures as § 19. That the homology of the
different parts of this line has been correctly stated will
be evident from a comparison of P. trite with C. eubule
and C. thalestris, in which species the elements of the
streak are visible in a separate condition. It is in P.
trite particularly worthy of note that in those interspaces
where D 3 and 4 form part of the streak, the corre-
sponding members of S, viz., 8S 15, 16, and 17 (which
are not wanted for this purpose), are visible well to the
outer side of the streak; whereas in the other inter-
spaces there are no marks between the streak and the
margin, the members of S having been, so to speak,
used up for another purpose, and having thus caused an
apparent interruption of the usual submarginal pattern.
In the interspace between the first and second median

“ This use of D is open to the objection that the same letter
has also been used for an entirely different set of markings in the
Nymphalidz (see Trans. Ent. Soc. Lond., 1890, p. 91). But I do
not think that this circumstance is likely to give rise to any
practical difficulty.

Phylogeny of the Pierinee. 275

nervules, S 18 appears as a submarginal spot of the usual
kind. Now, inasmuch as no member of series D ever
occupies this interspace, there is no material at hand for
continuing the streak ; and, carrying the eye up to the
apex of the interspace, where the streak should cross,
we find it, in fact, deficient at that place.* This may
seem a small point, but it is of interest as illustrating
the absence of anything that might be called violent or
arbitrary in the evolution of these various patterns, in
which, indeed, the closer the examination the more
difficult it is to find anything effected per saltwm.

In Iwvias the condition is again much the same as in
Colias; the discoidal spot of the forewing, however, is
often united on the upper surface with a dark band
running across the wing from the costa to the anal
angle. A similar feature occurs in Hebomoia glaucippe
(Fig.19) and other species of the same genus. On the lower
surface the discoidal spot varies considerably in size, and
in a few cases (as sometimes in J. marianne) may be
absent altogether. When it is large, as in other
specimens of J. marianne, it is frequently centred with
white. In the hindwing the series is absent from the
upper surface, and represented below only by D 4, which
may also be white-centred, or may exist as a simple
black dot of varying size.

In Teracolus, D is usually well marked. In some
species, such as 7’. vesta, I’. hewitsonii, and T. puellaris,
it occurs on the forewing as a conspicuous black patch
covering both disco-cellular nervules, and usually merged
anteriorly in a dark or dusky band which extends along
the costal border. In other species, as 7’. evanthe, T. vone,
T’. regina, ete., it takes the form of a circumscribed black
spot, sometimes minute or absent. On the lower surface,
the scales on and surrounding the disco-cellular nervules
are often whitish, thus giving Da pale centre. D in the
hindwing, when present, is usually small; on the under-
side of some species, as 7’. danae, T. evippe, and T.
omphale, it is centred or shaded with orange ;—this
tint belonging primarily to the disco-cellular nervules,
and spreading more or less widely from them.

* As above noted (p. 260), the corresponding streak in the fore-
wing of P. trite, and the somewhat similar feature on both wings
of Dercas lycorias, are entirely formed out of series 8.

276 Dr. Frederick A. Dixey on the

In Terias and Sphzxnogona, D is constantly absent
from the upper surface, but is usually visible below,
where it may appear as a small black dot or pair of dots
in each wing (7. lisa), or as a group of more or less
regular narrow-bordered rings (7. hecabe and T. floricola),
or in various intermediate forms (7. deva and S. gratiosa).
The transition from the condition of D in Colias to that
in Terias is well indicated by Xanthidia nicippe, most
specimens of which correspond pretty closely in the
markings of the lower surface with the latter genus ;
while the upper surface of the forewing bears a discoidal
spot much like that im some species of Colias. In the
closely allied genus Pyrisitia, D has altogether disap-
peared (see P. proterpia).

The genus Huchloe shows the discoidal spot on the
forewing in a well-marked condition (Fig. 24). It may
exist as a distinct spot, as in LH. cardamines, usually
larger in the female; or as a more or less quadrangular
patch reaching up to the costa, as in H. lucilla. On the
underside it is often white-centred, as in H. belemia and
others. On the hindwing, D is in many species of Huchloe
not visible at all. In some, however, it appears as a
small, at times very minute, patch of black scales sur-
rounding the second disco-cellular nervule (some speci-
mens of H. genutia and H. cardamines) ; in others, as
E. charlonia and FE. lucilla, it takes the form, on the
under surface, of a pale circular patch, closely resembling
D4 of Colias paleno in the same situation.

D in Belenois is usually well marked on the forewing,
as a rule enclosing both disco-cellulars, and often
prolonged anteriorly to join the outer extremity of a dark
costal band ; this is especially the case in the female, and
on the under surface in the male, as in B. mesentina, B.
teutonia, B. calypso, etc. The spot is sometimes small
and quite distinct, as in B. creona, D 1 being absent ;
sometimes, on the other hand, it is large and almost or
quite merged in the general dark field of the outer
portion of the wing, as in B.coronea. In the hindwing
there may be no discoidal mark at all, as in B. creona;
or all the nervures may be covered with dark scales
(as generally on the under surface of B. mesentina),
the disco-cellular nervules not being specially dis-
tinguished; or there may be a definite discoidal spot,
composed of D 4, as in B. mesentina ¢, upper surface ;

- ms amass I ipa a EE

Phylogeny of the Pierinee. a

and in B. calypso, under surface of both sexes and upper
surface of female.

In Appias and Catophaga a discoidal spot can scarcely
be said to exist; but in Hiposcritia and Pieris various
members of the series D are often well marked. H.
lalage ¢ (Fig. 11) has a conspicuous discoidal spot on
both surfaces of the forewing, formed by D2; and on
the under surface of the hindwing there appears a minute
representative of D4. In H. pandione, D 1 and 2 com-
pose a large spot which joins the dark costal band; while
on the under surface of the hindwing, D 4 is sometimes
indicated by a paling of the first disco-cellular nervule
and the immediately surrounding area. In Pieris the
forewing often shows a conspicuous discoidal spot, formed
by D 1 and 2 or by D 2 alone; the hindwing as a rule
possessing only a small dark representative of D 4 on the
under surface, which in P. bunie merely touches the
second disco-cellular, but in P. pylotis encloses it.

In Pontia and Huphina (Fig. 8), D in the forewing
appears generally as a mere darkening of the wing in the
region of the disco-cellular nervules, more pronounced
than the darkening of other nervures which is common
in these genera, but not forming a definite spot. In the
hindwing it is much less distinguishable or even absent
(P. crategi, P. soracta, H. phryne, H. timnatha, etc.).
In Metaporia agathon (Fig. 7) the same darkening of the
disco-cellular area occurs, which in MW. phrywe takes the
form ofa definite and conspicuous patch. A like condition
is seen in N. gea, and other species of Nepheronia.

The correspondence in pattern of the genera Delias and
Prioneris with those just discussed, already referred to on
p. 267, apples to the present as well as to other features
in the marking. Jelias, moreover, shows in many
species that paling of the disco-cellular nervules them-
selves, and sometimes of the immediately surrounding
area in the midst of the dark discoidal patch, which we
have seen to occur in Synchloe and other genera, and
which in Colias, Ivias, and their allies leads to remarkable
modifications in the general appearance of the discoidal
spots (see Delias aganippe, D. descombesi, D. crithoe,
etc.). In D. belisama ¢, the nervules remain dark,
though there is a surrounding pale area.

Nothing special needs to be said about the genera
Euterpe, Catasticta, Leodonta, and Eucheira. Their

2'78 Dr. Frederick A. Dixey on the

general correspondence in pattern with the old-world
genera last named, which has been already referred to,
involves a similar condition of the present series D. In
none of them does any member of D assume the condition
of a definite circumscribed spot; but in nearly all, the
series exists as a portion of the original dark ground
colour between the touches of intrusive white or yellow.
In C. toca, D on the underside of the hindwing consists
of an irregular dark ring with a yellow centre traversed
by the disco-cellular nervules, this representing an early
condition of the homologous ocellus in Oolias.

Summary.—This series also, like those already treated
of, represents a local survival of the original dark ground-
colour. Appearing in the first place as an ill-defined
accumulation of dark scales around the disco-cellular
nervules, it takes the form of definite spots as the in-
vasion of white or other pale ground tint progresses. As
in the case of the other series, resolution is generally best
marked in the males; the females showing a greater
tendency to adhere to the ancestral condition. When
fully resolved, the series consists of five spots, two for
the disco-cellular nervules in the forewing, and one for
the second disco-cellular in the hindwing, with two extra
spots, also in the hindwing. In many instances the
disco-cellular nervules, with a varying amount of neigh-
bouring ground-substance, may appear as pale streaks or
patches in the midst of the primitive agglomeration of
dark scales; and in the further development of the
pattern it may happen that either the pale or the dark
markings alone persist; or both pe be retained and
worked up as in species of Colias, Callidryas, Ivias, etc.,
into a system of more or less elaborate ocelli,

5. The markings on the wnderside of the hindwing.

a. The yellow precostal streak.—A. constant feature in
our common species of whites is a deep yellow or orange
streak which occupies the margin of the precostal space
on the underside of the hindwing, and is clearly dis-
tinguishable from the pale yellow of the general ground-
colour. This yellow precostal streak is conspicuous in
other species of Ganoris, as G. gliciria, and may also be
seen in S. daplidice, S. hellica, and many other members
of the genus Synchloe. It is, I believe, never found in
Pontia crategi; in the closely allied P. hippia and P.

Phylogeny of the Pierinee. 279

soracta, however, it is well marked. Metaporia agathon
and M. phryze, which resemble the last-named species
in other respects, also show a deep yellow mark in the
same situation; but in this instance it occurs only as a
spot bounded outwardly by the precostal nervure, and is
not prolonged as a streak along the costa.* Many
genera present this mark in much the same condition as
the species of Ganoris first referred to; of which good
examples may be seen in Nepheronia thalassina, N. argia,
the curious Herpenia eriphia, Pinacopteryx pigea and P.
capricornus, Mylothris chloris and M. agathina (deep
orange in these), Tatochila theodice, Glutophrissa mar-
garita, Appias zelmira, Phrissura_ sylvia, Daptonura
lycimnia, Teracolus icne, T'. regina, T. evis, ete.

Looking back to Synchloe hellica, we find that the
yellow precostal streak forms in that insect only one of a
series of yellow marks, one or two of which partially |
occupy each interspace. A similar condition obtains in
many species of Belenois; see for instance DB. mesentina
and B. tewtonia. On the underside of the hindwing in
these species, the dark lines following the course of the
nervures, and the dark markings belonging to the various
series above described, are laid down upon a ground
colour which is usually white or pale yellow, but which in
many specimens is relieved here and there by streaks and
touches of a deeper yellow or orange. One of these
streaks occupies the costa, and is plainly identical with
the yellow precostal streak in Synchloe, Ganoris, and the
other genera named. Although in the species of Belenois
just referred to, as in several others, this streak is easily
seen to form but one member of a series, it is never-
theless more constant and persistent than any of its
companions. ‘I'his is evident in those not uncommon
specimens of B. mesentinat in which the general
ground colour on the underside of the hindwing
takes on so deep a yellow tinge as to approach that of
the yellow streaks and touches. In these cases all or
some of the latter set of markings may cease to be
separately recognizable; the precostal streak, however,
is always the last to disappear. In certain species of the

* A specimen of M. agathon in Coll. Brit. Mus. has, however, a
few orange scales in the outer division of the precostal space.
+ I.e., the form known as B. auriginea.

280 Dr. Frederick A. Dixey on the
present genus, as B. gidica, the ground colour remains
pale ; but the precostal streak is the only member of its
series present. In others again, as B. coronea, the black
spots of S exist in a state of enlargement and fusion,
while the orange touches occupy nearly the whole of
the spaces that are left. The hght spets of series I (see
p. 269) between S and M, which in B. teutonia are only
touched with orange, are entirely of that colour in most
specimens of B. coronea. In B. peristhene the amount
of lhght ground colour is smaller still, but the orange
costal streak and orange series I are present as in B.
coronea. Both of these insects, B. peristhene in especial,
suggest at once a comparison with certain members of
-the genus Delias, particularly D.nysa and D. momea. In
these two species the yellow precostal streak and the
yellow or orange series I are unmistakably present. In
D. nysa, as in B. peristhene, these constitute the only
relief to the general dark colour of the wing; while in
D. momea § is partially defined by the presence of pale
touches on its mner aspect in addition to the spots of
series I along its outer margin.

While the species named suggest a passage in respect
of this pattern of the underside of the hindwing between
Belenois and Delias, there is not wanting evidence of
the same import in the case of other species in which the
blackening of the hindwing is a less conspicuous feature.
On the underside of D. belladonna we cannot fail to
recognize the counterpart of such a hindwing as that of
B. teutonia ; the dark and light areas occupy with slight
modification the same relative positions, and the same
spaces of pale ground-colour that are in B. teutonia
touched up with deep yellow, are wholly or partially of
the like colour in D. belladonna ; among these, of course,
being the precostal margin. ‘he basal portion of the
hindwing in such species as D. eucharis and D. hyparete
shows a more general yellow tinge than in D. belladonna ;
but in both of these, as in other allied species, the
deeper-coloured precostal streak is perfectly recognizable.
In very many species of Delias we meet with a new
feature, much of the ordinary yellow being displaced by
a brilliant red; but the former colour still displays a
tendency to cling to the region of the precostal space, as
may be seen in D. thisbe ; where, however, the precostal
yellow hardly reaches further outwards than the pre-

Phylogeny of the Pierinee. 281

costal nervure. In the very similar D. pasithoe it has
been driven even from this position.

Prioneris exhibits a condition very similar to that of
Delias. The underside of P. thestylis closely corre-
sponds with that of D. belladonna, and the resemblance
applies to the precostal streak no less than to other
features. In some species of Prioneris, as C. clemanthe
and P. autothisbe, the precostal yellow is again ap-
proached, and sometimes dislodged, by a greater or less
amount of bright red, as in D. pasithoe, D. thisbe,
D. crithoe, and other members of the former genus.

Leaving the red patches and other features of the
pattern of this region in Delias and Prioneris for dis-
cussion at a later stage, we may pass on to the
American genera Huterpe, Pereute, Leodonta, and Catas-
ticta. In the two last-named the arrangement of light
and dark markings corresponds generally with that in
Delias and Belenois, and similar touches of deep yellow
are mostly present in the same relative positions. One
of these, usually to be seen on the costal margin, is
clearly homologous with the precostal streak in the
insects already referred to; in many specimens of C,
nimbice, C’. semiramis, C. toca, and others, it bears very
much the same appearance as in the old-world genera
above mentioned. It may be noticed in passing that
in many instances, such as L. zenobia, L. dysoni, and
C. anaitis, the yellow precostal streak is found sharing
the precostal space with a greater or smaller amount of
brilliant red, as we have seen to be often the case in
Delias and Prioneris. The same struggle between
yellow and red is visible in the genera Huterpe and
Pereute. In H. tereas the space is shared, the red keeping
to the inner, and the yellow, when present, to the outer
side of the precostal nervure. In P. charops the snace is
usually all yellow; in P. autodice and P. leweddrosime it
is allred. In these two genera the other yellow marks
are reduced in number or completely abolished; P.
charops, however, generally has a conspicuous yellow
patch between the costal and subcostal nervures which
undoubtedly belongs to the series.

In the genus Pieris, which is also American, some
species, such as P. locusta and P. habra, show on the
under surface of the hindwing a pattern which is
evidently only slightly modified from that seem in many

TRANS. ENT. SOC. LOND, 1894.—PART II. (JUNE.) T

282 Dr. Frederick A. Dixey on the

species of Catasticta ; and in these also the red or orange
of the costa is a prominent feature. In other species of
Pieris a farther alteration has taken place, and the
markings have been swept from the basal portion of the
wing (as in P. demophile), or away altogether (P. buniz).
In most, however, if not all of these cases, the precostal
streak persists, again taking a yellow rather than red or
orange colour; and, in the absence of other yellow or
well-defined dark marks on the wing, it comes to
resemble very closely the corresponding feature in so
many species of Synchloe and Ganoris.

Summary.—The facts adduced in the course of the
foregoing remarks seem so far to allow of little doubt
as to the history of the yellow precostal streak. It is
evidently a survival of a series of yellow or orange marks
which is found, in many genera of both eastern and
western Pierinz, on the underside of the hindwing,
partially or wholly occupying the paler areas left between
the relics of the original dark ground colour. The
greater number of these marks may disappear with a
general lightening of the wing, or the whole wing may
become so yellow as to render them almost or quite
indistinguishable ; but the particular yellow streak that
occupies the margin of the precostal space is more per-
sistent than any of the others, and may remain, as in our
common species of Ganoris, after every other character-
istic of the ancestral marking has departed. It will be
seen later that this account of the precostal streak,
though no doubt correct as far as it goes, in all pro-
bability needs supplementing.

b. The red basal patch.—In both British species of
Colias, there occurs at the base of the hindwing, on the
under-surface, a pinkish patch, which occupying the
apices of the cell and of the median and submedian
interspace, and also in most cases asmall area at the root
of the precostal space, is often prolonged for a short
distance along the middle of the cell. This patch, which
is almost always present throughout the genus Colias, is
found in most if not all species of Meganostoma, and
also very commonly in Catopsilia, Callidryas, Phebis,
Aphrissa, and Metura, It is present, too, in Dercas,
Gonepteryx, Rhoducera, and Amynthia; im these, however,
it does not as a rule extend far from the body itself.
Beyond the limits of these closely-allied genera this

Phylogeny of the Pierine. 283

special feature does not often occur in a very clearly-
marked condition; it is, however, present in Xanthidia
nicippe, and in several species of Terias and Sphcenogona,
as J’. agave and S. mewicana; it may also be seen
occasionally in Teracolus, as in T'. antevippe, T. ewpompe,
and (sometimes) J’. erts, assuming in this genus a some-
what diffuse appearance. In some species of Appias, as
A. hombronii (occasionally), and A. lyncida, as also in
Herpxnia eriphia, there are deep yellow marks near the
root of the wing, which are probably homologous with
part of the patch now under discussion; and im the
genera Belenois and Tatochila touches of deep yellow
often occur at the base of the median space, though not
in the cell, which appear to correspond with the marks
just referred to in Appias and Herpexnia (see B. mesentina
and T’. autodice). ‘These yellow touches in Belenois are
undoubtedly members of the series spoken of on p. 279,
and so far it would seem that the well-marked pink patch
at the root of the cell in Colias, Gonepteryz, etc., 18 at
least in part developed from a portion of that series, of
which another member has given rise to the yellow
precostal streak. It is certain, however, that other
factors besides the series now indicated are chiefly,
though probably not entirely, answerable for the com-
position of the pink basal patch in Colias ; and it is at
least possible, as will presently be seen, that the pre-
costal streak itself owes something to their assistance.
These other factors are the red basal areas to which
reference has already been made, and which will now be
examined in greater detail.

c. The red basal areas. To begin with the under-
side of Delias pasithoe, we find the base of the hind-
wings occupied by a bright red patch forming about
a quarter of a circle on each wing, the body itself and the
immediately surrounding area of the wings being black.
The spaces affected by the red patch are six ; namely, the
precostal, costal, subcostal (or cell), median, submedian,
and internal—all those in fact whose apices reach to the
base of the wing. In D. thisbe there occurs a similar
red patch, occupying nearly the same spaces. In this
insect, however, there is no red in the precostal space,
which is occupied (as above noticed, p. 280) by the ordinary
yellow precostal streak ; while the red patch, which in this
butterfly is visible on the upper as well as the underside

284. Dr. Frederick A. Dixey on the

of the wing, includes the apex of the space between the
first and second subcostal nervules in addition to those
above enumerated. D. egialea shows the same condition
as D. pasithoe; but in D. crithoe, otherwise similar, the
precostal space is black. In D. descombes? and D. belisama
the red is confined to the costal interspace (7.e. the space
between the costal and subcostal nervures); while in
D. coeneus a submarginal set of roughly-defined red spots
or dashes continues round to the anal angle the series
begun by a red mark in the costal interspace, corres-
ponding with that in the two preceding species, The
submarginal series which, so to speak, becomes infected
by the red coloration, is undoubtedly that spoken of above
as series I (see p. 269). This latter feature of the Pierid
pattern, somewhat indefinite in D. ceeneus, becomes much
more distinct in such species as D. nigrina, D. harpalyce,
D. aganippe, D. eweharis, and D. argenthona. The latter
of these has another well-marked red spot surrounding
the second disco-cellular nervule, which represents a
diffused reddish areain D. duris, and amore circumscribed
patch in the same situation in D. cceneus. In D. hyparete
S is going from the underside of the hindwing; in
D. hierte it is gone ; but in both cases the red spots of I
remain in their full, development. D. mysis, D. isse,
D. echo, and other species exhibit the same feature in a
more or less conspicuous manner.

The same red coloration is visible, as we have seen, on
the underside of many species of Prioneris in the form of
a basal patch; and in one species (P. sita) it spreads to
the submarginal spots of series I, exactly as in D.
eucharis. In P. autothisbe the red is found in the costal
and subcostal interspaces ; in P. clemanthe and P. vollen-
hovit only in the inner division of the precostal space,
whence it spreads inwards upon the body.

In the American genera Huterpe, Pereute, Leodonta,
and Catasticta, the red is usually present; but as in
Prioneris and the pasithoe group of Delias, it is mostly
confined to the basal portion of the wing.* In #,

* An exception to this rule is furnished by Huterpe tereas and
E. critias, in which species the area of light ground colour
immediately internal to that region of the wing which corresponds
to the submarginal series §, is on both surfaces more or less
deeply tinged with the same red colour as that of the basal
patches. ‘his feature is due to mimicry, the two species named

Phylogeny of the Pierine. 285

tereas, H. critias, C. bithys, and C. anaitis, it most com-
monly occurs in the inner division of the precostal and
the internal space; in Leodonta zenobia and L. dysoni, in
the precostal and costal. In L. tellane, besides the bright
_ red patches of the precostal and costal spaces, scales of
the same colour occur in the apices of the subcostal,
submedian, and internal spaces—of all, in fact, except
the median. Pereuwte leucodrosime has the precostal and
costal red patches; so also has P. swainsonii; but in
P. charops these spaces are occupied by yellow streaks
with no accompaniment of red.

Even in the genus Dismorphia, profoundly altered as
it has been by mimicry, the same marks occur. D. melia
has a conspicuous red spot in the inner division of the
precostal space; while D. astyocha, D. praxinoe, and
others possess a very clear representative of the same
spot, with another one in the median interspace. ‘The
colour in these latter species is seldom so bright as in
the first-named ; it displays, in fact, a tendency to become
assimilated to the chestnut tinge of other portions of the
wing; the spots are nevertheless quite recoguizable, and
undoubtedly correspond with those in the former genera.
In some species, such as D. nemesis, there is no red, but an
indication of the yellow precostal streak is plainly visible.

offering a very close resemblance to the females of Papilio poly-
metus and some of its allies, in bringing about which resemblance
the red areas of the hindwing take a considerable share. It is
interesting to observe that good as is the general effect of the
imitation by these Pierines of the Papilio pattern, the imitative
process has its limitations, and is seen on a strict examination to
fail in more than one particular. Thus, (1) the Pierine is able to
produce an excellent representation of the Papilionine reds and
yellows, but apparently it never reproduces the metallic blues and
greens, of which touches are found in the males of several of the
mimicked species; (2) the costal and submedian spaces in the
Pierine invariably retain their yellow patches on the underside ;
these are never yellow in the Papilio; (3) the red basal patches
on the underside of the Pierine give just the same general effect as
similar patches on the Papilio ; but a close scrutiny will reveal the
curious fact that the patches of the Pierine belong always to the
wing, and those of the Papilio, in almost every instance, to the
body. The wide distribution of the red basal patches among the
Pierine forbids us to suppose that they were evolved for the pur-
pose of mimicry in these few species ; but it is worth noting that
their presence affords material ready to hand for a sufficiently
deceptive though not absolutely exact copy of a conspicuous
Papilionine feature. See also ncte on p. 298.

286 Dr. Frederick A. Dixey on the

In those species of Pieris (such as P. habra and
P. locusta) which present on the underside of the hind-
wing a pattern only slightly modified from that of
Leodonta and Catasticta, the red basal marks are clearly
to be distinguished. A bright red patch characterises
the inner division of the precostal space, and in most
specimens is also prolonged into the outer division, while
the apices of the median and internal spaces are likewise
provided with conspicuous red touches. Comparing
the underside of P. locusta with that of any of the
American mimetic forms of Mylothris, we cannot well
resist the conclusion that the central horizontal red or
chestnut band in the latter species represents the touches
of red in the median and internal spaces of P. locusta.
The relation is best traced in the case of M. lypera, m
which insect the part played by the yellow streak of the
costal interspace in the production of the mimetic
pattern is also clearly to be seen; but other species, such
as M. lorena and M. pyrrha, whose mimicry of Heli-
conine forms is further advanced than that of M. lypera,
still show the origin of the central red band almost
equally well. In Hesperocharis hirlanda a somewhat
similar effect is produced by slightly different means.
The basal red is here contined to the precostal and
internal spaces, not being found (as in Preris) in the
median. The horizontal red band is therefore not
central but costal, its mnermost extremity being con-
stituted not (as in Mylothris) by the red patch of the
internal space, but by that of the mner division of the
precostal. The whole of the precostal red, which is
absent in the three species of Mylothris just referred to,
is prominent in H. hirlanda. Although these differences
involve a change in the relative position of the horizontal
bands of red and pale yellow in the latter species, yet
the general resemblance of the underside to that of
M. pyrrha ¢ is considerable, and is probably quite
enough to tell perceptibly in the insect’s favour. Other
species of Hesperocharis, which are unaffected by
mimicry, show the basal marks in the same position,
but, as a rule, not very definitely, except at or near the
root of the precostal space. Here there generally
occurs an orange spot which partly represents the red
precostal patch in H. hirlanda (see H. nereis, H. mar-
chalii, and H.anguitia), but which in some species (as

Phylogeny of the Pierinee. 287

H. erota) can be distinctly seen to belong to the apex of
the median interspace as well as to the root of the pre-
costal.* A similiar orange spot is visible in several
species of Pieris, such.as P. buniw and P. thaloe; and
of Leptophobia, as L. elodia and L. eleusis. In the last-
named insect again it can generally be made out that
the orange spot does not belong entirely to the root of
the precostal space, but is furnished with a constituent
from the apex of the median interspace as well. This
double character of the spot is much more evident in
L. tovaria; and on referring once more to almost any
species of Colias, the conviction forces itself strongly
upon us that in these basal marks in Leptophobia,
Hesperocharis, and Pieris, and so in KHuterpe, Leodonta,
Catasticta, and consequently even in Delias and
Prioneris, we see represented the chief material out of
which the pink basal patch in Colias, Gonepteryx, Catop-
silia, and their allies is constructed. It is probable that,
as above suggested, another element may enter into the
composition of the basal patch in these genera, namely
one or more members of the series of yellow streaks; a
conclusion which seems to be somewhat favoured by the
condition in Belenois, Herpenia, and Appias; but the
two series are distinct enough from one another in sach
genera as Catasticta and Leodonta; and an unnamed
species of Hesperocharis in the British Museum shows, still
more plainly than those above mentioned, the co-existence
of a relic of the basal red in the situation of the pink
patch in Colias, with a series of yellow streaks in the
interspaces like those of Catasticta and Belenois.

Summary.—Witkh regard to the whole assemblage of
red and yellow marks on the underside of the hind-
wing, the following appear to be the most probable
conclusions :—

The yellow precostal streak so commonly seen in
butterflies of this group, including our common British
species of Ganoris, as also the pinkish patch at the apex

* In order to avoid a possible ambiguity, I may here mention
that I regard the “apices” of the interspaces as pointing towards
the “base” of the wing. When a precostal nervule is present, I
speak of an “outer” and “inner” division of the precostal space,
the nervule forming the line of demarcation. By the “ root” of
the precostal space, I mean the part immediately adjoining the
body.

288 Dr. Frederick A. Dixey on the

of the cell, of which our native species of Oolias and
Gonepteryc present good instances, are relics of a more
elaborate system of marking seen jn a high condition of
development in various exotic genera. This system
consists essentially of a series of red and yellow markings
occupying more or less completely the pale spaces in-
cluded between the radially disposed dark lines that
coincide with the nervures on the one hand, and the
concentrically arranged dark spots or bars of the marginal
and submarginal series on the other. That this system
of markings is a very primitive one is rendered probable
by the fact (1) that it is represented by vestiges i so
many genera of both hemispheres ; and (2) that it occurs
in a well-developed condition in genera so widely
separated in a geographical sense as the South American
Leodonta and Catasticta, and the Australian and Indian
Delias and Prioneris. Asa general rule, the spaces at
the base of the wing tend to be occupied with red, and
those on the dise and at the periphery with yellow; but
in some cases, as has been seen, the red may encroach
upon the submarginal yellow (as in Delias cceneus,
D. eucharis, D. argenthona, etc.), or may be prolonged
from the base in various directions across the wing
(Hesperocharis hirlanda, M. lypera, M. pyrrha, and other
American species of Mylothris). In the first-named
genera, which exhibit the system in its full state of
development, the distinction between the red and yellow
markings is a perfectly easy one ; but in such genera as
Pieris, Leptophobia, Hesperocharis, Belenois, Ganoris,
Synchloe, and Colias, whose markings are no doubt
ultimately derived from the Catasticta and Delias pattern,
it is not always easy to say to which part of the original
system the relics that are present belong. On an in-
spection of all the forms, it would, however, seem to be
the case that those members of the yellow part of the
system most often persist which are capable of being
reinforced, as it were, by a neighbourmg red patch
towards the base of the wing. For instance, the most
persistent marking of all is, as we have seen, the yellow
precostal streak. This is in most species of Leodonta
and Catasticta closely bordered on by a bright red spot
in the inner division of the precostal space ; and on tracing
the condition of that space from these more ancestral
genera downwards, through Pieris, Leptophobia, and

Phylogeny of the Pierinee. 289

Hesperocharis, we find it become tolerably evident
that the dark yellow vestige which at last alone
remains is the result of a kind of convergence both in
colour and position of the yellow and red markings that
at first lie simply side by side and are clearly dis-
tinguishable the one from the other.* A further imstance
of possible convergence is supplied by the basal pinkish
patch, found in the group of genera headed by Colvas,
which we have seen reason to identify with original
markings of both the red and yellow kinds.t In other
cases, the persistence of various members of the present
system is determined by the exigencies of a mimetic
pattern, as in the species of Mylothris and Hesperocharis
above referred to (p. 286).

III. Paytogenetic Conciusions.

1. The evidence of the Wing-markings.

We are now in a position to consider as a whole the
various sets of facts that have been above recounted,
and to endeavour to construct, from the evidence at
hand, a theory of the phylogenetic history of the entire
group. This, of course, is only attempted under the

* This, it is true, applies only or mainly to the New World
forms ; the similar basal red patch that partly occupies the pre-
costal space in certain species of Delias and Prioneris not seeming
to have left any traces in those Old World genera (Belenois and
Yeracolus), which appear to stand in much the same relation to
Delias and Prioneris as Pieris and Hesperocharis do to Leodontu
and Catasticta. 'The deep orange, however, of the precostal streak
in some Old World species of Mylothris (as M. chloris and M.
agathina), and in some species of Belenois (as B. helcida) which
resemble them, may perhaps be derived wholly or in part from the
precostal red ; but if so, it does not bear in itself a plain record of
its origin as does the like feature in the corresponding genera from
America.

+ Again, in Pieris pylotis the only marking to be seen on the
under surface of the hindwing (besides the basal spot) is a short and
narrow orange streak near the apex of the median interspace—
an interspace that in more primitive forms, such as P. locusta,
Mylothris lypera, and others, is provided with an apical red patch.
It is also worthy of notice that in many species of Belenots the
spots of series I are apt to retain or assume an unusually deep yellow
or orange colouring like that of the precostal streak—this series
being in some species of Delias, and at least one of Prioneris, a
sharer !n the bright red of the basal patches (see p. 284).

290 Dr. Frederick A. Dixey on the

limitations above referred to, and is not to be taken
as more than a connected statement of the probable
import of the facts derivable from one particular
source—those facts, namely, which relate to the colours
and markings. I need hardly say that I recognise to
the full that any phylogenetic conclusions founded on
these data must of necessity be open to checking and
correction in the light of information arrived at in other
ways.

The evidence that has now been examined seems to
indicate that the wings in the earliest form of Pierine
were uniformly overspread with a dark neutral tint.*
The first variation from this condition appears to have
occurred by the paling of certain areas in the principal
interspaces between the nervures; a modification that
may be seen in probably its simplest extant form in the
remarkable American Pierine Hucheira socialis (Fig. 1).
Here each interspace, including the discoidal cel! in both
wings, possesses a more or less definite pale patch, those
of successive interspaces being so arranged as to form a
somewhat indistinct and interrupted band crossing the
disc of both wings from the costa to the inner margin.
Besides this central series of pale patches, there is also
a submarginal row of much smaller and fainter spots of
the same greyish-white hue. The whole pattern is
repeated with very little change on the under surface,
but on the hindwing with even less distinctness than
above. The underside of the hindwing in this insect,
indeed, probably exhibits the very oldest kind of Pierine
colouring to be seen in any existing species.

The primitive system of marking manifested by
Hucheira socialis persists with little alteration on the
upper surface of many species of Catasticta, as, for

*“ This accords generally with the opinion expressed by Mr.
Wallace: “There are, in fact, many indications of a regular
succession of tints in which colour development has occurred in
the various groups of butterflies from an original grayish or
brownish neutral tint.”-—“‘ Darwinism,” 2nd edition, 1889, p. 274.

t+ While entirely agreeing with Staudinger and Schatz that the
remarkable forms Sty infernalis and Pseudopontia paradoxa are
probably of great antiquity, I cannot but regard the special
Pierine affinities claimed for them by these authors (and especially
for the latter) as more than doubtful. See Staudinger, Schatz,
and Rober, ‘‘ Exotische Schmetterlinge,” 1892, swb voc.

Phylogeny of the Pierine. 291

instance, C. bithys (Fig. 2), C. toca, and C. colla. In other
species of the same genus, the next steps are shown by
the enlargement of the pale spots (as in C. anaitis ¢),
their assumption of a purer white colour (as in C.
anaitis 9), and the confluence of those of the inner row,
as in O. trezene and C. ctemene ¢. In the latter insect
the enlargement and confluence of the white patches has
proceeded so far that the white must now be considered
the ground colour, the original dark neutral tint being
confined to the base and apices of the forewings, a
narrow and interrupted marginal band on the hind-
wings, and the course of the nervures with their branches
(Fig. 3). In C. corcyra, the same process is continued
almost to its furthest limit, the new ground colour has
supplanted the old in every place except the apex and a
narrow slip along the costa of the forewing. C. coreyra
is thus practically a “ white” butterfly ; and so within the
single genus Catasticta a complete transition is to be
found, from a dark almost black ground colour, with
small and indistinct pale greyish patches, to a ground
colour of dead white, with hardly more than a trace
remaining of the original dark surface tint. This
passage from C. bithys to C. corcyra is really an epitome
of the whole range of variation in pattern throughout
the entire group of Pierinx.

In such species of Catasticta as OC. semiramis, where
the pale patches are tolerably distinct, and have not yet
coalesced, the dark marginal and submarginal series of
spots, so characteristic of the Pierines as a whole, are
visible at an early stage of their emergence. As has
been shown above, on p. 267, the marginal series (called
M) is formed by the remains of the dark ground colour
between the outer series of primitive pale patches
and the outer border of the wing; while the sub-
marginal series S comes into view between the outer and
inner series of pale patches. Besides these, a relic of
the dark ground colour is seen to remain about the
disco-cellular nervules in the forewing, which forms the
first beginning of a definite discoidal spot ; and another
row of minute pale patches, each occupying the centre
of an interspace on the extreme outer margin of the
wing, begins to split up the marginal series in the
manner already spoken of. The definite character of
series M is assumed sooner on the forewing than on the

292 Dr. Frederick A. Dixey on the

hindwing, and in the latter situation the discoidal spot
has at this stage scarcely become recognizable ; in some
species, however, a patch of pale-coloured scales covers
the lower disco-cellular nervule of the hindwing in the
midst of a wide and not sharply-defined area of dark
ground colour.

