Peet tay tet ly tes ‘ ns peat ,
itn ietathe th isan! riettiathe
eaten attests Ne eat e atin etc!
rons eter es Sarat
leg Stn
he
.
be
ea
ahaa tet best
ni uiertmstssn
Me
Haatie xt Neti
hohe a Pes taceu tase ae tagiatathty Payteat |
ay ity Sa es ite a, tgs ty, Oa dig
pares ot pear safieal ecg Sah: |
x
Bin hm Pan a tata ht Bal td Ce
"
pe
ij
toate baa
Perens spar
pig this th
hatha
s
Hct
Si
me HS
Serial ashe’
Pecan
es
eee
Moh
ih
ftEg “y
iy
ii,
ihe,
fees
Giiis
tif
ye
ms res
Coatathtee ae
if
f
i
tif
Wits
F
if;
ij
fj
& .
Sia thig
ETE
a s
needed
t,
. tas an Oa Kg
tere ttntea big Wks
* ‘ s.
€ : . bee
: SOAR om Rint ‘ Ss ons
aaah . “he, ‘ i : a tg Peas te es, ~~ ee ate
tay tg he Me, . Ms im
aejbang tag . a
fey ~ %
ty,
r
-
PFs:
Fifi
‘s3
thea:
Premarin atte : . : sent : ‘ 2 ‘ Mu
phe tn ett Sept reitine Nea? inetel teks Nish Ncontnatana teat heade ‘ Neate : . : Peters
es ; nate i . , ie Yattntataeenusaiettlltags han ) iting tries it Sate tat eee
Me,
#2
fi,
ashing a hysteria M iy. . . Sather:
niteesertateete tet tert tyres SS Poiliathetacthstneeteas ya 4
si, nts Resta hy Pang ‘, Payahes, . ts "i reltes ae,
-
skh cts
Ye tall tagien* *
Mis hatter
ct
ee,
wii
YY
1,
mts,
hte?
ty
Pats
"
“antes!
taede tatty
vag ties eat
attired ting tay tte,
es
Z,
iti Jf
ip
arta tts
INS
SapPeactn as
Ma
4 on
.
Beaten
hh
Jecteesitna sayy . ; : . Pees tiasaseaas
HesSreiatenfetloai aes : . . ; : sets : Resin yhat mses tees Sta es
ee, Ma he
)
Letras
L niaaaee
a
Lid@00Y WALYSA1
- >
elm heen A teat Re tee amet NR CUR he ie the ete A A Se te
ee
eile am ~
PART Ic OF THE @iher VOLUME OF THE
CONTRIBUTIONS
TO THE
NATURAL HISTORY OF THE UNITED STATES
NORTH AMERICA,
BY
L.A Wee B68 ee
gee (ae Le
ESSAY ON CLASSIFICATION.
it from
On permanent depos
the Botany School
Cambridge University Library,
|
ESSAY ON CLASSIFICATION.
CHAPITEG” Fest.
THE FUNDAMENTAL RELATIONS OF ANIMALS TO ONE ANOTHER AND TO THE
WORLD IN WHICH THEY LIVE, AS THE BASIS: OF THE NATURAL SYSTEM OF
ANIMALS.
Sie TLOs. 1.
THE LEADING FEATURES OF A NATURAL ZOOLOGICAL SYSTEM ARE ALL FOUNDED
IN NATURE.
Mopern classifications of fan and plants are based upon the peculiarities of
their_structure, and this is generally considered as the most important, if not the
only safe guide in our attempts to determine the natural relations which exist
between animals. This view of the subject seems to me, however, to circumscribe
the foundation of a natural system of Zodlogy and Botany within too narrow limits, |
to exclude from our consideration some of the most striking characteristics of the
two organic kmgdoms of nature, and to leave it doubtful how far the arrangement
thus obtained is founded in reality, and how far it is merely the expression of our
estimate of these structural differences. It has therefore appeared to me appropriate
to present here.a short exposition of the leading features of the animal kingdom as.
an introduction to the embryology of the Chelonians, one of the most extraordinary
types among Vertebrata, as it would afford a desirable opportunity of establishing a
standard of comparison between the changes animals undergo during their growth,
and the permanent characters of full grown individuals of other types, and, perhaps,.
of showing also what other points beside structure might with advantage be consid-
4 ESSAY ON CLASSIFICATION. Part I.
ered in ascertaining the manifold relations of animals to one another, and to the
world in which they live, upon which the natural system may be founded.
~ In considering these various topics, I shall of necessity have to discuss many
questions bearing upon the very origin of organized beings, and to touch upon many
points. now under discussion among ‘scientific men. I shall, however, avoid contro-
versy as much as possible, and only try to render the results of my own studies and
meditations in as clear a manner as I possibly can in the short space I feel justified
in devoting to this subject in this volume. :
There is no question in Natural History on which more diversified opmions are
entertained than respecting classification; not that naturalists disagree as to the
necessity of some sort of arrangement in describing animals or plants, for since
nature has become the object of special studies, it has been the universal aim of all
naturalists to arrange the objects of their investigations in the most natural order
possible, and even Buffon, who began the publication of his great Natural History
by denying the existence in nature of any thing like a system, closed his work by
grouping the birds according to certain general features exhibited m common by
many ‘of them. It is true authors have differed in their estimation of the characters
on which their different arrangements are founded; it is equally true that they have
not viewed their arrangements in the same light, some having plainly acknowledged
the artificial character of their systems, whilst others have urged theirs as the true
expression of the natural relations which exist between the objects themselves. But
whether systems were presented as artificial or natural, they have, to this day, been
considered generally as the expression of man’s understanding of natural objects, and
not as a system devised by the Supreme Intelligence, and manifested in these
objects.? |
There is only one “point in these innumerable systems on which all seem to meet,
hamely, the existence in nature of distinct species, persisting with all their pecu-
liarities, for a time at least, for even the immutability of species has been questioned.”
Beyond species, however, this confidence in the existence of the divisions generally
admitted in zodlogical systems diminishes greatly.
With respect to genera, we find already the number of the naturalists who
1 The expressions constantly used with refer- own making, which ean, however, only be true in so
ence to genera and species and the higher groups far as these groups are not true. to nature, if the
in our systems as: Mr. A. has made such a species views I shall present below are at all correct.
a genus; Mr. B. employs this or that species to form 2 Lamarck (J. B. pe) Philosophie zoologique,
his genus; and in which most naturalists indulge Paris, 1809, 2 vols. 8vo.; 2de édit., 1830.—POWELL
when spéaking of their species, their genera, their (Tue Rev. Baven) Essays on the Spirit of the In-
families, therr systems, exhibit in an unquestiona- ductive Philosophy, etc., London, 1855, 1 vol. 8vo.
ble light the conviction that such groups are of their Compare, also, Sect. 15, below.
wna mista ei
Cnar. L FUNDAMENTAL RELATIONS OF ANIMALS. 5
accept them as natural divisions much smaller, few of them having expressed a
belief that genera have as distinct an existence in nature as species, and as to
families, orders, classes, or any kind of higher divisions, they seem to be universally
considered as convenient devices, framed with the view of facilitating the study of
innumerable objects, and of grouping them in the most suitable manner. The indif.
ference with which this part of our science is generally treated becomes unjustifiable,
considering the progress which Zodlogy in general has made of. late. It is a matter
of consequence, whether genera are circumscribed in our systematic works within
these or those limits, whether families inclose a wider or more contracted range of
genera, whether such or such orders are admitted in a class, and what are the natu-
ral boundaries of classes, as well as how the classes themselves are related to one
another, and whether all these groups are considered as resting upon the same foun-
dation in nature or not. .
Without venturing here upon an analysis of the various systems of Zoslogy, the
prominent features of which are sufficiently exemplified for my purpose by the SYS-
tems of Linnzus and Cuvier! which must be familiar to every student of natural
history, it is certainly a seasonable question, to ask whether the animal kingdom
exhibits only those few subdivisions into orders and genera, which the Linnean
system indicates, or whether the classes differ among themselves to the extent which
the system of Cuvier would lead us to suppose. Or is, after all, this complicated:
structure of classification merely an ingenious human invention which every one may
. shape as he pleases to suit himself? When we remember that all works on natural
history admit-some system or other of this kind, it is certainly an inquiry worthy
of a true naturalist to ascertain what is the real meaning of all these divisions.
Embryology, moreover, forces the inquiry upon us at every step, as it is impos
sible to establish precise comparisons between the different stages of growth of young
animals of any higher group, and the permanent characters of full grown individuals
of other types, without ascertaining first what is the value of the divisions, with
which we may have to compare embryos. This is my reason for introducing here,
in a work chiefly devoted to Embryology, a subject to which I have paid the most
careful attention for many years past, and for the solution of which I have made
special investigations. y
Before, however, I proceed. any further, I would submit one case. to the consider-
ation of my reader. Suppose that the imnumerable articulated animals, which are
counted by tens of thousands, nay, perhaps by hundreds of thousands, had never
made their appearance upon the surface of our globe, with one single exception,
that, for instance, our lobster (Homarus americanus) were the only representative of
1 Compare Chap. III.
6 : ESSAY ON CLASSIFICATION. Parr I.
that extraordinarily diversified type, how should we introduce that species of animals
in our systems? Simply as a genus with one species, by the side of all the other
classes with their orders, families, ete, or-as a family containing only one genus with
one species, or as a class with one order and one genus, or as a class with one
family and one genus? And should we acknowledge, by the side of Vertebrata,
Mollusks, and Radiata, another type of Articulata, on account of the existence of
that one lobster, or would it be natural to call him by a single name, simply as a
species in contradistinction to all other animals? It was the consideration of this
supposed case which led me to the investigations detailed below, which, I hope, may
end in: the ultimate solution of this apparently inextricable question.
Though what I have now to say about this supposed case cannot be fully appre-
ciated before reading my remarks in the following chapter,’ respecting the character
of the different kinds of groups adopted in our systems, it must be obvious that our
lobster, to be what we see these animals are, must have its frame constructed upon
that very same plan of structure which it exhibits now, and if I should succeed in
showing that there is a difference between the conception of a plan and the manner
in which it is executed, upon.which classes are founded in contradistinction to the
types to which they belong, we might arrive at this distinction by a careful investi-
gation of that single Articulate as well as by the study of all of them, and we
might then recognize its type and ascertain its class characters as fully as if the type
embraced several classes, and this class thousands of species. Then that animal has
a form, which we could not fail to recognize, and if form can be shown to be char-
acteristic of families, we could thus determine its family. Again, besides the general
structure, showing the fundamental relations of all the systems of organs of the
body to one another in their natural development, our investigation could be carried
into the study of the details of that structure in every part, and thus lead to the
recognition of what constitutes everywhere generic characters. Finally, as this
animal has definite relations to the surrounding world, as the individuals living at the
time bear definite relations to one another, as the parts of their body show definite
proportions, and as the surface of the body exhibits a special ornamentation, the
specific characters could be traced as fully as if a number of other species were at
hand for comparison, and they might be drawn and described with sufficient accu-
racy to distinguish it at any future time from any other set of species found atfter-
wards, however closely these might be allied to it. In this case, then, we should have
to acknowledge a separate branch in the animal kingdom, with a class, a family, and
a genus, to introduce this one species in its proper place in the system of animals.
But this class would have no order, if orders determine the rank as ascertained by
1 See Chap. IT.
ee a =O x TPR LS LM NL TS TT a ee EEE a
Cuar. I. FUNDAMENTAL RELATIONS OF ANIMALS. 7
the complication of structure; for where there is but one representative of a type,
there is no room for the question of its superiority or inferiority in comparison to
others within the limits of the class, orders being groups subordinate to the type of
the class. Yet, even in this case, the question of the standing of Articulata as a
type among the other great branches of the animal kingdom would be open to our
investigations ; but it would assume another aspect from that it now presents, as the
comparison of Articulata with the other types would then be limited to the lobster,
and would lead to a very different result from that at which we may arrive now
that this type includes such a large number of most extensively diversified represent-
atives, belonging even to different classes. That such speculations are not idle must
be apparent to any one who is aware that, during every period in the history of our
globe, during the past geological ages! the general relations, the numeric proportions,
and the relative importance of all the types of the animal kingdom have been ever
changing until their present relations were established. Here, then, the individuals
of one species, as. observed while livmg, simultaneously exhibit characters which, to
be expressed satisfactorily and in conformity to what nature tells us, would require
the establishment, not only of a distinct species, but also of a distinct genus, a
distinct family, a distinct class, a distinct branch. Is this not in itself evidence enough
that genera, families, orders, classes, and types have the same foundation in nature as
species, and that the individuals living at the time have alone a material existence,
they bemg the bearers not only of all these different categories of structure upon
which the natural system of animals is founded, but also of all the relations which
animals sustain to the surrounding world; thus showing that species do not exist in
nature in a different way from the higher groups, as is so generally believed? _
The divisions of animals according to branch, class, order, family, genus, and
species, by which we express the results of our investigations into the relations of
the animal kingdom, and which constitute the first question respecting the scientific
systems of Natural History which we have to consider, seem to me to deserve the
consideration of all thoughtful minds. Are those divisions artificial or natura] ? Are
1 A series of classifications of animals and plants, of an accurate knowledge of the relative standing
of all animals and plants, which can only be infer-
red from the perusal even of those palzontological
successive geological periods, considered singly and works, in which fossil remains