So far little or no essential difference has been noted
from the primitive pattern of Hucheira socialis; the
variations produced having simply resulted from a
greater or less extension of the intrusive pale tint along
the lines originally marked out. But, on turning to the
underside of any species of Catasticta, we find what at
first sight appears to be a very considerable divergence.
A careful examination, however, soon makes it plain
that the pattern of the lower surface is throughout the
genus essentially the same as that of the upper surface,
though one or two new features are superadded. Con-
fining our attention in the first place to the forewing,
for instance in C. nimbice, we find the submarginal series
S and the discoidal spot shown at least as clearly as on
the upper side; while from the greater prominence of
the pale spots at the extreme margin, M is brought still
more plainly into view below than it is above. On the
hindwing, the central pale band may be easily traced
across the disc of the wing, leaving on the one side of it
a basal, and on the other a broad marginal dark area.
Traversing the latter can be seen a row of elongated,
more or less wedge-shaped, yellow streaks, which repre-
sent the more easily recognized series I of the forewing ;
while a distinct row of yellow spots on the extreme
margin continues the similar series from above. Though
S and M are not yet sharply marked off from one
another, the portions of dark ground colour to which
they respectively belong are already separately recog-
nizable. The undersides of C. nimbice, C. colla, C. toca,
and C. corcyra will be found to make a very good
transitional series, showing the gradual emergence of 5
and M and the subsequent reduction of each to a mere
festooned line.* ‘The superadded features above alluded

* An unnamed species of Catasticta in the British Museum
presents a condition of the underside of the hindwing more exactly
intermediate between C. corcyra and the usual type than any of
the species mentioned. An individual of the same species is in

Phylogeny of the Pierines. 293

to are (1) the streaks and touches of yellow that begin
to occupy much of the area of the original pale patches,
including, as has been seen, the spots of I on the hind-
wing; and (2) the bright red patches visible in the
basal region of the same wing close to the body. These
have been already discussed at some length (see
pp. 281, 285), and their importance has been shown in
reference to the markings of more recent groups. In
this place it is only necessary to note once more that
their ancestral character seems to be proved not merely
by their existence in a fully developed condition in
genera so widely separated geographically as _ the
Western Catasticta and Leodonta and the Hastern
Prioveris and Delias, but also by the fact that there is
scarcely a genus throughout the whole sub-family,
whether in the Old or New World, that does not show
some relic of their former presence. With regard to
their origin, no clue appears now to exist. It seems
impossible to trace them further back than to the
HKastern and Western genera named; and the probably
still more primitive form, Huchetra socialis, to which we
should naturally turn for an indication of their develop-
ment, affords us in this particular no information
whatever. —

In the genus Leodonta we find some modification in
the shape of the wings, and only three instead of four
branches to the subcostal nervure of the primaries. But
the wing pattern remains much the same as in those
species of Catasticta where the white central band has
grown into a well-defined area and the two series 8 and
M have not yet become clearly distinguishable. The
yellow streaks and red basal marks are still prominent
on the hindwing beneath, and the separation between
S and M is, in this genus also, more evident on the
underside.

In Pereute and Huterpe, which are undoubtedly very
close allies of the genera just referred to, the development
of the pattern has taken a somewhat different direction.
The primitive dark ground colour is in the males of
several species of Pereute, as P. charops, P. autodyca, and

the Hewitson collection labelled as C. notha. This is undoubtedly
erroneous, as the underside of the true C. notha is almost exactly
like that of C. corcyra.

294 Dr. Frederick A. Dixey on the

P. swainsonii, relieved by dustings of pale pinkish or
bluish grey, which do not seem to bear any particular
relation to the lighter patches in Catasticta or Hucheira.
These greyish areas are often, especially in the females
(including those of the species named), brightened up
into bars or broader expanses of vivid red (P. lewcodro-
sime) or blue (P. telthusa), and the aspect thus produced
is very unlike that of nearly all the members of the alhed
genera. But as has been shown above, at pp. 281 and
285, an indication of affinity in coloration with those
genera is preserved in the red and yellow patches of the
underside of the hindwing ; and, what is very remarkable
indeed, there are two species of Catasticta, namely C.
teutamis and OC. ctemene, the males of which are of the
usual Catasticta type, while the females present, together
with the ordinary Catasticta neuration and structure, the
aspect characteristic of P. charops 9 and other highly
coloured members of the genus Pereute. In the case of
these two Catastictas there can, I think, be no doubt
that it is the male rather than the female that represents
the ancestral colouring of the group, and we are thus led
to the conclusion that some common cause has brought
about the divergence in the same direction of these
female Catastictas and both male and female Pereutes
from the ordinary character of their nearest relatives.
This cause I believe to be mimicry, the models for which
in the present instance are to be found in certain species
of Heliconius, particularly H. melpomene, H. phyllis, and
their allies.* ‘Che resemblance is not perfect,+ but in all
probability is quite sufficient to be of much service to the
Pierine mimics; and we find exemplified here, as in
many other cases, the much greater readiness with which
the female assumes the protective coloration. As we

** T also think it exceedingly likely that Papzlio euterpinus, Godm.
& Salv. (Ecuador), forms one of this mimetic group, It is, how-
ever, remarkable that its range seems not to coincide with that of
the Pierine, namely P. charops 2, which probably resembles it
most closely in size as well as colour.

+ The red colour of the species of Heliconius here mentioned (to
which may be added H. vulcanus and H. hydara), as they occur in
collections, is by no means so vivid as that of their supposed
imitators. But Mr. A. G. Butler and Mr. F. A. Heron both
inform me that the red in Heliconii has a special tendency to lose
its brightness, even in specimens carefully preserved in the dark,

re oma

Phylogeny of the Pierine. 295

have seen, the male Catastictas are not affected at all;
while in most species of Pereute the males have not
advanced nearly so far along the mimetic path as have
the females. Another point worthy of observation, which
is paralleled elsewhere, is the fact that the males show a
much closer approach to the complete mimetic pattern on
the lower than on the upper surface.*

A similar explanation will apply to the even more
remarkable divergence shown by the genus Huterpe,
though here the phenomena are so curious and complex
as to require a more detailed treatment. This genus (as
-restricted by Butler, Cist. Entom. 1., pp. 34, 42) does not
contain a single form that reproduces in general aspect
the typical Pierine features ; every species indeed is the
subject of a mimetic change, and such marks of their
origin and relationships as they retain, are used up in a
more or less modified condition to heip in the production
of the deceptive pattern. Thus we have seen how in
Huterpe critias, H. tereas, H. rosacea, and allied species,
the area representing the white central band on the hind-
wing, now tinged with rosy pink, has become an im-
portant ingredient in the general imitation of Papilio
zacynthus ¢ ; the red basal patches on the under surface
also taking their part in the picture. There is, moreover,
little doubt that the white spot on the forewings is
identical in origin with the usual white central bar, while
for the marginal yellow spots a counterpart is easily
found in Catasticta nimbice and many of its allies. In
Huterpe bellona we find the patch on the forewings
bright yellow instead of white, while the rosy patch is
intensified in colour and splt up into three or four
brilliant streaks radiating from the base towards the
margin of the wing. The general effect is not very
dissimilar from that of H. critias, and the identity of the
markings is beyond question ; nevertheless the changes,
slight as they are, are highly significant, for they import
nothing less than the substitution of a member of the
Heliconine for one of the Papilionine group as a model
for imitation. Huterpe bellona undoubtedly mimics
the Heliconine group of which H. thelxivpe and H.
burneyt are conspicuous members; and it would be
difficult to find a better instance to show how slight a

* See Weismann, ‘“ Studies,” vol. i., pp. 7, 8 (English Edition).

296 Dr. Frederick A. Dixey on the

modification of an existing pattern may suffice to produce
an effective copy of an entirely different insect. Facts of
this kind seem to go a long way towards answering such
objections to the theory of mimicry as those alluded to
by Mr. Beddard in his “ Animal Coloration,” 1892, pp.
214, 215.

It is very remarkable that red basal patches, like those
of the mimicking Pierines, occur on the underside of
the hindwing in most, if not all, of the Heliconii and
Papilionine mimicked by members of the genera Pereute
and Huterpe ; and in some, e.g., H. melpomene, there is
even a_ well-defined yellow precostal streak, Now
although there is no difficulty in ascribing most of the
features in the coloration of these Pierme genera to the
operation of mimicry, it would seem, for the reasons
given above (p. 285, note), that the origin of these par-
ticular marks, which are so wide-spread and so persistent
throughout the whole Pierine subfamily, must be
excepted. Nor, in the absence of any evidence of a
direct causal relation, does it seem to my mind more
satisfactory to consider the occurrence of these patches
in the three diverse groups, Papilionines, Heliconines, and
Pierines, as the effect of similar external conditions.
If we assert them to be purely “accidental,” we are met
by the fact that although they are found in some species
of both Papilio and Heliconius that are apparently not
the subject of mimicry, yet they are most distinct and
most prevalent in those species that are copied by
Pierine imitators ; and the same considerations (amongst
others) seem to show that the supposition that they are
simply due to inheritance from a common ancestor of all
the groups must be inadequate. Before the phenomenon
is dismissed as inexplicable, it may be worth while to
consider the following suggestion.

According to the well-known principle laid down by
Fritz Miller and expanded by Meldola, by which these
authors have been enabled to account for cases of parallel
resemblance between the species of protected genera,
and also of the grouping of allied inedible species into
distinct sets, each with its own scheme of coloration,* it

* I’. Miller in “ Kosmos,” 1879, p. 100 ; Meldola in “ Proc. Ent.
Soc. Lond.,” 1879, p. xx., and “ Ann. and Mag. Nat. Hist.,” Dec.,
1882. See also Wallace, ‘ Darwinism,” 2nd ed., 1889, pp. 249-257,
and Poulton, “Colours of Animals,” 1890, pp. 192-195.

Phylogeny of the Pierinee. 297

is advantageous for any two or more protected species
to join their forces, in order to share the toll levied upon
them by inexperienced enemies. In such cases it no doubt
often happens that one species serves as the standard to
which the others conform, whether by way of convergence
or of arrested divergence ; but there seems no reason
why, especially if there is no conspicuous inequality of
numbers, there should not be akind of ‘ give and take ”
arrangement between mimicker and mimicked, the latter
advancing some way to meet the former for their mutual
benefit. In other words, when two species, A and B,
form an association of this kind, it need not be supposed
that the form of A remains fixed, while B assimilates
itself to it, or vice versa ; but the association may really
be formed by both A and B converging towards a point
between them, or, in short, mimicking each other.
The acceleration of the process which in many cases
would result, must of itself be an advantage. Now if
the grouping of kindred inedible forms in associations of
this kind is beneficial, it would seem that the benefit
might extend to members of families far removed from
one another, like the three now under discussion, as well
as of the same family or genus;* the only requisites
being (1) that all should be more or less inedible, and (2)
that all should have patterns capable of assimilation to
one another. Nor does there seem to be any reason why a
mutual convergence of the kind indicated should not
take place under these conditions also, With respect to
(1), it has, I think, nearly always been assumed that the
Pievrine which resemble the members of other families
are edible; and this is no doubt the case with the
numerous members of the genus Dismorphia + (Leptalis
of Dalman), which were among the first to attract notice
to the subject of Mimicry in general. But no direct
proof seems to exist that the species of Huterpe and
Pereute now under discussion are edible; and indeed
Mr. Wallace considers (Trans. Ent. Soc. Lond., 3rd
series, iv., pp. 309, 310; Darwinism, 2nd ed., 1889,

* Such an association is already well known to occur between

Heliconide and Danaide.

+ This, however, has been questioned by Mr. Beddard, who cites
some observations of Scudder as tending to show the contrary.
See * Animal Coloration,” 1892, p. 215.

TRANS. ENT. SOC. LOND. 1894.—PART I. (JUNE.) U

298 Dr. Frederick A. Dixey on the

p:. 244) that the genus Delias (Thyca of Wallengren),
which is probably nearly related to Huwterpe and Pereute,
possesses a disagreeable flavour, or some other special
means of protection. If this is shared by its American
relatives, the first of the above requirements would be
satisfied, while the second (2) has been shown to be met,
in the special instance of the red basal patches, by the
occasional presence of somewhat similar spots or
patches (whose origin is not now under discussion) in
other species of both the Papilionine and Heliconine
groups, which afford quite sufficient material for the
assimilative process to work upon. Until, therefore,
direct proof is forthcoming of the edible qualities of the
Pierines in question, it will not be unreasonable to sup-
pose that they have joined an “inedible association,”
and to attribute this curious agreement in a detail of
pattern between members of such diverse groups to the
operation of what may perhaps be called “ reciprocal
mimicry.”’** The Pierines have no doubt moved furthest
from their original form, having in most respects clothed
themselves in Papilionine and Heliconine colours, but
the latter have themselves advanced some way to meet
the Pierines, in adopting from them a more distinct
and characteristic employment of the red basal patches.+

* This, it will be seen, is distinct from “convergence” in the
usual sense, inasmuch as that term has hitherto been employed
(as by Poulton, “ Colours of Animals,” 1890, p. 195) to signify the
assimilation of one form to another, rather than the mutual
approach by two forms toa mean between them.

t+ Fritz Miller notes (“‘ Kosmos,” 1879, p. 100, and translation
by Meldola, Proc. Ent. Soc. Lond., 1879, p. xxiv.) that “in the
province of Santa Catharina, Huterpe tereas is common in the
forest-paths almost throughout the entire year, while its model,
Papilio nephalion, is, on the other hand, a rare butterfly.” This is
so far in favour of the supposition that the resemblance is not due
to mimicry by the Pierine, at least in the strict sense.

There is one more piece of evidence that seems to favour the
conclusion arrived at above. So far as I am aware no explanation
has yet been offered of the fact that it is the females and not the
males of Papilio polymetus, P. zacynthus, etc., that are resembled
by Huterpe tereas and E., critias ; whereas the males, which display
brighter colours, afford at least as good if not better models for
imitation. I would suggest that this is really due to “reciprocal
mimicry.” The protection gained by the resemblance between the
Pierines and Papilios is not all on the side of the Pierines, but
mutual ; and the female Papilios have, as is usual, felt the need
of it more urgently than the males. For this reason the female

Phylogeny of the Pierinee. 299

Euterpe theano and FH. eurytele present us with another
kind of departure from the ordinary Pierine condition,
the latter being an excellent copy of Lycorea atergatis
and Ceratinia (Ithomia) dionea; while lH. theano ex-
hibits the form of H. ewrytele with a coloration much like
that of Pereute charops ¢.

We find then that, thus far back in the growth of the
Pierine stock, a large section has been diverted under
the influence of mimicry from the regular course of
development of the Pierine pattern; and in order to
continue the history of the latter, we must retrace our
steps and take up the thread where we left it before
beginning to discuss the mimetic forms of Pereute and
Euterpe.

Although it does not appear that the Old World can
show any truly Pierine form so ancient as Huchezra
socialis, there does exist a genus which seems to repre-
sent in the Hast nearly the same stage of development as
Catasticta, Leodonta, Pereute, and Huterpe in the West.
This is the genus Delias, the close relationship of which
with the western forms mentioned has been indicated by
Doubleday and Westwood (Genera of Diurnal Lepi-
doptera, vol. 1., p. 33), and more distinctly suggested by
Wallace (Trans. Ent. Soc. Lond., 3rd series, iv., p. 344).*
The pattern of Delias belladonna is essentially similar to
that of the early Catastictas, consisting as it does of a
dark ground-colour relieved by paler touches in the
interspaces, between which touches the ground-colour is
already beginning to show a rudimentary division into a
marginal and submarginal chain with a vaguely indicated
discoidal patch in each wing. On the underside we have
the same pattern in a slightly more distinct form; while,
as in Catasticta, the pale areas of the hindwing and the
apical region of the forewing are furnished with yellow
streaks. The red basal patches, so characteristic of

Papilios have been led to meet the Pierines by discarding, or at
any rate by not adopting, the bright metallic blues and greens that
ornament the other sex. This was no doubt a shorter and easier
way to the formation of an “inedible association,” than would
kave been the acquisition by the Pierines of colours more nearly
resembling those of the male Papilios.

** Delias agrees closely in neuration with Pereute and Leodonta.
See Butler, Cist. Entom., i., p. 40. Staudinger and Schatz, ‘ Exot,
Schmetterl.,” 1892, Theil. i1., p. 63,

300 Dr. Frederick A. Dixey on the

Catasticta and its allies, are not represented in D. bella-
donna, but in all the members of the pasithoe group they
are not only present, but have become a very conspicuous
feature in the coloration. It is not difficult to bring the
other markings of D. pasithoe, D. thisbe and their allies
into relation with those of D. belladonna, though the
dark series S and M are as a rule less clearly indicated.
The pasithoe and belladonna groups of Delias may thus
be considered as on the whole the most ancient.* Inthe
well-known D. eucharis we have the series S and M
complete; the female, as is usual, showing less departure
than the male from the more generalised form. As in
Catasticta, no sooner have the dark series emerged into
distinct existence than they begin to disappear ; they are
much less recognizable in D. hyparete and D. agostina
than in D. eucharis, and in D. hierte they reach the
vanishing point. D..euwcharis and its immediate allies
follow the early condition of Delias in having the inter-
spaces on the underside of the hindwing more or less
filled in with yellow, but they depart from it in having
lost the red basal patches, and in possessing a conspicuous
submarginal band of red spots (series I) between the
dark series S and M; these are best seen in D, ewcharis
itself. An early stage of this red series is probably
present in D. ceneus and the closely allied D. philotis,
which seem to be linked with the still more primitive
butterflies of the pasithoe group through such forms as
D. belisama and D. descombesi (see p. 284). Regarding
then D. cceneus as a’ new starting-point, we may trace
from it in one direction the Indian group headed by
D. euwcharis, and in another the Australian forms
D. aganippe, D. harpalyce, and D. nigrina. It is to be
observed that both D. ewcharis and D. aganippe, though
probably more recent than D. ceneus so far as regards
the underside of the hindwing, nevertheless retain in
other respects more of the primitive pattern ; from which
we may probably conclude that some form now lost,
rather than D. ceeneus itself, supplies the true link with
the belisama and pasithoe groaps, while D. coeneus and
D. philotis survive to show how “series 1” acquired in

* T follow, in nearly every particular, Mr. Wallace’s division of
this genus into groups. See Trans. Ent. Soc. Lond., 3rd series, iv.,
p. 344, ete,

Phylogeny of the Pierine. 301

the eucharis and aganippe forms its conspicuous character.
I have little doubt that the curious form D. aganippe is
one of the oldest existing species of Delias in the
Australian region, inferring this from its retention of the
primitive series S and M with the discoidal patch in the
forewing in fairly distinct form, from the presence of
yellow streaks in the interspaces of the under surface,
and from the occurrence of a basal red spot in the pre-
costal space of the underside of the hindwing. Many of
these points assimilate it to the pasithoe group, and even
more closely to D. belladonna.* D. harpalyce and
D. nigrina seem to follow naturally on from D. aganippe,
though in respect of the costal red they are perhaps a little
nearer the still more primitive D. belisama. Another
Australian offshoot of the D. ceneus stock is probably
represented by D. argenthona, D. mysis, D. isse, and
D. dorimene. The Indo-Malayan and Australian nysa
group is probably derived from the pasithoe and bella-
donna groups through D. orphne and D. momea. It
would be most interesting to attempt to trace in detail
the phylogenetic history of the whole of this extensive
genus, but it must here suffice to have indicated what ap-
pear to be the principal lines of derivation. ‘T'wo points
of analogy with the kindred neotropical genera may be
noted before we pass on. ‘The first is that although the
invasion of a paler tint does in Delias tend to split the
original ground-colour into marginal and submarginal
series quite similar to those of Catasticta, and though
these series in various stages of development and sup-
pression, as also in Catasticta, meet us here and there
throughout the entire genus, yet in many cases the series
never emerge in any recognizable form, and there seems
in several species a tendency for the white imvasion to
begin near the bases of the wings, and simply sweep the
dark ground-colour away towards the margins. Hven in
these cases, however (as in D. belisama and D. descom-
besi), the females, on the underside, will usually show
some indication of the primitive series. The second
point to be noted is the way in which the resources of
Pierine coloration are taxed to give the insects of this
genus a brilliant appearance. As in the case of some of
their neotropical congeners, this is effected not so much

® See Wallace in Trans. Ent. Soc. Lond., 3rd series, iv., p. 349.

302 Dr. Frederick A. Dixey on the

by the importation of any new feature as by the
brightening up and extension of features already present,
and indeed often common to the whole subfamily. ‘The
reason for this ornamentation is doubtless the same in
both cases—namely, to call attention to inedible qualities.
The Hastern genus, however, seems to have itself become
a model for mimicry (Wallace in Trans. Ent. Soc. Lond.,
ord series, iv., pp. 309, 344), while the Western genera
have modified their ancestral form in order to join an
alien company of inedible insects.

The genus Prioneris, though differing slightly from
Delias in neuration and other structural characters, is
probably nearly akin to it, and represents, so far as the
colouring is concerned, a similar degree of antiquity in
the Pierine stock.. The close resemblance of pattern
between different species of Delias and Prioneris, to
which reference has already been made (pp. 258, 284,
etc.), is no doubt a true case of mimicry, but represents
probably the result rather of arrested divergence than
of the acquisition by Prioneris of new imitative features.

The two groups that have just been discussed, namely,
those formed by Delias and Prioneris in the Old World,
and by Catasticta, Leodonta, Huterpe, and Pereute in the
New, thus constitute together a second grade, as it were,
in Pierine development. ‘The only earlier species yet
mentioned is Hucheira socialis, but there exist certain
other forms which appear to be but little inferior to that
insect in antiquity; and to these, with Hucheira, the
name of “ Pierines of the first grade” may be applied.
One of the forms now referred to is Metaporia agathon.
This remarkable insect is probably the representative of
an ancient group of Pierines, among which were to be
found the common ancestors of the two second-grade
assemblages already mentioned, and which, no doubt,
supplied the link at present wanting between Hucheira
and Catasticta. The relation of Metaporia with the Hastern
assemblage is more direct than with the Western, for
although it offers points of structural difference from
Delias, it shows, nevertheless, a condition of the primi-
tive Pierine pattern which is in all essentials identical
with that of the earlier kinds of that genus. The cor-
respondence of its markings on the upper surface with
those of Delias belladenna and D. eucharis is at once
evident, and, like D. belladonna, it has a patch of bright

Phylogeny of the Pierinze. 303

yellow in the precostal space on the under surface of the
lower wings. This, however, is usually confined to the
inner division of the space.* Mr. Wallacet considers
that Metaporia agathon forms with Pontia nabellica the
fragments of an extensive natural group. He also
points out the readiness with which the pattern of
M. agathon can be traced through P. nabellica, P. soracta,
and P. hippia, to its final disappearance in P. cratzxgi.
In this range of species, to which may be added
P. oberthiivi, P. leucodice, P. belucha, and others, we
recognise the now familiar phenomena of the emergence,
establishment, and evanescence of a marginal and sub-
marginal series of spots, together with a discoidal patch,
formed out of relics of an original dark ground-colour.
Another primitive Pierine feature, namely the per-
sistence of dark ground-colour along the course of the
nervures and nervules, is found throughout the group ;
and in P. crateegi survives the disappearance of almost
every other indication of the original coloration.

The line thus marked out ends with P. cratxgi; but
in another direction there is little difficulty in linking
Pontia with Hucheira, and so demonstrating the intimate
connection with one another of the three last-named
genera. Thus Pontia recalls Hucheira by the outline of
its wings, especially the concave costal margin,t and in
pattern P. nabellica shows no very great departure from
the same genus. Buta more striking sign of affinity
exists in the common larval habitation, which, though
merely rudimentary in P. cratxgi, and belonging only to
the early larval stages, is no doubt a degenerate or
undeveloped form of the elaborate silken nest con-
structed by H. socialis. Webs of a structure apparently
comparable with the latter are made by Neophasia ter-
lootit and an allied species mentioned (though not
described) by Behr.§ The affinity of the two latter
insects with the genus Pontia appears certain; and
though Behr is perhaps wrong in making them con-

* One specimen of J/. agathon in Coll. Brit. Mus. has a few
orange scales in the outer division of the precostal space as well.

+ Trans. Ent. Soc. Lond., 3rd series, iv., p. 313.

+ Noticed by Staudinger and Schatz, who compare it to that of
Parnassius, Exot. Schmetterl., Th. i1., p. 62.

§ Trans. Amer. Ent. Soc., 1869,.p. 303; Proc. Calif. Acad.
Sci., second series, vol. ii., 1890, p. 91.

304 Dr. Frederick A. Dixey on the

generic with H. socialis (which he does not seem to have
seen.),* his description, nevertheless, renders it extremely
probable that they are more closely related to that
species than any other known butterfly. The Pierines of
the first grade may accordingly be said to consist of
Eucheira, with Behr’s two “ Neophasias,” Pontia and
Metaporia. The prevalent larval habit of spinning is no
doubt an indication of the high antiquity of the group,
and suggests, as do other features, a relationship with
the Parnassids. This suggestion is further borne out by
the aspect of Mesapia peloria, which is no doubt an off-
shoot of the genus Pontia. But such relationship is
certainly of no close or direct kind, and is probably only
referable to an extremely remote ancestor of the two
subfamilies.+

Leaving the genus Pontia fora time, we may make
a fresh start with Metaporia agathon, from which point it
is not difficult to trace another principal stem, with
numerous and important ramifications. ‘The females of
several species of Mr. Moore’s genus Huphina, for
instance H. phryne ?, show what is to all intents and
purposes the same pattern as M. agathon (Figs. 7, 8) ;
and the males differ only or chiefly by the more ready
admission of the white invasion, at the expense of the
remains of dark ground-colour. The pattern of such a
form as H. nama 93, seems at first sight to belong to
a different category, but a very good transition from
that of M. agathon is afforded by H. eperia 9, which
shows how the arrangement of white patches in H. nama
? has grown out of the discal and cellular white, while
the more marginal series I sinks gradually into the back-
ground, and with its disappearance the two dark series
S and M lose of course their distinctive character. In
one ancestral point, namely the filing up to a greater
or less extent of the interspaces of the hindwing under-
side with yellow, Huphina shows a closer resemblance to
Delias and Prioneris than to M. agathon, in which insect
this feature is only slightly indicated. In many species

* N. menapia, included by Behr in the same genus, differs from
Eucheira is neuration and other points.

t+ Davidina armandi has been spoken of as a transitional form.
But, as remarked by Staudinger and Schatz (op. cét., Th. ii., p. 57),
it is shown by Oberthiir’s figure (Etudes, iv., pl. 1, fig. 1) to be
without any of the points characteristic of the Papilionide.

Phylogeny of the Pierinz. 305

of Huphina the yellow is very vivid, in some it 1s
warmed into a rich orange, and it not infrequently, as in
H. naomi, H. lea, and H. judith, appears on the upper
surface as well.

From the pattern of Huphina to that of Catophaga the
passage is easy through such species as H. cassida, H. nabis,
QO. paulina (Fig. 9), and C. ega. In the latter genus, as
in the former, the dark ground-colour is retained in
much larger measure by the females than by the males;
the latter indeed (as in most specimens of C. galena &)
have often lost it altogether. Other marks of speciali-
zation shown by the male Catophagas are the sharply-
pointed shape of the wings, and, above all, the presence
of a tuft of long hairs springing from the base of each
of the anal valves. All these characters belong equally
to the next genus Appias (which indeed is not easily to
be distinguished from Catophaga), though here the
specialization of the males has in many forms been
carried to a much greater extent, and is occasionally in
some respects shared by the females, as in A. nero. In
this insect the female shows the remains of the usual
dark marginal and submarginal series standing out upon a
ground colour of rich red almost as brilliant as that of the
male, and altogether different from the ordinary Pierine
white or yellow. The females, however, of A. celestina, A.
clementina (Fig. 10), and others, do not depart, like the
males, from the ordinary facies of the group, * and are
indeed, barely distinguishable from the females of C.
jacquinotit, C. alope, and other species of Catophaga.
The assemblage of species united by Mr. Distant as
Saletara (including S. panda, S. cycinna, ete.) is un-
doubtedly an offshoot from the celestina group of Appias.

In the three last-mentioned genera, although the two
series S and M are generally more or less traceable, and
although in most cases a decided remnant of ancestral
black persists along the costa of the forewing, there is
as a rule no relic of the original ground-colour in the
region of the disco-cellular nervules; that is to say,
there is no discoidal spot or patch. In Hiposcritia, how-
ever, which is apparently an early and purely Indian off-
shoot of Catophaga, some species (as H. pandione)
exhibit an incipient discoidal patch, still in connection with

* See Wallace, Trans, Ent. Soc. Lond., 3rd series, iv., p. 301.

306 Dr. Frederick A. Dixey on the

the dark-coloured costa ; in others (as H. lalage) this has
become a distinct discoidal spot, (Fig. 11). Hiposcritia,
by its anal tufts, belongs decidedly to the Catophaga and
Appias group; but the shape of its wings and the occa-
sional persistence of dark ground-colour about the disco-
cellular nervules indicate that its origin is to be placed
somewhat far back towards Huphina and Metaporia.

Starting again from Metaporia and Pontia, we find in the
small Siberian P. lewcodice an unmistakable link between
these genera and Synchloe. In S. callidice, which per-
haps come nearest to Pontia, the female shows S and M
in a well-defined condition, together with a large distinct
discoidal patch; the nervures and nervules are also in
many instances clothed with black scales. From S.
callidice we can advance in one direction through
S. chloridice to 8. glauconome, S. johnstonii, and SN.
hellica ; while S. daplidice and its immediate allies form
another slightly divergent branch from S. chloridice.
S. callidice again in all probability marks the point at
or near which the assemblage of species grouped as
Ganoris leave the main Synchloe stem; G. napi being no
doubt the species which is closest to the original stock,
as is shown by the large persistence of S and M, the
tendency towards blackening of the wnervures, the
occasional indication of a discoidal spot, and the peculiar
coloration of the underside of the hindwings. It is
noticeable that Ganoris generally, including G. napi,
retains the precostal yellow streak, which, though
present in most species of Synchloe, happens to be
absent in S. callidice.

Most species of the genus Tatochilu strongly resemble
Pontia in pattern (the resemblance between Tatochila
and P. lewcodice has been pointed out by Mr. Butler,
Proc. Zool. Soc., 1872, p. 62), while 7’. autodice 9 comes
nearer to MW. agathon than does any species of Synchloe.
The whole neuration of Tatochila is very similar to that
of Pontia; and even the peculiar arching of the Ist
subcostal of the hindwing (well seen in P. cratzgi) is a
noticeable feature in 7. theodice and other members of
the same genus.* Tutochila may, therefore, be considered
to be a derivative from the Pontia stem at a point some-
what further back than the existing species of Synchloe.

* See Mr. Butler’s figures in Cist. Entom.,vol.1., pl. i1., figs, 7 and 9.

Phylogeny of the Pierinee. 307

A comparison of Tatochila (especially of J. theodice)
with Phulia nymphula will show an almost exact identity
of pattern, the correspondence extending even to the
chevron-shaped spots of S in the hindwing, and to the
peculiar triple striation of the nervules on the under
surface. The neuration of Phulia is distinct, but not
really far removed from that of Tatochila, some species
of which show a near approach to its most remarkable
feature ; viz., the emission of the second radial from the
subcostal, and the consequent obliteration of the upper
disco-cellular, Phulia again is closely allied in structure
with Mr. Moore’s genus Baltia,* which, however, retains
the short 3rd subcostal nervule lost by Phulia and
several species of Synchloe. Phulia and Baltia are thus,
in all probability, the terminal twigs of another branch
which issued from the Pontia stem between the departure
of Tatochila and Synchloe. Neophasia menapia appears
to me to be an offshoot of the same stem at an earlier
stage than Tutochila. It may possibly belong to the
Bucheira group, but it is not known to make a social
web,+ and Behr gives no real grounds for making it
congeneric with “ N.” terlootii. As above noted, its
neuration is very distinct from that of Huchetra.

The African species of the genus Mylothris{ appear
to hold a somewhat isolated position. Their neuration
shows points of likeness with the equally isolated
Australian genus Hlodine and the widely-spread and
probably ancient Nychitona, || which genera they also
somewhat resemble in texture of wing. In pattern
they are chiefly remarkable for the strong and distinct
development of series M, and of the precostal orange-red

* Moore’s type is “ Mesapia” shawii of Bates, which is certainly
generically distinct from J/. peloria, and much nearer Synchloe.
The butterfly described by Moore in Proc. Zool. Soc., 1882, p. 234,
as Synchloe butleri is undoubtedly a Baltia.

+ Stretch, however (Papilio, ii, pp. 106, 107), describes the
larvee of N. menapia as suspending themselves from great heights
at the end of long silken threads. Even the pup were, in some
cases, suspended. It is probable that the numerous threads cover-
ing the bark of the trees seen by Stretch (ébid.), were also made
by these larvee.

+ I cannot but agree with Mr. Trimen (South African Butter-
flies, 1887, vol. iii, p. 29) that the American P. pyrrha, Fabr.,
and allies, are not generically akin to the African J/. agathina, M.
chloris, etc., with which Mr. Butler unites them on account of
their correspondence in neuration (Proc. Zool. Soc., 1892, pp. 37, 38).

|| Distant, Rhopalocera Malayana, 1882—1886, p. 287.

308 Dr. Frederick A. Dixey on the

on the underside of the hindwing. We may, perhaps,
regard all three genera as relics of an ancient fauna of
the Eastern Hemisphere coeval with the earliest forms
represented by the present Delias stock, and anterior to
the various branches which have diverged from that
genus or from Metaporia. The precostal orange suggests
a kinship with Delias on the part of Mylothris, though
no such link exists in the case of the other two genera,
and, as pointed out by Mr. Trimen, who considers
Mylothris and Thyca (Delias) to be allied genera, the
former genus, like the latter, undoubtedly contains
subjects of mimicry by Pierine of other groups. Thus,
“The imitation of M. agathina by P. thysa, Hopff., is
deceptively close in both sexes, and M. poppxa, Cram.,
is similarly copied by P. rhodope, Fabr., on the West
Coast. M. agathina is also mimicked by the female
Hronia argia, Fabr.’’*

We now have to deal with the genus Belenois, which
presents some special difficulties. In the first place, we
find an assemblage of species (B. lasti, B. nagare, B.
majungana, and B. isokari) from East Africa and Mada-
gascar, with respect to which Messrs. Grose Smith and
Kirby, after noting that they are now placed with Phris-
sura in the Collection of the British Museum, go on to
observe that they “differ entirely in neuration from the
types of Phrissura, agreeing in this particular with
Belenois, in which genus we prefer to include them.’’+
The type of Mr. Butler’s Phrissura is apparently
P. illana, Feld.,t and in 1872 (Proc. Zool. Soc., 1872,
p. 51) the only other species of Phrissura admitted by Mr.
Butler was P. palisma, which is undoubtedly a very near
relative of P.illana. Both of these species offer differ-
ences in neuration from B. lasti and its allies.|| Now,

“ South African Butterflies, vol. ui., p. 39 (1887).

+ Rhopalocera Exotica, Oct. 1892.

~ Mr. Butler first gave it as P. cynis (Cist. Entom., 111., 1870,
p- 19), but afterwards corrected it to P. illana (Trans. Ent. Soc.
Lond., 1871, p. 171). Mr. Distant has since made cynis the type
of his new genus Udaiana. (Rhopal. Malayan., 1882—1886, p. 286
and note).

|| In P. illana (forewing) the discoidal cell is unusually short,
the second subcostal starts from the end of the cell, and the
second and third median nervules come off near together; in
B. lasti the cell is of the ordinary length, the second subcostal is
emitted before the end of the cell, and the second and third
median nervules do not start particularly near together.

9

Phylogeny of the Pierinee. 309

however, certain forms are included under Phrissura in
the Collection of the British Museum (P. phaola, P.
sylvia, P. eudowia, etc.) which appear to me to agree in
structural characters with B. lasti, and to differ from
P. illana. If, therefore, Messrs. Grose Smith and
Kirby are right (which I do not doubt) in separating
B. lasti, etc., from Phrisswra as represented by P. illana,
I am strongly of opinion that P. phaola, P. sylvia,
P. eudowia,* and P. coniata should go with them ;
and to this assemblage I would add every so-called
Belenois that is furnished with anal tufts, together
with ‘ Belenois” or ‘ Glutophrissa” saba. We should
then have a natural group of African and Malagasy
Pierines, between which there would exist no assignable
difference in structure, while they would be all alike
characterised by the possession of anal tufts like those
of Catophaga and Appias. They may, perhaps, be
considered as a section of Belenois, but to my mind they
seem by their neuration, no less than by the obvious
character of the anal tufts, to come much nearer to
Appias, of which genus I am disposed to regard them
as an African offshoot. The South American species
Glutophrissa poeyi, G. margarita, G. castalia, etc., are
very closely related to the present section.t+

Although the structural affinity of the forms that have
just been discussed with each other and with Appius
seems undeniable, there is no doubt that in pattern they
mostly show a marked divergence from that genus.
This appears to be due to mimicry, the models for which
are usually supplied by the genus Mylothris. Thus B.
lasti is said by Messrs. Grose Smith and Kirby to be
“nearest to B, trimenia, Butl.” ; the latter, however, is a
true Mylothris with the characteristic neuration of that
genus. Considerable resemblance also obtains (as men-
tioned above, p. 308) between P. rhodope, Fabr., and M.

“ P. eudoxia, Cram., is apparently identical with P. sylvia ?,
Fabr.

+ Mr. Wallace (loc. cit., p. 312) includes these American and
African forms with Appias, Catophaga, and Hiposcritia in his
genus Tachyris. For the purposes of the present paper it will
perhaps be sufficient if I refer to the American and African
species with Appias-like structure and anal tufts collectively as
ce meee BL,” while designating polisma and illana as “ Phris-
sura A.”

310 Dr. Frederick A. Dixey on the

poppea, Cram.* The peculiar facies of G. saba 2 seems
to be most likely due to mimicry of Nyctemera apicalis, a
protected moth. Those members of the group that have
not been affected by mimicry retain few traces of the
original ground-colour, and present very much the
appearance of an ordinary male Appias (G. saba 6, G.
castalia, etc.).

The other species usually included under Relenois,
besides differing im points of structuret from those just
discussed, show as a rule a greater persistence of dark
ground-colour. Both § and M are usually present in
fair development, either separate or fused, and the
discoidal patch on the forewings is generally well
marked. 'The markings in sever al. species show a strong
resemblance to those of Synchloe hellica and S. johnstonit ;
but notwithstanding this, I am disposed to think that
Belenois proper really represents an offshoot of another
part of the Old World Pierine stem, that, namely, re-
presented by Delias and Prioneris. The distribution of
dark and light ground-colour in such species as B
mesentina right easily be derived from those of D.
belladonna and D. ewcharis, and the underside of the
hindwing in this and other forms of Belenois offers only
slight modifications from that of D. belladonna. 8B.
peristhene exhibits a curious resemblance on both sur-
faces to D. nysa which may perhaps be due to mimicry,
although the ranges of the two insects only coincide for a
small part of their extent ; it is not improbably in any case
an indication of real affinity. In neuration, those species of

*“ T adopt Mr. Trimen’s unravelling of the strange confusion
that surrounds the synonymy of rhodope, Fabr., and poppea, Cram.
(South African Butterflies, vol. iii, p. 35, and note). The upshot
no doubt is that a true Mylothris (Papilio poppea of Cramer
according to Mr. Trimen) is closely copied by at least one Pierine
of the “B” group of Phrissura (Papilio rhodope of Fabricius
according to the same authority). I do not propose to embark
upon the question further than to observe that the ‘‘Synonymic
Catalogue” identifies the two, and that Mr. Trimen himself
unfortunately speaks of rhodope in the text, when he must mean
poppea (ibid. p. 35).