exhibiting each a natural system of the types known
to have existed. simultaneously during the several
are illustrated accord-
ing to their association in different geological forma-
show in a strong light the different relations in tions, as in these w
without reference to the types of other ages, would
orks these remains are uni-
formly referred to ‘a system established upon the
study of all animals now known, thus lessening the
impression of their peculiar combination for the
trate in the most impressive manner the importance _ period under consideration
which the classes, the orders, the families, and even
the genera and species, have stood to one another
during each epoch. Such classifications would illus-
———————
a nena
8 ESSAY ON CLASSIFICATION. Part I.
they the devices of the human mind to classify and arrange our knowledge in such
a manner as to bring it more readily within our grasp, and facilitate further investi-
gations, or have they been instituted by the Divine Intelligence as the categories of
his mode of thinking?! Have we, perhaps, thus far been only the unconscious
interpreters of a Divine conception, in our attempts to expound nature, and when,
in our pride of philosophy, we thought that we were inventing systems of science,
and classifying creation by the force of our own reason, have we followed only, and
reproduced in our imperfect expressions, the plan whose foundations were laid in the
dawn of creation, and the development of which we are laboriously studying, thinking,
as we put together and arrange our fragmentary knowledge, that we are anew intro-
ducing order into chaos? Is this order the result of the exertions of human skill
and ingenuity, or is it inherent in the objects themselves, so that the intelligent
student of Natural History is led unconsciously by the study of the animal kingdom
itself to these conclusions; the great divisions under which he arranges animals being
indeed but the headings to the chapters of the great book which he is reading? To
me it appears indisputable that this order and arrangement of our studies is based
upon the natural, primitive relations of animal life; those systems, to which we have
given the names of the great leaders of our science who first established them, being
in truth but translations into human language of the thoughts of the Creator. And
if this is indeed so, do we not find in this adaptability of the human intellect to the
facts of creation, by which we become instinctively, and, as I have said, unconsciously,
the translators of the thoughts of God, the most conclusive proof of our affinity with
the Divine Mind, and is not this intellectual and spiritual connection with the Almighty
worthy our deepest consideration? If there is any truth in the belief that man is
made in the image of God, it is surely not amiss for the philosopher to endeavor by
the study of his own mental operations to approximate the workings of the Divine
Reason, learning from the nature of his own mind better to understand the Infinite
Intellect from which it is derived. Such a suggestion may, at first sight, appear irrev-
erent. But, which is the truly humble? He who, penetrating into the secrets of crea- |
tion, arranges them under a formula, which he proudly calls his scientific system, or
he who, in the same pursuit, recognizes his glorious affinity with the Creator, and, in
deepest gratitude for so sublime a birthright, strives to be the faithful interpreter of
that Divine Intellect with whom he is permitted, nay, with whom he is intended
according to the laws of his being, to enter into communion.
1 Jt must not be overlooked here that a system . of a Creator, but merely as the expression of a
may be natural, that is, may agree in every respect fact existing in nature, no matter how, which the
-with the facts in nature, and yet not be considered -human mind may trace and reproduce in a system-
by its author as the manifestation of the thoughts atic form of its own invention.
Se OR Bark or a a aes eee
1 i pa re
Cuap. I. FUNDAMENTAL
RELATIONS OF ANIMALS. 9
I confess that this question as to the nature and foundation of our scientific
classifications appears to me to have the deepest importance, an importance far greater
indeed than is usually attached to it. If it can be proved that man has not
invented, but only traced this systematic arrangement in nature, that these relations
and proportions which exist throughout the animal and vegetable world have an
intellectual, an ideal connection in the mind of the Creator, that this plan of crea-
tion, which so commends itself to our highest wisdom, has not grown out of the
necessary action of physical laws, but was the free conception of the Almighty
Intellect, matured in his thought, before it was manifested in tangible external forms,
—if, in short, we can prove premeditation prior to the act of creation, we have done,
once and for ever, with the desolate theory which refers us to the laws of matter as
accounting for all the wonders of the universe, and leaves us with no God but the
monotonous, unvarying action of physical forces, binding all things to their imevitable
destiny.. I thmk our science has now reached that degree of advancement, in which |
we may venture upon such an investigation.
The argument for the existence of an intelligent Creator is generally drawn from
* T allude here only to the doctrines of material- for in whatever manner any state of things which
ists; but I feel it necessary to add, that there are
physicists, who might be shocked at the idea of being
considered as materialists, who are yet prone to be-
lieve that when they have recognized the laws which
regulate the physical world, and acknowledged that
these laws were established by the Deity, they have
explained every thing, even when they have consid-
ered only the phenomena of the inorganic world, as
if the world contained no living beings and as if
these living beings exhibited nothing that differed
from the inorganic world. Mistaking for a causal
relation the intellectual connection observable be-
tween serial phenomena, they are unable to perceive
any difference between disorder and the free, inde-
pendent, and self-possessed action of a superior mind,
and call mysticism, even a passing allusion to the
existence of an immaterial principle in animals, which
they acknowledge themselves in man. [Powett’s
Essays, ete., p. 478, 385, and 466. ] I would further
remark, that, when speaking of creation in contra-
distinction with reproduction, I mean only to allude
to the difference there is between the regular Course
of phenomena in nature and the establishment of that
order of things, without attempting to explain either ;
2
has prevailed for a time upon earth may have been
introduced, it is self-evident that its establishment
and its maintenance for a determined period are two
very different things, however frequently they may
be mistaken as identical. It is further of itself plain
that the laws which may explain the phenomena of ;
the material world, in contradistinction from the or-
ganic, cannot be considered as accounting for’ the
existence of living beings, even though these have a
material body, unless it be actually shown that the
action of these laws implies by their very nature the
production of such beings. Thus far, Cross’s experi-
ments are the only ones offered as proving such a
result. I do not know what physicists may think
about them now; but I know that there is scarcely
a zodlogist who doubts that they only exhibited a
mistake. Life in appropriating the physical world
to itself with all its peculiar phenomena exhibits, how-
ever, some of its own and of a higher order, which
cannot be explained by physical agencies. The cir-
cumstance that ‘life is so deeply rooted in the inor-
ganic nature, affords, nevertheless, a strong tempta-
tion to explain one by the other ; but we shall see
presently how fallacious these attempts have been.
ae ESSAY ON CLASSIFICATION. Paneth
the adaptation of means to ends, upon which the Bridgewater treatises, for example,
have been based! But this does not appear to me to cover the whole ground, for
we can conceive that the natural action of objects upon each other should result in
a final fitness of the universe, and thus produce an harmonious whole; nor does _—
the argument derived from the connection of organs and functions seem to me more '
satisfactory, for, beyond certain limits, it is not even true. We find organs without
functions, as, for mstance, the teeth of the whale, which never cut through the gum,
the breast in all males of the class of mammalia; these and similar organs are pre- _
served in obedience to a certain uniformity of fundamental structure, true to the
original formula of that division of animal life, even when not essential to its mode
’ of existence. The organ remains, not for the performance of a function, but with
reference to a plan? and might almost remind us of what we often see in human s
structures, when, for instance, in architecture, the same external combinations are :
retained toe the sake of symmetry and harmony of proportion, even when they have
ascertained by scientific investigations, and the discussions now carried on i
the origin of organized beings. And though I know those who hold it to be very
unscientific to believe that thinking is not something imherent in matter, and that
there is an essential difference between inorganic and living and thinking beings, I
shall not be prevented by any such pretensions of a false philosophy from expressing
——
1 The Bridgewater Treatises, on the Power, Wis- edit. 1837. — Kirpy, (Witt.,) The Power, Wisdom, |
wry
a ccaaiinniihiaiiedamniiieaibaaiiaabmele 7a cieraiiaien Dela
dom, and Goodness of God, as Manifested in the
Creation: Cuatmers, (Tuomas,) The Adaptation of
External Nature to the Moral and Intellectual Consti-
tution of Man, Glasgow, 1839, 2 vols. 8vo.— Kipp,
(Joun,) On the Adaptation of External Nature to
the Physical Condition of Man, London, 1833, 1 vol.
8vo. — WHEWELL, (WILL.,) Astronomy and General
Physics considered with Reference to Natural Theol-
ogy, London, 1839, 1 vol. 8vo. — Beit, (CHARLES,)
The Hand, its Mechanism and Vital Endowments, as
evincing Design, London, 1833, 1 vol. 8vo. — Roger,
(Peter Mark,) Animal and Vegetable Physiology,
considered with Reference to Natural Theology, Lon-
don, 1834, 2 vols. 8vo.—BucKLanp, (WILL.,) Ge-
ology and Mineralogy considered with Reference to
Natural Theology, London, 1836, 2 vols. 8vo.; 2d
and Goodness of God, as Manifested in the Creation
of Animals, and in their History, Habits, and Instincts,
London, 1835, 2 vols. 8vo.— Provt, (WILL.,) Chem-
istry, Meteorology, and the Function of Digestion,
considered with Reference to Natural Theology, Lon-
don, 1834, 1 vol. 8vo. Compare also: STRAUSS-
Durxuerm, (Herc.,) Théologie de la Nature, Paris,
1852, 3 vols. 8vo.— Mitier, (Hvexn,) Footprints of
the Creator, Edinburgh, 1849, 1 vol. 12mo.— Bas-
pace, (C.,) The Ninth Bridgewater Treatise, a Frag-
ment, London, 1838, 1 vol. 8vo.; 2d edit.
2 The unity of structure of the limbs of club-
footed or pinnated animals, in which the fingers are
never moved, with those which enjoy the most per-
fect articulations and freedom of motion, exhibits this
reference most fully.
mates
Cuap. I. FUNDAMENTAL RELATIONS OF ANIMALS. 11
my conviction that as long as it cannot be shown that matter or physical forces do
actually reason, I shall consider any manifestation of thought as evidence of the
existence of a thinking being as the author of such thought, and shall look upon an
intelligent and intelligible connection between the facts of nature as direct proof of
the existence of a thinking God,! as certainly as man exhibits the power of thinking
when he recognizes their natural relations.
As I am not writing a didactic work, I will not enter here into a detailed illus
tration of the facts relating to the various subjects submitted to the consideration of
my reader, beyond what is absolutely necessary to follow the argument, nor dwell at
any length upon the conclusions to which they lead, but simply recall the leading .
features of the evidence, assuming in the argument a full acquaintance with the
whole range of data upon which it is founded, whether derived from the affinities or
the anatomical structure of animals, or from their habits and their geographical distri-
bution, from their embryology, or from their succession in past geological ages, and
the peculiarities they have exhibited during each? believing, as I do, that isolated and
disconnected facts are of little consequence in the contemplation of the whole plan
* IT am well aware that even the most eminent
investigators consider the task of science at an end,
as soon as the most general relations of natural phe-
nomena have been ascertained. To many the in-
quiry into the primitive cause of their existence
seems either beyond the reach of man, or as be-
longing rather to philosophy than to physics. To
these the name of God appears out of | place in a
scientific work, as if the knowledge of secondary
agencies constituted alone a worthy subject for their
investigations, and as if nature could teach nothing
about its Author. Many, again, are no doubt pre-
vented from expressing their conviction that the
world was called into existence and is regulated by
an intelligent God, either by the fear of being sup-
posed to share clerical or sectarian prejudices; or
because it may be dangerous for them to discuss
freely such questions without acknowledging at the
same time the obligation of taking the Old Testament
as the standard by which the validity of their re-
sults is to be measured. Science, however, can only
prosper when confining itself within its legitimate
sphere; and nothing can be more detrimental to its
true dignity than discussions like those which took
place at the last meeting of the German association
of naturalists, in Géttingen, and which have since
then been carried on in several pamphlets in which
bigotry vies with personality and invective.
* Many points little investigated thus far by most
naturalists, but to which I have of late years paid
particular attention, are here presented only in an
aphoristic form, as results established by extensive
investigations, though unpublished, most of which will
be fully illustrated in my following volumes, or in a
special work upon the plan of the creation. (See
AGassiz, (L.,) On the Difference between Progres-
sive, Embryonic, and Prophetic Types in the Succes-
sion of Organized Beings, Proceed. 2d Meeting Amer.
Assoc. for the Advancement of Science, held at Cam-
bridge in 1849, Boston, 1850, 1 vol. 8v0., p. 432.)
Meanwhile I refer in foot notes to such works as con-
tain the materials already on hand for the discussion
of these subjects, even when presented in a different
light. I would only beg leave to add, that in these
references I have by no means attempted to quote all
the writers upon the various topics under consider-
ation, but only the most prominent and most instruc-
tive, and here and there some condensed accounts
of the facts in more elementary works, by the side
of the original papers.
a
pape ren oe
a ee
FS
12 ESSAY ON CLASSIFICATION.
Part I.
of creation, and that without a consideration of all the facts furnished by the study
of the habits of animals, by their anatomy, their embryology, and the history of the
past ages of our globe, we shall never arrive at the knowledge of the natural system
of animals.
Let us now consider some of these topics more specially.
SECTION ITI.
SIMULTANEOUS EXISTENCE OF THE MOST DIVERSIFIED TYPES UNDER IDENTICAL
CIRCUMSTANCES.
It is a fact which seems to be entirely overlooked by those who assume an exten-
sive influence of physical causes upon the very existence of organized beings, that
the most diversified types of animals and plants are everywhere found under iden-
tical circumstances. The smallest sheet of fresh water, every point upon the sea-
shore, every acre of dry land, teems with a variety of animals and plants. The
narrower the boundaries are, which may be assigned as the primitive home of all
these beings, the more uniform must be the conditions under which they are assumed
to have originated; so uniform, indeed, that in the end the inference would be, that
the same physical causes could produce the most diversified effects’ To concede,
1 Jn order fully to appreciate the difficulty al-
luded to here, it is only necessary to remember how
complicated, and at the same time how localized the
conditions are under which animals multiply. The
egg originates in a special organ, the ovary; it grows
there to a certain size, until it requires fecundation,
that is, the influence of another living being, or at
least of the product of another organ, the spermary,
to determine the further development of the germ,
which, under the most diversified conditions, in dif-
ferent species, passes successively through all those
changes which lead to the formation of a new per-
fect being. I then would ask, is it probable that
the circumstances under which animals and plants
originated for the first time can be much simpler,
or even as simple, as the conditions necessary for
their reproduction only, after they have once been
created? Preliminary, then, to their first appearance,
the conditions necessary for their growth must have
been provided for, if, as I believe, they were crea-
ted as eggs, which conditions must have been con-
formable to those in which the living representatives
of the types first produced, now reproduce them-
selves. If it were assumed that they originated in
a more advanced stage of life, the difficulties would
be still ereater, as a moment’s consideration cannot
fail to show, especially if it is remembered how com-
plicated the structure of some of the animals was,
which are known to have been among the first in-
habitants of our globe. When investigating this sub-
ject, it is of course necessary to consider the first
appearance of animals and plants, upon the basis of
probabilities only, or even simply upon that of pos-
sibilities; as with reference to these first-born, at
least, the transmutation theory furnishes no explana-
tion of their existence.