+ Negatively by the absence of anal tufts, positively by the
presence (in many) of anal hooks, also by the straight direction and
greater relative length of the upper disco-cellular nervule in the
forewing. In many species of this group, which we may designate
Belenois proper, the first subcostal branch anastomoses with the
costal.

Phylogeny of the Pierinee. dll

Belenois in which the first subcostal is distinct are very
near Prioneris, and the remainder seem to approximate to
Delias by the partial loss of a subcostal branch, as well
as by the contour and direction of the disco-cellular
nervules. It is to be observed that some species of
Belenois proper, like those of the “ Phrissura B”’ group,
are mimics of various species of Mylothris, as B. thysa of
M. agathina. Pinacopteryx is probably a collateral or
derived branch of Belenois; the female of P. capricornus
retains S and M on both surfaces in a well-marked
condition.

We now come to a large and important. group of
genera which appears to take origin from the older
Pierine stock at a point nearest to the genus Synchloe.
An early stage of divergence is reached by Teracolus ;*
many species of which show the primitive series S and
M, together with the discoidal spot and the precostal
yellow of the underside of the hindwing. The curious
genus Herpxnia is probably a survival of the links that
once united Teracolus with Synchloe ; im neuration it is
intermediate between the two, and in pattern, together
with aberrations peculiar to itself, it shows points of
contact with both. The pattern of the upper surface in
Teracolus is easily derivable from that of Synchloe, the
nearest approach to Synchloe in this respect being made
by the Jdmais group ; compare, for instance, 7. dynamene
with S. hellica 2. But the passage from the underside
of the hindwing in Synchloe to that of Teracolus is more
difficult ; Herpenia, however, enables us to bridge over
the interval very fairly, for if H. tritogenia and H.
lacteipennis be interposed between S. glauconome and
T. puellaris 2, the abruptness of the transition is
removed. The pupa of Yeracolus tends to be boat-
shaped, with a sharply-pointed rostrum and large
prominent wings+t—which characteristics we shall find

* T follow Mr. Butler (Cist. Entom. vol. 1., p. 36), with whom Mr.
Trimen is in agreement (South African Butterflies, vol. i11., p. 82),
in uniting Teracolus, Idmais, and Callosune under the single head
of Teracolus,

+ These features are not equally well developed in all species of
Teracolus. They are very distinctly shown in pupe of 7. evarne
(Coll. Hope) ; pupx of Z' calais (Coll. B. Mus.), on the other hand,
are slender, less recurved, and nearer the Ganoris or Synchloe form,
The pupa of 7. pleione (Coll. B. Mus.) is stout, and not unlike
that of Gonepteryx rhamni; compare Mr. Trimen’s description, op.

312 Dr. Frederick A. Dixey on the

in a greater or less state of development in all the
genera of the particular group of Pierines now under
discussion. Other features, which appear first in Teracolus
and will be met with again later on in the history of the
group, are the pinkish fringe of the wings in some species
(as 7. wallengrenii, and often in T. protractus) and the
faint pinkish Colias-like spot or patch at the root of the
cell in the hindwing underside of others (as 7. tri-
punctatus, T. celestis 2, T. eupompe, and T. theogone).

The genus IJvias follows easily upon Teracolus, the
females of the two genera showing, as usual, a greater
affinity in colouring than the males (compare, for instance,
the males and females of 7. ione and I. marianne *),
Series S is often well preserved in Jvias, especially on the
underside and in the female; the discoidal spots are also
prominent, and begin on the lower surface to assume an
ocellate character. In neuration, Jwias differs only
shghtly from Teracolus; while the pupa, as shown in
drawings by Captain Boys of I. marianne and I. evippe
(Coll. Hope), has the same characters as Teracolus in a
more strongly-marked condition.

From the usual system of colours and markings in
Tvias, there can be little doubt that that genus represents
the transition from Teracolus to Colias. ‘The underside
of several species of the latter genus (for instance, C.
subaurata) is strongly recalled by that of I. marianne,
in which the Colias-like condition of the discoidal spots
is one of the most noticeable features. The affinity
suggested by the colour-pattern is borne out by the
structure of the antenne, which in Jvias show a distinct
approximation to the gradually thickened form so
characteristic of Colias and its immediate allies. The
pupa in Colias, as in Teracolus, seems to vary somewhat
in form; but in all known cases it shows a tendency,
sometimes strongly pronounced, towards the acuminate
and boat-shaped outline characteristic of this group of
oenera.

cit., vol. iii., p. 82. Lrefrain from using the terms “ wing-covers”’

or “ wing-cases,” the inapplicability of which has been shown by

Prof. Poulton (Trans. Linn. Soc., 1890, series i1., vol. v., part 5,
. 188).

Pe Mr. Butler points out the intermediate character of the two

African species, Jvias eulimene and I. venatus. Proc. Zool. Soc.,

1871, p. 254.

Phylogeny of the Pierinee. 313

The genus Xanthidia is transitional between Colias
and Jerias, in neuration coming nearer the latter. The
pattern on the upper side is scarcely modified from that of
Oolias; on the under surface, however, S has lost much
of the distinctness it possesses in so many species of the
latter genus, and its relics take part in a general
mottling which is very probably protective in object.

In Terias the resolution of series Sand M, which is still
visible in most of the females and many of the males of
Colias, has usually disappeared from the upper surface ;
the underside of the hindwings, however, generally shows
S in a somewhat modified condition. The pink edging
to the wings, so characteristic of Colias, and occasionally
visible in Xanthidia nicippe, is indicated in several
species of Terias, as T. messalina, T. delia, and T’, rhodia.
The pupa of Terias is more sharply acuminate and re-
curved than that of Colias (see pupa of 7. mandarina and
T. excavata in Coll. B. Mus.).

Sphenogona presents in pattern no marked differences
from Terias, with which genus it is so closely allied.
S. gratiosa, like T. agave, X. wicippe, and some other
species of these genera, shows a relic of the pinkish Colias-
patch at the root of the cell on the underside of the
hindwing. In neuration, Sphenogona, while generally
resembling Terias, is peculiar in emitting the first and
second subcostal branches of the hindwing from a short
footstalk beyond the end of the cell. In this respect it is
intermediate between Jerias and Leucidea, which latter
genus presents no markings to guide us, but has no
doubt taken its origin directly or indirectly from Terias.*
Another probable descendant of Terias is the genus
Nathalis, which agrees very fairly with Terias in neuration,
except that it wants one nervule in the forewing, probably
a branch of the subcostal. There isa striking resemblance
of pattern between NV. iola and T. elathea 3. In the
absence of paronychia Nathalis reverts to the condition of
Colias.

Pyrisitia seems to represent an early offshoot of the
stem leading from Colias to Terias. In most points it

* Staudinger and Schatz (op. cit., Theil. i, p. 66, etc.) consider
Leuczdea to be more closely related to Pontia (Nychitona) than to
Eurema (Terias). The balance of evidence seems to me to be
against this view.

TRANS. ENT. SOC. LOND. 1894.—paRT U. (JUNE.) X

314 Dr. Frederick A. Dixey on the

agrees with the latter genus, but in the position of the
subcostal nervules of the hindwing it retains the condition
of the former.

A fresh departure from Colias is headed by the genus
Meganostoma, which offers a close resemblance to Colias
in both structure and pattern.* The series S and M,
fairly distinct in the female of M. philippa, are also
indicated on the upper surface in the males of some of
the species. In the males of some other species they
are fused above, but in all they are distinguishable
beneath. In the outline of the wings Meganostoma
shows a close approach to Gonepteryzx, from which genus
indeed the females of some of the species are hardly to
be distinguished.

From Gonepteryx the line passes on to Amynthia and
Rhodocera. All these’ genera retain many Colias-like
points, particularly the pinkish patch at the apex of the
cell on the hindwing undersurface. The males of the two
latter, like those of Meganostoma and many species of
Colias, also possess the well-known patches of raised
scales above the subcostal nervure of the hindwing ; and
in the same two genera is seen for the first time the
contrast between areas of flat and raised scales over the
whole upper surface of the wings which is so conspicuous
a feature in Catopsilia, Phoebis, and Callidryas.

Dercas appears to be an Indian offshoot of Gonepteryx.
A good transition from the latter to the former is
afforded by D. wallichii, as pointed out by Mr. Wallace,
Trans, Ent. Soc. Lond., 3rd series, iv., p. 398.
Kricogonia is probably an analogous derived form in the
Neotropical Region.

The Hastern genus Catopsilia forms with the Western
Callidryas, Aphrissa, Metwra, and Phebis, a group which
clearly belongs to the present section. Their structure
and coloration relate them closely to Gonepteryz, though
in some respects they show signs of a more ancient

* Mr. Butler (Cist. Entom., iii., p. 46) describes the neuration in
the forewing of Meganostoma as being like that of Gonepteryz,
“ excepting that the second subcostal is emitted just before the end
of the cell.” In some individuals, at any rate, the second subcostal
is emitted at the end of the cell, and in M. cesonia it may even be
thrown off after the end of the cell, as often in Colias. This indeed
is the condition represented in Cist. Entom,, vol. i., pl. i1., fig. 4.

Phylogeny of the Pierine. 315

ancestry. ‘The retention of the pink patch on the under-
side of the hindwing, and (in several species) of the pink
fringe, brings them near to Colias; to which they also
approximate by the form of the antenne, by the very
general occurrence of special patches of raised scales on
the hindwing of the males, by the frequent presence,
especially in the females, of the series S and M and the
discoidal spots in a more developed condition than that
characteristic of Gonepteryz, and by the common
tendency of the latter spots on the lower surface towards
ocellation. The oldest forms of the whole group appear
to be those contained in the genus Catopsilia. C. florella,
for example, is very closely related to Gonepteryx, and
still more nearly to Amynthia, with which it corresponds
in colour and in texture of wings (compare especially
the undersides of C. florella ¢ and A. clorinde). The
peculiar thickening of the nervures, especially the sub-
costal and median, on the under surface of the hindwing,
which in Gonepterye and Amynthia give almost the
effect of a folding of the surface, is plainly visible in
C. florella. In neuration, OC. florella agrees minutely
with A. clorinde. Another indication of the superior
antiquity of the Hastern Catopsilia as compared with the
Western Callidryas is found in the shape of the pupa.
This in Catopsilia (as remarked by Mr. Trimen, op. cit.,
vol. i., p. 184) is only moderately acuminate and slightly
recurved, thus showing no very great departure from
the Colias and Gonepteryx form ; in Callidryas, however,
so far as is known, it is always very sharply acuminate
and strongly recurved, showing an exaggeration of the
*“poat-shaped ”’ condition almost as marked, in a differ-
ent way, as that of Huchloe.* The Colvas-like pink
edging appears also to be found more frequently in
Catopsilia than in Callidryas (though it occurs in Calli-
dryas senne) ; and while the Colias-like spot at the root
of the cell on the underside of the hindwing occurs in
both the Hastern and the Western divisions of the
group, it has in the latter lost the ancestral pink tinge

*T agree with Mr. Butler that the pupa figured in Lep.
Exot., pl. xlv., fig. 4a, as P. agarithe is very probably that of
C. philea. It closely resembles a pupa of C. ewbule in the Hope
Collection, which last exactly corresponds with Burmeister’s figure
in the “ Atlas de la Description Physique de la Rép. Argent.,”
1880, pl. v, fig. 2.

316 Dr. Frederick A. Dixey on the

which it usually retains in the former. It is not very
easy to form an opinion as to the relative antiquity of
the four Western genera; if we are to judge from the
pup, so far as they are known, it would seem that
Aphrissa has undergone less modification than either
Phebis or Callidryas. Another possible indication of
the greater antiquity of Aphrissa is afforded by the
shape and size of the palpi, which in this genus,
especially in the females, show less departure than is the
case in either Phebis, Metura, or Callidryas, from the
Colias and Gonepteryx type. Phebis with its offshoot
Metura, from which it differs only in the contour of the
wings, is probably the most highly speciahsed genus of
all; this being shown by the possession of a tuft of
long hairs on the hindwing of the male, which is not
found in Aphrissa and Callidryas, and by the absence in
most species of nearly all indication of dark ground-
colour from the upper surface. It is remarkable that
the Western genera just treated of are less closely akin
to the South American Amynthia than is the Eastern
genus Catopsilia, and especially the African C. jlorella.
The genus Hronia seems to represent a branch of the
present section which leaves the main stem somewhere
between the points marked by TYeracolus and Jzias.
With the exception of the presence of a fifth subcostal
in the forewing (which, however, is sometimes wanting),
the neuration of Hronia agrees fairly with that of
Teracolus. The antenne in Hronia differ in different
species, but are all intermediate between the Teracolus
and the Coltas type; and the pupa of H. cleodora, with
its very convex and prominent keel, is hke that of one
of the stout forms of Teracolus, e.g., T. evarne. The
assemblage of species distinguished by Mr. Butler as
Yepheronia is probably older than Hronza proper, as is
shown by the tendency of its antennz to terminate in a
definite club, ike the more ancient genus Teracolus.
N. thalassina also retains a primitive Pierine feature in
the yellow precostal streak of the hindwing underside,
which again is found in some species of Teracolus.
Eronia proper, on the other hand, is slightly nearer to
Teracolus in neuration. The curious FHronia (?) lucasia
from Madagascar, which has only four subcostal nervules
in the forewing, and whose antenne are slender, with a
definite club, is probably one of the oldest and most

———

ee

Phylogeny of the Pierine. 317

generalised members of the Hronia and Nepheronia
group now extant.*

The last-named insect presents points of resemblance
with Hebomoia, which again seems to be an offshoot of
the same stem, that, namely, leading from Teracolus
towards Ivias and Colias. The pupa of Hebomoia
glaucippe, as fioured by Horsfield (E. J. C. Catalogue,
see Distant, Rhopal. Malayana, 1882—6, p. 283) and
Moore (Lep. Ceylon, 1880—1, pl. 49, fig. 1b), is stout,
moderately acuminate, and much recurved, in which
particulars it agrees well with the pupa of Ivias.

Most of the insects of the genera Hronia, Nepheronia,
and Hebomova, retain in greater or less measure some por-
tions of the primitive marginal and submarginal series.
These, as usual, are most often to be met with in the
females, and in several species of Nepheronia are utilised
in the formation of mimetic patterns modelled on those
of various Danaids and sometimes of other Pierines. A
noticeable feature in some members of this group, per-
taining chiefly to the males, is the brightening of the
pale ground colour of the apex of the forewing into a
brilliant yellow or orange patch. ‘his character is first
seen in Teracolus, where the orange of the apex may
further deepen into crimson or violet; it passes on to
Hebomoia, to Ixias and to Rhodocera ; in Colias, however,
it gives place to a general yellow or orange suffusion of
the pale ground colour, still strongest in the males.t+
It is found in Hronia (?) lucasii and EH. leda, but not in
other members of that genus; it is also absent in
Nepheronia.

* I. (?) lucasii was originally described (as Callidryas lucasi) by
Grandidier (Rév. et Magas. de Zool., Aug. 1867, p. 273). He,
however, took the female for the male, and his supposed female
C. lucasi is really the female of Catopsilia thauruma. Mabille in
the. Hist. Phys. Nat. et Pol. de Madagascar, vol. xviil., 1887,
p. 281, gives a correct description of both sexes under the name of
Eronia lucasii, but makes no mention of Grandidier’s mistakes.
This species will not come into the genus Lronia as at present
defined. By Brauer and others it has been called a Ptychopteryz ;
the latter genus, however, was characterised by Wallengren from
a species of Teracolus (T. subfasciatus, Swains., Vid. Trimen,
South African Butterflies, vol. iii., 1889, p. 92), and has no real
claim to stand.

+ In many species of the latter genus, indeed, the females may,
as is well known, revert almost entirely to the ancestral white.

318 Dr. Frederick A. Dixey on the

This last feature in coloration is again met with in
Hirvoessa and Huchloe, the neuration of which genera
corresponds pretty closely with that of Hronia, not only
in the presence of five subcostal branches in the forewing,
but also in other particulars. The general likeness
between Hronia leda and Huchloe belia, Linn., is very
striking, and strongly suggestive of a near affinity
between them. The well-known form of the pupa in
Euchloe is an exaggeration of that seen in Hronia
cleodora.* In some other points, however, Huchloe is
nearer to Colias, as in the strong development of the
discoidal spot in the primaries, and in the possession by
some species of pink legs and a pink edging to the wings.
This last feature is characteristic of the charlonia group
of Huchloe, and is best seen in EL’. lucilla. The underside
of the hindwing in the same group has very much the
character of the corresponding region in Colias paleno,
including the pale undeveloped discoidal spot. The
antennee, however, of Huchloe are very distinct in form
from those of Colias, and indeed are not much nearer
those of Hronia. On the whole it seems most likely that
Huchloe is a somewhat aberrant branch which takes its
rise from the Pierine stem at a point near the divergence
from the same stem of Hebomoia on the one hand, and
HH. (2) lweasit with the rest of the Hronia and Nepheronia
group on the other. The isolated form Hroessa chilensis,
which in neuration approaches the older Hronias (as
E. (?) lucasti) and Hebomoia, is perhaps a survival of a
once more widely-spread and numerous assemblage,
among which were to be found the immediate ancestors
of the present-day Huchloes. Zegris seems to be a some-
what highly modified offshoot of the Huchloe branch.

We must now retrace our steps as far as to the group
which I have called ‘*‘ Pierines of the second grade,” those,
namely, that are typified by Delias in the Hastern and
Catasticta in the Western hemisphere. The latter genus
with its near ally Leodonta forms a starting-point for a
New-World division of the Pierine stem, which, if not
equal in magnitude to the great division headed in the

* The pupa in Euchloe is not always recurved. See Edwards's
figures of Anthocharis (Euchloe) genutia and A. ausonides in
“ Butterflies of North America.” See also Schatz, Hxotische
Schmett., Theil 11., 1892, p. 71.

Phylogeny of the Pierine. 319

Old World by Delias, Prioneris, and Metaporia, is never-
theless of high importance and very great interest.

The first departure from the condition of Catasticta
seems to be that taken by the butterflies of the genus
Pieris as restricted by Butler, closely associated with
which must come the American species of Mylothris. The
underside of Pieris locusta exhibits a pattern which is but
little removed from that of Catasticta, the yellow streaks
and red basal patches being still apparent on the under-
side of the hindwing; while the upper surface of both
wings is shared between the original dark and intrusive
light ground colour in much the same manner as in (O.
ctemene, C. corcyra, and other species of Catasticta. In
Pieris as a whole, the dark ground-colour has to a great
extent disappeared from the upper surface; several
species however (as P. pylotis and P. bunie) retain a
discoidal spot in the forewing, which in some, as FP.
thaloe ?,1s connected with a dark streak along the costa,
and in others, as P. demophile 2, is included in a larger
remnant of ground-colour which passes as a dark fascia
obliquely across the wing from the costa to the outer
border. The underside of the hindwing in this genus
tends to lose the Catasticta-like character preserved in
P. locusta, in consequence of a general paling which takes
effect first in the basal half and spreads outwards (as in
P. demophile), until in such species as P. bunie it reduces
the wing to very much the same condition as that seen
in Ganoris brassice or G. rapt. The ground-colour in
P. bunie and P. pylotis is indeed even paler than in
these species of Ganoris, being without the powdering of
black scales which the latter possess; the hindwing
however of both P. bunie and P. pylotis retains a dis-
coidal spot, and, as has been already noted (pp. 287, 289,
note), the predominance of the paler colouring is never
so great as not to leave unmistakable relics of the yellow
streaks and red basal patches.

The genus Leptophobia appears to be a kind of con-
tinuation of Pieris. The arrangement of light and dark
ground-colour preserves a parallel course in the two
genera, and the inclusion of the discoidal spot of the
forewings in a dark fascia which passes from the costa
for a greater or less distance obliquely towards the outer
margin is a common feature in Leptophobia as well as in
Pieris. In the present genus the underside of the hind-

320 Dr. Frederick A. Dixey on the

wings is almost uniformly pale, but distinct indications
of the primitive red patches are nevertheless still to be
met with (see p. 287).

There would also seem to be little doubt that the
American species allied to M. pyrrha, which are included
by Mr. Butler* under Mylothris, with the neuration of
which they agree, are closely related to Pieris. The pattern
of every one has been more or less altered by mimicry,
but in those males whose upper surface is unaffected by
this kind of modification, the arrangement of the dark
and light ground-colour is seen to present the ordinary
features of Pieris or Leptophobia (compare, for instance,
the upper side of M. pyrrha ¢ with that of P. thaloe). In
M. lorena is found an oblique dark bar crossing the
forewing just as in P. demophile and L. stamnata, this
mark being utilised, both in M. lorena and the female of
M. pyrrha, for the formation of the mimetic pattern.
It has already been shown} how the primitive yellow
streaks and red basal patches have been turned to account
in the same direction on the underside of the hindwing,
which, from the additional necessity for protection ex~
perienced by the insect when at rest with its wings
closed, becomes the most important field for the mimetic
process. It may be here remarked that the antennz of
these American forms, while agreeing in character with
those of Leptophobia, Pieris, Oatasticta, Leodonta, and the
genera allied to these last, differ conspicuously from those
of M. agathina, M. poppea, and the other African species
of Mylothris.

Hesperocharis diverges somewhat widely from the
genera last discussed, both in neuration and in the
character of its antenne; it retains, however, in many
cases indications of the primitive marginal and sub-
marginal dark series in a more recognizable form than
any (see, for instance, the chevrons on the underside of
H. erota, which represent series 8). The yellow streaks

* Proc. Zool. Soc., 1872, pp. 36-38. It appears to me that the
neuration of the American forms of Mylothris is simply that of
Pieris, minus the third subcostal nervule in the forewing, which
branch is already almost obsolete in the latter genus.

+ See above, p. 286. The transitional series which is there made
to begin with M. lypera and M. lorena might easily be carried back
to P. thaloe, which shows the true ‘Pierine pattern all ready, as it
were, to take on the mimetic condition of the other species.

Phylogeny of the Pierine. 321

and red basal patches, present in all species of Hespero-
charis, are in some (as H. nereis) marked with special
distinctness. The curious manner in which these have
been made use of in H. hirlanda for the production of
a mimetic pattern, has already been fully discussed
(p. 286).

I cannot but think that U. monuste shows by its
pattern that it stands on a level with Pieris as a
derivative from the Catasticta group. Its neuration
hardly differs from that of Pieris, and it would probably
be more appropriately placed (together with its imme-
diate allies, U. joppe, U. swasa, etc.) in or near that
genus than with U. cynis in Mr. Distant’s genus Udaiana,
as at present in the National Collection.

The position of the genus Dismorphia is not easy to
determine. ‘The pattern of those species that appear to
have undergone least modification may, however, be
derived without much difficulty from Pieris or Lepto-
phobia ;* and the persistence in some cases of the red
basal spots has already been remarked (see p. 285). The
structure of the antennze points to the same line of
ancestry. On the other hand, the very remarkable
neuration is quite unlike that of Pieris; a certain
approach to it, however, is made by Hesperocharis, which
is almost without doubt a close ally of that genus.
Moschoneurat is very nearly akin to Dismorphia, from
which it differs only slightly in neuration; while the
Palearctic genus Leptosia has characters which link it
with both. We may probably regard the three last-
named genera as terminal twigs of a branch now lost,
which left the main stem at or near the genus Pieris,
and of which Hesperocharis is a still earlier offshoot. In
Dismorphia and a few species of Moschoneura much of
the original colouring has been retained and modified for
purposes of mimicry. In Leptosia and the remainder§ of
Moschoneura this colouring has given way to the usual
Pierine invasion of white.

* A somewhat different and, as it seems to me, less probable view
is advanced by F. Miiller, Jenaische Zeitschr., x., pp. 1-12.

+ The figure in Cistula Entomologica, vol. i., pl. iv., fig. 9, omits
the second discoidal of the forewing.

{ The forewing is nearer to Dismorphia and the hindwing to
Moschoneura.

§ Pseudopieris of Godman and Salvin.

322 Dr. Frederick A. Dixey on the

2. The evidence of distribution.

It now remains to briefly indicate the bearing of the
geographical distribution of the various forms that have
been mentioned upon the question of their kinship and
relative antiquity.

As we have already seen, the oldest form of Pierine
now extant is probably Hucheira socialis. This insect
appears to be as limited in its geographical range as it is
isolated in its zoological position, for itis found only in the
mountain-ranges of Mexico, which may be considered as
a southern extension of the “ Rocky Mountain” division
of the Nearctic Region.* Its nearest allies appear to be
Behr’s two species of Neophasia (see p. 303), which inhabit
the same region with itself, and the Pontias and Metaporias
of the high lands of Central Asia, most of which forms
are known to retain the ancient larval habit of spinning.
These facts seem to point to the conclusion that Hucheira
is the relic of an archaic group of Pierines which once
occupied the great mountain regions of both the Palw-
arctic and Nearctic continents, and whose immediate
descendants, still represented in the Hast by Metaporia
and Pontia, have in the West become extinct (unless
Behr’s Neophasia be a survival) after giving origin to
the group of genera headed by Catasticta.

From one or other of these two primary stems, the
Kastern or the Western, nearly the whole of the existing
genera of Pierines may be derived. There are, however,
a few exceptions, which, perhaps, constitute relics of an
ancient Pierine fauna coeval with the groups above
mentioned, but not, like them, the progenitors of a
numerous and varied offspring. The chiet of these are
the genera Hlodina and Nychitona, the former of which
is entirely confined to the Australian Region, while the
latter has a very wide distribution throughout the
Hthiopian, Oriental, and Australian. The African

* T here follow Mr. Sclater’s division of the earth’s surface into
six Zoological Regions, which arrangement, adopted by Mr. Wallace
in his “‘ Geographical Distribution of Animals,” 1876, has stood the
test of time and experience better, in my opinion, than any alterna-
tive distribution that has been proposed. I also adopt, for conve-
nience, the smaller divisions, or “sub-regions,” as determined by
Mr. Wallace in the above-named work.

Phylogeny of the Pierinee. 328

species of Mylothris belong possibly to the same
category.

The genera derived from the Catasticta group remain,
for the most part, within the confines of the Neotropical
Region. This is the case with Pieris, Leptophobia,
Hesperocharis, the American species of Mylothris,* Dis-
morphia, Moschoneura, and those species allied to
monuste at present included in the genus Udaiana.t+
It is remarkable that the Nearctic Region does not
furnish a single species that can be supposed to be
derived from the present stem.{ Inasmuch, however,
as the Palearctic genus Leptosia seems to belong
rather to this than to any Hastern branch, the conjecture
may be hazarded that connecting forms now extinct
once occupied the Nearctic Region, from which the
Palearctic continent received the forerunners of its
present Leptosias, probably by way of Behring Strait.

Turning now to the Kastern Metaporia, which inhabits
the borderland between the Palearctic and Oriental
Regions, we find it emitting one clearly-defined branch
in the Palearctic direction. This is the branch to
which belong the various species of Pontia, as P. nabel-
lica, P. soracta, P. hippia, P. belucha, P. leucodice, and
P. crategi. In the Chilian or Andesian division of the
Neotropical Region we find the genus Tatochila, which
appears not to belong to the regular Neotropical Pierine
stock, but to be closely related to the Palearctic
Pontias. It is conceivable that the latter stem may
have spread from Asia into the western portion of the
Nearctic continent, and thence down the mountain-
chains to the south. Neophasia menapia, at present
inhabiting the Californian and Rocky Mountain sub-
regions, seems to me to be more nearly allied to both
Pontia and Tatochila than (as Behr thinks) to Hucheira
socialis, and may very possibly be a relic of the original
invasion, Another indication of the same invasion is
afforded by the genus Phulia, now found with the
nearly-allied Tatochila only in the Andesian or Clnhan

* See p. 320, note.

t See p. 321.

t The instance of U. monuste, which straggles into the southern
districts of the Nearctic Region, hardly forms an exception to the
above statement.

324 Dr. Frederick A. Dixey on the

sub-region, to which it no doubt made its way along the
great mountain-chains in a similar manner. Its close
ally, Baltia, remains in the high lands of Central Asia,
where it bears much the same relation to Synchloe as
Phulia to Tatochila. Another early offshoot from the
Hastern Pontia stem is Mesapia peloria,* which has no
representative in the Western Hemisphere.

The above descendants of the mountain Metaporias
belong, as has been seen, in the first place, to the
Paleearctic and western portion of the Nearctic Region,
only reaching the Neotropical by extension along the
chain of the Andes. Other derivatives of Metaporia,
however, took their course directly southwards. The
first of these is the Delias and Prioneris group, the more
ancient members of which are, speaking generally, to be
found in the northern portion of the Indian peninsula,
while the Australian and other southern forms represent,
as a rule, a somewhat later stage of development.
Another is the important branch headed by Huphina,
which genus, like Delias, has spread downwards through-
out the Oriental Region, and by way of the Indo-
Malayan and Austro-Malayan islands to the Australian
continent. The Australian species of Huphina are
clearly derived from the Oriental, and those forms (such
as H. phryne 9) which are nearest to M. agathon in
colouring are also its closest neighbours geographically.
Of the two genera (Hiposcritia and Catophaga) which
appear to be immediately derived from Hwphina, the
former is confined to the Oriental Region; while the
latter, ike Huphina itself, has spread along the Austro-
Malayan Islands to the Australian mainland. ‘This is
also the case with Appias,t the origin of which genus
from the Catophaga stock is no doubt to be assigned to
the Oriental Region. But, unlike the other genera,
Appias seems to have extended its borders westwards,
and to have given rise to the “ Phrissura B”{ group in
the Hthiopian Region, and even to Glutophrissa in the
Neotropical. If this be the real origin of these two
latter genera, we have to enquire how they reached the
African and South American continents respectively.

* See p. 304.

t It would seem, however, that no true Appias actually reaches
the Australian continent.

£ See p. 309, note.

Phylogeny of the Pierinee. 325

With regard to the first, there is little difficulty in
supposing the passage to have been effected by land
either now or formerly existing, the Ethiopian Region
having been in this, as in so many other instances, first
entered from the north. But it is not easy with our
present knowledge to imagine an overland passage for
these butterflies from the Oriental or Ethiopian Region
to the Neotropical. The northward route, which we saw
to be the one probably adopted by the ancestors of the
Chilian Phulias and Tatochilas in spreading from Central
Asia, is excluded in the present instance by the entire
absence of any trace of such a passage from both
the Palearctic and Nearctic Regions; and although a
transit by way of a formerly existing “ Antarctica” is
conceivable, it would seem more likely that the crossing
from east to west was effected in the region of the tropics.
After all, however, the difficulty of supposing an Atlantic
Sea-passage is not overwhelmingly great. The unusual
facilities possessed by insects for crossing large extents of
sea have been remarked by many writers,* and among
insects the butterflies of the Pierine group are especially
given to migration for great distances in countless hordes. +
It is worth noting that im the case of each of the other
three chief Pierine genera whose present distribution
seems to have involved one or more long sea-passages, 7.e.,
Terias, Colias, and Callidryas, special observations exist
of their migratory propensities. In 1874 a large swarm
of Terias lisa reached the Bermudas from the American
continent ;{ the swarm of butterflies described in a well-
known passage|| by Mr. Darwin consisted chiefly of a
species of Colias; while descriptions of the migratory
flight of Catopsilia and Callidryas are numerous,
among the most striking pieces of testimony being that

* See especially Wallace’s “Geographical Distribution,” 1876,
vol. i., p. 832; and the same author’s “ Darwinism,” 1889, p. 359, etc.

+ Trimen, Trans, Ent. Soc. Lond., 1870, p. 382 ; “ South-African
Butterflies,’ 1887, vol. ui., p. 32. Moore, ‘‘ Lepidoptera of
Ceylon,” 1880, 81, p. 116. Distant, “ Rhopalocera Malayana,”
1882—86, p. 285, etc. Mr. Trimen suggests that there is “an
evident connection or relation between these wonderful migrations
of certain species of Pieréne and the well-known habit of nearly
all the members of the Sub-family of flying straight onward in
one direction.”

t “ Psyche,” Dec. 1875, p. 121.

|| “ Voyage of the Beagle,” ed. 1860, p. 158.

326 Dr. Frederick A. Dixey on the

of Mr. Spruce, who saw Callidryas “launching boldly
out over the Pacific Ocean.’’*

The earliest species of Synchloe were undoubtedly
differentiated from Pontia or Baltia in the Palearctic
Region, from which the genus spread (probably east-
wards) into the Nearctic. Synchloe proper can hardly
be said to enter the Indian Region,+ but in its progress
westwards it has sent an offshoot downwards into the
EKthiopian, consisting of S. johnstonii and SS. hellica.
S. glauconome of Arabia and Egypt remains to mark the
course of the invasion. Ganoris, a further Palearctic
development of Synchloe, has accompanied that genus
into the Nearctic Region and has also spread into the
Oriental. A curious extension of the range of the
Palearctic G. rapx into the Nearctic Region has been in
progress during the last thirty-three years, the first
transatlantic specimens having been seen at Quebec in
the year 1860.t This introduction was undoubtedly
effected by human agency, and differs from the natural
passage of species between the two Regions in having
taken place by the Atlantic instead of the Pacific route.

Though Synchloe itself is far more characteristic of
temperate than of tropical districts, it has given rise to a
large and important Pierine branch which has spread far
and wide through tropical and temperate parts alike.
The birthplace of Herpxnia and Teracolus, the two
earliest members of this extensive section, is apparently
the eastern portion of the Mediterranean division of the
Palearctic Region; from which locality the former has
spread through Arabia and Abyssinia into the African
continent, while the latter has not only followed Herpenia
into Africa, but has also largely occupied the two western
Oriental sub-regions. Those forms of the genus Jxias
that show least divergence from Teracolus are found in
the Nile provinces of Hastern Africa, but the bulk of this
genus has moved eastwards, its distribution being
characteristically Indian. A few species, however, are
found in some of the Indo-Malayan islands, and in
Austro-Malaya as far east as Timor.

* Journal Linn. Soc., Zool., ix., pp. 355—357.

+ See Wallace, Trans. Ent. Soc. Lond., 3rd series, iv., pp. 242, 3.

¢ Seudder, ‘‘ Butterflies of the Eastern United States,” 1889,
vol. 1i., pp. 1175-1190 ; Edwards, “ Butterflies of North America,”
vol. 1., 1868-72, sub. voc. P. virginiensis.

Phylogeny of the Pierinze. 327

To the same borderland of Western Asia and Hastern
Africa may be assigned the place of origin of Nepheronia,
which has sent a western branch into Africa, and an
eastern into the Indian peninsula and Malayan islands,
one species reaching the Australian continent. The
African branch has given rise to Hronia proper. Attention
has already been drawn to the curious fact that the form
which links the Hronia group most closely with Teracolus,
viz., H. (?) lweasti, survives in Madagascar. Hebomoia,
another offshoot of this part of the Pierine stock, is now
almost entirely Malayan ; its place of origin was, however,
in all probability further west. The birthplace of Huchloe
is problematical, but the present distribution of the
charlonia group, which seems to contain the oldest
members of the genus, would appear to make it probable
that the Mediterranean sub-region witnessed the rise of
this, as of so many other more or less direct descendants
of Synchloe, from which central area it successively over-
spread the Palearctic and Nearctic continents. The
isolated geographical position of Hroessa chilensis is very
remarkable, its affinities being apparently with Hastern
rather than Western forms. It is probably, as before
suggested, a solitary survival of a once more widely-
spread group, among which were to be found the
immediate ancestors of the present-day Huchloes.

No other genus in the whole sub-family has so extensive
a range as Colias, species of which are found in every one
of the six great Zoological Regions. Here again, I have
little doubt that the site of original divergence is Asiatic,
and is most nearly represented in the present condition of
the earth’s surface by the borderland between the
Paleearctic and Oriental Regions on the north-west
frontier of India. From this centre one or two species
have ranged into South Africa and the Indian peninsula ;
but the greater number have turned northwards, and
after populating the Palearctic and Nearctic continents
with numerous species, have penetrated to the circum-
polar lands within the Arctic Circle, have passed down
the great mountain chains of Central and South America
to Chili and Patagonia,and have even established outposts
in Venezuela and the Sandwich Islands.*

The powers of dispersal possessed by the genus Terias

© The occurrence of Colias in the last-named locality is, how-
ever, not entirely free from doubt.

328 Dr. Frederick A. Dixey on the

are almost as remarkable as those of Oolias ; perhaps
even more so when we take into account their weak
flight, and the fact that their migrations must have been
intertropical Mr. Wallace, however, has drawn
attention to their habit of frequenting “gardens and
plantations and skirts of forests rather than their deeper
recesses,” and also of ‘assembling on the margins of
streams and on the sea beach,” and has remarked that
“these habits lead to their being frequently carried olf
by winds,” and that ‘‘it is thus perhaps that some of the
species have so wide a range and offer such perplexing
variations.”* Whatever may have been their means of
dispersal, there can, I think, be no doubt that they took
their rise from the Colias stock in the Western Hemi-
sphere, the line of descent passing through Xanthidia
to Terias and Sphenogona; Pyrisitia, Nathalis, and
Leucidea being given off by the way. All these genera
are mainly Neotropical with Nearctic extensions. Terias
itself, however, as is well known, so far from remaining
within these limits, has overspread the warmer portions
of the Ethiopian, Oriental, and Australian Regions, and is
even found in the Manchurian sub-region of the Pale-
arctic.