For every species belonging to the first fauna and
the first flora which have existed upon earth, special
-
|
|
Z
:
7
:
,
:
Cuap. I. DIVERSIFIED TYPES FOUND EVERYWHERE. 18
on the contrary, that these organisms may have appeared in the beginning over a
wide area, is to grant, at the same time, that the physical influences under which
they existed at first were not so specific as to justify the assumption that these could
be the cause of their appearance. In whatever connection, then, the first appear-
ance of organized bemgs upon earth is viewed, whether it is assumed that they
originated within the most limited areas, or over the widest range of their present
natural geographical distribution, animals and plants beg everywhere diversified to
the most extraordinary extent, it is plain that the physical influences under which
they subsist cannot logically be considered as the cause of that diversity. In this,
as in every other respect, when considering the relations of animals and plants to
the conditions under which they live, or to one another, we are inevitably led to
look beyond the material facts of the case for an explanation of their existence.
Those who have taken another view of this subject, have mistaken the action and
reaction which exist everywhere between organized beings, and the physical influences
under which they live’ for a causal or genetic connection, and carried their mistake
so far as to assert that these manifold influences could really extend to the production
of these bemgs, not considering how inadequate such a cause would be, and that
even the action of physical agents upon organized beings presupposes the very exist-
ence of those begs.” The simple fact that there has been a period in the history
relations, special contrivances must therefore have two questions, the influence of physical agents upon
been provided. Now, what would be appropriate animals and plants already in existence, and the ori-
for the one, would not suit the other, so that exclud- gin of these beings. Granting the influence of these
ing one another in this way, they cannot have origi- agents upon organized beings to the fullest extent
nated upon the same point; while within a wider to which it may be traced, (see Sect. 16,) there
area, physical agents are too uniform in their mode remains still the question of their origin upon which
of action to have laid the foundation for so many neither argument nor observation has yet thrown any
such specific differences as existed between the first light. But according to some, they originated spon-
inhabitants of our globe. taneously by the immediate agency of physical forces,
1 See, below, Sect. 16. and have become successively more and more diver-
? A critical examination of this’ point may dis- sified by changes produced gradually upon them, by
pel much of the confusion which prevails in the dis- these same forces. Others believe that there exist
cussions relating to the influence of physical causes laws in nature which were established by the Deity
upon organized beings. That there exist definite in the beginning, to the action of which the origin
relations between animals as well as plants and the of organized beings may be ascribed; while accord-
mediums in which they live, no one at all familiar ing to others, they owe their existence to the im-
with the phenomena of the organic world can doubt ; mediate intervention of an intelligent Creator. It
that these mediums and all physical agents at work is the object of the following paragraphs to show
in nature, have a certain influence upon organized that there are neither agents nor laws in nature
bens is equally plain. But before any such action known to physicists under the influence and by the
can take place and be felt, organized beings must action of which these. beings could have originated ;
exist. The problem before us involves, therefore, that, on the contrary, the very nature of these be-
ee ee
14 ESSAY ON CLASSIFICATION. Part I.
of our earth, now well known to geologists! when none of these organized beings as
yet existed, and when, nevertheless, the material constitution of our globe, and the
physical forces acting upon it, were essentially the same as they are now,” shows that
these influences are insufficient to call into existence any living being.
Physicists know, indeed, these physical agents more accurately than the naturalists,
who ascribe to them the origin of organized beings; let us then ask them, whether
the nature of these agents is not specific, whether their mode of action is not spe-
cific? They will all answer, that they are. Let us further inquire of them, what
evidence there is, in the present state of our knowledge, that at any time these
physical agents have produced any thing they no longer do produce, and what prob-
ability there is that they may ever have produced any organized bemg? If I am
not greatly mistaken, the masters in that department of science will, one and all,
answer, none whatever.
But the character of the connections between organized beings and the physical
conditions under which they live is such as to display thought;® these connections
are therefore to be considered as established, determined, and regulated by a thinking
being. They must have been fixed for each species at its beginning, while the fact
of their permanency through successive generations* is further evidence that with
their natural relations to the surrounding world were also determined the relations
of individuals to one another, their generic as well as their family relations, and
every higher grade of affinity,’ showing, therefore, not only thought, in reference to
the physical conditions of existence, but such comprehensive thoughts as would
embrace simultaneously every characteristic of each species.
Every fact relating to the geographical distribution of animals and plants might
be alluded to in confirmation of this argument, but especially the character of every
ings, and their relations to one another and to the to contain fossils at all, there is a variety of them
world in which they live, exhibit thought, and can found together. (See Sect. 7.) Moreover, the simi-
therefore be referred only to the immediate action larity in the character of the oldest fossils found in
of a thinking being, even though the manner in different parts of the world, goes far, in my opin-
which they were called into existence remains for ion, to prove that we actually do know the earliest
the present a mystery. types of the animal kingdom which have inhabited
1 Few geologists only may now be inclined to our globe. This conclusion seems fully sustained by
believe that the lowest strata known to contain fos-
sils, are not the lowest deposits formed since the
existence of organized beings upon earth. But even
those who would assume that still lower fossiliferous
beds may yet be discovered, or may have entirely
disappeared by the influence of plutonic agencies,
(Poweti’s Essays, ete., p. 424,) must acknowledge
the fact that everywhere in the lowest rocks known
the fact that we find everywhere below this oldest
set of fossiliferous beds, other stratified rocks in
which no trace of organized beings can be found.
2 See, below, Sect. 21. ?
8 See, below, Sect. 16.
4 See, below, Sect. 15.
> See, below, Sect. 17.