It seems on the whole most probable that the origin of
Gonepteryx is also to be referred to the Western Hemi-
sphere, where Meganostoma marks the transition from
Colias. Gonepterya itself seems to have passed to the
north by way of California and so across into the
Palearctic Region, while Rhodocera and Amynthia re-
present a Neotropical development of the same stock, the
Central American genus Kricogonia perhaps remaining
near the original seat of divergence. Gonepteryx having
reached the Palearctic Region has extended to its
westernmost extremity. Its only offshoot appears to be
Dercas, which probably arose in the debateable Man-
churian area, where the Palearctic and Oriental faunas
are much mixed, and thence spread southwards through
the Indo-Chinese sub-region to Sumatra and Borneo,

Catopsilia and Callidryas, like Terias, must, it would
seem, have undergone intertropical migration. Their
oldest forms appear to be Catopsilia florella, C. hyblza,

* Trans. Ent. Soc. Lond., 3rd series, iv., p. 320. See also
above, p. 325.

Phylogeny of the Pierinee. 329

C. thaurwma, ete., which are probably derived from the
Neotropical genus Amynthia, coming nearest to A.
clorinde. Inasmuch as all these are African insects, and
the New World Callidryas, Pheebis, and Metura are less
closely allied to Amynthia, it seems necessary to suppose
that the earliest forms of this group in the Neotropical
Region have become extinct, the present Callidryas
group surviving as their modified descendants ; while an
early dispersal of these ancestral forms took place across
the Atlantic to Africa, of which invasion C. jlorella, etc.,
remain as comparatively unmodified relics. ‘lhe Oriental
and Australian Catopsilias are the ultimate developments
of this invasion.

The distribution of Belenois is remarkable, the bulk of
the species belonging to the Ethiopian and Australian
Regions. The Oriental Region is poorly supplied, except
for the abundant B. mesentina, which is found in all
parts of the Indian peninsula, and even enters the
Mediterranean district of the Palzearctic Region as far as
Asia Minor. Notwithstanding the present poverty of
the Oriental Region in species of Pelenois, it seems
probable that this area is really the birthplace of the
genus, which, as we have seen, appears to be derived
from that primitive part of the Pierine stem now repre-
sented by Delias and Prioneris. B. mesentina and
B. taprobana, of India and Ceylon, may probably be
regarded as survivors of the original race of Belenois,
whose descendants have spread south-eastwards to
Australia, and south-westwards to Madagascar and the
African continent. Pinacopteryx is in all probability a
local modification of elenois within the Ethiopian
Region, while Daptonura, whose history is otherwise
hard to account for, may perhaps have originated from a
branch of the African Belenois which at some remote
period found its way westwards across the Atlantic.

In concluding this paper I wish to express my great
indebtedness to several friends who have given me
valuable help during its progress. It was by the kind-
ness of the late Professor Westwood that I was enabled
to begin the study of the Pierine group in the Hope
Collection at Oxford, and the facilities for work afforded
me by him have been continued and increased by his
successors in the charge of the department, first by

TRANS, ENT. SoC. LOND. 1894.—ParT 11. (JUNE.) Ni

330 Dr. Frederick A. Dixey on the

Mr. W. Hatchett Jackson, and now, in a special manner,
by Professor Poulton, F'.R.S., the present occupant of
the Hope Chair, at whose request I have undertaken the
arrangement of this part of the Hope Collection. I am
also under great obligations to Colonel Swinhoe, who
has very kindly helped me in various ways, and
especially in the determination of the Eastern species, of
which he has so intimate a knowledge. Lastly, my
thanks are due to the members of the staff of the
Natural History Department of the British Museum,
particularly to Messrs. A. G. Butler, W. F. Kirby, and
Ff, A. Heron, who have given me every assistance in
examining the fine series of Pierine preserved in
the National Collection.

ITV.—lInpex or Species MENTIONED.

The Order ws that of the National Collection in the
British Musewm.

PIERINA,
Prioneris thestylis, Dowbl., 258, 267,; Delias harpalyce, Don., 257, 284,
281 300, 301
;, clemanthe, Doubl., 258,281,284 » aganippe, Don., 257, 277,
» vollenhovii, Wall. . 284 284, 300, 301
» autothisbe, Hubn., 258,281,284 » thisbe, Cram., 257, 258, 280,
Sita: Weld. 1s 45 oe) e 284 281, 283, 300
Delias eucharis, Drury, 257, 267, , belladonna, Fabr., 257, 258,

268, 280), 284, 288, 300, 310
hyparete, Linn. 257, 280, 284,

300
hierte, Hiibn. . . 284, 300
agostina, Hew. . 268, 300
mysis, Labr. . 284, 301
isse, Cram. . 284, 301
echo, Wall. ~ 5 284
argenthona, Fabr., 284,

301

philotis, Wall. . . 300
ceeneus, Linn., 268, 284, 288,

300
duris, Hew. 284
dorimene, Cram. 301

belisama, Cram., 277, 284,
300, 301

descombesi, Boisd., 268, 277,
284, 300, 301
257, 284, 300,
301

nigrina, Mabr.,

267, 280, 299, 300
nysa, Fabr. . 280, 301, 310
momea, Boisd., 268, 280, 301
egialea, Cram. . . . 284
pasithoe, Linn., 257, 258, 267,

281, 283, 300
crithoe, Boisd., 277, 281, 284
orphne, Walls BOL

288 | Pereute autodyca, Boisd., 281, 293
5 Swainsonil, Gray .

285, 294

5, charops, Boisd., 281, 285, 293
,, leucodrosime, Koll., 281, 285,

5, telthusa, Hew.

294
294

Euterpe tereas, Grodé., 258, 281, 284,

295, 298
critias, Feld., 284, 295, 298

rosacea, Butl. . 295
bellona, Cram. 295
theano, Boisd. 299
eurytele, Hew. 299

Phylogeny of the Pierinee.

Mylothris lorena, Hew. . 286, 320
» pyrrha, Fabr., 286, 288. 307,320
lypera, Koll. 285,288, 289, "390
chloris, Fabr. 219, 289) 30%
3 agathina, Cram., 268, 279, 289;
307, 308, 320

» poppea, Cram., 268, 308, 310,

320

a rhodope, Fabr.** . 308, 310
trimenia, Buti. 309
Blodina egnatia, Godt.. .307, 362

Nychitona. xiphia, Fabr. i 307, 322

Hesperocharis hirlanda, Stéol/., 286,
288, 321
mA marchalii, Guér, . 286

a4 erota, Luc. . 287, 320

» anguitia, Godt. . 286
nereis, Feld... 286, 321

Eucheira socialis, Westw., 259, 290,

303, 322

Leodonta zenobia, Feld. . 281, 285
», tellane, Hew. - .209, 285

» dysoni, Doubl. 259, 281, 285

Catasticta nimbice, Boisd., 259, 281,
292, 295
2 age 22
259, 285, 291

colla, Doubl.
bithys, Hibn.,

» anaitis, Hew., 259, 281, 285,
29

» Semiramis, fuc. . .281, 291

», toca, Dowbl. . 278, 281, 292

» notha, Lue. . : 293

,, teutamis, Hew. 294

,, ctemene, Hew., 291, 294, 319

» coreyra, Feld. . 291, 292, 319
troezene, Feld. . 291
Nathalis lola, Boisd.. 313
Colias cunninghamii, Buti. 270
ae meadii, Edw. . 270

» fieldii, Ménétr. 270

. edusina, Feld. 270

edusa, Fabr,. 259, 264, 271
phicomone, Hsp... 259, 264
hyale, Linn. . 259, 264, 270

,, subaurata, Butl. . 312
», barbara, H. Edw. 270
5, pelidne, Boisd. 270

paleeno, Linn., 259, 264, 270,
272, 276, 318

Xanthidia nicippe, Cram., 276, 283,
313

331

Terias lisa, Boisd. & Lec., 276, 325

oy) Geva, Dowdle. We 206

» Mmandarina, De ?Orz. 313

,, floricola, Boisd. . 276

» hecabe, Linn. . 276

» excavata, Moore . 313

»» messalina, abr. ole

» agave, Cram. . . 283, 313

* delia, ‘Cram. a he weoillia}

es rhodia, Feld. 313

elathea, Cram. - 313
Sphzenogona eratiosa, Doubl. &

Hew. » 210; 313

mexicana, Boisd., 283
Pyrisitia proterpia, Fabr., 276, 313
Gonepteryx cleopatra, Linn., 259,

202

p rhamni, Linn., 259, 264,

272, 311, 328

Amynthia moerula, Fabr., 260, 272,
328

ie clorinde, Godt., 260, 272,

315, 329

Dereas wallichii, Doubl., 260, 273,
314, 328

», lycorias, Doubl., 260, 273,
275

Meganostoma philippa, Fabr., 265,
14

; cesonia, Sfoll., 265, 314
Teracolus calais, Cram. . ela
» dynamene, Klug. . ole

» amata, Fabr. . 261, 266

» protractus, Buil.. . . 312

», Phisadia, Godt. 266

» puellaris, Buti. . 275, 311

» eris, Klug. . wale 200

» vesta, Retche 5 PALS

,», hewitsonil, Kirb., 261, 266, 275

es tripunctatus, Bull. "312

», Pleione, Klug. . 311

,, ccoelestis, Swinh. 312

,, Subfasciatus, Swains. 317

», regina, Trim., 261, 266, 275,
279

» lone, Godt., 261, 266, 275, 279

» danae, Fabr. . 261, 275

5 eupompe, Klug. Byteloy oily

» wallengreni, Butl. 312

» etrida, Boisd. 261

» evanthe, Boisd. 275

* Probably not a Mylothris ; see Trimen,

flies,” vol. ii1., 1889, p. 35, note.

“ South-African Butter-

302

Teracolus eucharis, Fabr. 261
» evarne, Klug. . . 311, 316

,, theogone, Botsd. . 312
,, antevippe, Boisd. 283
», omphale, Godt. 275
» evippe, Linn. 275
Txias eulimene, Klug. . 312
» venatus, ‘Butl. . 312
5» evippe, Drury . 312

», marianne, Cram., 261, 266,
275, 312

Hebomoia glaucippe, Linn., 261,
ZlD, old

Ptychopteryx lucas, Grandid., 316,
ols 318, 327

Rhodocera leachiana, Godt., 260,

265, 279, 273, 328
Callidryas thalestris, Hiibn., 254,

274

3 philea, Linn., 254, 260,
273, 315, 329

3 senne, Linn. 315
eubule, Linn. .274, 315

Metura rurina, Feld. . 316, 329
Pheebis trite, Linn. . 260, 274, 329
Ks agarithe, Boisd. 315

Aphrissa godartiana, Swains., 260,
273, 316
Catopsilia flava, Butl. . .200, 266
catilla, Cram. . 260, 273, 274
phlegeus, Wall. 260
hyblea, Boisd., : ooh
thauruma, Reak. MO, Olesoae
» florella, Fabr. . 273, "315, 308
Kricogonia lyside, Hiibn. se 314, 328

Leptophobia eleusis, Lue. . 287
us elodia, Boisd. 287

% stamnata, Lue. . 320
tovaria, Feld. 287

Pieris habra, Doubl. . . 281, 286

locusta, Feld., 281, 286, 289,
319

., thaloe, Godt., 287, 319, 320
demophile, Linn., 282, 319,
320

pylotis, Godi., 277, 289, 319
» bunie, Hiibn., 277, 282, 287,
319

Hiposeritia pandione, Hiibn., ae
305

lalage, Doubl., 256, 277, 306
O00

”

Catophaga ega, Boisd. .

- zamboanga, Feld., 256
. paulina, Cram. 305

Dr. Frederick A. Dixey on the

Catophaga lankapura, Moore. 256
iH galena, Feld. . .. 305

- jacquinotii, Wall., 305

ie alope, Wall. . . 305
Appias celestina, Bofsd. . 269, 305
» Clementina, Feld. . . 305

» nero, Fabr. 256, 305

», hombronii, Lue. Ar tsi3)

» ‘lyncida, Cram. . .269, 283

» zelmira, Cram. . 28)
Glutophrissa poeyi, Butl. . . 309
» margarita, Hibn., 279, 309

» castalia, Fabr.. . 309, 310

se Sabah GOT S09 anO
Saletara panda, Godt. . 305
3 cyeinnma, ew. 305
Phrissura phaola, Doubl. es)
» sylvia, Fabr. 279, 309

» eudoxia, Cram. . 309

coniata, Butl. eee)
illana, Feld.. . .308, 309
lasti, Grose Smith, 308, 309
nagare, Grose Smith, 308
majungana,Grose Smith, 308
isokari, Grose Smith . 308
polisma, Hew. . 308, 309
Daptonura lycimnia, Cram., 279), 329
Belenois helcida, Boisd. . 289
thysa, Hopf. 308
peristhene, Boisd., 256, 268,

280, 310
», taprobana, Moore 329
» auriginea, Buil. . 279

mesentina, Cram., 255, 268,
276, 219, 283, 310; 329
calypso, Drury, 268, 276
creona, Cram. . a2
teutonia, Fabr., 256, 268,
276, 279, 280

coronea, Cram., 256, 268,
276, 280

gidica, Godt. 280
» severina, Cram. . 256
| Synchloe daplidice, Linn., 253, 254,
259, 263, 267, 270, 278, 306
glauconome, Klug., 306,
311, 326
Crowley, 268,
306, 310, 326
hellica, Linn., 255, 264,
268, 270, 278, 279, 306,

johnstonii,

310, 311, 326
callidice, Hsp., 253, 254,
264, 268, 270, 306

Phylogeny of the Pierinee.

Synchloe protodice, Boisd. & Lec.,
264, 268, 271

,, chloridice, Hiibn. 306
Tatochila autodice, Hiihn., 254, 264,
270, 272, 283, 306
theodice, Boisd., 254, 264,
ZA, 299; 306

Phuha nymphula, Blanch., 307, 323
Neophasia menapia, Fe/d., 304, 307,
325

terlootii, Behr., 303, 307, 322
Sp. Benn. 303, 307, 322
Pontia crategi, Linn., 257, 267, 277,
278, 303, 306, 323

hippia, Brem., 278, 308, 323
soracta, Moore, 257, 267, 2,
279° 303, 323

belucha, Marshail, 303, 323
leucodice, Hversm., 303, 306,

”

”

393
» nabellica, Boisd., 303, 323
oberthiiri, TH. 303

Mesapia peloria, "Hew., 304, 307, 324
Baltia shawii, Bates 307, 324
PA butleri, Moore : 307, 324
Metaporia agathon, Gray, 257, 267,
277, 279, 302, 304, 324

phryxe, Boisd., 277, 279
Ganoris napi, Linn., 252, 253, 263,
bryoniz, Ochs. . 270
brassicze, Linn., 252,253, 263

”
”

» giuciria, Cram., 253, 264,
278

» rape, Linn, 252, 253, 263,
326

Pinacopteryx pigea, Boisd. 2S
3 larima, Boisd. . 256

7 capricornus, Ward,
268, 279, 311

Huphina cassida, Fadr., 305

phryne, Fabr., 257, 277,

304, 324
coronis, Cram. 257
timnatha, Hew., 258, 277

”

Huphina eperia, Boisd.
naomi, Wall. .
lea, Doubl. .
aspasia, Stoll,
judith, Fabr .
nabis, Lucas .
nama, Moore
Udaiana cynis, "Hew.
monuste, Linn.
suasa, Boisd.

5 joppe, Boisd.
Herpeenia eriphia, (Godt.,
tritogenia, Klug.

”

”
7

”

”
Nepheronia valeria, Cram.
grea, Feld.

EDD we
. 308, 3:
noeleae
279,

lacteipennis, Bull. .

lobea, Boisd. .
thalassina, Boisd., 266,

262

. 267, 277

262
979, 316

argia, Fabr., 279, 308

Eronia cleodora, Hiibn. . 316, 318
» leda, Doubl., 262, 266, ilies
318

Kuchloe belia, Zinn. . . 318
eupheno, Esp. 261

reakirtii, Hdw.
genutia, abr.
belemia, Msp. .
ausonia, [iibn.,
ausonides, Luc.
hyantis, Hdw.
tagis, Hiibn.

lucilla, Butl., 261,
Zegris eupheme, Esp.
Leptosia sinapis, Linn. .
Eroessa chilensis, Guér.

261,

cardamines, Linn., 261,276

261

-276, 318

276
266
318

261

261, 266
charlonia, Donz., 276, 318,

327
276, 318
318

. 321, 323
. 318, 327

Moschoneura methymna, Godt., 321

Dismorphia melia, Godt.
”
7

i nemesis, Lat.

DANAIN@.

astyocha, Hiibn. :
praxinoe, Douwbl,

ae

Lycoreaatergatis, Doubl.d: Hew.299 | Ceratinia (Ithomia) dionza, Hew.299

HELICONINA.
Heliconius melpomene, Linn., 294, | Heliconius hydara, Hew.

296
. thelxiope, Hiibn. . 295
7 vuleanus, Butl. . 294

phyllis, Fabr.
burneyi, Hiibn.

bP)
”)

« 204
294
295

334 On the Phylogeny of the Pierinee.

PAPILIONINA.
Papilio nephalion, Godt. . . . . 298
zacynthus, Fabr. . 295,298
2 { polymetus, Godt. . 285,298
euterpinus, Godm. & Salv., 294

INCERTA SEDIS.

Styx infernalis, Staudgr. . . . 290
Pseudopontia paradoxa, Feld. . 290
Davidina armandi, Oberthr. . . 304

bh}

EXPLANATION OF PLATES Tin Veeco WE

PEAR hy,

Fic. 1. Eucheira socialis.
2. Catasticta bithys.
3. C. ctemene.
4, Delias belladonna.
5. D. eucharis °.
6. D. nysa ¢.
7. Metaporia agathon.
8. Huphina phryne 9.

PATE DY:

Fic. 9. Catophaga paulina 9.
10. Appias clementina 9.
11. Hiposcritia lalage %.
12. Mylothris agathina.
13. Belenois mesentina 2.
14. B. peristhene.
15. Synchloe daplidice ¢.
16. Ganoris napi @.

PLATE V.

Fic. 17. Teracolus hewitsonii.
18. Izias marianne Q.
19. Hebomoia glaucippe 9.
20. Colias hyale 2.
21. Catopsila crocale, var. flava ¢.
22. Callidryas philea 9 .*
23. Eronia leda 9.
24. Euchloe charlonia.

These figures are only designed to illustrate the actual points
mentioned in the text. They are not intended to show specific
characters. The same letters and numbers stand for the corre-
sponding markings throughout all the figures. See explanations
in the text, pp. 254, 264, 269, 273, 274.

Nore.—In Fig. 15, S 8 is placed one space too high up.

* This figure was drawn from a specimen in the Hope Collec-
tion, which had been erroneously labelled C. thalestris. The error
has unfortunately found its way into the plate.

———————————— rr

Trans Fnt.Soc. Lon&l.I8 94. Pt 17.

a se emeial

M719

Lrg
Hucherra socialis T9. Mia Catasticta ctemene

Catasticta bithys

ME

M20

= ie
Dehas nysa 6 ae
Metaporia agathon Huphina phryne “

FADicey del. West, Newman hth.

Wings Of VE Wereaiees

Hiposeritia.

~ dalage

SI5

M20... : Ni o>

Mylothris agathina

ae SI we

Oe Sr"

Belenois mesentinad
Pay”

Belenois peristhene 5%

16

Gamoris napi g

Poona S18

Synchloe daplidice g
15

West,Newman hth. is =

Wings of SP ier pss.

[xzias marianne Q
SY aE

2 ae
mares

Ae

aR

23 \\ \ONG es

) Catopsiia crocale
Var flava,
PUAgisocey del.

Eronia leda @

West, Newman lith.

Wing s of Pierine:

’ *
hy f
4
j : ee
: 1 “I
My
} Y a J
moe Ae | é
Vea NG te
Wace
i
i } :
, if
4)
; }
ius a 4
f
‘ , .
\
l
‘
2)
|
i \
HU
i ;
j Ae
> is
in| i J i

oe

ON

WALKER’S AMERICAN TYPES

OF

LEPIDOPTERA

IN THE

OXFORD UNIVERSITY MUSEUM.

BY

W. SCHAUS, FZS.

[From the PROCEEDINGS OF THE ZOOLOGICAL Society or Lonvon,
June 16, 1896. |

[1]

634 MR. W. SCHAUS ON WALKER'S [June 16,

On Walker’s American Types of Lepidoptera in the Oxford
University Museum. By W. Scuavs, F.Z.S.

The following notes on Walker’s American types in the Oxford
University Museum are to be foliowed by others, wherein the
complete synonymy will be given of many of the species, and
references will also be made to those species which as yet remain
unidentified. My special thanks are due to Prof. E. B. Poulton,
F.R.S., for the trouble he took in selecting the American Moths
from the Hope Collection, and sending them family by family to
the British Museum to be compared with the collections there and
with my own collection; and to Mr. G. F. Hampson for his
untiring kindness and assistance. Those species marked with an
asterisk are represented in my own collection ; those of which I do
not possess specimens, and which are not in the British Museum
either, have been figured in duplicate, one set of figures being
placed in the Entomological Department of that Museum. The
species described by Walker in parts 27-30 of his Catalogue, and
in the corresponding portions of the Supplement, as being in
“Coll. Saunders ” never formed part of the Hope Collection of the
Oxford Museum, but have lately been purchased by the British
Museum, where the types are now to be found.

The references given refer to Walker’s ‘ List of the Specimens of
Lepidopterous Insects in the Collection of the British Museum,’

Vou. II.
P. 775. *Norape puella described from the Fry coll. is now in the
Saunders coll., and is the same as Archylus pectoral,

Walk.
Von. IV.
P. 801. Sarsina purpurascens. I have not yet been able to find
the type.

P. 895. *Darala falcata=Lonomia submacula, Walk.
P. 957. Lsychagrapha floccosa. Not identified.

Wor, iV.

P. 1046. *Naprepa camelinerdes is a distinct species belonging to
the Notodontide.

P.1115. Laruma heterogenea is a distinct species, the genus
being the same as Hydrias.

P. 1152. Nesara apicalis belongs to the genus Ocha, Walk.

P. 1155. *Pamea excavata and Pamea notata are the sexes of one
species.

P. 1155. *Pamea vittata belongs to the genus Carthara, Walk.

P. 1170. osema deolis is not Cramer’s species, and I therefore
propose the name of &. walkeri for it ; the species is
well described by Walker.

[2]

1896.]

AMERICAN TYPES OF LEPIDOPTERA. 635

Vou. V. (continued),

P.
iE:

Vou. VI.

P. 1264.

or on ot oy

1176.
1195.

. 1300.

1301.

1301.
1303.

. 1313.
1326.

1329.
1338.
1364.

*Tepla biluna is the same as Phecada confinis, Walk.
*Lonomia albigutta is a well-known species, but will no
doubt sink as a synonym of one of Cramer’s species.

Tropea dictynna. Evidently a distinct species and not
a mere var. of 7’, luna.
*Hyperchiria memuse. A good species allied to H. leucane,
Hbn.
*Hyperchiria cinerea, The Q of H. janeira, Westwood.
Hyperchiria pyrrhomelas is a good species.
*Hyperchiria submacula has been redescribed by Bois-
duval as H. diowvippus.
* Hyperchiria vagans is a species of Dirphia.
Rhescynthis meander, This is well figured by Maassen
and Weymer.
*Dysdemonia glaucescens. A distinct species.
Mimallo plana belongs to the genus Perophora.
*Dirphia multicolor is a distinct and well-known species.

1402. *Hydrias albidifascia. A distinct species.
1402. *Hydrias plana. <A distinct species.
1403. Hydrias confusa. The type is the only specimen I have
seen of this species.
1507. Hydrias tenebrosa. Not identified.
Wor. Vit.
P. 1598. Seryda cincta. Not identified.
P. 1601. Pseudomya consolata belongs to the genus Lemocharis.
P. 1602. Pseudomya desperata. Closely allied to P. tipulina, Hiibn,
P.1602. Gymnelia byuncta. Subsequently described by Walker
as G'‘. consociata.
P. 1603. Gymanelia simplex. A distinct species.
P. 1603. *Gymnelia wanthocera. A distinct species.
P. 1604. Isanthrene odyneroides is a species of Erruca.
P. 1606. Pacilosoma sperans belongs to the genus Marissa,
P. 1606. Pecilosoma insperata also belongs to the genus Marissa.
P. 1607. Pecilosoma gaudens belongs to the genus Dycladia.
P. 1608, *Lagaria acuminata. Redescribed and figured by Schaus
in Lep. Am. as Gartha dalsa,
P. 1609. Lemocharis contracta belongs to the genus Erruca,
P. 1610. Jlipa tenthredoides. Also in B. M.
P.1611. Lhipa scita=S. hilaris, Walk., in B. M.
P. 1613. Cosmosoma marginatum is a distinct species.
P. 1615. *Eurata transiens= Dycladia lucetius, Cr.
P. 1617. *Hunomia vacillans is a good species.
P. 1617. *Hunomia abdominalis= Corematura chrysogastra, Perty.
P. 1618. Eunomia separata. Not identified.
P. 1619. Pseudosphea consobrina. Also in B. M.
P.1619. Pseudosphex cognata=Ps. fasciolata, Butl., in B. M.
P. 1620, Myrmecopsis opaca= Ps. vespa, H.-S., fig. 426.

41*
[3]

MR, W. SCHAUS ON WALKER’S [June 16,

Vou. VIL. (continued).

RH SRR RR OR OW

gd ge) a ashenclinel nellac|inel|ac lnc] ipo) sel ge) achealiae (8c) ae

» G27.
. 1623.
. 1629.

. 1629.
. 1634.
. 1635.

1635,
1636.
1636.

1638.
1638.
1639.
1639.
1640,

1640.
1644,
1645.
1647.

1647.
1648,
1649.
1650,
1651.
1652.

1652.
1654,

1655

1656.
1657.
1657.
1659.
1661.
1661.
1662.
1663.

1677

1678.
1679.
1693.
1698.
1701.
702!
. 1704.

[4]

Calonota persprcua. A distinct species.
Calonota interrupta. Allied to the preceding.
* Pampa acuminata. Redescribed and figured by Schaus
in Lep. Am. as Sychesia hartmanni,
Pampa fusiformis = Scepsis trifasciata, Butl., in B. M.
*Automolis angulosa=A. flavicinctus, H.-S.
Automolis saturata. Figured by Felder in the ‘ Reise d.
Novara,’ t. cit. f£. 5, as A. pretewta.
Automolis basalis. A distinct species.
* Automolis chrysomelas= A. geometrica, Feld.
*Automolis leucomela. Figured in the ‘ Biologia Centr.-
Amer.’ by Druce as Pterygopterus superba.
* Automolis reducta= Sutonocrea incertus, H.-S.
Eucerea rhodophila. A distinct species.
*Kucerea latifascia= HE. archias, Stoll.
Eucerea mitigata= EF. reticulata, Butl., in B. M.
*Eucerea albiceps. Gen. nov., allied to Pseudapistosia,
Mosch.
* Hucerea discolor. A very distinct species.
Consoprium diisum. Also in B. M.
*Josia mitis. Also in B. M.
*Scea puella. Belongs to the Chrysaugine, and was
described by Warren as Semniomina albiapicalis.
Scea infans. A good species.
Ephialtias simplex = FE. abrupta, Hiibn.
Leucopsumis quitipalpis. A distinct species.
Corydalla cryptoleuca. A. distinct species.
Euagra discalis. A distinct species.
Agyrta secta is a Pyralid=Lrilusa dioptalis, Walk.=
E. pseudauxo, Feld.
Agyrta nana. <A distinct species.
Perwopis larvata. A good species.
Pericopis disjuncta. Not identified.
Lyces plagifera. A distinct species.
Lyces albiventris belongs to the genus Flavinia, Walk.
Flavinia fusifera. Also in B. M.
Avela diwersa. Not identified.
*Carahsa editha. Genus allied to Charidea.
*Sangala beata. A well-known species.
Melanchroia subvittata= Rhosus posticus, Walk.
Arina obtusa. A distinct species.
Pheochlena quadricolor. A distinct species.
*Spiris mgrilinea. A distinct species.
* Pagara venosa= Agorea longicornis, H.-S.
* Daritis marginalis= Pericopis lycaste, Klug.
*Tsia intricata. Genus allied to Kepantheria.
*Pithea ferruginea. Genus allied to Phaegoptera.
Aloa lanceolata. Gen. nov., allied to Halisidota.
Amastus mesorhoda. A distinct species.

~~

1896.]

AMERICAN TYPES OF LEPIDOPTERA. 637°

Vou. VIL. (continued).

P. 1704.
ecb:
Ph 706.
PB. 1706.
P. 1706.
Bei 07;
Rel (O07:
len dU Os

pel (08:
Pe Li08.
L709.
e709:

P. 1709.

iP. A hO:
legally xy

lea aee
Peli,
pe G26
le 1727.
Pu li23.
Pe biog.
P. 1749.
PB: 1761.

*Opharus basalis, A distinct species.
Halesidota flavescens. Genus allied to /dalus.
* Halesidota apicalis. A good species.
Halesidota discalis. Not identified.
Halesidota catenata= Phegoptera flavopunctata, Walk.
Halesidota corticea. Not identified.
* Halesidota semivaria. Gen. nov.
*Halesidota hasipennis=Phagoptera subtilis, Butl.=
Sychesia fimbria, Mosch.
Halesidota semirufa. A good species.
* Halesidota antica. Belongs to the genus Huchetes.
*Halesidota niveigutta. A distinct species.
*Halesidota binotata, gen. nov. This species was
described by Boisduval as Phay. cinnamomea.
*Halesidota disciplaga. Redescribed by Walker as H,
breviuscula.
*Halesidota cingulata. Belongs to the genus Mazeras.
*Ambryllis neurophylia. Redescribed and figured by
Dognin as Eepantheria hebona.
* Minara pardalina=Drymonia histrionica, H.-S.
* Podalia vesta= Megalopyge orstlochus, Cr.
Eloria mesta. A distinct species.
Eloria lucida, Also in B. M.
*Simena luctifera. A well-known Geometrid.
Gee lineosa = Andriasa margindlis, Walk.
Votodonta plagiata. Not identitied.
Ce punctata. A distinct species.

Vox. VIII.

Rae
do.
oo.

L15.

BRAS as

~L90:
eave
. 233.

aoRaciae)

Vor. IX.

BS GI:
12 195.
P, 235.

Wor xX.
Pe 268.
P. 269.

12 AKO.
. 430,

Aigeria buprestiformis. A good species.
Aigeria panisciformis, A good species.
Aiygeria blaciformis=Sesia equatus, Walk., in B. M.
Enys prominens. Figured by Felder in the ‘ Reise d.
Novara,’ t. Ixxxil. f. 5, as 7’. smerinthordes,
* Pachylia inconspicua== P, resumens, Walk.
*Oryba robusta= O. achemenides, Cr.
* Lapara bombycoides = Ellema harrisii, Clem.

Nocturip ®.

* Acronycta declaratt= Mamestra adjuneta, Bdv.

* Prodenia latifascia= Prodenia variolosa, W1k.

*Mimestra crista=M. obscurus, Dogn.=M. infernalis,
Schs.

*Celena plagiata belongs to the genus Perigea.
*Celena expuncta be longs to the genus Oliyi t.
*Graphiphoru inaja= Ne oct major, Gn.
*Teniocampe subsocit. A distinct species.

[5]

638 MR. W. SCHAUS ON WALKER’S [June 16,

Vor. XI.
P. 588. Hadena subjecta. A distinct species.
P. 606. Casandria emittens. Not identified.
P. 629. *Xylina bipunctata. A good species.
P. 737. Agrotis emittens belongs to the genus Acanthodica, Schs.
P. 739. Agrotis hirtipalpis. A distinct species.

Vou. XII.
P. 787. Acontia decisa. Not identified.
P. 819. *Xanthoptera aurifera, A distinct species.
P. 819. *Xanthoptera furcata. A distinct species.
P. 848. *Palindia punctangulata= P, alabastraria, Hiibn.
P. 917. *Plusia admonens= P. basigera, Walk.
P.977. Lymphorta unilinea, Not identified.

Vou. XIII.

. 1007. Scedisa designans. Not identified.
1034. *Chabuata ampla. A good genus and species.
1058. *Homoptera configurata. A. distinct species.
1094. *Cenipeta illustrans= C. suttea, Gn.
1094. Ccenipeta abscondens. Not identified.
1132. Stictoptera subaurata. Also in B. M.
1171. Coronta surrepens= Melipotis strigifera, Walk.
Graphigona antica. Not identified.

1251. Brujas basicincta= Ramphia evinga, Gn.

1255. *Brujas laticincta= Letis magna, Gmel.

1271. *Letis implens= Letis cortex 9, Gn.

1273. *Letis integra= Letis cortew $,Gn. The type of L, integra
is now in the B. M.

1274. *Letis albicans. The type of this species is also in the
B. M.; it is in very poor condition, but represents, I
believe, a very distinct species, of which I possess
several perfect specimens.

. 1284. *Latebraria quadriplaga=R. evinga 3, Gn.
. 1323. Hypopyra configurans. Not identified.
. 1472. *Poaphila revoluta= Hypena scabra, Fabr.

Oln XV.

1555. Orthogramma perseverans. A distinct species.
1568. *Thermesia signans= Azeta uncas, Gn.

1569. Thermesia tripunctifera=O. perseverans, Walk.
1572. *Thermesia lenis= Epidromia pannosa, Gn.
1584. Selenis amans. Not identified.

1620. Hypernaria integrans = H, augusta, Cr.

1620. Hypernaria interponens=H. augusta, Cr.
1629, *Plaxia faleigera. A distinct species.

1632. Palyna metagona=Galapha sublineata, Walk.
1640. Edyma significans. Genus allied to Thermesia.
1642. Pessida interlineata. Not identified.

. 1644. *Ausava triplaga. A good genus and species.

[6]

WW 4 WA iA
ps
bo
Ce
e

kg kg kg

rR to Pg Pb Pd Pd Pl bd

—

1896.]

AMERICAN TYPES OF LEPIDOPTERA. 639

Von. XV. (continued).

P. 1646.
. 1647.
. 1653.
1657,

1659.
1663.
1669,
1669.
1677.
NOT.
1685.
1687.
1690.
1690.
1694.
1694,
1699.
Ale
1714.
ALS:
1719.
Vey

MR or ho

1726.
1730.

1731.
1733.
1742.
1742.
. 1754.
aor
1768.
1773.
Ibe

.

Wis2.
1784.
1785.
1788.
1790.
1793.
1796.
7s
IWVASE
1800.
1800.
. 1814.

ate atae e tel dacla ded

*Oymatophora temperans= Orthodes infirma, Gn.
*Bryophila expetita, A. distinct species.
Molynda humeralis = Oroatis signata, Butl., in B. M.
Eragisa lanifera. A Notodont allied to the genus
Elymiotis.
*Leucania cinereicollis. A distinct species.
* Alpesa villicosta. Also in B. M.
* Hyabra certissima = Azelina hedularia, Gn., a Geometer.
*Becula chromatophila= Dyops ocellata, Cr.
* Laphygma congressa= Dantona discerpta, Walk.
*Laphygma trientiplaga = Oligia expuncta, Walk.
* Mamestra dentistrigata belongs to the genus Perigea, Gn.
Celena inquieta. A distinct species.
Celena tetera. A distinct species.
*Oelena subobliqua. A distinct species.
Caradrina distans = Celena inquieta, Walk.
*Caradrina laphygmoides =Perigea concisa, Walk.
* Agrotis interferens. A distinct species.
*Cirredia satellifera= Anomis exaggerata, Gn.
*Dianthecia eros. Also in B. M.
*Valeria anguliplaga. A distinct species.
* Angitia directa. A distinct species.
*Hadena vacillans=Perigea fidelia, Druce, figured in
‘ Biol. Centr.-Amer.’
* Hadena pennitarsis =H, tessellata, Sepp.
* Acroria villipes=Dargida niphanda, Druce, figured in
‘ Biol. Centr.-Amer.’
Lithomia buddhe. A distinct species.
*Xylina patefacta. A good species.
*Nesia mesta, A distinct species.
* Nystalea equipars=N. seminivea, Walk.
Pastona rudis. A good genus and species.
Palindia spectabilis= P. perlata, Gn.
Palindia ceruleilinea. Also in B. M.
* Agraga fimbripes. A good genus and species.

. *Penicillaria abscondens. Well figured in the ‘ Biologia

Centr.-Amer,’

* Abrostola interrumpens= Edema nana, Walk.

* Adrana pseudopsis =Ingura fuscescens, Walk.

*Plusia intracta=P. basigera, Walk.

Thyria aurifundens. A distinct species.

*Gonodonta ditissima. A good species.

*Cosmophila punctifera=Gonitis editria, Gn.

*Selambina trajiciens. Also in B. M.

* Homoptera separabilis belongs to the genus Campometra.

* Homoptera hadenoides belongs to the genus Nenia.

* Homoptera stipatura belongs to the genus Phosphila.
Homoptera indecidens belongs to the genus Homopyralis
Stibera hostilis. Not identified.

[7]

640 MR. W. SCHAUS ON WALKER’S [June 16

Von. XV. (continued).
. 1819. Letis discopalina. New genus near Homoptera.
. 1844. *Phurys asseverans. A good species.
1845. *Onoba trogonoides= Baniana pohli, Feld.
1846. *Phuphena fusipennis = Perigea ? trilinea, Schs.
1851. Escua extollens. Belongs to the Thermesiide.
1852. Ccervania clandestina. A Deltoid.
Amphigonia postponens. Alsoin B. M. .
1856. *Thermesia imitatura belongs to the genus Physula.
1857. Thermesia bigutta. A distinct species.
1857. Obucola expandens belongs to the genus Peosina, Gn.
1858. Capnodes extima. <A distinct species.
1859. Donacesa miricornis. Allied to Orthogramma, Gn.
1860. *Hypernaria discessura, A distinct species.

I rd bg rob bd A ed ro Pb Fd
i
i¢0)
On
(or)

Detrorp# and PyRaLipsz.
Vou. XVI.

P. 80. *Hypena acclinalis= Hypena anicina, Druce, Biol. Centr.-
Amer., Het. i. p. 434 (tab. xxxv. fig. 13).

P. 81. *Hypena mestalis belongs to the genus Rejectaria, Gn.,
and is allied to R. cocytalis, Gn.

P. 81. *Hypena hastatalis. Subsequently described by Walker
as Crymona receptalis, Trans. Ent. Soc. Lond. 3rd
ser. i. p. 117. The species will stand as Crymona
hastatalis.

P. 186. *Bocana orionalis = Simplicia tibialis, Felder, ‘ Reise d.
Novara,’ t. exx. fig. 43.

P. 190. Jpnea erebusalis belongs to the genus Ceromacra, Gn.,
of the Mocilline.

P. 242. *Bleptina proliferalis. A distinct species.

P. 251. Galanda hebrusalis. A good species belonging to the
Hypenide.

Vou. XVII.
P. 438. *Cataclysta? pegasalis belongs to the genus Dicymolomia,
and was redescribed by Walker as C. principalis, Cat.
Het. B. M. vol. xxxiv. p. 1333.
P. 442. Cataclysta pantheralis. A good species.
P. 448. Cataclysta phedralis belongs to the genus Ambia.

Vou. XVITI.

P. 513. *Prakellura dardusalis=Mesocondyla stiqmatalis, Led.
Wiener ent. Monatsch. vol. vii. ¢. 13. fig. 3.

P. 513. *Phakellura eumeusalis belongs to the genus Sestia.

P. 522. Margaronia argealis= M,. aquarialis, Led. MS., in B, M.

P. 523. Margaronia ianthealis belongs to the genus Sozoa, Walk.,
and was redescribed by Walker as Sozoa costalis, Cat.
Lep. Het. B. M. vol. xxxiv. p. 1373.

P, 523. *Margaromia hypheusalis. A good species.

P. 536, Chromodes armeniacalis. A good species.

P. 593. Botys mnemusalis. Not identified.

[8]

1896. ] AMERICAN TYPES OF LEPIDOPTERA. 641

Vor. XVIII. (continued).

lee
Pe

Pe

lee
‘Ps

RH rit thd

. 595. Botys eubulealis belongs to the genus Hyalea.
. 595. *Botys nerissalis belongs to the genus Phlyctenia, and is

allied to P. cunetfera, Warr., in B. M.

596. *Botys cyprealis=Tanaura sublutalis, Warr., in B. M.

597. *Botys remusalis= Anarmodia inscriptalis, Gn.

600. Botys pyrrhusalis. Not ideutitied.

601. *Botys chlorisalis belongs to the genus Pantographa, Led.

602, * Botys melitealis= Blepharomastix colubralis, Gun.

609. *Botys quirinalis=Sylepta pactolals, Gn.

610. Botys thalloalis= Allactostigma inguinalis, Gn.

610. *Botys peranthusalis= Eulepte concordalis, Gn., in B, M.

611. Botys niavialis. Not identified.

615. Botys elathealis belongs to the genus Celorhyncidia,
Hamps., Hydrocampine.

615. *Botys sylvialis= Hyalorista myopicalis, Led.

617. *Botys agenoralis= Microthyris prolongalis, Gn.

617. Botys damonalis belongs to the genus Sylepta.

618. Botys pandaralis belongs to the genus Cvlorhyneidia.

622. *Botys evippeulis belongs to the genus Syllepis.

623. Botys persiusalis=Phostria confluentalis, Warr., in B. M.

626. Botys asiusalis=romalis, Druce, belongs to the genus
Massepha, Walk.

627. *Botys odiusalis belongs to the genus Sylepta.

627. *Botys pieralis=Azochis gripusalis, Walk. vol. xviii.
p- 42.

628. *Botys turnusalis=Prenesta scyllalis, Walk. vol. xviii.
p- 565,

629. *Botys claudiusalis belongs to the genus Calamachrous.
631. *Botys sabalis= Hedylepta vulgalis, Gn.

Wome, XULX.

PB:
FP.
Pe
iE:
EB:
ley
P.
le
12

E:
IE:

833. Geroda xeneusalis. A Noctuid belonging to the Trifine
near the genus Amynd.

835. *Nachaba congrualis. A distinct species of the Chrysau-
gine.

835. Nachaba oppositalis. A distinct species of the
Chrysaugine.

836. *Licha undilinealis= Leucania cicatriv, Feld. Reise d. Nov.
fepelsy MS. .S.

837. Lancia phrontisalis. Not identified.

838. Pterhemia otusalis=P. uncinalis, Hubn.

839. *Lascoria phormisalis belongs to the genus Tortricodes,
and is figured in Biol. Centr.-Amer., Het. i. t. 38.
figs. 14, 15.

840. *Hypena deldonalis. Very similar to Britha hirtipalpis,
Walk.

841. *Hypena xenaresalis. A distinct species.

842. Hypena lyrcusalis. A distinct species.

842. *Hypena lysoalis= H. evoletalis, Gn.

[9]

642

MR. W. SCHAUS ON WALKER’S [June 16,

Von. XIX. (continued).

Rid Pe Hi Re See SD ee eS oe ee

843.
844,
846.
846.
847.
850.
851.
857.

857.
858.
8959.

862.
863.

863,

869.
870.
870.
871.
880.
881.
881.
885.
893.
893.
894.

894.
896.

923.
927.

928.
928.
936.
[10]

*Hypena degesalis. A distinct species.
*Hypena subbasalis. A distinct species.
*Mursa calisalis. A distinct species.
Gisira endeisalis. Not identified.
Hormisa abeluvalis=Phurys basilans, Gn.
*Langasa perillalis. A good genus and species.
* Hydara biconalis= Psaliodes paleata, Gn., a Geometrid.
*Herminia meonalis. A very distinct species belonging
to a new genus.
* Herminia apisalis belongs to the genus Palthis.
* Herminia asteralis= Palthis aspisalis, Walk.
Hermina baresalis=Mastygophorus epitusalis, Walk.
vol. xvi. p. 150.
* Bleptina metopcalis = B. confusalis, Gu.
Bleptina pollesalis. Apparently a faded specimen of
B. confusalis, Gn.
* Bleptina bogusalis belongs to the genus Heterogramma,
Gn.

. *Bleptina opiteralis= Tortricodes phormisalis, Walk.
. *Bleptina oppialis = Heterogramma endorealis, Gn.
. *Bleptina bizialis=Palthis agroteralis, Gn.

Bleptina styrusalis. A distinct species.

. *Bleptina cepioalis= Het. bogusalis, Walk.
. *Bleptina fadusalis=also Het. bogusalis, Walk.

Bleptina ophelasalis= B. styrusalis, Walk. p. 866.

. *Bleptina ceusalis= Het. bogusalis Walk.

Bleptina abarusalis. Nota Bleptina. Near the genus
Catada.
Bleptina stalemusalis. A distinct species.
* Bleptina pagasusalis. A distinct species.
* Bleptina bogesalis= B. confusalis, Gn.
Bleptina watusalis. A good species.
*Renia? decelusalis= Bleptina pagasusalis, Walk.
Renia? lytocalis. A distinct species.

*Renia? borgesalis belongs to the genus Megachyta.
Megatomis euphrionalis. A good species.

* Pyralis antenoralis belongs to the genus Bradina.
Pyralis thiastoralis belongs to the genus thodoneura.
Pyralis ninniusalis belongs to the genus Hypolamprus of

fam. Thyridide.
Pyralis? byzesalis. Not identified.

*Pyralis? atialis belongs to the Tineidx, genus Tortrico-

morpha=varipes and vescatilis, Walk.

*Rhodaria probalis=Hamatia panopealis, Walk.

Desmia pisusalis=reconditalis and minualis, Walk.,
belongs to the genus Diathrausta.

*Desmia bulisalis = D. ufeus, Cr.

Desmia nerinalis belongs to the genus Diathrausta.

*Samea calonalis belongs to the genus Scioresta.

1896,]

AMERICAN TYPES OF LEPIDOPTERA. 643

Von. XIX. (continued).

hg RA

WH rh fro ht

. 937.

. O44.
. 945.

948.
949.
949,

eo)
Ou
oS

P, 23.
P. 45.

*Samea luccusalis=S. ecclesialis, Gn.
* Hymenia? phrasiusalis =H. perspectalis, Hiibn.
*Tsopterya? staiusalis=Phlyctenia scitalis, Led.
Lineodes peridialis. Not identified.
* Hydrophysa adiantialis. A good species.
Hydrophysa cepiosalis belongs to the genus Parthenodes,
Gn.
Oligostigma scuthesalis belongs to the genus Aulacodes,
and is the same as -A. psyllalis, Gn.

. *Oligostigma iasusalis. A distinct species.

Cataclysta eglesalis. A distinct species.

. *Cataclysta cesoalis. A distinct species.
. *Cataclysta walis, A distinct species.
. *Cymoriza etalis. Nymphula lotials, Feld., ‘ Reise d.

Novara,’ t. exxxv. fig. 4.
Cymoriza bocusalis. A good species.
Cymoriza badiusalis belongs to the genus Nymphula.

. *Cymoriza narcissusalis belongs to the genus Musotima.

Cymoriza abrotalis. A distinct species.
Cymoriza bolusalis=C. damescalis, Gn.,in B. M.
Zebronia lacrinesalis belongs to the genus Conchylodes.

. *Zebronia deicoonalis belongs to the genus Aripana,

Zebronia celiusalis. Not identified.

. *Zebronia bunusalis= Aripana levinia, Cr.

Zebronia ? bialis. Not identified.
Zebronia? abronalis= Platytes pusillalis, Hiibn.

. *Botys tytiusalis belongs to the genus /sosalbia.

. *Botys autoclesalis belongs to the genus Notaspis, Led.

. *Botys azionalis = Dolichosticha cochrusalis, Walk. p. 959.
. *Botys dimichealis belongs to the genus Tegostoma.

. *Botys graviusalis=Samea paolinalis, Warr., in B. M.

Botys imbrexalis belongs to the genus Ceratoclasis, Led.
* Botys nocmonalis = Phlyctenia nerissalis, Walk. vol. xviii.
p- 995.
Botys acilialis. Not identified.

. *Botys gelliasalis =Steniodes lutealis, Snell., in B. M.
. *EHbulia? ialis belongs to the genus Hapalia.
. *Pionea cemaroalis belongs to the genus Tholeria.

Pionea ademonalis. A distinct species.

eT Lee Withosidaaleo ns Bae

Davara azonaxsalis. A. Phycyta.

. *Dantona busalis=N. discerpta, Walk. This is a Noctuid,

and will stand as Dantona discerpta, Walk.

. *Motya abseusalis. A good species.

(GEOMETRID &.

2.3%

* Oherodes invariaria= dischropteryv tetragonata, Gn.
*Olysia absconditaria = Rio form of C. tasima, Cr.

[11]

644°

‘MR. W. SCHAUS ON WALKERS | [June 16,

Von. XX. (continued).
Poo.
BAG
P62.
P. 64.
P64.
1B (Ch
P. 94.

°

.

oF re bd od dd td

Fe Eo be bo ba bb do te dd oo

109.
109.
110.
alO:
Juki
147.
iba
194.
195.
220.
999

223.
225.
225.
226.
226.
227.
229.
229.
230.
234.
235.
236,
236.
237.
238.
238.
239.
240.
240.
241.
241.
242.
246.
251.
245.
254.
256.
262.
268.
269.

. 275.

[12]

*Oxydia noctuitaria =O. vitiligata, Feld.
Cherodes assyllusaria. Not identified.
* Mucronodes oricusaria=Oxydia trychiata, Gn.
*Oxydia alpiscaria=Oxydia apidama, Cr.
Oxydia cariaria. A distinct species.
* Drepanodes agronaria. A. distinct species.
*Gynopteryx telysaria=G. rhombaria 2 , Gn.
* A picia rhumata= A. lintearia, Gn.
Apicia nazadaria. A distinct species.
* Apicia uxiaria=Gynopteryx seriaria g, Gn.
* Apicia alphiusaria. A distinct species.
* Apicia? gaumnaria= Drepanodes hamulata, Gn.
* Nematocampa varicata. A good species.
* Caberodes carcearia = UC. fundaria, Gn.
* Azelina asilasaria=A. denticulata, Butl.
Azelina amyclaria, Not identified.
*Urapteryx palindiaria = Aischropteryx onustaria, Hiibn.
* Cherodes contemnaria=Certima muscistriyata, Gn.
Oxydia nerisaria. A distinct species.
* Drepanodes arnataria=D. pholata, Gn.
* Drepanodes excavaria. A distinct species.
* Drepanodes apertaria=Pyrinia erythrocephalata, Gn.
* Drepanodes grata. A distinct species.
* Drepanodes diffundaria. A distinct species.
Pyrinia madiaria. A distinct species.
*Pyrinia mephasaria. A distinct species.
*Pyrinia aleandraria. <A. distinct species.
* Apicia wpaliusaria =A. spinetaria $, Gn.
* Apicia significaria= Renodes brevipalpis, Gu.
Apicia incrassata. Not identified.
* Apicia extimaria. A Boarmid of the gen. Ketropis, Hiibn.
* Apicia atillaria= Renodes brevipalpis, Gn.
Apicia molusaria. Not identitied.
* Apicia anseraria belongs to the genus Drepanocdes.
* Apicia inficitaria=Apicia asopia, Druce.
Epione allutiusaria, Not identified.
Epione ardysaria, Not identified.
*Hpione mitranaria. A distinct species.
*Hpione relictaria. A distinct species.
* Angerona expulsaria= Alana transitaria, Gn.
* Nematocampa nyparia belongs to the genus 4nictes, Warr.
* Caberodes asanderaria. <A distinct species.
Dasmeuda aleimusata. A distinct species.
*Husenea eniasaria. In B. M. under the genus Azelina.
* Azelina fusaria=A. stolidata, Gn.
* Halesa enetusaria = H. glauca, Butl.
* Laudosia buddloraria = Cirsodes acuminata, Gn.
*Bassania amethystata. A good species.
Berambe gallaria. Not identified.

1896.] AMERICAN 'TYPES OF LEPIDOPTERA. ‘645

Vou. XXI.

P. 296. *Meticulodes wylochromaria=M. wylinaria, Gn.
354. Boarmia contraria belongs to the genus Huctenectropis.
304. *Boarmia vacillaria=B. vacillaria, Gn.
357. Boarmia mollearia. A distinct species.
357. *Boarmia detractaria=Tephrosia dimidiaria, Gn.
358. *Boarmia guttularia= Bryoptera leprosata, Gn.
359. Boarmia defimaria belongs to the genus Huctenectropis.
360. *Boarmia delinquaria. A distinct species.
361. *Boarmia larentiata= Pterocypha umbrinata, Gn.
362. *Boarmia denticularia= Tephrosia hyberniaria, Gn.
363. Boarmia consimilaria. A distinct species.
363. Boarmia locupletaria belongs to the genus Pterocypha.
363. Boarmia stigmaria. Not identified.

411. *Tephrosia incongruaria= Bryoptera leprosata, Gn.
412. * Tephrosia ineffectaria= Tephrosia responsaria, Walk.
424, *Paraphia macariata =Semothisa pernicata, Gn.
425. Paraphia epioneata, A distinct species.
482, Gazena diwulsa, <A distinct species.

ee. O.G i

. 503. *Achlora veniliata=Cambogia insiynata, Walk.
. 903, *Achlora catenularia. A distinct species.
-512. Geometra basiplaga. A distinct species.

. 583. *Racheospila marginiplaga=R. ocellata, Cr.

. 983. *ltacheospila satisfacta. A distinct species.

. 993. Thalera distracta. A distinct species.

- 662. Hyria subtectata. Not identified.

P. 732. *Acidalia obliviaria. A distinct species.

P. 742. Acidalia justata. Not identified.

Vou. XXIII.

788. * Acidaha indecretaria =A, obliviaria, Walk.

. 788. *Acidalia responsaria, A distinet species.

789. *Acidalia suffusaria=Certima muscistrigata, Gn.
799. Timandra viridiplaga. A distinct species.

827. *Ratiaria argentilinea = Urapteryw platinata, Gu.
828. Ratiaria metavantha. Not identified.

839. *Hrosia leucospilaria. A distinct species.

839. *Hrosta senilaria belongs to the genus Schidaw.
841. *Hrosia lacerataria. A distinct species.

Erosia distincta belongs to the genus Psaliodes.
. *Erosia subsignaria. A distinet species.

859. *Paloda dentifera = Erosia acutangularia, Walk.
910, *Macaria subitaria=Semiothisa triplicaria, H.-S.
911. Macaria manduta, A distinct species.

912. *Macaria concisaria. A distinct species.

. *Macaria percisaria=Semiothisa gambaria, Hiibn.
5. *Macaria continuaria=Semiothisa pernicata, Gu.
919. *Macaria externaria=S. pernicata, Gn.

. *Macaria fractaria=S. nervata, Gn.

hd bd rd ed dd

dhe hte ho

Vv

ie}

avaohalacha-lachac)

by be hd

(oa)
mse
Or

Ne}
—_
Oo

Mir td rot roth td tod be
Wo) 10.0)
“4 r=
2 =

ie]
ie)
—
<

[13]

646 MR. W. SCHAUS ON WALKER’S [June 16

Vou. XXIV.

P. 1069. Aspilates perlineata. A distinct species.
P. 1081. <Alydda lignosata. Not identified.

P. 1100. Gustiana subflewata is a Deltoid.

P. 1264. Thera perarcuata, A distinct species.

Vou. XXV.

1310. *Coremia lateraria= C. fringillata, Gn.

1338. *Phibalapterya mediata=Plemyria fluviata 2 , Hibn.
1339. *Phibalapteryx intrusata=P. fluviata g , Hiibn.
1351. Scotosia nitidulata= Gazena divulsa, Walk.
1369. *Pterocypha divulsata= P. floccosaria 2, Walk.
1370. *Pterocypha celerata. A distinct species.

1396. *Cidaria perspicuata= C. emberizata, Gn.

1396. *Cidaria patulata. A distinct species.

1397. Cidaria eductata=C,. emberizata, Gn.

1397. *Cidaria intercalata. A distinct species.

ot. XX VI.

1486. Lagyra? dentilineata. Not identified.

1490. Pyrinia reflectaria. A distinct species.

1491. Pyrinia concisata. A distinct species.

1492. Pyrinia subaurata. <A distinct species.

1493. Pyrinia saturata. A distinct species.

1493. Pyrinia radiolata. Not identified.

1499. *Rumia defivata=S. deprwata, Gn.

1502. Hyperetis tessellata. A distinct species.

1502. *Hyperetis quadrilineata = Semiothisa contorta, Druce.
1505. Endropia? subapicata. Not identified.

1515. Tetracioinequaria. An Apicia allied to cayennaria, Gn,
1533. *Boarmia perspectata= B. vacillaria, Gn.

1534. *Boarmia subapicata=B. syrniaria, Gn.

1534. Boarmia tenerata is the ¢ of B. mollearia, Walk.
1553. Cariprea mendaciaria, Not identified.

1560. *Thalassodes glauculata, A distinct species.
1578. *Anisodes congruaria.@ A distinct species.

1579. Anisodes fimbripedata. Not identified.

1579. *Anisodes ordinata=directata=A. urcearia, Gn. ?
1587. Hyria gavisata. A distinct species.

1587. Cambogia albopunctata. <A distinct species.
1599. Acidalia calidata. Not identified.

1600. *Acidalia tepidata. A distinct species.

1600. <Acidalia indignaria=Cambogia marcearia, Gn., in B. M.
1626. Hrosia integrata. <A distinct species.

1627. Erosia subtruncata. Not identified.

1627. *Erosia quadruncata=Phyllodonta caninata, Gn.
1628. *Hrosia subpatulata= Epiplema incolorata, Gun.
1629. FErosia bipartaria. Not identified.

1633. Carmala flewata. Not identified.

1636. *Arcobara microniata= Pigia teryeninaria, H.-S.

[14]

RDO ED i Ot RA Po bob RA thd

1896.]

AMERICAN TYPES OF LEPIDOPTERA. 647

ee XXVI. (continued).

12. ee

Macaria vitriferaria. A distinct species.

P. 1657. Tephrina signataria. A distinct species.
P: 1658. elses ina responsaria. A distinct species.
P. 1659. *Lephrina albipunctata. A distinct species.
P. 1687. Cadyanda lugens=Calospila posthumaria, H.-S.
P. 1690. *Budara conversata. A distinct species.
P.1702. Larentia inquinata=Hammaptera perturbata, W1k., 3.
P. 1710. *Lobophora bifiliferata belongs to the genus Nola.
P.1718. Phibalapteryx erosiata. Not identified.
P. 1723. *Scotosia spilotata=Homopyrals indecidens, Walk.
P. 1730. Cidaria effrenata. Not identified.
P. 1737. Eubolia vicaria. Not identified.
P. 1754. *Cambogia porphyrinata, A distinct species.
P. 1755. Cambogia turbata, A distinct species.
P.1755. Acidala illiturata. Not identified.
P.1756. Acidalia isographata. A distinct species.
P. 1757. *Erosia niveinotata belongs to genus Dagassa,
P. 1759. Stegania quadrinotata. A distinct species.
SUPPLEMENT’.
Vou. XXXI.
P. 21. Cotena mediana. A distinct species and good genus.
P.142. Gerra hyelosioudes=Gonora heliconiata, Walk.
P. 257. *Aucula jostoides belongs to the Agaristide.
P. 304. Elysius signatus. A distinct species.
P. 317. *Addua inclusa= Pericopsis parnassioides, Walk.

WOls SOOX LL.

. 339.

Wiha
use
HS
bo

*Hloria canescens belongs to the genus Hyalospila.

. *Compsa saturata= Tarchon trilunula, H.-S.

. *Notodonta seitipennis=N. straqula, Grote.

. *Parathyris ennomoides belongs to the genus Olceclostera.
. *Gopha mixtipennis. A distinct species.

. *Blera cerruroides. A good species.

. *Rifargia wylinoides. A good species.

. *Nagidusa xylocampoides. A good species.

Luca herbida, Allied to Heterocampa.

. *Phastia basalis. A good species.

Limacodes concolor. Not identified.

Athrula saturniocides == Rolepa delineata, Walk.

Siculodes annuligera. A. distinct species.

Vadata macropterana. <A distinct species ; the species
figured under this name in the ‘ Biologia Centr.-Amer,’
is a new species.

. *Soswetra grata. A Noctuid.
. *Cistissa ewpansa= Megalopyge fuscescens, Walk.

* Batatara fusifascia= Hylesia approwimans, Walk.
Perigea adornata. Not identified.
[15]

648

MR, W. SCHAUS ON WALKERS [June 16,

Wont soon:

clinch eRCN RCH Ro) 2) ACR) AC] 5x) aac ch aC inc) aches Hac tac} act ac) ac} iec| inc} a2) ia|lac)ige|lvch as

. 1160

1028.
1037.
1048.
1049.
1051.
1052.
1053.
1053.
1068.
1073.
1073.
1074.
1075.
1079.
1081.
1087.
1088.
1091.
1100.

P. 731. *Hadena subapicalis= Heterochroma erropioides, Gn.
Tests zamora basiplaga= Az. tortriciformis, Walk.
P. 798. *Xanthoptera alboflava. A distinct species.
P. 811. *Callopistria vittata=Oligia subobliqua, Walk.
P. 814. *Penicillaria areusa belongs to the genus Jngura.
P. 852. *Hemiceras tllucens=: H. barina, Gn.
P. 861. *Gonitis reversa=G. exaggerata, Gn.
P. 866. Coruncala latipennis. Not identified.
P. 877. Homoptera discalis=Platydia mollealis, Walk.
P. 877. Homoptera gratiosa. Not identified.
P. 878. *Homoptera punctilinea. A distinct species.
P. 883. *Homoptera privata= HH. exhausta, Gn.
P. 883. Homoptera phocleuca. Not identified.
P. 884. *Homoptera parvula. A good species.
P. 915. Carthara albicosta. Not identified.
P. 998. *Phurys partita belongs to the genus Capnodes.
P. 1026. Thyridospila compta. Not identified.
P. 1027. *Thyridospila quadriocellata. New genus.

Thyridospila amena= Mulelocha calligramma, Hibn.
* Thermesia absumens = Huthermesia inexacta, Walk.
*Thermesia caliginosa = Mulelocha exsiccata, Walk.

Thermesia brevistriga. Not identified.

Thermesia divulgata. Not identified.

Thermesia subfixa belongs to the genus Henodes, Gu.

Thermesia conficita. Not identified.

Thermesia inficita. Not identified.

Selenis sttpata=S. humeralis, Walk.

Capnodes basalis= Bleptina proliferalis, Walk.

Capnodes schizospila, A distinct species.

*Capnodes concinnula, A distinct species.

Capnodes mundicola is near the genus Dagassa.

Ctypansa obtusa. Not identified.

Hypernaria rudis. Not identified.

* Hypernaria chlorospila = H. discessura, W1k.
* Hypernaria leucospila = Thermesia gemmatalis, Hubn.

Hypernaria punctulosa, Not identified.

Lhixoia subocellata, Not identified.

ou. XXXIV.
1129.
1132.
1132.
1134.
1135.
1145.
1158.
1158.
1160.

Gaala dispunctalis= Gustiana subflewata, Walk.

* Hypena bisignalis. A distinct species.

*Hypena pyralalis= Psaliodes paleata, Gn.

*Hypena disseptalis=H. ancara, Druce.

* Hypenu dissutalis=H. scabra, Fabr.

*Boana semialba. A distinct species.

* Herminia inostentalis= Megachyta borgesalis, Walk.
Herminia figuralis=Gustiana subflecata, Walk.

*Bleptina responsalis= Palthis aspisalis, Walk.

. *Bleptina penicillalis belongs to the genus Mastygophorus,

116}

1896.]

AMERICAN TYPES OF LEPIDOPTERA. 649

Vou. XXXIV. (continued).

- 1161

LG 7.
1174.
1180.
1180.
Se
kee
1191.
1192.
1199.
1224.
1225.
1225.
1225,
1232.
1262.
1283.
1303.

* Bleptina diruptalis= Megachyta borgesalis, Walk.
Bertula excelsalis belongs to the genus Mastygophorus.
*Gizama anticalis=Renia deceleusalis, Walk.
*Bononia niveilinea= Licha undilinealis, Walk.
*Crymona receptalis= H. hastalalis, Walk.
Bolica armata, A distinct species.
*Sorygaza didymata. A distinct species.
Orocala distentalis. Near the genus Notarcha.
* Alicurda vewatilis=A. atialis, Walk.
*Tibracana wanthialis. A distinct species.
Maguza albiguttalis= Pastona rudis, Walk.
Pyralis intermedialis= Hypsopygia sodalis, Walk.
* Pyralis eaternalis= Hedylepta antenoralis, Walk.
* Pyralis varipes=Alicarda atialis, Walk.
Pyralis crassipes is the 2 of Tosale pyralidoides, Walk.
*Zarania cossalis= Ethnistis munitalis, Led.
*Rhodaria directalis = Hyalorista teniolalis, Gn.
*Samea obliteralis = Sameodes niceusalis, Walk.
Oligostigma amenalis belongs to the genus Glaphyria.
Oligostigma exhibitalis. A distinct species.
Glyphodes rutilalis=G. suavis, Feld.
Margaronia auricostalis= M. argealis, Walk.

. *Botys additalis= Acharana pheopteralis, Gn.

. * Botys ineffectalis = Blephoramastia colubralis, Gn.

. *Botys fuliginalis=Stenomeles agavealis, Walk.

. *Botys cellatalis= Acharana pheopteralis, Gn.

. *Scopula permixtalis belongs to the genus Phlyctemia.

Bouchis scoparioides belongs to the genus Ethnistis.

. *Scoparia stupidalis= Illice batialis, Walk., of the family

Lithosiide.

Ole Oko.

1543.
1549.
1639.
1702.
1743.
7 Li69:

783:
. 1800.

. 1958.

. 1963.
lee

Cig WW Wid Wet Winn Nitti mdr droite ror bord bord ho iro Pore nies
©
On
tS

Pyrinia xantharia belongs to the genus Capnodes.
* Azelina immundaria= A. stuposaria, Gu.

Ceronaba cinctaria= Molybdophora concinnaria, H.-S.

Lephana tetraphorella belongs to the Noctuide. Type
in B. M.

Gabaleca bilineatella belongs to the genus Hrupa. Type
in B. M.

Zolca congruella belongs to the genus Hrupa. Type
in B.M.

Pandemis securiferana. Type in B. M.

Torda metamelana=Tosale pyralidoides, Walk. Type
in B. M.

Celena canifimbria belongs to the Noctuide. Type in

B. M.
Acontia quadrata. Type lost.
Thyridospila ceca. Type lost.

The remaining references are to species described in the Trans-
actions of the Entomological Society for 1862 :—

P. 76. *Cingilia humeralis = Caterva catenaria, Cr.
Proc. Zoou. Soc.—1896, No. XLII. 42

[17]

650

Ped Sr Pg dd Bt Pg Pg

re Te foes

ON WALKER’S AMBRICAN TYPES OF LEPIDOPTERA. [June 16.

[15]

Heterocampa thyatiroides. Not identified.

Miresa divergens=LInthacodes fasciola, H.-S.

Gora equalis. Not identified.

Erysthia obliquata (locality doubtful). Not identified.
Cottobara concinna. A Notodont.

Gaphara sobria. Allied to Celena tetera.

a usin

. *Neenia signiplena belongs to the genus Pesula.
. *Asthana erecta = Pesula transversaria, Walk.
. *Asthana directa belongs to the genus Pesula.

Baniana inequalis. A distinct species.
Gammace magniplaga. Not identified.

. *Remigia consistens=Renodes brevipalpis, Gn.

Gangra atripustula belongs to the Thermesiide.
Focilla abrupta belongs to the Thermesiide.

. *Marthama conspersa=M. squamivaria, Walk.
. *Hypena murina= HH, exoletalis, Gu., in B. M.
. *Bocana marginalis= B. orionalis g , Walk.

Salbia varialis belongs to the genus Phostria. In B. M.
Asopia depressalis. Not identified.
Cataclysta insulalis. A distinct species.

Scopula desistalis belongs to the genus Ebulea.

Scoparia fascialis=Hapalia illibalis, Hiibn.

Hadena opima. Not identified.

Poaphila plagiata. Not identified.

Poaphila figurata. Not identified.

Phurys mensurata. Not identified.

. *Hypena scissilinea belongs to the genus Saserna and is

well figured in the Biol. Centr.-Amer.
Rhagonis bicolor. Not identified.

. *Pacilocampa plurilinea= Tolype opalina, Walk.

Reprinted from the Journal of the Marine Biological Association,
N. S., Vol. w., No. 3, August, 1896.

Contributions to Marine Bionomics.

By

Walter Garstang, M.A.,

Fellow and Lecturer of Lincoln College, Oxford.

I. The Habits and Respiratory Mechanism of Corystes
cassivelaunus.

Corystes cassivelaunus is a crab of unusually narrow and elongated
form, which has received the popular name of “masked crab” from the
grotesque resemblance which its sculptured carapace bears to a human
face. It is common round all the coasts of the British Isles, and,
although normally an inhabitant of the deeper water, is occasionally
found at home in sandy pools on the sea shore, and is frequently cast
up in hundreds on sandy shores after heavy gales.

I. SYSTEMATIC POSITION.

The systematic position of the Corystoidea has long been a disputed
point among carcinologists. Henri M. Edwards (1834) placed the
Corystoid crabs near the Dorippide among the Oxystomata, and re-
garded them as connecting links between the Cancroidea (vid the
Calappidee) on the one hand, and the Anomoura on the other.

De Haan (1849) removed the family from the group Oxystomata
altogether, and placed it with the Cyclometopa and Catometopa of
M. Edwards, in a separate sub-division of the Brachyura, the Brachy-
gnatha.

Dana (1852) made of the Corystoidea an independent and primary
tribe of the Brachyura, distinct from the Cancroidea and Leucosoidea
alike.

Alphonse Milne-Edwards (1860) reverted to the older view, and
placed the Corystidze near the Calappoid Oxystomata. Heller also
(1863) placed the Corystide among the Oxystomata.

Finally, Claus (1880) definitely placed the Corystide in the Cyclo-
metopa. In this he has been followed by Miers (1886) and Stebbing
(1893).

224 CONTRIBUTIONS TO MARINE BIONOMICS.

It cannot be said, however, that the real position and affinities of the
Corystide are yet established. The reason for this uncertainty is
probably due to the fact that, as will appear further on, the structure
of these animals is remarkably modified in relation to sand-burrowing
habits. Some of these adaptive modifications of structure, which re-
appear in certain other groups of Crustacea, have undoubtedly impressed
the minds of certain writers with ideas of homology and genetic re-
lationship between the Corystide and groups having no real affinity
with that family. The case affords a new illustration of the inadequacy
of the purely morphographic method, when unchecked by considerations
of functional adaptation, for the solution of problems of relationship
and genetic classification.

II. STRUCTURAL PECULIARITIES.

The structure of Corystes cassivelaunus is noteworthy on account
of the following features. The second antenne are greatly elongated—
as long as, or longer than, the body—and are fringed along their entire
length by two rows of hairs, one of which runs along the ventral, while
the other runs along the dorsal border of the antenna. The hairs of
each row curve inwards towards those of the corresponding row on the
second antenna of the opposite side. The second antenne shew a
marked tendency to approximate to one another longitudinally; the
opposing rows of hairs then interlock, with the resulting formation of a
median tube, the lateral walls of which are formed by the jointed
flagella of the antennze, while the dorsal and ventral walls are fenes-
trated along their whole extent by the interspaces between the inter-
locking hairs. The organ formed by the apposition of the second
antennze I shall term the “antennal tube.”

The long axes of the three stout basal joints of the second antenna
are disposed at right angles to one another, and bring about a character-
istic double bend in the basal part of the antenna. The double row of
hairs found on the flagellum of the antenna is continued backwards
along these three basal joints. The hairs on the most distal of the
three joints interlock with those of the corresponding joint of the
opposite antenna ; the hairs on the anterior face of the deflected middle
joints bend inwards towards the median line along the sides of the
rostrum, and together with a median triangular tuft of hairs springing
from the rostrum itself, form the hairy roof of the proximal part of the
antennal tube.

The antennal tube opens posteriorly into a rectangular chamber in
front of the mouth. This “ prostomial chamber,” as it may be termed,
is roofed by the rostrum in front, the antennal and epistomial sternites

CONTRIBUTIONS TO MARINE BIONOMICS. 225

in the middle, and the prelabial plate behind. It is flanked by the two
basal joints of the second antenne in front, and by a forward process of
the pterygostomial region of the carapace behind. Its floor is imperfect,
and is formed by the anterior part of the third maxillipeds behind, and
by a quadrangular sieve in front, furnished by the hairs springing from
the two basal joints of the second antennz, the anterior pterygostomial
processes, and a special anterior process of the fourth joint of the
external maxillipeds. The hairs from all these parts are directed
inwards towards the centre of the quadrangular space outlined by the
boundaries of the prostomial chamber, and constitute a complete sieve-
like floor to the chamber in question. On each side this prostomial
chamber leads by a wide aperture into the branchial cavity.

The participation of the epistome together with the prelabial space in
the formation of a prostomial chamber is one of the features which
strongly distinguishes the Corystoid crabs from typical Cyclometopa,
Catometopa, and Oxyrhyncha. The arrangements of these parts approxi-
mates in some respects to that found in the Oxystomata, where the
buccal frame or the peristome is prolonged anteriorly as a definite
prostomial chamber to the very tip of the snout. This chamber in the
Oxystomata, however, is completely closed in by the third maxillipeds,
and is very narrow anteriorly ; in the Corystoidea, on the other hand, it
is broad in front, and is imperfectly closed by the third maxillipeds.

III, PREVIouS OBSERVATIONS ON HABITS.

In Bell’s “ British Stalk-Eyed Crustacea” (1853) a brief reference is
made to the sand-burrowing habits of Corystes cassivelaunus. Couch
had already described the crab as “burrowing in the sand, leaving
the extremities of its antenne alone projecting above the surface.”
The actual process of burrowing appears not to have been observed
at the time when Bell wrote, for he quotes Couch’s suggestion that the
elongated antennz possibly “assist in the process of excavation.” This
theory of the function of the antenneze was subsequently rejected by
Gosse (1865), as a result of his own observations on the habits of the
crab, and again by Hunt (1885), who correctly states that the crab
descends into the sand backwards with the greatest agility, “thus leaving
the antennz no opportunity of assisting in the operation.”

The first writers to offer anything approaching a real explanation of
the use of the antennze were the veteran naturalist of Cumbrae,
Mr. David Robertson, and Mr. P. H. Gosse. It is difficult to say, and
would indeed be ungenerous to enquire, which of these two naturalists
has the priority in the matter. Gosse, in 1855, described the outer
antenne of Corystes as “together forming a tube” (Manual of Marine

226 CONTRIBUTIONS TO MARINE BIONOMICS.

Zoology, I., p. 158), but he did not apparently publish his observations
in full until 1865.