6 See, below, Sect. 6.
. Cuap. I. DIVERSIFIED TYPES FOUND EVERYWHERE. 16
. fauna and every flora upon the surface of the globe. How great the diversity of
| animals and plants living together in the same region may be, can be ascertained by
. the perusal of special works upon the Zodlogy and Botany of different countries, or
| from special treatises upon the geographical distribution of animals and plants. I
| need, therefore, not enter into further details upon this subject, especially since it is
| discussed more fully below2
| It might, perhaps, be urged, that animals living together in exceptional conditions,
| and exhibiting structural peculiarities apparently resulting from these conditions, such
as the blind fish,» the blind crawfish, and the blind insects of the Mammoth Cave
| m Kentucky, furnish uncontrovertible evidence of the immediate influence of those
. exceptional conditions upon the organs of vision. If this, however, were the case, \
| how does it happen that that remarkable fish, the Amblyopsis speleus, has only such. ) ae
remote affinities to other fishes? Or were, perhaps, the sum of influences at work to
make that fish blind, capable also of devising such a combination of structural charac-
ters as that fish has in common with all other fishes, with those peculiarities which
at the same time distinguish it? Does not, rather, the existence of a rudimentary
eye discovered by Dr. J. Wyman in the blind fish show, that these animals, like all
others, were created with all their peculiarities by the fiat of the Almighty, and this
rudiment of eyes left them as a remembrance of the general plan of structure of —
the great type to which they belong? Or will, perhaps, some one of those natural-
ists who know so much better than the physicists what physical forces may produce,
and that they may produce, and have produced every living bemg known, explain
also to us why subterraneous caves in America produce blind fishes, blind crustacea,
and blind insects, while in Europe they produce nearly blind reptiles? If there is \
no thought in the case, why is it, then, that this very reptile, the Proteus angwinus,
forms, with a number of other reptiles living in North America and in Japan, one of
ee
* Scumarpa, Die geographische Verbreitung der
Thiere, 3 vols. 8vo. Wien, 1853. — Swaryson, (W.,)
A Treatise on the Geography and Classification of
Animals, London, 1835, 1 vol. 12mo.— ZimmEeRMANN,
(E. A. G.,) Specimen Zoologiz geographic, Quadru-
pedum domicilia et migrationes sistens, Lugduni-Ba-
tav., 1777, 1 vol. 4to.— HumBoupr, Essai sur la géo-
graphie des plantes, 4to., Paris, 1805; and Ansichten
der Natur, 3d edit., 12mo., Stuttgardt and Tiibin-
gen, 1849. — Ropert Brown, General Remarks on
the Botany of Terra Australis, London, 1814.—
Scuouw, Grundziige einer allgemeinen Pflanzengeo-
graphie, 1 vol. 8vo., with atlas in fol., Berlin, 1823.
—ALPH. DE CANDOLLE, Géographie botanique rai-
sonnée, 2 vols. 8vo., Paris, 1855. References to
special works may be found below, Sect. 9. |
2 See, below, Sect. 9.
° Wrman, (Jer.,) Description of a Blind Fish,
from a Cave in Kentucky, Srnuiman’s Jour., 1848,
vol. 45, p. 94, and 1854, vol. Lis po 2o8. — Ter
KAMPF, (TH. G.,) Ueber den blinden Fisch der Mam-
muthhéhle in Kentucky, in Miitier’s Archiv, 1844,
p. 381. — TeLLKampr, (Tu. G.,) Beschreibung eini-
ger neuer in der Mammuthhéhle aufgefundener Gat-
tungen von Gliederthieren, Wrrqman’s Archiv, 1844,
vol. L., p. 818. — Agassiz, (L.,) Observations on the
Blind Fish of the Mammoth Cave,'S
nal, 1851, vol. 11, p. 127,
ILLIMAN’S Jour-
cc “RS A RR CR NR ARRON ANANTRRNN Anna
pian ih NB aie ieee mat eae a
- - —
a I AS te
16 ESSAY ON CLASSIFICATION. Part I.
.
| the most natural series known in the animal kingdom, every member of which
| exhibits a distinct grade! in the scale?
After we have freed ourselves from.the mistaken impression that there may be
some genetic connection between physical forces and organized beings, there remains
a vast field of investigation to ascertain the true relations between both, to their full
extent, and within their natural limits? A mere reference to the mode of breathing
of different types of animals, and to their organs of locomotion, which are more
particularly concerned in these relations, will remind every naturalist of how great
importance in classification is the structure of these parts, and how much better they
might be understood in this point of view, were the different structures of these
organs more extensively studied in their direct reference to the world in which ani-
mals live. If this had been done, we should no longer call by the same common
name of legs and wings organs so different as the locomotive appendages of the
insects and those of the birds? We should no longer call lungs the breathing
cavity of snails, as well as the air pipes of mammalia, birds, and reptiles? A great
reform is indeed needed in this part of our science, and no study can prepare us
better for it than the investigation of the mutual dependence of the structure of
animals, and the conditions in which they live.
en al men
|
| | | SECTION ELE.
REPETITION OF IDENTICAL TYPES UNDER THE MOST DIVERSIFIED CIRCUMSTANCES.
| As much as the diversity of animals and plants living under identical physical
. conditions, shows the independence of organized beings from the medium in which
| they dwell, so far as their origin is concerned, so independent do they appear again
| from the same influences when we consider the fact that identical types occur every-
| | where upon earth under the most diversified circumstances. If we sum up all these |
various influences and conditions of existence under the common appellation of
. cosmic influences, or of physical causes, or of climate in the widest sense of the
i : word, and then look around us for the extreme differences in that respect upon the
a whole surface of the globe, we find still the most similar, nay identical types (and I
\ | allude here, under the expression of type, to the most diversified acceptations of the
word) living normally under their action. _ There is no structural difference between
the herrings of the Arctic, or those of the Temperate zone, or those of the Tropics,
Ga SANE eSNG .
1 See, below, Sect. 12. 2 See, below, Sect. 16.
PERL A I
nn ee
a ene ASSET
came ma cm
‘Cuap. I. IDENTICAL TYPES FOUND EVERYWHERE.
or those of the Antarctic regions; there are not any more between the foxes and
wolves of the most distant parts of the globe.’ Moreover, if there were any, and
the specific differences existing between them were insisted upon, could any relation
between these differences and the cosmic influences under which they live be pointed
out, which would at the same time account for the independence of their structure
in general? Or, in other words, how could it be assumed that while these causes
would produce specific differences, they would at the same time produce generic
identity, family identity, ordinal identity, class identity, typical identity? Identity in
every thing that is truly important, high, and complicated in the structure of ani-
mals, produced by the most diversified influences, while at the same time these
extreme physical differences, considered as the cause of the existence of these ani-
mals, would produce diversity in secondary relations only! What logic!
Does not all this show, on the contrary, that organized beings exhibit the most
astonishing independence of the physical causes under which they live; an independ-
ence so great that it can only be understood as the result of a power governing
these physical causes as well as the existence of animals and plants, and bringing all
into harmonious relations by adaptations which never can be considered as cause and
effect ¢
When naturalists have investigated the influence of physical causes upon living
beings, they have constantly overlooked the fact. that. the features which are thus
modified are only of secondary importance in the life of animals and plants, and
that neither the plan of their structure, nor the various complications of that struc-
ture, are ever affected by such influences. What, indeed, are the parts of the body
which are, in any way, affected by external influences? Chiefly those which are in
immediate contact with the external world, such as the skin, and in the skin chiefly
its outer layers, its color, the thickness of the fur, the color of the hair, the feathers,
and the scales; then the size of the body and its weight, as far as it is dependent on ,
the quality and quantity of the food; the thickness of the shell of Mollusks, when |
they live in waters or upon a soil containing more or less limestone, ete. The |
rapidity or slowness of the growth is also influenced in a measure by the course of |
the seasons, in different years; so is also the fecundity, the duration of life, etc.
But all this has nothing to do with the essential characteristics of animals.
A book has yet to be written upon the independence of organized beings of
physical causes, as most of what is generally ascribed to the influence of physical
agents upon organized beings ought to be considered as a connection established
between them in the general plan of creation.
1 Innumerable other examples might be quoted, naturalists; those mentioned above may suffice for
which will readily present themselves to professional my argument.
3
ES oy ee
sa albdenetien taeieaenlaaein ieamemebemmanaiiieliae
ESSAY ON CLASSIFICATION.
SHEULLON LV.
UNITY OF PLAN IN OTHERWISE HIGHLY DIVERSIFIED TYPES.
Nothing is more striking throughout the animal and vegetable kingdoms than the
unity of plan in the structure of the most diversified types. From pole to pole, in
every longitude, mammalia, birds, reptiles, and fishes, exhibit one and the same plan
of structure! involving abstract conceptions of the highest order, far transcending the
broadest generalizations of man, for it is only after the most laborious mvestigations
man has arrived at an imperfect understanding of this plan. Other plans, equally
wonderful, may be traced in Articulata, in Mollusks, in Radiata,? and in the various
types of plants? and yet this logical connection, these beautiful harmonies, this infi-
nite diversity in unity are represented by some as the result of forces exhibiting no
trace of intelligence, no power of thinking, no faculty of combination, no knowledge
of time and space. If there is any thing which places man above all other beings
in nature, it is precisely the circumstance that he possesses those noble attributes
without which, in their most exalted excellence and perfection, not one of these
1 With reference to this point, consult: OKEN,
(Lor.,) Ueber die Bedeutung der Schiidel-Knochen,
Frankfort, 1807, 4to. (pamphlet.)—Srrx, (J. B.)
Cephalogenesis, sive capitis ossei structura, formatio
et significatio, Monachii, 1815, fol. — Grorrroy Sr.
Hivaire, (Et.,) Philosophie anatomique, Paris,
1818-1823, 2 vols. 8vo., and several papers in the
Annal. des se. nat., Annal. and Mém. du Muséum,
etc. — Carus, (C. &) Von den Ur-Theilen des
Knochen- und Schalengeriistes, Leipzig, 1828, fol.—
Owen, (R.) On the Archetype and Homologies of
the Vertebrate Skeleton, London, 1848, 8vo.
2 OxeN, (Lor.,) Lehrbuch der Naturphilosophie,
Jena, 1809-11, 8 vols. 8vo.; Engl. Elements of
Physio-philosophy, Ray Society, London, 1847, 8vo.
— Cuvier, (G.,) Sur un nouveau rapprochement a
établir entre les classes qui composent. le Regne Ani-
mal, Annales du Muséum, vol. xix., 1812. — Savi-
eny, (J. C.,) Mémoires sur les animaux sans verte- —
bres, Paris, 1816, 8vo.—Bazr, (C. E. v.,) Ueber
Entwickelungsgeschichte der Thiere, Konigsberg,
1828, 4to.—LevKARDT, (R.,) Ueber die Morphologie
und die Verwandtschaftsverhiiltnisse der wirbellosen
Thiere, Braunschweig, 1848, 8vo.— Acassiz, (L.,)
Twelve Lectures on Comparative Embryology, Bos-
ton, 1849, 8vo.—On Animal Morphology, Proc. Amer.
Assoc. for the Adv. of Science, Boston, 1859, 8vo., p.
411. I would call particular attention to this paper,
which has immediate reference to the subject of this
chapter. — Carus, (V.,) System der thierischen Mor-
phologie, Leipzig, 1853, 1 vol. 8vo.
8 Gorne, (J. W.,) Zur Naturwissenhaft tiber-
haupt, besonders zur Morphologie, Stuttgardt, 1817-
24, 2 vols. 8vo.; French, Oeuvres d’histoire natu-
relle, comprenant divers mémoires d’Anatomie com-
parée, de Botanique et de Géologie, traduits et an-
notés par Ch. Fr. Martins, Paris, 1837, 8vo. ; atlas
in fol. DeCanponin, (Ay “P.) Organographie
végétale, Paris, 1827, 2 vols. 8vo. — BRAUN, (At.,)
Vergleichende Untersuchung iiber die Ordnung der
Schuppen an den Tannenzapfen, als Einleitung zur
Untersuchung der Blattstellung iiberhaupt, Act. Nov.
Ac. Nat. Curios., vol. xv., 1829.— Das Individuum
der Pflanze, Akad. d. Wiss., Berlin, 1853, 4to.
Cuap. I. HOMOLOGIES IN DISCONNECTED ANIMALS. 19
general traits of relationship so characteristic of the great types of the animal and
vegetable kingdoms, can be understood, or even perceived. How, then, could these
relations have been devised without similar powers? If all these relations are almost
beyond the reach of the mental powers of man, and if man himself is part and
parcel of the whole system, how could this system have been called into existence
if there does not exist One Supreme Intelligence, as the Author of all things?
SCE Ou oY
CORRESPONDENCE IN THE DETAILS OF STRUCTURE IN ANIMALS OTHERWISE ENTIRELY .
DISCONNECTED.
During the first decade of this century, naturalists began to study relations among
animals which had escaped almost entirely the attention of earlier observers. Though
Aristotle knew already that the scales of fishes correspond to the feathers of birds?
it is but recently that anatomists have discovered the close correspondence which
exists between all the parts of all animals belonging to the same type, however dif:
ferent they may appear at first sight. Not only is the wing of the bird identical in
its structure with the arm of man, or the fore leg of a quadruped, it agrees quite as
closely with the fin of the whale, or the pectoral fin of the fish, and all these
together correspond in the same manner with their hind extremities. Quite as strik-
ing a coincidence is observed between the solid skull-box, the immovable bones
of the face and the lower jaw of man and the other mammalia, and the structure of
the bony frame of the head of birds, turtles, lizards, snakes, frogs, and fishes. But
this correspondence is not limited to the skeleton; every other system of organs
exhibits in these animals the same relations, the same identity in plan and structure,
whatever be the differences in the form of the parts, in their number, and even in
their functions. Such an agreement in the structure of animals is called their
homology, and is more or less close in proportion as the animals in which it is
traced are more or less nearly related.