In the meantime Mr. David Robertson communicated to the Philo-
sophical Society of Glasgow, on March 13th, 1861, an interesting note
on the function of these antenne. He described the burrowing habits
of the crab, and shewed that, under these circumstances, the antennal
tube preserved “a free passage for the purpose of enabling the animal
to carry on the process of its aqueous respiration.” Mr. Robertson
believed, with Gosse, that the current through the tube was exhalent in
character. In another paper he stated that “he had seen the ova cast
up through the opening [of the antennal tube]—the inference being
that the animal had placed it by means of its claws within the influence
of the current.” (Proc. Nat. Hist. Soc., Glasgow, vol. i. p. 1.)

Gosse (1865) similarly observed that each antenna, from the form and
arrangement of its bristles, constituted a “semi-tube, so that when
the pair was brought face to face the tube was complete.” He also
carefully watched a living specimen, as it was sitting upright on the top
of the sand, close to the side of a glass aquarium, and observed that
the antennal tube formed a channel for a definite current of water. To
quote his own words: “I immediately saw that a strong current of
water was continuously pouring up from the points of the approximated
antenne. ‘Tracing this to its origin, it became evident that it was pro-
duced by the rapid vibration of the foot-jaws, drawing in the surrounding
water, and pouring it off upwards between the united antenne, as
through a long tube. . . .” “I think, then, that we may, with an
approach to certainty, conclude that the long antennz are intended
to keep a passage open through the sand, from the bottom of the burrow
to the superincumbent water, rendered effete by having bathed the gills ;
and it is one of those exquisite contrivances and appropriations of
structure to habit which are so constantly exciting our admiration . . .
[and] are ever rewarding the research of the patient observer.”

We shall see below that while Gosse’s conduit-theory of the function
of the antennz is perfectly correct, his inferences as to the function of
the antennal conduit are true only to a limited extent. Gosse assumed
that the habits of the crab when beneath the sand were similar to its
habits when above the sand, and confined his observations to the crab
in the latter condition. Experiment shews, however, that there may be
a marked difference in the working of certain organs under the different
conditions.

A third theory as to the function of the antenne in Corystes
cassivelaunus is due to Mr. A. R. Hunt (1885). He says, “I incline to
think that the function of the antenne is to maintain a communication
between the buried crab and the water above, as without some such con-

CONTRIBUTIONS TO MARINE BIONOMICS. 227

nexion there would be a risk of the animals being occasionally buried
to a dangerous depth by the accumulation of sand above them. Mr.
W. Thompson’s statement that the antenne in very small specimens are
much longer in proportion to the carapace than in the adult harmonizes
well with this hypothesis, as to ensure safety the young would have to
burrow to a greater depth compared with the adults than would be pro-
portionate to their size.” Mr. Hunt was not aware of Gosse’s view
when he framed the above theory; but, subsequently, in a footnote
to his paper, he referred to Gosse’s theory as identical with his own.
The two are, however, essentially distinct, if I correctly understand Mr.
Hunt’s language. According to Gosse’s view, the function of the
antennz is to produce a tube subservient to respiration; according
to Mr. Hunt’s, the function of the elongated antennz is essentially
sensory, viz., to enable the buried crab to determine the depth to which
it burrows. The “danger” to which Mr. Hunt refers is clearly not the
danger of suffocation, but the danger of dislodgment from the sand by
wave-currents. The arenicolous habits of Corystes are adduced by Mr.
Hunt to illustrate one of the various methods adopted by marine
animals for resisting wave currents—a view which, in the case of
Corystes, 1 am unable to accept, partly on account of the normally deep
water habitat of the crab, and partly on account of evidence given
below which tends to shew that the burrowing habits of Corystes are
adopted primarily for concealment.

IV. NEw OBSERVATIONS AND EXPERIMENTS.

(a) Burrowing Habits. A number of living Corystes cassivelaunus
were placed in a series of vessels containing sand of different degrees of
coarseness, and it was soon noticeable that these crabs readily burrow
in fine sand, but find great difficulty in penetrating very coarse sand or
gravel composed of small pebbles. Moreover, a crab that has obstinately
declined for several hours to burrow in coarse, gravelly sand, will imme-
diately bury itself, if placed in an aquarium of fine sand. In all cases
the process of burrowing is effected exclusively by means of the
thoracic legs. The crab sits upright on the surface of the sand; the
elongated, talon-like claws of the four hindmost pairs of legs dig deeply
into the sand ; the body of the crab is thus forcibly pulled downwards
by the grip of the legs, and the displaced sand is forced upwards on the
ventral side of the body by the successive diggings and scoopings of the
legs ; the slender chelate arms of the first thoracic pair assist in the
process of excavation by thrusting outwards the sand which accumulates
round the buccal region of the descending crab. This action at the same
time, no doubt, loosens the sand in the immediate neighbourhood, and

228 CONTRIBUTIONS TO MARINE BIONOMICS.

renders easier and quicker the descent of the crab into its sandy
burrow. Briefly stated, in fact, the four hindmost pairs of legs are
all engaged in pulling the crab downwards, while the first or chelate
pair is engaged in pushing away the more superficial sand in the neigh-
bourhood of the crab’s maxillipeds. The two actions combine to drive
the crab downwards and obliquely backwards. The main object of this
latter motion appears to be the prevention of any forcible intrusion
of sand into the buccal apparatus.

When the carapace of the crab has completely disappeared beneath
the surface of the sand, the antenne are frequently seen to be rubbed
obliquely against one another for two or three strokes, whereby the hairs
on the antenne are cleansed from adhering particles. This very charac-
teristic action of the antennz was noticed long ago by Couch, and
correctly recognised by him as a process of cleansing (vide Bell, p. 161).
After this cleansing process, however, the crab proceeds still further in
its act of burrowing, and descends deeper and deeper until nothing
is visible above the sand but the most distal portion of the antennal
tube.

Resting passively in its bed of sand, Corystes cassivelawnus spends the
daytime thus concealed from all observation. In aquaria an individual
will occasionally emerge and remain on the surface of the sand for some
time, but this can usually be attributed to the restlessness resulting from
strange conditions. Iam inclined to think that if the water and sand
provided be of a perfectly suitable character, Corystes will remain
imbedded throughout the day. (cf. Robertson, l.c. supra).

I have noticed, however, that individuals which were inactive and
concealed beneath the sand during the day, shewed 2 marked tendency
to activity at night. I have observed on several occasions that my
aquarium, containing some half-dozen of these crabs, was the scene
of distinct excitement and activity late at night; the crabs had
emerged from the sand, and were restlessly hobbling about on the
surface, as though in search of food. Although I cannot make a final
statement upon the point, all my experiences incline me to the view
that Corystes cassivelawnus is a nocturnal animal; it conceals itself
in the sand by day as a protection from sight-feeding fishes, but
emerges at night for food and recreation. If these habits were ab-
solutely constant, we should expect to find the eyes of Corystes
undergoing retrogressive changes, as, for example, in the case of
Pinnotheres. Such is not the case, however, for the eyes are capable
of forming distinct images, as well as, no doubt, of distinguishing light
from darkness.

(b) Respiratory Currents. We have seen that Gosse observed a
current of water setting upwards from the buccal region of the crab

CONTRIBUTIONS TO MARINE BIONOMICS. 229

through the antennal tube, and carrying upwards the water which had
previously bathed the gills. This current was caused, according to
Gosse, by the “vigorous vibration of the foot-jaws.” The crab observed
by Gosse was sitting on the top of the sand—not beneath it.

If some sea-water be coloured by the addition of a little Chinese ink,
or finely powdered carmine (the former is the better material), and if a
few drops of the coloured water be added to the water in the neighbour-
hood of the antennal tube of a buried crab, it will invariably be found
that the current which sets through the antennal tube is from above
downwards, and not vice versa. The same current may often, and indeed
generally, be shewn to exist, even when the crab is not imbedded in the
sand.

It will then be noticed that the coloured water is sucked between
the hairs of the antennal tube, and passes downwards and backwards
to the prostomial chamber. Here, in front of the labium, the current
divides into two streams, one right and one left, which pass outwards
and backwards into the right and left branchial chambers respectively.
Finally, the coloured stream emerges from the branchial chamber
beneath the edge of the branchiostegite, not at any one point, situated
either anteriorly or posteriorly, but along its whole extent, and espe-
cially between the bases of the legs.

The direction of this current through the branchial chamber is the
reverse of that which has hitherto been recognised in all other Decapod
Crustacea. In these (¢.g., Maia, Cancer, Carcinus, Astacus) the current
which bathes the gills is known to enter this chamber beneath the
branchiostegite, and to emerge in front by the lateral aperture at the
side of the mouth. The normal peribranchial current in Decapod
Crustacea is from behind forwards; I shall, therefore, term the
current of the buried Corystes a “reversed current,” and shall speak
of the whole phenomenon as a “reversal” of the normal current.

Although Corystes cassivelaunus constantly exhibits this reversed
current when imbedded in the sand, yet it is occasionally possible
to observe the normal current in the same specimen when the animal
is not buried. The coloured water is then rejected when added near the
antennal tube; but if deposited near the bases of the legs, is sucked
inwards, and eventually emerges from the branchial cavity into the
prostomial chamber, and thence passes either directly to the exterior or
forwards by way of the antennal tube. When the normal current is at
work it frequently happens that the exopoditic palps of the maxillipeds
begin to vibrate. The action of these palps still further intensifies the
force of the exhalent currents, and at the same time disperses the
streams of water laterally, ze, the water, instead of passing to the
exterior anteriorly in an even stream, is partially diverted to the sides of

230 CONTRIBUTIONS TO MARINE BIONOMICS.

the crab’s body, and is scattered outwards and laterally by the vigorous
lashings of the exopoditic palps.

Gosse’s observations on the respiratory currents of Corystes cassive-
launus are thus seen to be incomplete rather than inaccurate. A
current may be directed outwards through the antennal tube, and the
effete water from the branchial chamber may be carried away by that
channel; but such a direction of the current in Corystes cassivelaunus is
not constant, as Gosse believed, or even usual. Moreover, when the
crab is imbedded in sand, the current is always reversed, except for
a few seconds now and then, when the crab desires to eject distasteful
particles which have entered the prostomial chamber with the respira-
tory current. Under such circumstances the reversed inhalent current
through the antennal tube is temporarily replaced by a forcible exhalent
current. But as soon as the desired ejection has been effected, the
reversed current is again set up. This voluntary inhibition of the
reversed current can be easily demonstrated by the addition of carmine
to the water setting through the antenne. Oddly enough, a weak
solution of Chinese ink is less distasteful to Corystes than a mixture
of powdered carmine and sea-water.

(c) Cause of the Currents. The direction of the respiratory currents
is exclusively due to the movements of the scaphognathite, the valve-
like and highly muscular appendage of the second maxilla, which
is known to produce the regular respiratory currents of other Decapoda.
H. Milne-Edwards first demonstrated the important rdéle played by the
scaphognathite in Decapod Crustacea; and he maintained that the
direction of the respiratory current was absolutely constant, z.¢, from
behind forwards in all Decapods (1839, p. 136). De Haan (1850,
p. 117) has indeed suggested that the current to the branchiz passes
from before backwards; but his remarks on this subject are obviously
the result of mere inference, and are not determined by actual experi-
ment. He states, for example, that in Portunus the inhalent current
sets inwards not only through the aperture between the base of the
cheliped and the edge of the branchiostegite, but also through the
anterior aperture at the side of the mouth, Experiments on Portunus
have shewn me that this is quite devoid of foundation; the water
certainly enters—in part—through the former of these apertures, but
the aperture at the side of the mouth is invariably exhalent in function.

In the case of Corystes I observed the action of the scaphognathite by
removing the three maxillipeds and the edge of the pterygostomial
fold of a living specimen. The scaphognathite was completely ex-
posed by this preparation, and its movements were readily followed.

When the normal current—from behind forwards—was at work, the
propulsion of the water could be seen to be effected by a sharp, prompt

CONTRIBUTIONS TO MARINE BIONOMICS. Zo

blow dealt by the posterior lobe of the scaphognathite, which was
succeeded by an undulatory movement from behind forwards of the
remaining part of the scaphognathite. As the crab lay on its back
the anterior lobe could finally be seen to descend slowly and gently
upon the anterior edge of the roof of the chamber, gliding along, and,
as it were, stroking its polished surface.

When the current is reversed, however, the action of the anterior
lobe is quite different; it strikes the water in front with a prompt,
decisive blow, and this is succeeded by an undulatory movement of the
rest of the scaphognathite from before backwards. The water lying
between the valve and the roof of the chamber is thus driven back-
wards into the branchial cavity. The action of the scaphognathite
is fairly rapid, but after a little observation, checked by the employment
of coloured water to test the currents, it becomes quite easy to detect
with certainty the direction of the current by inference from the move-
ments of the scaphognathite alone.

The action of the exopoditic palps of the maxillipeds in causing
currents has already been described. Such currents are purely
accessory, and Gosse (1865, p. 130) and De Haan (1850, p. 117)
have undoubtedly erred in assigning to the maxillipeds an important
share in the production of respiratory currents.

V. EVOLUTIONAL SIGNIFICANCE.

The habits of Corystes cassivelaunus described above seem to me
to demonstrate the adaptive nature of the entire organization of this
Crustacean, and slight consideration is all that is required to enable
a naturalist to recognise the utility of these adaptive features,

The burrowing habit is useful as a mode of concealment from enemies.
The elongation and smoothness of the carapace, and the elongated claws
of the four hindmost pair of thoracic legs, are all features usefully
correlated with the specialization of the crab for a sand-burrowing
existence.

The elongation of the antennie and the arrangement of the hairs upon
them, the double bend of their basal joints, the structure of the parts
bounding the prostomial chamber, and the arrangement of hairs upon
them, are characters which, in conjunction with the reversal of the
respiratory current, adapt the respiratory mechanism of the crab in
a remarkably complete manner to an arenicolous mode of life. The
antennal tube enables the crab to draw its supplies of water directly

from the superincumbent reservoir of water, while the arrangement
of hairs is such as to constitute a sieve, keeping the sand away from the
respiratory organs.

2a2 CONTRIBUTIONS TO MARINE BIONOMICS.

The upright position of the crab is itself a most unusual feature, and
is correlated with the formation of an elongated antennal tube; the
posterior position of the legs is WLS aEEy correlated with the adoption
of the upright attitude.

VI. ANALOGIES.

A reversal of the respiratory current similar to that which I have
just described in Corystes also takes place under certain conditions
in the allied form Afelecyclus heterodon. The habits of this crab are
much more complex than those of Corystes, and will form the subject of
a later article.

An elongation of the antennz, and their conversion into an antennal
tube by the interlocking of hairs along their margins, also takes place,
as I have recently discovered, in an East Indian Crustacean, Albunea
symnista, Fabr., which belongs to the Hippinea among the Macrura
Anomala (Anomura). In this type, however, the antennal tube is formed
by the first and not by the second pair of antenne. The antennal tube
has obviously been produced independently in Corystes and <Albunea,
and affords a remarkable example of homoplastic modification. In
all probability the function of the tube is the same in both cases, but
no direct observations on this head in the case of Albunea have yet
been made.

It seems to me not unlikely that further observation of the habits of
Hippa talpoida of the American coasts will reveal an essentially similar
sieve-like function for the curiously bent and setose second antennz of
that animal.

BIBLIOGRAPHY.

Bell, T. (1853).—British Stalk-Eyed Crustacea, pp. 159-163.
Couch, J. (1878).—Cornish Fauna, 2nd Ed., pp. 75, 76.
Dana, J. D. (1852).—‘‘Crustacea.”” U.S. Exploring Expedition, vol. xiii.
Gosse, P. H. (1865).—A Year at the Shore, pp. 127-131.
Haan, W. de (1850).—‘‘ Crustacea.” Siebold’s Fauna Japonica.
Hunt, A. R. (1885).—‘‘On the Influence of Wave-Currents on the Fauna inhabiting
Shallow Seas.” Proc. Linn. Soc., xviii. Zool., p. 269.
Miers, E. J. (1886).—-*‘ Brachyura.” Challenger Reports, vol. xvii.
Milne-Edwards, H. (1834).—WHistoire Nat. des Crustacés, 3 vols.
5, (1839.) ‘‘Recherches sur le Mécanisme de la Respiration chez les Crustacés.”
Ann. Sci. Nat. (2) xi. pp. 129-142.
Robertson, David (1861).—“On the Uses of the Antenne of Corystes cassivelaunus.”
Proc. Philosoph. Soc. Glasgow, v., completed 1864, pp. 55, 56 (with a good figure).
5, (1886-88).—Proc. and Trans. Nat. Hist. Soc. Glasgow, ii. (N.S.), pp. 143, 144.
Stebbing, T. R. R. (1893).—‘‘ A History of Crustacea.” Int. Sci. Series.

Reprinted from the Journal of the Marine Biological Association,
N.S., Vol. w., No. 4, March, 1897.

Contributions to Marine Bionomics.
By

Walter Garstang, M.A.,
Fellow and Lecturer of Lincoln College, Oxford.

II. The Function of Antero-lateral Denticulations of the
Carapace in Sand-burrowing Crabs.

THE antero-lateral margins of the carapace in many of the crabs of
our own and of foreign coasts are beset with a row of teeth or spines,
which vary in character and number in different species and genera.
In the Oxyrhyncha (Spider-crabs) the whole surface of the carapace
is generally studded with spines and stiff hairs of a peculiar character,
but there is no general restriction of these processes of the carapace
to the antero-lateral margins of the body. These crabs, moreover, do
not adopt burrowing habits. Their armature of spines, tubercles, and
hairs is employed, as is well known, for protective purposes: in some
cases possibly as an actual defence against attack, in others (ae.,
Hurynome aspera) as a means of protective resemblance to their
surroundings; but in the great majority as mere pegs and hooks for
the fixation of foreign bodies, such as alge, hydroids, polyzoa, and
ascidians, for purposes of concealment and disguise.

In the Catometopa (Land-crabs, etc.) the carapace is usually amoeth
over its whole surface. These animals often burrow in sand, but for
the most part their burrows are permanent subterranean tunnels and
chambers.

In the Cyclometopa, however—the group which includes most of our
commoner British crabs—the back of the carapace is generally smooth,
while the antero-lateral margins are in most forms conspicuously
serrated. Most of these animals inhabit sandy or gravelly areas,
and show a marked propensity towards burrowing habits. Their
burrows are never* permanent channels or tunnels in the sand, but
are mere temporary excavations, the sand, mud, or gravel being in
actual contact with their bodies when imbedded.

So far as I am aware no one has hitherto elucidated the remarkable
constancy of antero-lateral serrations of the carapace in this group of
crabs. I here present evidence which tends to show that the presence

* Scylla serrata of the Natal coast appears to be exceptional in this respect. (KRAUSS,
Die Siidafricanischen Crustaceen, 1843, p. 12.)

CONTRIBUTIONS TO MARINE BIONOMICS. 397

of conspicuous serrations on these margins of the carapace is func-
tionally related to the exigencies of respiration when these animals are
buried in sand.

The marginal teeth are perhaps best developed and most conspicuous
in crabs of the family Portunide (Swimming-crabs). As M. Alphonse
Milne-Edwards has remarked: “Je ne connais aucun Portunien ot
le bord latéro-antérieur de la carapace soit entier ou armé d’épines
arrondies ou de tubercules obtus.” (1860, p. 202.)

In Bathynectes longipes there are five sharp-pointed teeth on each
of the antero-lateral borders. These teeth increase in size regularly
from before backwards, and the posterior tooth is a particularly stout
and sharp structure. This crab is almost invariably an inhabitant of
sandy areas (¢.g., Mounts Bay in Cornwall); and the individual whose
habits I am about to describe was also dredged upon a bottom of fine
sand in the neighbourhood of the Eddystone.

In an aquarium containing sand the crab burrows into the sand just
beneath the surface, leaving its eyes and the transverse slit-like aperture
of the buccal frame exposed. The crab is actually imbedded up to the
anterior edge of the external maxillipeds; but it pushes away the sand
in front of it by means of these appendages, and when at rest maintains
these appendages in a sloping posture, so that they act as a quadrangular
sieve-like fence in front of the buccal area. This happens both in very
fine siliceous sand and in fine shell sand. The crab was not seen at any
time to go completely beneath the surface, though I do not mean to
imply by this that the crab never buries itself entirely. This may
or may not be the case. Atelecyclus heterodon is another sand-burrowing
crab, whose habits I have studied for a much longer period; and this
crab has very diversified habits. It may remain partially imbedded at
the surface of the sand, with its eyes and a broad funnel formed by the
second antenne alone protruding, or it may disappear completely beneath
the sand to a depth of several inches.

When the crab (Bathynectes longipes) is partially imbedded in the sand
as above described, it may be noticed that the chelipeds are flexed and
approximated to the under side of the antero-lateral regions of the
carapace in an attitude precisely similar to that assumed by Azelecyclus
heterodon, or the Oxystome crab Matuta, under the same conditions
(1897). The position of the cheliped is such that the marginal teeth
of the antero-lateral region of the carapace exactly overhang the slit-like
orifice between the distal half of the cheliped (carpopodite and propodite)
and the pterygostomial fold of the carapace. There is thus produced on
each side of the crab, between cheliped and carapace, a channel similar
to that which would be produced by the approximation in parallel
planes of two flat plates. This channel communicates below with the

398 CONTRIBUTIONS TO MARINE BIONOMICS.

afferent (inhalant) aperture of the branchial chamber, which is situated
at the base of the cheliped, and opens above through the notches
between the teeth of the antero-lateral margins of the carapace. Since
the back of the crab is covered with sand, it will readily be understood
from this description that the antero-lateral teeth act as a coarse sieve
or grating placed over the orifice of this accessory channel, and that
they prevent the accidental intrusion of sand-particles into the lumen
of the channel, a function which it was easy to determine that they
efficiently discharged.

The pair of accessory channels produced by the approximation of
chelipeds to carapace I propose to term the “exostegal channels,” owing
to their situation on the external face of the branchiostegite. I show
elsewhere (1897) that these channels probably represent in a generalised
condition certain remarkable accessory afferent branchial canals of the
Oxystome Brachyura, which attain their most specialised form and
relations in Hbalia and other Leucosiide.

M. Alphonse Milne-Edwards (1860, p. 207) states that in the
Portunidee “les mains ne sont jamais conformées de facon a pouvoir
s'appliquer exactement contre la région buccale, ainsi que cela se voit
chez quelques autres Brachyures nageurs tels que les Calappes et les
Matutes.” This contrast is quite in accordance with my view, that the
afferent channel of the Portunide represents a primitive and relatively
unspecialised type, from which the highly elaborate canals of the
Oxystomata have been derived.

That these accessory channels in the Portunide are functionally
connected with the respiratory process, was demonstrated by me in
the case of Bathynectes longipes in the following manner :—

When the crab was partially imbedded in sand with its face close to
the front of a square glass aquarium, in the attitude already described,
it could be seen that beneath the body of the crab was a shallow ventral
water-chamber, free from sand. ‘The crab was resting with its body in
an approximately horizontal plane. Sand-particles were supported over
the orifice of the exostegal channel by the sieve-like row of teeth along
the antero-lateral margins. Some water, coloured black with Indian
ink, was then added by means of a pipette to the water lying above the
slit between cheliped and carapace. The coloured water was at once
sucked downwards between the grains of sand into the exostegal
channel in waves which apparently corresponded to blows of the
scaphognathite, and after a few seconds emerged in a black stream
out of the afferent orifice of the branchial chamber situated in front
of the mouth. It was quite clear that the water passed downwards
through the exostegal channel to the afferent aperture at the base of
the cheliped, and that it entered the branchial chamber by this aperture.

CONTRIBUTIONS TO MARINE BIONOMICS. 399

Similar observations and experiments were made upon numerous
specimens of Afelecyclus heterodon, a crab belonging to an altogether
different family. In this crab the antero-lateral margins are provided
with as many as nine teeth, but the function of the teeth was found
to be essentially similar. Owing to the different form of the body, and
the different shape of the cheliped in the two crabs, the orifice of the
channel between cheliped and carapace is of greater relative extent in
Atelecyclus than in Bathynectes; but the length of the denticulated
margin of the carapace was found to correspond precisely with the
extent of the inhalant gap in each case. The following conclusions
may be drawn, therefore, from these observations :—

(1) Antero-lateral denticulations of the carapace in crabs may
subserve a sieve-lke function.

(2) The extent of the denticulated area corresponds with the extent
of the inhalant gap between the carapace and the cheliped
when the latter appendage is approximated to it in the
flexed position.

It is also obvious that a new function must be ascribed to the
chelipeds of sand-burrowing crabs provided with antero-lateral
denticulations of the carapace. In such cases the chelipeds act as
organs temporarily subservient to the respiratory process by providing
a broad operculum to the exostegal channel. Attention may be
recalled in this connection to the fact elucidated by Milne-Edwards in
1839, that in the Leucosiide the floor of the afferent branchial channel
is also provided by one of the appendages, in this case by the external
maxillipeds. The relations of the afferent channel in the Leucosiide to
the external channel which I have now described in the Cyclometopa
are discussed by me in the paper to which reference has already been
made (1897).

The subservience of the chelipeds to the respiratory process enables
me, moreover, to explain the function of a remarkable spine which
in the Portunidee is almost universally present on the inner margin of
the distal extremity of the carpal joint (carpopodite or wrist) of the
cheliped. This carpal spine, though usually strong and conspicuous,
presents various minor modifications of form which are employed by
systematists in the discrimination of different species.

The appearance of the spine in Bathynectes longipes is represented by
Bell and Risso. When the cheliped is fully extended the carpal
spine projects freely from its anterior margin; but when the propodite
is flexed towards the proximal part of the cheliped, it is arrested at a
certain angle with the carpopodite by the carpal spine in question. If
now the arm (meropodite) of the cheliped be approximated to the carapace

in the position requisite for the completion of the exostegal canal, it
*

400 CONTRIBUTIONS TO MARINE BIONOMICS.

will be found that the angle at which the propodite has been arrested
by the carpal spine is precisely the angle required for the proper
apposition of cheliped to carapace in connection with the respiratory
process. The carpal spine acts then as a stay or barrier to excessive
flexion of the cheliped. Its function corresponds, therefore, in part to
the function of such skeletal processes as the olecranon of the human
ulna, which prevents excessive extension of the arm. Examination of a
series of Portunids reveals that the variations in the form of the carpal
spine in different species and genera are all functionally correlated with
the different shapes and proportions of the carapace, and of the segments
of the cheliped in the forms examined; the result in all cases being
that the shape of the carpal spine is adapted to ensure the due amount
of flexion of the cheliped for the completion of the respiratory channel
between cheliped and carapace.

A similar function seems also to be discharged by the enlarged posterior
spine of the antero-lateral margins in Bathynectes longipes, since the car-
popodite presses upwards against it during flexion of the cheliped. An
examination of preserved specimens of the Mediterranean Lupa hastata,
and of the American Callinectes sapidus, in which the posterior spine is
greatly elongated, seems to me to support this view, though I do not
regard the evidence in this case as altogether unequivocal. A complete
explanation of the enlargement of this posterior antero-lateral spine
should also throw light on the great epibranchial spines of the Oxystome
genus Matuta, and of the Lencosiid genera Jphis and Iza. In the latter
cases any relation between the development of the spines and the forma-
tion of an inhalant chamber between cheliped and carapace is precluded
by the known course of the afferent current in a gutter running between
the pterygostomial plate and the exopodite of the third maxilliped.

The phenomena presented by the respiratory processes of these sand-
burrowing crabs throw light, as it seems to me, not only on the problem
of the utility of a number of morphologically trivial, but systematically
important features of Decapod Crustacea, but also on an altogether
different problem, viz. the phylogeny of the Brachyura Oxystomata.
Crabs of the latter group are all characterised by their sand-burrowing
habits of life. Similarity of habits often induces homoplastic changes
of form in types genetically distinct; but there are certain significant
details of structure in the different Oxystome types which appear to me
to be only explicable on the view that these crabs are descended from
ancestors in which the form of the body closely resembled that of sand-
burrowing Cyclometopa in being provided with antero-lateral serrated
margins, and in which the chelipeds were employed for the production
of an extensive inhalant channel, completely roofed over by the pro-
jecting teeth of the carapace. For a fuller discussion of this subject I
must refer the reader to another paper to be published in the Quarterly
Journal of Microscopical Science (1897).

CONTRIBUTIONS TO MARINE BIONOMICS. 401

BIBLIOGRAPHY.

Bell, T.— British Stalk-Eyed Crustacea, 1853.

Garstang, W.—‘‘On some Modifications of Structure subservient to Respiration in
Decapod Crustacea which burrow in sand, with remarks on the Utility of
Specific Characters in the genus Calappa, and the description of a new species
of Albunea.” Quart. Jour. Micr. Sct., 1897.

Milne-Edwards, A.— “ Hist. des Crust. Podophth. Fossiles.” Ann. Sct. Nat. (4) xiv. 1860.

Milne-Edwards, H.—“Rech. sur le Méchanisme de la Respiration chez les Crustacés.”
Ann. Sct. Nat. (2) xi. 1839.

Ric. 1.

Fig, 1.—Bathynectes longipes. Dorsal view, showing the five teeth of the antero-
lateral margins. The chelipeds are in a half-extended condition; their pro-
podites (hands) are shown resting against the carpal spines. The specimen
shows an abnormality in the union of the two anterior marginal teeth of the
right side to form a single bifid tooth.

Fic, 2.

Fig. 2.—Bathynectes longipes. Dorsal view, showing the position of the chelipeds
after flexion of the wrists (carpopodites) as well as of the hands. The left
cheliped is in the attitude assumed by the crab when imbedded in sand; the
antero-lateral teeth are seen to form a sieve above the orifice of the inhalant gap
between cheliped and carapace. On the right side the arm (meropodite) of the
cheliped does not rest in its proper position beneath the enlarged posterior
marginal tooth; hence the inhalant gap is imperfectly formed, and its aperture
is imperfectly covered by the marginal teeth.

402 CONTRIBUTIONS TO MARINE BIONOMICS.

III, The Systematic Features, Habits, and Respiratory
Phenomena of Portumnus nasutus (Latreille).

The crab whose habits I now describe has not previously been
recorded as an inhabitant of British seas. I found two specimens,
both male, imbedded in a patch of coarse shell sand on the south side
of Drake’s Island at low water, spring tides: one on August 11th, 1896,
and the other on the following day.

1. NOMENCLATURE.

My first impression on noticing this remarkable little crab
was that I had an abnormal specimen of a young Carcinus maenas
before me; but the possibility of such a leap from the normal as the
frontal area of this specimen would produce on a_ variation-chart
was soon disposed of by Professor Weldon, and we identified the crab
with the Portunus biguttatus of Risso (1816), now usually known under
the name Platyonichus nasutus of Latreille (1825, p. 151; cf. also
Milne-Edwards, 1834; Costa, 1853, p. 11; Carus, 1885).

The genus Platyonichus of Latreille (1818) was originally coextensive
with the genus Portumnus of Leach (1815), Latreille having simply
altered Leach’s name owing to its similarity to the name Portunus,
with which he feared it might be confused. Dana (1852), however,
and Bell (1853), showed that the species included within the genus
Platyonichus were separable into two well-marked groups, which were
accordingly named by these writers Platyonichus and Portumnus
respectively, the latter name being reapplied to the group which
included Leach’s type, viz, Portumnus latwyes. It is to the latter
group that Platyonichus nasutus belongs, so that I must refer to it
for the future as Portumnus nasutus.

It is true that the earliest specific name applied to the present species
is biguttatus of Risso (1816), the name nasutus of Latreille (1825) being
nearly ten years later. Since, however, the species has been invariably
referred to under Latreille’s name, probably owing to the influence of
Milne-Edwards’ adoption of it, I submit that we have here an ex-
ceptional case which demands exceptional treatment. The rule of
priority provides a decisive method of dealing with a confused and
complicated synonymy; but its application in the present case could
not be urged on such grounds, and would be distinctly inconvenient.
I shall therefore adhere to the employment of Latreille’s name nasutus
in referring to the species under discussion. In the event, however,
of possible differences being discovered between Mediterranean and
Atlantic races of this species, I would point out that Risso’s name

CONTRIBUTIONS TO MARINE BIONOMICS. 405

was created for Mediterranean specimens, while Latreille’s type came
from the west coast of France.

2. GENERIC CHARACTERS.

The genus Portwmnus takes its place together with Carcinus,
Platyonichus, and Polybius in the Platyonichine, a sub-family of the
Portunide distinguished from the Portunine by the absence of lateral
ridges on the prelabial plate, and by the absence of a distinct accessory
lobe to the endopodite of the first maxillipeds.

Portumnus is distinguished from Platyonichus.by having the dactylus
of the fifth thoracic leg of a slender lanceolate form, and the carapace
not broader than long. In Platyonichus the dactylus is elliptical or
broadly oval, and the carapace is broader than long. To these dis-
tinctions I may add that in Platyonichus the interorbital margin is at
most tridentate or quadridentate, while in Portumnus the inner angle of
the orbit contributes a distinct accessory tooth to the frontal margin,
rendering this margin five-toothed, as in Polybius Henslowi.

3. SPECIFIC CHARACTERS.

The two.species of the genus which alone are known to me are
P. latipes (Pennant) and P. nasutus. A description of the former
species may be found in Bell (1853) under the name Portumnus
variegatus. The characteristic features of P. nasutus are as follows :—

Frontal area projecting in front of the orbits in the form of a
conspicuous triangular lobe with gently undulate lateral margins.

The undulations mark the subdivision of the interorbital margin into
five rounded lobules, which correspond to the five interorbital teeth
of P. latipes. The interorbital lobe bends downwards in front.

The carapace is relatively broader than in P. /atipes, so that the
antero-lateral margins make a sharper angle with the median transverse
axis.

The orbit shows two superior fissures and one inferior fissure (pace
Latreille and H. Milne-Edwards, who mention only one superior
fissure), while in P. latipes the orbit is stated to be either entire
(Bell; Leach, 1815) or provided with a single fissure above (H. Milne-
Edwards, 1834).

The basal joint of the second antenna is movable.

4, CoLour.

The colour of the carapace of Portumnus nasutus is thus described by
Risso (1816, p. 31)—“yellowish-white, adorned with two great spots
of coral-red ... The red spots are larger in the female than in the

404 CONTRIBUTIONS TO MARINE BIONOMICS.

male.” On account of the presence of these spots Risso named the
species Portunus biguttatus, portune & deux taches, portune bimaculd
(p. 25).

Costa, on the other hand (Addizioni, 1853, p. 11), describes the colour
as “livid olive-brown tending towards purple; that of the feet and of
the inferior face more pallid. In fresh specimens one may sometimes
observe two rose-coloured spots in the middle of the carapace, which
vanish after death.”

Of my own specimens the larger one was of a uniform dull greenish
yellow colour, the smaller one having the carapace and basal joints of
the legs absolutely white, and the two terminal joints of the four
posterior pairs of thoracic legs coloured pale brown and amethyst-violet.
No reddish spots were visible in the living specimens. It is possible
that these spots are only to be observed in the breeding season, and
that they are due to the colour of the reproductive glands showing
through the carapace. Such a phenomenon is at any rate described by
Risso for Lathynectes longipes. He states (1816, pp. 30, 31): “La
femelle, dans le temps des amours, est ornée de deux grandes taches
d'un rouge foncé sur la partie antérieure du tét.” The eggs of the
latter species are described as “d’un rouge aurore,’ which would
sufficiently account for the red colour of the ovarian regions before
deposition of the ova; those of P. nasutus are described as “dun
jaune doré.” Risso states that the eggs of P. nasutus are laid in May
and August.

5. SAND-BURROWING Habirs.

The habits of Portumnus nasutus have hitherto been very imperfectly
described. Risso (1816, pp. 25-31) states simply that at Nice the crab
inhabits “la région des polypiers corticifcres” (p. 25), or ‘la région des
coraux” (p. 31). Latreille’s specimen (1825, p. 151) was obtained by
D’Orbigny on the coast of La Vendée, which probably implies a sandy
habitat, especially as Latreille’s specimens of “ Platyonichus variegatus ”
(Portumnus latipes) were obtained by the same naturalist on the same
coast (Nouv. Dict. d’ Hist. Nat., 1818), and the latter species is known
to have sand-burrowing habits.

My own observations are, however, unequivocal. The specimens
were found burrowing in coarse shelly gravel, and when the crabs were
introduced into an aquarium containing a deep layer of the same gravel
they were observed to burrow into it at once with extreme agility until
their bodies were completely covered to a depth of an inch or more,
The act of burrowing is effected by means of the hinder thoracic legs,
as is usual among Portunids. The crabs can also burrow in fine siliceous
sand.

When imbedded, P. nasutus seems always to adopt a nearly horizontal

CONTRIBUTIONS TO MARINE BIONOMICS. 405

position—not the upright attitude exhibited by Corystes cassivelaunus
(this Journal, 1896, p. 223). The anterior part of the body is, however,
generally a little higher than the posterior.

6. RESPIRATORY CURRENTS.

Under these circumstances, Portwmnus nasutus exhibits a reversed
water-current through its branchial chamber, though this is much more ~
difficult to demonstrate in the present species than in the case of
Corystes. The method I adopted was as follows :—

The depth of gravel in the aquarium was so regulated that the crab
could’ not burrow far beneath the surface. The fragments of sand
and shell which lay upon the front of its carapace and upon its inter-
orbital lobe were then gently removed, one by one, with a pair of fine
forceps, until the aperture of the buccal frame was exposed. These
proceedings were, however, incessantly watched by the crab, which, not
unnaturally, did not hesitate to disturb my preparations whenever it
conceived that there was due cause for alarm. I therefore took the
precaution to leave some fragments of shell over its eyes, and thus did
not seriously disturb its impression that it was safely ensconced. I
eventually succeeded in getting the crab so suitably situated that, on
the addition of a little black-coloured water by means of a pipette to
the region in front of the crab’s maxillipeds, I had the satisfaction of
seeing the water sucked inwards on both sides, to reappear again in a
pair of streams at the base of the chelipeds. The two exhalant streams
rose above the surface of the sand in a pair of clouds, one on each side
of the body. Suddenly, and without warning, the normal current was
set up, and then the lateral clouds of inky water were rapidly sucked in
again on each side, to re-emerge again a second or two afterwards in a
continuous stream in front of the mouth. Without this kindly co-
operation on the part of the crab it would have been difficult, if not
impossible, to get so successful a demonstration of the reversal of the
currents. One of the most interesting phenomena presented by this
crab is indeed the frequency with which, when under observation, it
will alternate the direction of the respiratory currents.* It may even
suspend the respiratory currents altogether for long intervals; eg., for
as long as fifty-five seconds. At such times there is absolutely no
movement in the surrounding water.

7. UTILITY OF SPECIFIC CHARACTERS.

The interorbital prolongation of the frontal area, which gives both
its name and most peculiar feature to the species Portumnus nasutus, is

* Probably to eject distasteful particles. This is undoubtedly the explanation of similar
phenomena in the case of Corystes. (See this Journal, vol. iv. 1896, p. 230.)

406 CONTRIBUTIONS TO MARINE BIONOMICS.

a feature usefully correlated with a habit of burrowing in coarse shelly
gravel. It acts as an efficient buckler for the protection of the anterior
sense-organs ; but its unusual size and its downward bend seem to be
more directly correlated with the reversal of the branchial currents,
which I have shown to take place when the crab is imbedded. The
advantage of reversal in the present case is a point to which I shall
recur when dealing with the phenomenon in a more general manner ; but,
eranted the reversal, the utility of the possession of a stout triangular
shelf over the inhalant orifices is obvious after a study of the animals
habits and of the nature of the objects amid which the crab excavates
its dwelling-place. In Corystes, which lives in fine sand, the inhalant
antennal tube has been shown (1896) to subserve the double purpose of
a supply pipe and a sieve. In P. nasutus a sieve is unnecessary so long
as the crab inhabits coarse shell-gravel, the fragments of which are too
large to enter the respiratory channels; and this appears to be the
specific habit of the crab. But if the anterior inhalant apertures (during
reversal) were altogether unprotected, the pointed fragments of shell
might easily penetrate the inhalant orifices (during reversal), and so
occlude their lumen. Such occlusion would prevent the crab from
burrowing in the kind of material most suitable to its respiratory
organisation, and thus expose the animal to increased risks of destruction
by its ever-watchful enemies among fishes. The overhanging buckler
provided by the prominent frontal lobe acts, however, as a very
efficient means of supporting the shell-fragments well above the
inhalant orifices—a function the existence of which I do not throw
out as an academical suggestion, but the value of which I had frequent
opportunities of observing and appreciating in my aquaria.

The interorbital lobe of P. nasutus is remarkably similar to the frontal
protuberance of Carcinus maenas in the Megalops stage, which becomes
reduced in later stages of development. Since I have found no
indications of a reversal of the respiratory currents in the latter species,
I am inclined to believe that the retention of this larval feature in
P. nasutus is to be correlated with the reversal of the currents which
occurs, as I have shown above, in this type; while its eventual: loss in
Carcinus maenas is to be indirectly attributed to the lack of any further
use for it after the larval stages. The larval forms of P. nasutus are at
present, however, unknown, and it is impossible to support this view
with the necessary embryological facts.

The other specific characters of P. nasutus (viz., breadth of carapace,
retention of two supra-orbital fissures, mobility of basal joint of second
antenna) are not new features acquired within the history of the present
species, but are merely heirlooms from Portunid ancestors of less
specialised habits, It is not their presence in P. nasutus which is to

CONTRIBUTIONS TO MARINE BIONOMICS. 407

be accounted for, but their absence in Portumnus latipes. The elucida-
tion of those features will be attempted in a subsequent article dealing
with the habits of the latter species.

In conclusion I may add that a good figure of P. nasutus is given in
Costa’s classical memoir on the fauna of the Bay of Naples (1853).

BIBLIOGRAPHY.
Bell, T.—l.c. (1853).
Carus, J. Victor.—Prodromus Faune Mediterranee. Stuttgart, 1885.
Costa, O. G.— Fauna del Regno di Napolt, 1836. Addizioni w Decapodi Brachiuri,
February, 1853, pp. 14, 15, Tav. 6, fig. 4.
Dana, J. D.—‘‘ Crustacea.” U.S. Exploring Expedition, vol. xiii. 1852.
Garstang, W.—1. “The Habits and Respiratory Mechanism of Corystes cassi-
velaunus.” This Journal, iv. pp. 228-232. 1896.

- 2. “On the Function of certain Diagnostic Characters of Decapod
Crustacea.” Rep. Brit. Ass. Liverpool, 1896, pp. 828-830.
Latreille, M.—1. Nowv. Dict. d’Hist. Nat. 1818.

5 2. Encycl. Méthodique, x. 1825.
Leach, W. E.—1. Trans. Linn. Soc., xi. pp. 306-400. 1815.
6 2. Malac. Podoph. Brit. 1815.

Milne-Edwards, H.—Hist. Nat. des Crustacés. 1834.
Risso, M.— Hist. Nat. des Crustacés des environs de Nice. 1816 (Plate L, fig. 2).

[Reprinted from SctENCE Proaress, Vol. V., March, 1896.|

Pie MOKPHOLOGY OF THE MOELUSEA

>: ea recent publication of a number of new manuals and

monographs dealing with the Mollusca offers a favour-
able opportunity for a review of our knowledge of this
great phylum of the animal kingdom. It is not fifteen
years since Professor Lankester’s classical article on Mollusca
was published in the Eucyclopedia Britannica, yet the con-
tributions to Molluscan morphology since that date have
been not only numerous, but in many cases of prime im-
portance.

The older method of inquiry, that of the comparison of
types more or less arbitrarily selected from different groups,
has been succeeded by investigations more directly in-
fluenced by the idea of evolution. The comparison of types
has been replaced by the study of groups. The founda-
tions of the morphological edifice were laid upon the former
method ; the superstructure and details are the result of
the latter. Homologies having been to a large extent
determined, we now seek phylogenies. It happens also
from time to time that the detailed study of a group with
the object of reconstructing the phylogeny of its members
leads occasionally to the discovery that homologies based
on the simple method of anatomical comparison turn out
to be nothing more than analogies—recurrent examples of
similar modifications.

One result of these phylogenetic inquiries has been the
concentration of particular attention upon forms which are
presumably the most primitive in each group; and great
advances have thus been made in our knowledge. Kow-
alewsky and Marion, Pruvot, Wirén, and Thiele have
enormously extended our acquaintance with the Apla-
cophorous I[sopleura; primitive Prosobranchs (Docoglossa
and Rhipidoglossa) have been thoroughly investigated by

2 SCIENCE PROGRESS.

Haller and Boutan; Bouvier has thrown new light upon the
Opisthobranchia by his researches on Acteon ; Boas and
Pelseneer have revolutionised our ideas of the Pteropoda
by their work upon Lzmacena among the Thecosomata, and
upon Dexiobranchea and other types among the Gymnoso-
mata ; the morphology of the Pelecypoda has been further
elucidated by Pelseneer’s observations upon Vucu/a and
other primitive forms, and important contributions to our
knowledge of the Cephalopoda were made during the past
year by Huxley and Pelseneer in the case of Spzvzla, that
last survivor of the ancient types of Decapod Dibranchiates.
We doubt if any equivalent group of the animal kingdom,
except perhaps the Echinoderma, has been the subject of
such productive researches as the Mollusca during the period
under consideration ; and certainly the phylogenetic method
of inquiry has attained no greater triumphs than in the
hands of Bouvier, Haller, Pelseneer, and other inves-
tigators of the Gastropod and Lamellibranch series.

In the present article | propose to deal more especially
with recent contributions to our knowledge of the Molluscan
nervous system, reserving a fuller consideration of other
questions for a later article.

There is one writer, however, whose views must first of
all be dealt with, as on a great number of fundamental
points they are opposed to all current conceptions of
Molluscan morphology. These views merit some detailed
consideration, moreover, for they are based on propositions
which are not without a certain appearance of plausibility,
and may well serve as test-questions by which to examine
into the accuracy of the homologies which have been
generally admitted to exist between the different sections
of the Molluscan phylum.

Thiele has published his views in a series of lengthy
papers, the references to which will be found in the biblio-
graphy (23, 24, 25). He regards the Mollusca and Anne-
lida as direct descendants of Polyclad Turbellarians, and

TE MORPHOLOGY. OF THE MOLLUSCA. 3

his identifications of homologous organs in the different
Molluscan groups are determined, not by a direct comparison
of the organisation of these types one with another, but
by independent comparisons of the organisation of the
different Molluscan types with that of sucker-bearing
Polyclads. The group Mollusca is thus made to lose its
compactness, and characteristic organs, such as mantle and
ctenidium, which have been regarded as homologous
throughout the Molluscan series, are interpreted in different
ways in the different types, as the exigencies of Thiele’s
theory demand. One of the first propositions assumed by
this writer is that the foot of the Mollusca is simply a colossal
enlargementof the ventral sucker of the Polyclad; thesuctorial
function of the foot in C#ztonx and the lower Gastropoda is
pointed to in support of this comparison. A series of
more revolutionary propositions is then promulgated in
consequence of the necessity under which the author is
placed of discovering the primitive body-edge of the
Mollusca comparable to the edge of the body of the Tur-
bellaria. This primitive body-edge Thiele identifies by
means of the lateral sense-organs which characterise the
epipodium in the Rhipidoglossa and the margin of the
mantle in Pelecypoda. The epipodium in Gastropoda and
the mantle edge in Pelecypoda are thus taken by this writer
to represent the sides or edge of the body in the Tur-
bellarian ancestor. The epipodium in Gastropoda and the
mantle edge in Pelecypoda consequently separate the
dorsal from the ventral regions of the body in those groups.
It follows from this that the ctenidia of Gastropoda, which
are supra-epipodial in position, are not homologous with
the ctenidia of Pelecypoda, which are infra-pallial. How we
are to regard the anus, which is dorsal in the one group and
ventral in the other, is not explained. But since in oper-
culate Rhipidoglossa the operculum, like the shell, is
situated above the epipodium, we are told that the oper-
culum must also be regarded as dorsal in position, as well

4 SCIENCE PROGRESS.

as serially homologous with the shell proper. This, in
Thiele’s eyes, compares well with the condition of affairs in
Chiton, whose shelly plates are without doubt serially
homologous. Moreover, although the existence of an
epipodium in C&zfon has not been hitherto recognised,
Thiele argues that, since the pallial fold in this form re-
presents the primitive body-edge, it must also, together with
the series of ctenidia which are attached to its lower surface,
be regarded as the homologue of the epipodium of the
Rhipidoglossa. The ctenidia of Czton are, in fact, re-
garded as modified epipodial cirri. The consequence of
this view is that while the mantle of C4z¢ox and the mantle
of Pelecypoda are regarded as homologous, the mantle of
the Gastropoda is supposed to represent only a portion of
the mantle in these other forms, and its projecting rim,
similar as it appears to be in the two cases, is held to be a
new and secondary formation unrepresented in the Am-
phineura and Pelecypoda.

Nowhere, however, do we find in Thiele’s voluminous
writings any explanation of the anomaly which ought to
have occurred to him, that while in C&Zzton the anus is
“ventral,” and lies well beneath the ‘‘epipodium” and the
last shell-plate, in operculate Gastropods the intestine opens
not only above the epipodium, but between the operculum
and the shell of the embryo—a relation which could only be
represented in C/zton, if Thiele’s theories were correct, by
the situation of the anus between two of the shell-plates
upon the back of that animal !

The nervous system of the Mollusca is treated by Thiele
with a ruthlessness no less than that which is meted out
to the external organs of the body. Let us take the
Amphineura first. In this group, if the relations of the
nervous system in Cfzton be taken as typical, we have
dorsal to the gut a great ganglionic nerve-ring whose lateral
components are usually referred to as the lateral or pleuro-
visceral cords. Connected anteriorly with the cerebral

THE MORPHOLOGY OF THE MOLLUSCA. 5

enlargements of this nerve-ring is a pair of ventral or pedal
cords, connected with one another by a series of commis-
sures lying beneath the gut, and also with the lateral cords
by means of lateral connectives. The lateral cords inner-
vate the pallial sense-organs, gills, and viscera; the ventral
cords the musculature of the foot. The lateral cords are
regarded by Thiele as the homologues of the lateral cords
or nerve-ring of the Turbellarians, and the ventral cords are
taken to correspond to the ventral longitudinal nerves of
the same forms. So far we find nothing either erratic or
original, for the same view has already been taken by Lang
(16).

But the novelties begin with Thiele’s interpretations of
the nervous system of Gastropoda and Pelecypoda. We
have already pointed out Thiele’s view that the epipodium
of Gastropods represents the primitive body-edge. Now
at the base of the epipodium in /7ssurella and Hlaliotis there
lies a ganglionic plexus ; and this plexus, which takes the
form of an incomplete ring, is regarded as the homologue
of the lateral cords of Turbellariansand Amphineura. The
series of epipodial nerves which connect the epipodial plexus
with the upper half of the pedal cords in Rhipidoglossa is
compared with the series of connectives between the lateral
and ventral cords in Amphineura.

This seems very plausible until one recollects (1) that,
the epipodium being infra-rectal, the epipodial plexus is
also infra-rectal and thus difficult to compare with the
lateral cords of Amphineura, whose ‘‘commissure” is supra-
rectal; and (2) that, whereas in Amphineura the lateral
cords innervate practically the whole of the pallium and
viscera, in Rhipidoglossa the epipodial plexus has nothing
to do with any other organs except the sense-organs of the
epipodium. If the pallium of the Gastropoda is really, as
Thiele maintains, a secondary differentiation of the primary
pallium of the Amphineura, one would expect that its
innervation would also be effected by progressive differen-

6 SCIENCE PROGRESS.

tiation of the nerve-centres which supplied the primary
pallium, vzz., from the lateral or epipodial centres. So far
from this being the case, however, Thiele himself (xxv., pp.
587-9) adopts the view that the pallial nerves as well as the
pleural ganglia of Gastropoda are secondary derivatives of
the ventral or pedal cords.

The recklessness of Thiele’s comparisons reaches its
high-water mark, perhaps, in his remarks on the nervous
system of Pelecypoda. Correlated with the existence of
numerous sense-organs (eyes, tentacles, etc.) along the
mantle edge, there exists in many forms (Avca, Pecten,
Pinna, etc.) a nervous ring around the mantle which may
take the form either of a complete ring of peripheral ganglia
united by a plexus, or of a circumpallial ganglionated nerve,
as was recognised by Duvernoy (5) more than thirty years
ago. Since the mantle-lappets of the two sides of the body
unite posteriorly above the anus, this pallial nerve-ring lies
above the gut. The ring is connected with the cerebro-
pleural ganglia by means of the anterior pallial nerves, and
with the visceral (parieto-splanchnic) by means of branches
from the great posterior pallial nerves. Accordingly Thiele
homologises the circumpallial nerve-ring with the lateral
cords of C/z¢on and with the epipodial plexus of the Rhi-
pidoglossa.

The first of these homologies seems not unreasonable, for
no one disputes the homology between the mantle of Chztox
and that of Pelecypoda. Moreover Kowalevsky’s discovery
that Cz¢on in its later embryonic phases is provided with
a pair of transitory eyes which lie outside the velar area
and have some close connection with the lateral nerve-
cords, renders this comparison particularly worthy of
attention. But how the circumpallial nerve of Pelecypoda
can be in any sense homologous with the epipodial plexus
of Gastropoda, when the latter structure lies beneath the
gut and has no connection with the cerebral ganglia, either
directly or by the intermediation of the pleural ganglia, it

ine MORPHOLOGY OF Tit MOLEUSCA. 7

is altogether impossible to conceive. And this is not all.
The posterior connection between the circumpallial nerve
of Pelecypoda and the visceral ganglia is compared by
Thiele with the posterior connectives between the lateral
and ventral cords of Amphineura; and the time-honoured
visceral nerve-cords of Pelecypoda, with the visceral (parieto-
splanchnic) ganglia upon them, are homologised with the
ventral cords of the Amphineura. To reveal the absurdity
of these comparisons it is sufficient, | think, to remind my
readers that the ventral cords of Chzéox are concerned ex-
clusively with the innervation of the musculature of the
foot; while the visceral cords of Pelecypoda innervate
the body-wall, ctenidia and viscera, in addition to the
posterior adductor muscle. How these supposed homo-
logues of the ventral cords of Chzton have come to assume
so many of the functions of the lateral or pallio-visceral
cords, is not explained; and since Pelecypoda possess a
pair of pedal ganglia in the foot, as typical in their relations
as those of any Gastropod—in Mucula to the extent even
of having separate cerebro-pedal and pleuro-pedal connec-
tives (18, 19)— it seems profitless to pursue these ill-
balanced speculations any further.

The utmost ingenuity cannot overcome the fact that
there is a fundamental disparity between the Turbellarian
and Molluscan body. This disparity is revealed by em-
bryology ; but to embryology Thiele pays scant attention.
Thiele’s argument is practically this (24, p. 504),—that
the only route from Ccelenterates to Bilateralia is v2@ the
Ctenophores to Polyclads, and that Annelids and Molluscs
are consequently to be derived from Polyclad ancestors.
Embryology seems to me, however, to point to two lines of
descent at least, from the Ccelenterates to the Bilateralia.
In each case the oral surface of the Ccelenterate ancestor
became the ventral surface of the Bilateral descendant ; but
along one line of descent the primitive mouth or blastopore
retained its ancestral form as a simple circular orifice in the

8 SCIENCE PROGRESS.

middle of the ventral surface, and opened into a gastral
cavity devoid of an anal orifice (Polyclads) ; while along the
line of descent which led to the Annelida and Mollusca the
blastopore elongated along the ventral surface, as Sedg-
wick has so ably contended, its lips coalesced except at the
two extremities, and these open ends constituted the mouth
and anus of the Ccelomate descendants. Thiele has
altogether overlooked the significant behaviour of the blas-
topore in Annelidan and Molluscan embryos; and since
no similar modification of the blastopore is known in the
case of Turbellarians and Trematodes, in which groups the
absence of an anus is so marked a characteristic, we are
amply warranted, I think, in drawing the conclusions which
I have emphasised above.

The admission of this distinction is however fatal to
any theory of the Polyclad ancestry of the Mollusca. The
foot of the Mollusca is a development of the fused lips of
the elongated blastopore, and can in no case be homo-
logised with the ventral sucker of Turbellarians which lies
entirely behind the blastopore. The same remark applies
to Lang’s comparison of the Molluscan foot with the ventral
surface of the Turbellarian. The foot is undoubtedly part
of the ventral surface of the Mollusc, and as such may be
compared, in a general way, with the creeping surface of a
Planarian ; but as a specialised organ, developed from the
fused lateral margins of a slit-like blastopore, it has no
homologue in the organisation of the Turbellaria.

Let us now see what light has been thrown on the
problems of Molluscan morphology by the researches of
other investigators.

The visceral commissure.—One of the greatest dif-
ficulties in comparing the Amphineura with the Gastropoda
or other Molluscan types has long been the fact that the
lateral or pleuro-visceral cords of C4z¢on, which innervate
the gills, viscera, and mantle, are united to one another
posteriorly by a “commissure” lying above the rectum ;

THE MORPHOLOGY OF THE MOLLUSCA. 9

whereas the visceral commissure of Gastropoda and Pelecy-
poda, etc., lies below the intestine.

A little care in the use of words would have prevented
much of the confusion and controversy which has arisen on
this subject of the position of the visceral commissure.
Words, as Bacon phrases it, put constraint upon the in-
tellect, and there is no doubt that the disagreement and
perplexity of naturalists concerning this point have been
caused by one of the zdola_forz which they have themselves
set up, rather than by any intrinsic incompatibility in the
facts themselves. If the language must still be maintained,
I must at least point out that there are commissures and
commissures, and that one may be a commissure in fact,
and another only in name. The suprarectal “commissure”
in Amphineura is ganglionic, and, like the rest of the
pleuro-visceral nerve-ring, is formed zz set by delamination
from the ectoderm (15). It is not a commissure in the
strict sense of the word, but an integral portion of an
annular central nervous system. But the visceral loop of
other Molluscs consists merely of nerve-fibres connecting
usually a couple of visceral ganglia with one another, and
with the pleural ganglia. | Now nerve-fibres are,outgrowths
from nerve-cells, and if two groups of nerve-cells should
happen to take a somewhat deep-seated position in the body
before their fibres have grown out (which is not a rare
embryological phenomenon), there should be nothing in-
comprehensible in their fibres taking the shortest route and
meeting beneath the gut instead of over it. Clearly, there-
fore, the ventral position of the visceral commissure in
most Mollusca by no means precludes the possibility of the
essential homology between the visceral loop of these
forms and part of the pleuro-visceral ring of Amphineura.

The other differences between the visceral loop of most
Mollusca and the pleuro-visceral ring of Amphineura are
principally differences in the degree of segregation and
concentration of ganglion-cells and nerve-fibres. The

10 SCIENCE PROGRESS.

pleuro-visceral ring of Chzton represents a very primitive
nervous system, characterised by the more or less even
diffusion of ganglion-cells over the whole length of the
cord, while the nerves arising from it are not united into
large trunks, but are given off at repeated intervals in a
manner which is almost metameric. The nerves springing
from it innervate the same parts of the body as the com-
bined pleural and visceral ganglia of Gastropods and other
Molluscs, vzz., mantle, ctenidia, intestine, heart, nephridia,
and gonads. But if, after the reduction of the ctenidia to
a single pair, we imagine a process of segregation to set in
between these various elements, the more strictly visceral
centres would become separated from the superficial pallial
centres, and would assume a deeper position in the body.
The law of concentration would apply in this as in other
cases of evolution of nervous systems (3), and the result of
the whole process would be the differentiation of a visceral
nervous system, consisting of ganglia and commissural
fibres, out of the primitively mixed and diffuse pleuro-visceral
system. If the primitive relations to the gut and ring-like
form were retained at all, they would be retained, not
necessarily by the visceral system, which has ex hypothesz un-
dergone considerable changes, but by the pallial (= pleural)
system, which has undergone no change, except possibly
one of incipient concentration.

The position of the commissural fibres of the visceral
ganglion in relation to the gut becomes a matter of sub-
ordinate importance if the evolution of the nervous system
has proceeded upon these lines, as will be made evident
later on. As a matter of fact the visceral commissure is
situated below the gut—a relation which is possibly fore-
shadowed in CZztox by a connection beneath the gut of the
two gastric nerves described by Haller (8).

Pelseneer (19) indeed goes so far as to identify these
gastric nerves of Czfonm with the visceral commissure of
Gastropoda and Pelecypoda; but the considerations which I

THE MORPHOLOGY OF THE MOLLUSCA. II

have emphasised above show that the typical visceral nerves
and commissure have not yet arisen in the Amphineura ;
they do not arise, in fact, until the branchial, nephridial,
genital and enteric branches of the primitive pallio-visceral
cords are all united into one common trunk. There is
some doubt, moreover, as to the existence of the gastric
nerves described by Haller, since two investigators, Plate
(20) and Thiele, have been unable to discover them in
species of Chzton examined by themselves.

A valuable contribution to this part of the subject is
contained in Haller’s recent Studien (11). In the
common cyclobranchiate types of Limpet the pallial nerves
are separate from one another behind, and seem to be
mere outgrowths of the pleural ganglia (Bouvier, 3, p. 19);
but in Loé¢éza, one of the more primitive monobranchiate
forms, Haller shows that the pallial nerves of the two sides
are directly continuous with one another posteriorly, and make
a complete arch round the edge of the mantle. They are
moreover not mere nerves, since they consist of a core of
fibres surrounded by an outer coating—discontinuous, it is
true—of ganglion-cells. They are clearly the posterior
continuations of the pleural ganglia, and represent the re-
mainder of the pallio-visceral nerve-ring of the Amphineura
after the separation of the visceral elements. This view is
further borne out by the existence of several connectives
between the pallial ring and the pedal cords in addition to
the stout ganglionic ‘connective which in higher forms
becomes the persistent pleuro-pedal connective.

The pleural ganglion.—Haller's discovery recorded in
the preceding paragraph shows clearly the error of the
view by which the pleural ganglion is regarded as a
derivative of the pedal cords (Bouvier, Pelseneer, etc.,
passim). This view is founded on the fact that in the lower
Gastropoda (Docoglossa and Rhipidoglossa) the pleural
ganglia are directly continuous with the anterior ends of
the pedal cords, while in the higher types the pleural ganglia

12 SCIENCE PROGRESS.

gradually move further and further away from the pedal
ganglia, and, travelling along the cerebro-pleural connectives,
eventually come into contiguity with the cerebral ganglia
(Tenioglossa) or even fuse with them to form a single
cerebro-pleural ganglion on each side (Pelecypoda).

The close connection between the pleural and_ pedal
ganglia in the lower forms may now be _ interpreted
in a different manner. The ganglion-cells which were
primitively distributed over the whole extent of the pallial
nerve-ring have been concentrated at the anterior ex-
tremities of its lateral portions, as Haller’s observations
on Lottza show—or rather in the region of the first
pleuro-pedal connective, for the most anterior portion of
the primitive pallial cords is represented by the cerebro-
pleural connective. The shortness of the _ pleuro-
pedal connecting piece and the great concentration of
ganglion-cells which takes place at its two extremities
prevent any sharp demarcation between the pleural and
pedal ganglia in these lower forms; but a comparison of
the nervous system of Lof¢za with that of Chztox (Thiele,
23, p. 387) leaves no room for doubt as to the correct-
ness of this interpretation, which throws a flood of light
upon numerous other points which have been difficult to
understand upon the older views. It explains, for example,
why the cerebro-pleural and cerebro-pedal connectives
should be already distinct from each other in the lower
Gastropods at a stage when the pleural ganglia are in
actual continuity with the pedal cords, and it sets at rest
the controversy as to the meaning of the lateral furrow
in the pedal cords of Rhipidoglossa which has been waged
with so much skill in the rival pages of the Archives de
Zoologte and the Bulletin Scientifique de la France et de la
Leloique.

Development of the pleural ganglion.—That the pleural
ganglion is essentially distinct from the pedal is, I think,
sufficiently clear from the facts of development. Although

THE MORPHOLOGY OF THE MOLLUSCA. 13

these ganglia are placed so close together and are so inti-
mately connected in the lower Gastropods there is not a
single case on record in which the pleural ganglion has been
observed to arise from the pedal ganglion, or from a
common pleuro-pedal rudiment in the embryo. It is
equally true on the other hand that Sarasin’s derivation of
the cerebral and pleural ganglia from a common rudiment
in Bzthynia (the cephalic sense-plate) has been opposed by
v. Erlanger, who shows that all the great ganglionic centres
arise separately, and do not become connected with one
another until after their differentiation (7).

A renewed investigation of the origin of the cerebro-
pleural ganglion in Pelecypoda would be of great interest
in this connection. Pelseneer’s (18) observations on Vucula
have placed the fact of the composite nature of this ganglion
in Pelecypoda beyond all doubt; and still, to the best of
my knowledge, no one has yet observed the appearance in
the embryo of a pleural element distinct from the main body
of the ganglion. This apparent community of origin of the
cerebral and pleural ganglia in Pelecypoda may be compared
with the direct continuity of the cerebral and_ pleural
elements of the nervous system in Amphineura.

Development of the visceral ganglia. — Sarasin en-
deavoured to show that the visceral ganglia of Azthynza,
together with the pedal and abdominal ganglia, arise in the
embryo from acommon ventral proliferation of the ectoderm
which he compares with the ventral ganglionic chain of
Annelida. On this point also Sarasin has been corrected
by v. Erlanger, who shows that all these ganglia arise
separately from one another in Lzthynza (7), as well as in
Paludina (6). |

The visceral ganglia are also quite distinct from the
pleural ganglia in their origin, as v. Erlanger’s observations
show. In one important respect, however, the visceral
ganglia and the pleural ganglia betray a marked similarity,
the significance of which seems, however, to have escaped

14 SCIENCE PROGRESS.

the attention of its discoverer. In Paludina v. Erlanger
figures the pleural ganglia arising from the ectoderm on
each side of the body at a point just outside the velar area,
but in actual contiguity with the cells of the ciliated ring.
In Bithynia: (7; Vat. xxvi., fe. 16)ehe figuresathegsamte
condition of things for the pair of visceral ganglia. The
only difference in origin between the two ganglia is that the
visceral ganglia arise behind the pleural ganglia. If the
Molluscan veliger possessed a nerve-ring beneath its proto-
troch (velum), as occurs in the trochosphere of the Annelida,
it is quite clear that the pleural and visceral ganglia of
Lithynia and Paludina would represent a series of gangli-
onic thickenings along the course of the nerve-ring. Apart
from this inference, however, the topographical relations to
which I have called attention seem sufficient to establish
the proposition that the pleural and visceral ganglia, and,
as I shall show directly, the abdominal ganglion also, of
Gastropods—and, therefore, of other Mollusca—belong to
a group of dorso-lateral nerve-centres quite distinct from
that which is represented by the ventral or pedal cords.
Here again we are reminded of the direct continuity of the
pleural and visceral nerve-centres in the Amphineura.

Development of the abdominal ganglhon.—In Chiton,
as Kowalevsky has shown (15), the unpaired abdominal
ganglion, or, as it 1s often called, the visceral ganglion,
arises by a proliferation of the ectoderm at the hinder pole
of the embryo, dorsally to the site of the future proctodzeum.
In the adult this ganglion is simply a special concentration
of ganglion-cells on the supra-anal portion of the pleuro-
visceral ring.

The abdominal ganglion of Gastropods is also situated
at the hinder end of the visceral loop, but lies of course
ventral to the gut. Can these two ganglia be regarded as
homologous ?

If Molluscs were mere mechanical models the answer
would be undoubtedly in the negative; but embryology

THE MORPHOLOGY OF THE MOLLUSCA. « 15

points unhesitatingly to the opposite conclusion. Von
Erlanger has shown that in Azthynza as well as in Paludina
the abdominal ganglion develops as an ectodermal pro-
liferation of the floor of the mantle-cavity, ze., that the
ganglion is essentially a dorsal ganglion. Its final situation
on the course of the sub-intestinal nerve-loop is rendered
possible by the fact that its connectives with the visceral
ganglia are not delaminated from the ectoderm, as are the
ganglionic pleuro-visceral cords of Chzton, but are mere
fibrous outgrowths from the ganglia themselves. Embry-
ology is thus in complete accord with the views which have
been maintained in the earlier part of this paper as to the
homologies and origin of the visceral nervous system in
Mollusca.

The palhal and visceral commussures tn Cephalopoda.
—It has long been known (Hancock) that in many Cepha-
lopoda the stellate ganglia on the pallial nerve-cords are
connected with one another above the gut by a transverse
commissure. Is this commissure a relic of the pallio-visceral
nerve-ring of the Amphineura and homologous with the
pallial ring of Zoé¢za, or is it merely a secondary connection ?

In Stirula a remarkable arrangement of the pallial
commissure has been recognised by Huxley and Pelseneer
in their recent memoir (12). The commissure is not in
this case a straight transverse band, but consists of two
curved cords which arise from the right and left stellate
ganglia respectively, and at their junction in the median
line of the body give off a median pallial nerve which runs
for a short distance forwards, and then passing over the
anterior margin of the shell—which is, of course, internal—
becomes recurrent and runs along the part of the mantle
contained within the last chamber of the shell. Pelseneer is
thus led to regard the commissure with its median nerve as
formed by the two original pallial nerves fused together.
The connection between the stellate ganglia having thus
arisen in the primitive Dibranchiates (apparently in con-

16 SCIENCE PROGRESS.

nection with the reduction in size and enclosure of the
chambered shell), higher forms show a series of stages in
its subsequent degradation, until it is finally lost in the
Octopoda. The absence of a pallial commissure in Vautzlus
also supports Pelseneer’s view that in Cephalopoda this
structure is not of any primary importance.

At the same time when Pelseneer added a paragraph to
the effect that the supra-rectal commissure of the Amphi-
neura is also a merely secondary junction of the pallial
nerves, he was probably not yet acquainted with Haller’s
work on Loé¢éza, and allowed his views upon the Polychete
ancestry of the Mollusca to bias his interpretation of the
Molluscan nervous system.

In a recent paper on the anatomy of Maztz/us Mr.
Graham Kerr (13) also refers to the question of the supra-
rectal commissure. It will be remembered that in Mazdéz/us
the pleuro-visceral ganglia of the two sides form a stout
ganglionic band encircling the cesophagus in the region of
the cerebral ganglia. The pallial nerves radiate from the
lateral portions of this half-ring, and the pair of viscera
nerves arise from the ventral portion. The visceral cords
pass backwards on either side of the vena cava, and, after
giving off the branchial nerves, are prolonged posteriorly as
far as the post-anal papilla, behind which Mr. Kerr has
recognised an apparent anastomosis. Mr. Kerr adds that
in this case “the homologue of the pleuro-visceral cord of
Chiton is not merely the posterior sub-cesophageal nerve-
mass, but rather the two lateral portions of this, together
with the post-branchial prolongations which run on either
side of the vena cava. The mesial part of the posterior
sub-cesophageal nerve-mass would therefore be a secondary
fusion between the nerve-masses of the two opposite
sides.”

In his suggested homology of this possible post-anal
(z.e., supra-rectal) commissure of the visceral nerves in
Nautilus with the supra-rectal “commissure” of Chz¢on,

THE MORPHOLOGY OF THE MOLLUSCA. 17

Mr. Kerr has undoubtedly failed to appreciate the true
nature of the posterior sub-cesophageal loop of Maztzlus, as
well as the relation of the visceral nerves to the pleuro-
visceral cords of Chzton. The explanation of the Cephalo-
pod nervous system is most readily found by comparing it
with that of Dextalium, whose organisation in many respects
supplies connecting links between that of the Cephalopoda
and that of the primitive pra-torsional Gastropod or
primitive Pelecypod. In Dentalium (22, p. 401) we find
a pair of post-anal prolongations of the visceral nerves
precisely resembling those described by Kerr in Nautilus ;
yet in Dendalium, owing to the smaller degree of concen-
tration or cephalisation which has taken place in the
nervous system, it is easy to see that the typical sub-intes-
tinal visceral commissure exists as in Gastropods and
Pelecypods. The posterior sub-cesophageal nerve-mass
of Cephalopods has clearly been produced, not, as Mr.
Kerr suggests, by a secondary fusion of the pleuro-visceral
nerve-masses of the two opposite sides, but by a simple
shortening of the visceral loop as it occurs in Dentalium.
This would bring the visceral ganglia into continuity
with the pleural ganglia and with one another,—a process
of condensation with which we are already familiar in the
Tenioglossa and the Euthyneura among Gastropoda.

It may here be mentioned that Willey’s simultaneous
account (26) of the visceral nerves of Nautilus, while con-
firming Mr. Kerr’s observations as to the existence of post-
anal prolongations of a pair of visceral nerves, differs from
his statement as to their origin. Willey states that the

nerves supplying the post-anal papilla arise independently
from the sub-cesophageal visceral loop, although at their
origin they are adjacent to the branchial nerves and for a
large part of their course are actually contiguous with them.
The significance of this separation is not remarked upon by
Willey ; but if the separation really exists it is certainly a
difficulty in the way of his contention that the post-

18 SCIENCE PROGEKESS.

anal papilla represents an approximated posterior pair of
branchial sense-organs, since the anterior osphradium and
both gill-plumes are all innervated from the outer visceral
nerve.

Euthyneurisnt.—Since the publication of Spengel’s paper
on the olfactory organ and nervous system of Mollusca, a
division of the Gastropoda into two groups, the Strep-
toneura and the Euthyneura, has been generally adopted.
This classification has been accepted, moreover, not merely
as an expression of the anatomical facts concerning the
condition of the visceral loop in the two groups, but as a
classification of phylogenetic significance. It is to be in-
ferred that the two groups have been independently derived
from a common type of archi-Gastropod, possessing an un-
twisted visceral loop—the Prosobranchs (Streptoneura) by
the twisting of the loop, the Opisthobranchs and Pulmonates
(Euthyneura) by the mere shortening and concentration of
the untwisted loop. This view derives support from the
fact that the persistent ctenidium retains its primitive posi-
tion on the right side of the body in Opisthobranchs, while
in Prosobranchs it shows a marked displacement and lies
on the left side. Bouvier’s observations on Acton
(= Tornatella), however, have completely altered the posi-
tion of affairs. Acteon is a very primitive Opisthobranch,
as may be inferred from the high development of its shell,
the persistence of its operculum, and the absence of pleuro-
podial fins. Bouvier tell us (4) that Acteon resembles the
Prosobranchs, not only in these points, but also in possess-
ing a distinct twist of the visceral loop (streptoneurism,
chiastoneurie). The ctenidium is innervated from a supra-
intestinal ganglion, which lies on the left side of the body.
We. are accordingly led to the conclusion that che
euthyneurous condition of Opisthobranchs and Pulmonates
has not been directly inherited from the orthoneurous
ancestors of the Gastropoda, but has been derived from a
previously streptoneurous condition. In other words the

THE MORPHOLOGY OF- THE MOLLUSCA. 19

Opisthobranchs and Pulmonates have descended from
Prosobranch ancestors, and the right-sided position of the
gill-plume in Opisthobranchs is not primitive, but the result
of a secondary process of detorsion.

Orthoneurordism.—WV ithout going further into the
matter it may also here be mentioned that the supra-in-
testinal commissure has been recently discovered in various
species of Nerita, Neritina, and Navicella by Boutan (2),
Bouvier (3a), and Haller (11)—a discovery which de-
stroys the last refuge of orthoneurism in Prosobranchiate
Gastropods. Streptoneurism may now be affirmed of all
Prosobranchiate Gastropods.

Origin of the Molluscan nervous system.—The attempts
of previous writers to explain the relations of the nervous
system of Mollusca have been based almost exclusively
upon comparisons with the fully constituted nervous
systems of such types as the Turbellaria and Annelida.
With Thiele’s theory of the Turbellarian ancestry of the
Mollusca I have already dealt, and I do not propose to
deal with the Annelidan hypothesis, since this theory can-
not provide any satisfactory explanation of the high develop-
ment of the pleuro-visceral nervous system of the Mollusca.
Those authors who, like Thiele and Pelseneer, homologise
both the pleural and pedal centres of the Mollusca with the
ventral cords of Annelids, base their view upon the sup-
posed origin of the pleural centres from the pedal cords.
This derivation I have already shown in this article to be
completely erroneous. Pelseneer's theory of the origin of
the Mollusca from Polychete ancestors (18@), and all
theories which seek the origin of the Mollusca in the
specialised representatives of any of the vermiform groups,
may at once in my opinion be dismissed from considera-
tion.

Apart from matters of minor importance it will, I think,
be conceded that the following cardinal points in regard
to the morphology of the Molluscan nervous system have

20 SCIENCE PROGRESS.

been established by the facts and arguments which have
been presented in this article :—

(1) That the pleural ganglia have not been derived by
segregation from the ventral or pedal cords.

(2) That the pleural, visceral, and abdominal ganglia
of Gastropoda form a group of dorsal nerve-
centres—the two former owing to their dif-
ferentiation in the immediate neighbourhood of
the velum, and the latter owing to its differentia-
tion from the mid-dorsal wall of the body (floor
of mantle-cavity).

(3) That the dorso-lateral nerve-ring of Amphineura
iS primitive and is represented in other groups
of Mollusca by both the pallial and visceral
nerve loops, or their derivatives.

(4) That the sub-intestinal position of the visceral loop
in all groups except the Amphineura is a
secondary one, which has been rendered possible _
only by the decentralisation of the primitive
pleuro-visceral nervous system, and its separa-
tion into special ganglia and nerves, the latter
being formed ontogenetically as fibrous out-
growths from the ganglionic centres.

Venturing now, in conclusion, upon more speculative
ground, I believe that the embryonic relations, to which I
have drawn attention, between the pleural and visceral
ganglia and the ciliated band are of phylogenetic importance.
It has long puzzled me that the larval forms(trochospheres) of
two groups so closely allied as the Annelida and Mollusca,
while presenting a close similarity in general structure,
should differ so remarkably in regard to their nervous
system. The Annelid trochosphere has a _nerve-ring
beneath its ciliated band, while the Molluscan trocho-
sphere has none. In this respect the Molluscan trocho-
sphere appears to be less primitive than that of the
Annelida. The explanation of this now appears to me to

THe MORPHOLOGY OF THE MOLLUSCA. 21

be as follows. In the evolution of the Annelida the proto-
troch and nerve-ring remained for a long time unmodified,
and did not share in the elongation of the postero-ventral
region of the body which gave rise to the trunk of the
Annelid. This would explain the absence of the dorsal
nerve-ring in the adult Annelid, provided that the nerve-
ring, together with the prototroch, came to have merely a
larval significance,—as actually happens in the ontogeny of
Annelids to-day. On the other hand, in the evolution of
the Mollusca from the same simple type of ancestor, the
whole body must have shared in the elongation—the proto-
troch and nerve-ring as well as the more ventrally placed
parts of the body. This elongated nerve-ring I identify
with the pleuro-visceral ring of Amphineura, although the
phyletic connection between the nerve-ring and the ciliated
band is inferred from the development of certain Gastro-
pods rather than from the Amphineura themselves. Asa
larval adaptation for conveniences of natation I imagine
that a separation became gradually effected in embryonic
life between the ciliated ring and the nerve-ring, the former
becoming restricted to the anterior end of the larval body,
while the latter became more and more extended far? passu
with the elongation of the trunk. Such a separation is to
some extent paralleled in the development of Holothurians
from the Auricularia larva, as described by Semon. On
this theory alone can I explain to myself the absence of the
ancestral nerve-ring in the trochospheres of Mollusca, and
I find some support for this view in the ontogeny of Nemer-
tines. The lateral nerve-cords in this group have the same
relation to the gut and brain as have the pleuro-visceral
cords of Chz¢on, since they form a dorso-lateral ring, the
posterior commissural portion passing above the rectum.
In Nemertines there can be very little doubt that this
nerve-ring has been derived phyletically by the elonga-
tion of a nerve-ring which underlay the ciliated band of a
more or less Prlzdium-like ancestor, as it underlies the

22 SCIENCE PROGRESS.

ciliated band of the P2dedéum-larva, although this phyletic
origin is disguised by the profound metamorphosis which
breaks the continuity of the ontogenetic record in Nemer-
tines. On this theory of course the lateral cords of Nemertines
do not correspond to the ventral cords of Annelids. The
latter are represented by the general ventral plexus of
Nemertines and by the pedal plexus or cords of Mollusca.
These ventral nervous systems appear to bear relations to
the dorso-lateral ring-nerve similar to those of the subum-
brellar plexus of Medusa to the circumferential nerve-
ring.

It will be recognised from these remarks that the
conclusions to which I have arrived present distinct points
of agreement with those of Balfour (1, p. 378) and Sedg-
wick (21) on the same subject, although attained throughout
by an independent series of inductions. With both these
writers I agree in tracing back the Molluscan nervous
system to a primitively annular type, such as might be
expected to exist in’ a Coclenterate -ancestom | Balioun
derives the whole Molluscan nervous system from a
peripheral nerve-ring which followed the course of a hypo-
thetical ciliated ring ; Sedgwick derives it from a broad
plexus surrounding an elongated blastopore, such as occurs
in existing Actinians. | Sedgwick’s theory was practically
an alternative to Balfour’s, but | find myself able to give a
partial acceptance to both these views. For the nervous
system of Mollusca appears to me to consist of two parts, a
circumferential ring and a peri-blastoporal plexus. The
circumferential ring, which was primitively associated with
a ciliated ring, is represented by the pleuro-visceral nervous
system, which I have shown to possess significant relations
with the velum or prototroch of the larva; and the peri-
blastoporal plexus seems to me to be recognisable in the
pedal nervous system, which in primitive Molluscs has a
very diffuse plexus-like arrangement, and in Amphineura,
at any rate, reveals its peri-blastoporal character in the

THE MORPHOLOGY OF THE MOLLUSCA. 23

cerebro-pedal connectives in front and its connectives with
the supra-rectal abdominal ganglion behind.

BIBLIOGRAPHY.

(1) BALFOUR, F. M. Comparative Embryology, ii., 1885.
CyPBOUGAN eAxch. Zool. Exp. (3), 1. pp. 221-265, 1893.
(3) BOUVIER. Systeme Nerveux des Prosobranches. Ann. Sci.
Nat. (7), iii., 1887.
(3a) BOUVIER. Comptes Rendus, cxiv., p. 1281, 1892.
(4) BOUVIER. Comptes Rendus, cxvi., pp. 68-70.
(5) DUVERNOY. Mém. sur le systeme nerveux des Mollusques
Acephales. Alem. Acad. Sci. Paris, xxiv.
(6) ERLANGER, R. VON. Zur Entwicklung der Paludina vivipara,
J.u. I]. Theil. Morph. Jahrbuch, xvii., 1891.
(7) ERLANGER, R/ VON. Zur Entwicklung von Bithynia ten-
taculata. Mztth. Zool. Stat. Neapel. x., 1892.
(8) HALLER, BELA. Die Organisation der Chitonen der Adria.
Arb. Zool. Inst. Wren, 1882-3.
(9) HALLER, BELA. Untersuchungen iiber marine Rhipido-
glossen, I. Morph. Jahrb., ix., 1884.
(10) HALLER, BELA. Die Morphologie der Prosobranchier. J/orph.
WaHhro,, SAV. 1888.
(11) HALLER, BELA. Studien iiber Docoglosse u. Rhipidoglosse
Prosobranchier, 4to, 1894.
(12) HUXLEY and PELSENEER. Report on Spirula. “Challenger”
Reports, Zool., part \xxxiii., Appendix, 1895.
(13) KERR, J. G. On some Points in the Anatomy of Nautilus
pompilius. Pvoc. Zool. Soc., part il1., 1895.
(14) KORSCHELT u. HEIDER. Lehrbuch der Entwicklungs
geschichte, ili., 1893.
(15) KOWALEvSKyY, A. Embryogénie du Chiton polit. Azz. Mus.
Hist. Nat. Marseille., Zool., i., 1883.
(16) LANG, ARNOLD. Lehrbuch der Vergl. Anat., 3 heft.
(17) LANKESTER, E. Ray. Mollusca. Encycl. Brit., ninth
edition.
(18) PELSENEER. Contribution a l’étude des Lamellibranches.
Arch, de Biol. xi., p. 166, pl. vi., fig. 3, 1891.
(18a) PELSENEER. Classification Générale des Mollusques. Az//.
Sct. France et Belg., xxiv., p. 346, 1892.

24 SCIENCE PROGRESS.

(19) PELSENEER. Introduction a l’étude des Mollusques. Bruxelles,
1894.

(20) PLATE. Bemerk. iib. d. Phylogenie u. d. Entstehung d.
Asymmetrie d. Mollusken. Spengel’s Zool. Jahrbiicher, Abth.
VY. Anat U. Ones Veni POO loose

(21) SEDGWICK, ADAM. On the Origin of Metameric Segmenta-
tion. Quart. Jour. Micr. Scz., xxiv., 1884.

(22) SIMROTH. Svonn’s Klassen u. Ordnungen des Thier-Reichs.
Mollusca. I. Amphineura u. Scaphopoda, 1892-94.

(23) THIELE, J. Ueber Sinnesorgane der Seitenlinie und das
Nervensystem von Mollusken. Zez¢. f/ Wiss. Zool., x\ix., pp.
385-432, 1890.

(24) THIELE, J. Die Stammesverwandschaft der Mollusken. /ena
Zelin., KXVe, Pa oO, MoO le

(25) THIELE, J. Beitrage zur Kenntniss der Mollusken. Zezt. 7.
Wess. Zool., liti., p. 578, 1892.

(26) WILLEY, A. Natural Science, vi., p. 412, 1895.

WALTER GARSTANG,

Report of the Hope Professor of Zoology.

———————ow

By the end of the previous year it had become evident that
the immense number of specimens requiring to be re-pinned
and re-set would demand the attention of a special assistant
for many years. Mr. Holland being occupied in arranging
and classifying various parts of the Collection, in separating
various sections for the work of others, and in looking out
specimens to illustrate lectures, could devote but little time
to this necessary labour. I therefore decided to employ
a junior assistant for this purpose, and after much considera-
tion, engaged H. Smith of Reading, who had already acquired
considerable experience in manipulating the British Lepi-
doptera and Coleoptera. He began work towards the end of
January, and by the end of the year had made considerable
progress, especially with the Lepidoptera Heterocera.

The British Lepidoptera which had been commenced by
Mr. Holland in the previous year, were completed, except the
staging of the minute species. In the general collection the
Sphingidae, Noctuinae, Geometrinae, Bombycinae, Syntomidac,
Psychidae, Arctiidae, Agaristidae, Zygaenidae, Castntidae, and
Uranidae were completed, with the exception of those
American specimens which had been adjusted by Mr. Holland
in 1894. Among the Lepidoptera Rhopalocera the majority
of the Exploeinae, Danatinae, Acraecinae, and Heliconinae were
also re-set. A considerable amount of printing was also
undertaken by H. Smith during the latter part of the year.

Mr. Holland named and classified the general collection of
Sphingidae, arranging nearly the whole of it in three small
cabinets containing altogether fifty drawers. When this
arrangement has been completed by the addition of printed

2

locality and type labels, together with coloured geographical
labels, the Spzngidae will constitute an exceedingly fine and
valuable collection, in every way available for convenient
feference:

Mr. Holland has also named and classified the Zygaenidae
and Syztomidae, so that these groups are ready to be arranged.
He also in large part worked out the Heliconinae and
Fleliconoid Danainae. Many of the more obscure species were
taken to London and compared with the splendid Godman-
Salvin Collection. I wish to express my sincere thanks to
these gentlemen and to the heads of the Insect Department
of the British Museum for their invariable courtesy, and for
their kindness not only in granting me free access to the
Collections, but in bestowing much time and trouble in helping
to compare and identify the species. I am glad to think that
we have been enabled in some slight degree to return this
kindness by bringing a few of the types, and other specimens
of the greatest interest, to London for examination and study.
I wish also to thank Mr. W. F. H. Blandford and Mr.
Champion for their kind help in the comparisons with the
Godman-Salvin Collection.

Mr. Schaus completed his work upon the American moths,
and his valuable catalogue of the types in the Hope Collection
will be published during the present year.

Dr. Dixey has been arranging the Pzerznae in the finest of
the cabinets purchased for the Department in 1894, adding
the geographical labels and maps, and making out the most
obscure groups.

Mr. Sidgwick has continued his arrangement of the British
Lepidoptera, and towards the end of the year has been helped
by Mr. Pogson Smith. The butterflies and the larger moths
are already arranged, and this part of the Collection has been
found very useful by undergraduates and others who. have
consulted it in order to name their specimens.

Col. Swinhoe has continued his work upon the Oriental
Heterocera, and the arrangement of this part of the Collection.

In the rearrangement of the cabinets in the enlarged Hope
Museum, three very conspicuous and unsuitable cabinets were

3

removed, the sale of the old cases assisting to provide new
ones for the old drawers. The new cases were made of such
dimensions as to bring several cabinets in the Museum up to
a uniform height.

On the upper floor the east room has been fitted up as
a biological laboratory, and Mr. and Mrs. Garstang have
worked in it since October.

In Lent Term the course of Lectures on ‘ Charles Darwin
and the Problems of Modern Biology’ was continued ; and in
Michaelmas Term a course upon ‘ Mimicry’ was begun.

Additions to the Collection :—

Owing to the confusion caused by the building operations,
several additions to the Collection made in 1894 escaped
record in the Report of that year. They are accordingly
inserted in this year’s Report.

Donations in 1894 (not included in Report of that year) :—

Lepidoptera Rhopalocera (23 specimens), from various
localities, presented by G. C. Griffiths, Esq.

An example of a species of Acridiidae from Egypt, presented
by A. J. Butler, Esq., M.A.

A series of Leucophasia sinapis (8 specimens), from Reading,
presented by Mr. W. Holland.

A valuable series of Orthoptera (21 specimens), from various
localities, presented by M. Henri de Saussure.

Purchases in 1894 (not included in Report of that year) :—

A valuable series of Danainae and Acraeinae (226 speci-
mens), from various localities, from the Collection of the late
J. Jenner Weir, Esq., purchased at Stevens’.

Donations in 1895 :—

Lepidoptera Rhopalocera (17 specimens), captured in 1894
by F. E. Pollard, Esq., at Etshowe, Zululand, presented by
Miss Pollard.

Rare Coleoptera (6 specimens), from Sussex, presented by
pee Jenner, Esq:

Lepidoptera (115 specimens), chiefly Rhopalocera, from the
Khasia Hills, India, presented by Col. Swinhoe.

4

Parnassius mnemosyne (2 specimens), from the Pyrenees,
presented by H. M. Wallis, Esq.

Myriapoda, Arachnida, and Insecta (58 specimens), chiefly
Lepidoptera, from Teneriffe, presented by Mrs. Holt White.

Purchases in 1895 :-—

Lepidoptera (almost exclusively Rhopalocera), and one
specimen of a Coleopterous species (647 specimens), chiefly
from Venezuela and Colombia, purchased from Watkins and
Doncaster. The great majority of the specimens will form
the nucleus of a special Collection illustrating Mimicry.

Lepidoptera Rhopalocera (6 specimens), from Africa, pur-
chased from E. Swinhoe.

Professor Westwood’s private Collection, containing about
1450 Lepidoptera and about 300 Coleoptera (captured by
General Hearsey in India), purchased from Miss Swann.

THE HOPE LIBRARY,

Many necessary works of reference were purchased during
the year, including the parts of Barrett’s ‘ British Lepidoptera’
and Saunders’ ‘ British Hymenoptera aculeata.’

The following works were presented by Professor Poulton :—

Eight volumes of the Ray Society, 1885 to 1892 inclusive.

Transactions, Entomological Society, from 1893 to 1895
inclusive.

Transactions and Journal of Linnaean Society, from 1893 to
1895 inclusive.

Vols. i to vi (inclusive), vol. viii, vols. xv to xxix (inclusive)
of the Zoological Record, thus completing the series in the
Library.

The first four volumes of The Entomologist’s Record, from
its beginning in 1890.

Weismann’s Essays on Heredity, two vols., Oxford, 1891,
1892.

Butterflies and Moths of Teneriffe, by A. E. Holt White,
one vol.

Catalogue of the Library of the Entomological Society of
London, one vol.

5

Tertiary Rhynchophorous Coleoptera (one vol.), presented
by the author, S. H. Scudder, Esq.

The Spiders of Burmah (one vol.), presented by the Trustees
of the British Museum.

Indian Forest Zoology (one vol.), and the volume on Silk,
No. 23 of the Handbooks of Commercial Products, presented
byathe author, Ey ©. Cotes, Msq:

Revisio Insectorum Familiae Mantidarum, by the late Prof.
Westwood (one vol.), presented by Miss Swann.

The Parts of the work on Membracidae in the Biologia
Centrali-Americana, published during the year, presented by
the author, Canon W. W. Fowler.

A copy of Diversae Insectarum Volatilium, by D. I.
Hoefnagel (1630), presented by T. W. Taphouse, Esq.

Copies of Original Papers were also presented to the
Library by the following authors:—Baron Osten Sacken,
ee vusten, sq: G. EH, Carpenter, Esq. Fl Heron, Bsqy
Rev. T. R. R. Stebbing, F. A. Bellamy, Esq., Prof. Sigismondo
Orlandi, J. W. Shipp, Esq., C. O. Waterhouse, Esq., M. Henri
de Saussure, Prof. Enzio Reuter, Rev. E. N. Bloomfield, A. G.
Butler, Esq., G. F. Hampson, Esq., and S. H. Scudder, Esq.

A very complete and numerous set was presented by
Meek. Kirby, Esq.

The University of Genoa presented copies of the Reports
of the Museum of Comparative Anatomy.

The Bombay Natural History Society and the Boston
Society of Natural History presented their publications for
the year.

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Report of the Hope Professor of Zoology.

THE year 1896 was an extremely successful one for the
Hope Department; for large and valuable presents have
been received, and a great deal of work has been accom-
plished, not only by the staff, but also by many friends who
have kindly helped in their special lines of research.

Thus the whole Collection of British Aculeate Hymen-
optera has been revised by Mr. Edward Saunders; a part
of the Collection of Phytophaga (Coleoptera) by Mr. M.
Jacoby ; the Membracidae and Cicadae by Canon Fowler,

assisted by Mr. W. F. Kirby. In order to render this kind ©

and valuable help possible the specimens were sent to the
gentlemen named above, but nearly all of them have now
been returned.

Much help has also been received from friends who have
visited the Department. Mr. Philip P. Calvert of Phila-
delphia assisted in making out Rambur’s types of Odonata ;
Mr. Roland Trimen, F.R.S., and Mr. G. A. K. Marshall with
the African Rhopalocera; Col. Bingham with the general
Collection of Aculeate Hymenoptera; Mr. G. A. Boulenger,
F.R.S., with the Collections of fishes, amphibia, and reptiles.

Among residents Dr. Dixey has continued his arrangement
and study of the Pierinae, Col. Swinhoe of the Oriental
Heterocera, Mr. Arthur Sidgwick and Mr. Pogson Smith of
the British Lepidoptera.

Mr. Sidgwick kindly presented the Department with a
fine set of entomological forceps.

Mr. A. W. Pickard-Cambridge began the revision of the
British Coleoptera, but was prevented from carrying on the
work by the pressure of other duties.

It is my pleasant duty to thank all the eminent entomo-
logists I have named for their kind help to the Department
and the University.

Mr. and Mrs. Garstang have continued to work, principally
upon Crustacea, in the East Laboratory, for which a Jung

B

2,

microtome was purchased, -the expense being defrayed by
the Common University Fund.

The event of the year has been the generous gift of
a large Collection of butterflies by Mr. Godman and Mr.
Salvin. A general description of the Collection and the work
which has been done upon it, will be found in the account of
the additions to the Department during 1896. The selection
and packing of the specimens for conveyance to Oxford
required many visits to London by the Professor, Dr. Dixey,
and Mr. Holland.

The work on the Collections also necessitated many journeys
to London, for comparison with the specimens in the British
Museum and the Godman-Salvin Collection. I wish to thank
the Head and Assistants in the Insect Department of the
former, and Mr..Godman, Mr. Salvin, and Mr. Champion,
for their invariable kindness.

“The Council of the Entomological Society of London
were invited to visit Oxford, June 27-29, and I am pleased to
say that many of them were able to be present, including
the President, Professor Meldola, F.R.S., the Treasurer, Mr.
KO Mclachlan, F-R.S. Mr. Salvin, HRS. Mr: @irimen, Pb Ress
Mr. Blandford, and Mr. Champion, as well as the members
resident in Oxford. Many kind friends helped to offer
hospitality to our visitors. The Hope Collections were in-
spected, and will benefit very greatly from the valuable
suggestions made by the eminent authorities who were
present. While the visit was in every way a great pleasure
‘and advantage to us in Oxford, it is very satisfactory to learn
from the allusion in the Presidential Address to the Society
(Jan. 1897) that it was also enjoyed by our visitors.

Now that the visit of the Council, to which I have long
looked forward, has taken place, I trust that it may be
repeated annually.

During the year Mr. Holland has been engaged in naming
and arranging many sections of the butterflies, in making
out the forms of labels for printing in the Department, and
in looking out, arranging and numbering the specimens to
be sent to those who have helped us. During the latter
half of the year, the Godman-Salvin specimens have been
brought to Oxford, and much of Mr. Holland’s time has

3

been occupied in working them out and arranging them,
parallel with the corresponding groups in the Hope Collec-
tion. The work already done is indicated in the table printed
in the description of this gift. Earlier in the year the general
Collection of Danainae was in large part arranged in a final
form, with coloured labels indicating the geographical dis-
tribution, &c.; but the great additions which were made later
in the year, made it necessary to postpone this work for
a time.

A large amount of re-pinning and re-setting was done by
H. R. Smith, so that all the groups of butterflies, with the
exception of the Papilioninae, the Hesperidae, and part of the
Nymphalinae Lycaenidae and Erycinidae, are now finished.
The very numerous specimens added to the Department’
during the year have also been set, with the exception of
parts of the Godman-Salvin gift indicated in the table
printed in the account of this Collection.

At the beginning of 1896 it was decided after much con-
sideration to modify the style of setting in order to bring it
into harmony with that now adopted in the British Museum,
and other great Collections in this country. The specimens
are now set with the wings as flat as possible, and are raised
high on the pin; so that there is abundant room for small
labels below the insect itself. In order to carry out this.
change, a set of new boards was purchased, and a considerable
amount of Smith’s time was devoted to making others.

Furthermore, many hundreds of label-holders were screwed
on to the fronts of cabinet drawers, a certain number of
drawers were re-papered, and several shelves were fixed in
the small East Laboratory. Hence, with a large amount of
label-printing, especially in connexion with the specimens
added during the year, Smith’s time was very fully occupied.

In Lent Term the Professor lectured upon “Mimicry ”;
in the Summer Term he gave two Public Lectures on
“The Hope Collections.” There were no lectures during
Michaelmas Term.

Additions to the Collection :—

A very valuable Collection of Rhopalocera (butterflies),
chiefly from Central and South America, but also including
a large number from other parts of the world, was presented

B 2

4

by iF. Ducane Godman, Esq. F.R:S.° and ‘Osbertasalum
Esq., F.R.S. This important Collection, constituting by far
the largest accession to the Department during recent years,
was formally accepted by a Decree of Convocation on May 11,
1897, when the further Decree conveying the thanks of the
University to the Donors was also passed unanimously.

The specimens were however presented and brought to
Oxford during 1896, and the work upon them occupied
a large part of the Assistants’ time, so that they are best
included in the Report of that year. The following account,
reprinted from the Uzzversity Gazette for April 30, 1897,
affords a brief description of this valuable gift, and also
indicates the nature of a large part of the work upon which
the Hope Department was engaged during the second half
of 1896, and the special needs of the Department at the
present time.

“ Note.—The following note has been prepared by the Hope
Professor, explaining the value of the Collection and the
expenditure which may be caused by its acceptance :—

The specimens in this Collection are of especial value
because of the excellent geographical data which accompany
them. Although specimens from all countries are included,
the Collection is especially rich in species from Central
America, a district of peculiar interest, hitherto but poorly
represented in the Hope Collection. Many specimens of
historic interest are also present—the captures of H. W.
Bates in Brazil, of T. Belt in Nicaragua, and of A. R. Wallace
in the Malay Archipelago. The majority of the more
recently captured specimens were taken by the greatest
living collectors, such as G. C. Champion and H. H. Smith
(Central America), and C. M. Woodford (Solomon Islands) ;
so that all localities can be entirely depended upon. No
conditions are attached to the gift, so that the specimens
can be at once incorporated with those of the General
Collection, as soon as they have been adequately labelled.

The Collection also contains a large amount of material
which will be available to illustrate the principles of Protective
Mimicry, Geographical Distribution, Isolation, &c.

The following table indicates the numbers of specimens
now in Oxford. The numbers of all Groups which are

5

marked as ‘named’ are final: those of the others will be
somewhat reduced when they have been named and com-
pared with the existing Collection :—

Families of Number of : |
- ished.

Rhopalocera. Specimens. Wisriggesoutpicted
I. NYMPHALIDAE—

a. Danainae ... 2,142 Named, arranged, re-set.

B. Satyrinae ... 1,677 Named, arranged, re-set.

y. Llymniinae ... 18 Named.

d. Morphinae ... 153 Named.

e. Lrassolinae ,.. 163 Named.

(. Acracinae ... 256 Named, arranged, re-set.

n. Heliconinae ... 513 Named, arranged, re-set.

6. Nymphalinae... ean Named, partially arranged and re-set.
2 RVGINIDAE steers. 1,182 Named, arranged, re-set.

r ~ !
3. LYCAENIDAE... ... 995
4. PAPILIONIDAE—

Cin TERA ke oe Qe iri Mostly re-set.

B. Papilioninae ... 1,092 Named.
5. HESPERIDAE... ... 463

TOVaAL 16,116

As regards the Old-World species in the above-named
Groups, the whole of the duplicates of the Godman-Salvin
Collection have been placed at our disposal; but as regards
the New-World species, Mr. Godman and Mr, Salvin kindly
promise that further specimens will be available in the future.

The approximate value of the gift is very difficult to
estimate. In the autumn of 1895 the Department purchased
522 specimens of South American Lepidoptera for 4£21—
a sum which was evidently considered to be exceptionally
small and was only arrived at after much discussion. Many
of the specimens in the Hope Department, selected by the
late Professor, still retain the price upon their labels, proving
that 25. 6d. or 3s. 6d. apiece was paid for them. The Hope
Collection contains some few (perhaps a dozen) specimens
from the Solomon Islands, purchased by Professor Westwood
at a cost of from 3s. 6d. to 10s. 6d. apiece: whereas among
the Godman-Salvin specimens there are 826 specimens from
this locality, captured by C. M. Woodford, but of far greater
scientific value, in that several islands of the Group are
represented, including the extremely dangerous Maleita

B3

6

Island, where the collector could not venture beyond the
range of the rifles of his guard. The few Hope specimens,
also captured by C. M. Woodford, are all from the best-known
island, Guadalcanar. The South and Central American
specimens, constituting by far the greatest part of the Collec-
tion which is now presented, are of much greater scientific
value than those which were purchased in 1895, and than
the majority of the Hope specimens from the same localities,
because of the greater accuracy and precision of their
geographical data. To obtain specimens with such data
it would be necessary again to send out, and maintain on
the spot for many years, the best living collectors. From
these considerations some conception of the great value of
the gift may be arrived at.

Phe cost involved in the acceptance ‘or (the citvismas
follows :— |

(1) Transfer of specimens to Oxford.

This has been paid for out of the income of the Hope
Department, and amounts to about 415. [The cost was
under 412. 4. B. P., May 14, 1897,|

(2) Re-setting, printing, naming, arranging.

Most of this work has been done: it will be completed
(including the printing) by the Departmental staff without
any extra expense to the University.

(3) Cabinets.

New cabinets are imperatively needed for the present
Collections, which are densely overcrowded; and apart from
the Godman-Salvin gift, it would have been necessary for me
to apply soon to the University for a grant nearly as large as
may be involved by its acceptance, for a large proportion
of these specimens will occupy the spaces which would have
been necessarily left blank in the rearrangement of the present
Collections, while others will replace specimens which are in
bad condition.

The right arrangement now would be to raise a sum of
£600 for the purchase of 10 cabinets of 60 drawers, each
made in 3 sections of 20 drawers, all the drawers to be made
interchangeable. I have already concluded a contract with

~
d

a well-known London maker to supply half this number,
with the option of taking the second half at the same rate.
Towards this sum the Delegates of the Museum have voted
£100, and the Delegates of the Common University Fund
#100. I have raised by subscriptions about 4£2c0, and it
is possible that I may obtain 4250 in this manner. There
remains £150, which I trust may be raised in some way.
If however this sum cannot be obtained, I shall make the best
possible use of the funds which are now available, although
this will involve ultimate expense in consequence of the
adoption of a more crowded arrangement. The careful work
which is necessary for insect-cabinet-making is necessarily
very slow, and consequently the 4150 will not be required
until the autumn, or perhaps the beginning of next year.”

The following copy of one of the labels printed in the Hope
Department, serves to indicate the information which will be
available upon each of the specimens as it is incorporated in
the general Collection.

AOLA
Guadalcanar
Solomon Islands
Capt. March 30.
to Sept. 25. 1887.
byC.M. Woodford.
Ex Godman-Salvin

byED.GandO.s.

The contributions which have been promised or paid to the
fund for the purchase of new cabinets are as printed below.
I am glad to take this opportunity of thanking those who
have helped to overcome the great difficulties of the present
position. Further assistance is much needed.

hens Sade
George Palmer, Esq. wie a SOs On 1
GoW. Palmers Hsq. i 1s ae 67, OV =O
A@itdimersisg. = i. IG Ons
The Principal of Beene eat EGU On S
Prof. Poulton oh ae bet BO Gro
E. Chaparan, Hisq. ree a 5 Orr ©
Dr Ge Bs onestate Cus ai 25. Oo 76
Capt. J. W. Woodall Sow .o

The Department has also received many other valuable
accessions during 1896. The large numbers of Rhopalocera,
kindly presented by A. G. Cardew, Esq., J. J. Walker, Esq.,

§

R.N., and G. A. K. Marshall, Esq., are of especial value
because of the accurate data which accompany them. Those
of Mr. Marshall are accompanied by notes giving precise date,
locality, height above the sea, and statement as to wet or dry
season form. They are the most perfectly recorded specimens
in our whole Collection.

The specimens presented by A. G. Cardew, Esq., consist of
398 specimens of Rhopalocera from the Nilgiri Hills and
Cannanore ; and 36 Heterocera from Nilgiris, 4 from Can-
nanore, 1 from Madras, and 1 from Coimbatore. I have
already alluded to the excellent data which accompany the
specimens.

J. J. Walker, Esq., R.N., presented a very valuable set
of 579 specimens of Rhopalocera, 20 Heterocera, 59 Cole-
optera, and 4 Oceanic Hemiptera (Hylobates). Nearly all
the specimens were captured by Mr. Walker in the countries
visited during the Voyage of H.M.S. “ Penguin” (1890-93),
and during other voyages. The specimens are chiefly Ori-
ental and Australian, although there are some valuable
additions from Central and S. America, S. Europe, and the
Levant. The data accompanying the specimens are most
excellent. The RKhopalocera include the very rare Evroessa
chilensis (new to the Department), and a fine series of
Polynesian forms of Hypolimnas bolina.

The 714 specimens of Rhopalocera presented by G. A. K.
Marshall, Esq., were all captured by him in S. Africa. The
admirable condition of this valuable series has been already
described.

Forty-two specimens of Danainae and 54 of Euploeinae
were presented by Col. Swinhoe.

Two specimens of Limuas Kilugii were presented by
C. A. V. Peel, Esq., captured by him in Somaliland.

Fifty-three specimens of Lepidoptera, chiefly Oriental,
were presented by Professor Poulton. These specimens are
chiefly intended to illustrate “ Mimicry.”

Twenty-eight specimens of Rhopalocera were presented
by O. V. Aplin, Esq., captured by him in Soriano (Uruguay),
the Sahara, and Arctic Norway.

A valuable set of 297 specimens from various localities,
chiefly of Rhopalocera, but also containing examples of

9

Heterocera, Diptera, Neuroptera, and Orthoptera, were pre-
sented by G. C. Griffiths, Esq.

A curious form of /feliconius erato from British Guiana was
presented by Mr. A. H. Hamm.

The Collections of British Insecta were also enriched during
the year. As regards the Lepidoptera, a series of 12 Hesperia
lineola from Sheerness were presented by J. J. Walker, Esq.,
R.N.; 2 specimens of the very rare Platypteryx Sicula (from
the Leigh Woods, Clifton), 1 specimen of Sesta scoliaeformis
from Rannoch, and a series of 20 Acidalia holosericata from
Clifton, were presented by G. C. Griffiths, Esq.; a series of
7 Catocala promissa from Lyndhurst by C. A. V. Peel, Esq.
Professor Poulton also presented 3 British specimens of
Vanessa antiopa (“Camberwell Beauty”), 2 captured at
Cromer in 1872, and 1, a hybernated specimen, captured
near Reading in the spring of 1873; his son, Edward P.
Poulton, presented an extremely small specimen of Lycaena
argiolus, and 2 rare or local moths,—captured by him at
St. Helens, Isle of Wight.

Among the other Orders of British insects, the Orthoptera
were enriched by a series of to Periplaneta americana from
the Zoological Gardens, and a specimen of P. australasiae
from Kew, presented by Malcolm Burr, Esq.; while the
Neuroptera received an addition of 9 specimens of Odonata
from the neighbourhood of Oxford, presented by H. R.
Smith.

There were comparatively few purchases of specimens
during the year. Four, specimens of Papilio meriones from
Madagascar, and 3 Oriental species of Lwsemia, being the
only additions obtained in this way during 1896.

A few additions to the Collection of British Birds made
in 1895, omitted from the Report of that year, are now
included.

Bittern (Botaurus. stellaris) ¢, shot and presented by Mr.
T. Dewe, of Longworth, January 10, 1895, at 7 p.m, while
duck shooting on land in the occupation of Mr. Chandler, at
Duxford, 63 miles N.E. of Faringdon, Berks.

Young Land-rail (Gallinula crex) ¢. Age 6 to 8 weeks.
Taken at Shippon, near Abingdon. Presented by Mr. H.
Trim, University Museum. July 15, 1895.

i fe)

Little Auk (Mergulus melanoleucos) ¢, shot on Port
Meadow, Oxford, while diving in the floods, in January, 1895,
by E. Mott, from whom it was purchased.

THE HOPE LIBRARY.

Miss Swann presented 4 lithograph portraits of naturalists,
a set of coloured sketches of flowers, and a large number
of valuable manuscript notes by the late Professor Westwood,
and 2 volumes and 1 pamphlet which belonged to him.

Two valuable books containing manuscript notes by Sir
Sydney Saunders, on his collection of Hymenoptera, now
in the Hope Department, were presented by Edward
Saunders, Esq.

The Transactions of the Entomological Society, and the
Transactions and Journal of the Linnaean Society for the
year 1896, were presented by Professor Poulton.

The Biological Department of the Owens College, the
Bombay Natural History Society, the Boston Society of
Natural History, the Chicago Academy of Sciences, the
Zoological Museum of the University of Genoa, presented
their publications for the year. The Radcliffe Library pre-
sented the Catalogue of Books added during 1896. The
New York State Museum presented its Report for 1894.
The acknowledgement was inadvertently omitted in the
Report for the year.

Canon W. W. Fowler presented the Parts of his monograph
on the Membracidae in the Biologia Centrali-Americana,
published during the year.

Several volumes and pamphlets formerly in the Ashmolean
Museum were transferred to the Department, including a very
fine Buffon’s Natural History in 127 volumes.

A few volumes and pamphlets from the Proceedings of
the Ashmolean Society were given to the Department.

Copies of Original Papers were also presented to the
Library by the following authors :—Rev. T. R. R. Stebbing,
Sir George F. Hampson, Bart., S. H. Scudder, Esq, Col.
Swinhoe, Hamilton Druce, Esq., Edward Saunders, Esq.,

ipa

C. O. Waterhouse, Esq., Dr. Fritz Miller, Rev. E. N. Bloom-
field, A. G. Butler, Esq., Mons. P. Lesne, Dr. and Mrs. G. W.
Peckham, Baron Osten Sacken, G. A. K. Marshall, Esq., Lord
Walsingham, Peter Cameron, Esq., Prof. R. Warington, and
Pb Calvert, Esq.

A few volumes and pamphlets were purchased for the
Library, including a fine coloured copy of the “ Thesaurus ”’
of Professor Westwood. The serial works purchased in
previous years were continued.

EDWARD B. POULTON.

SMITASUNIAN INSTITUTION LIBRARIES

3 9088 01268 4742

ee