The same agreement exists between the different systems and their parts in Artic-
ulata, in Mollusks, and in Radiata, only that their structure is built up upon respec-
tively different plans, though in these three types the homologies have not yet been
traced to the same extent as among Vertebrata. There is therefore still a wide
1 AristoTELss, Historia Animalium, Lib. I., Chap. Sect. 4, notes 1 and 2, and the many other works,
1, Sect. 4. 6 ydo év dort ategor, tovto év iyGvi pamphlets, and papers, quoted by them, which aré too
éott demic. — Consult also the authors referred to in numerous to be mentioned here.
a
or
7 . .
a ae Ra Ree ee ca
though they perform the same functions. The alimentary canal is formed in a very
20 ESSAY ON CLASSIFICATION. Pane T
field open for investigations in this most attractive branch of Zodlogy. ~ So much,
however, is already plain from what has been done in this department of our science,
that the identity of structure among animals does not extend to all the four branches
of the animal kingdom; that, on the contrary, every great type 1s constructed upon
a distinct plan, so peculiar, indeed, that homologies cannot be extended from one
type to the other, but are strictly limited within each of them. The more remote
resemblance which may be traced between representatives of different types, 1s
founded upon analogy, and not upon affinity. While, for instance, the head of
fishes exhibits the most striking homology with that of reptiles, birds, and mammalia,
as a whole, as well as in all its parts, that of Articulata is only analogous to it and
to its part. What is commonly called head in Insects is not a head like that of
Vertebrata; it has not a distinct cavity for the brain, separated from that which
communicates below the neck with the chest and abdomen; its solid envelope does
not consist of parts of an internal skeleton, surrounded by flesh, but is formed of
external rings, like those of the body, soldered together ; it contains but one cavity,
which includes the cephalic ganglion, as well as the organs of the mouth, and all the
muscles of the head. The same may be said of the chest, the legs and wings, the
abdomen, and all the parts they contain. The cephalic ganglion is not homologous
to the brain, nor are the organs of senses homologous to those of Vertebrata, even
different way in the embryos of the two types, as are also their respiratory organs,
and it is as unnatural to identify them, as it would be still to consider gills and
lungs as homologous among Vertebrata now embryology has taught us that im differ-
ent stages of growth these two kinds of respiratory organs exist in all Vertebrata in
very different organic connections one from the other.
What is true of the branch of Articulata when compared to that of Vertebrata,
is equally true of the Mollusks and Radiata when compared with one another or
with the two other types, as might easily be shown by a fuller illustration of the
correspondence of their structure, within these limits. This inequality in the fun-
damental character of the structure of the four branches of the animal kingdom
points to the necessity of a radical reform in the nomenclature of comparative ;
anatomy? Some naturalists, however, have already extended such comparisons
respecting the structure of animals beyond the limits pointed out by nature, when
they have attempted to show that all structures may be reduced to one norm, and
1 See Swanson, (W.,) On the Geography and = mologies of Radiated Animals, with Reference to j
Classification of Animals, London, 1835, 12mo., p. the Systematic Position of the Hydroid Polypi,
129, where this point is ably discussed. Proc. of the Amer. Assoc. for the Adv. of Science
2 See Acassiz, (L.,) On the Structure and Ho- for 1849, Boston, 1850, 1 vol. 8vo. p. 389.
Cuap. I. DEGREES AND KINDS OF RELATIONSHIP. 21
when they have maintained, for instance, that every bone existing in any Vertebrate
must have its counterpart In every other species of that type. To assume such a
uniformity among animals, would amount to denying to the Creator even as much
freedom in expressing his thoughts as man enjoys.
If it be true, as pointed out above, that all animals are constructed upon four
different plans of structure, in such a manner that all the different kinds of animals
are only different expressions of these fundamental formule, we may well compare
the whole animal kingdom to a work illustrating four great ideas, between which
there is no other connecting link than the unity exhibited in the eggs in which their
most diversified manifestations are first embodied in an embryonic form, to undergo
a series of transformations, and appear in the end in that wonderful variety of inde-
pendent living beings which inhabit our globe, or have inhabited it from the earliest
period of the existence of life upon its surface.
The most surprising feature of the animal kingdom seems, however, to me to
rest neither in its diversity, nor in the various degrees of complication of its struc-
ture, nor in the close affinity of some of its representatives, while others are so
different, nor in the manifold relations of all of them to one another and the sur-
rounding world, but in the circumstance that beings endowed with such different and
such unequal gifts should nevertheless constitute an harmonious whole, intelligibly
connected in all its parts.
Se Pen VI:
VARIOUS DEGREES AND DIFFERENT KINDS OF RELATIONSHIP AMONG ANIMALS.
The degrees of relationship existing between different animals are most diversified.
They are not only akin as representatives of the same species, bearmg as such the
closest resemblance to one another; different species may also be related as members
of the same genus, the representatives of different genera may belong to the same
family, and the same order may contain different families, the same class different
orders, and the same type several classes. The existence of different degrees of
affinity between animals and plants which have not the remotest genealogical connec-
tion, which live in the most distant parts of the world, which have existed in periods
long gone by in the history of our earth, is a fact beyond dispute, at least, within
certain limits, no longer controverted by well informed observers. Upon what can
this be founded? Is it that the retentive capacity of the memory of the physical
forces at work upon this globe is such, that after bringing forth a type according to
one pattern, in the infancy of this earth, that pattern was adhered to under conditions,
22 ESSAY ON CLASSIFICATION. Part I.
no matter how diversified, to reproduce, at another period, something similar, and so
on, through all ages, until at the period of the establishment of the present state of
things, all the infinitude of new animals and new plants which now crowd its surface,
should be cast in these four moulds, in such a manner as to exhibit, notwithstanding
their complicated relations to the surrounding world, all those more deeply seated
general relations, which establish among them the different degrees of affinity we
may trace so readily in all the representatives of the same type? Does all this
really look more like the working of blind forces than like the creation of a reflec-
tive mind establishing deliberately all the categories of existence we recognize im
nature, and combining them in that wonderful harmony which unites all things into
such a perfect system, that even to read it, as it is established, or even with all the
imperfections of a translation, should be considered as the highest achievement of
the maturest genius ?
Nothing seems to me to prove more directly and more fully the action of a
reflective mind, to indicate more plainly a deliberate consideration of the subject,
than the different categories upon which species, genera, families, orders, classes, and
branches are founded in nature, and manifested in material reality in a succession of
individuals, the life of which is limited in its duration to comparatively very short
periods. The great wonder in these relations consists in the fugitive character of the
bearers of this complicated harmony. For while species persist during long periods,
the individuals which represent them are ever changing, one set dying after the
other, in quick succession. Genera, it is true, may extend over longer periods; fami-
lies, orders, and classes may even have existed during all periods during which
animals have existed at all; but whatever may have been the duration of their
existence, at all times these different divisions have stood in the same relation to
one another and to their respective branches, and have always been represented
upon our globe in the same manner, by a succession of ever renewed and short-lived
individuals.
As, however, the second chapter of this work is entirely devoted to the consider-
ation of the different kinds and the different degrees of affinity existing among
animals, I will not enter here into any details upon this subject, but simply recall
the fact that, in the course of time, investigators have agreed more and more with
one another in their estimates of these relations, and built up systems more and
more conformable to one another. This result, which is fully exemplified by the
history of our science is in itself sufficient to show that there is a system in nature
1 Sprx, (J.,) Geschichte und Beurtheilung aller naturelles, Paris, 1826, 4 vols. 8vo.— Histoire des
Systeme in der Zoologie, Niirnberg, 1811, 1 vol. 8vo. sciences naturelles, etc., Paris, 1841, 5 vols. 8vo.
— Cuvier, (G.,) Histoire des progrés des sciences — DrEBLAINVILLE, (H.,} Histoire des sciences de
Cuap. I. RABIAEST TYPES -OF ANIMALS. 20
to which the different systems of authors are successive approximations, more and
more closely agreeing with it, m proportion as the human mind has understood
nature better. This growing coincidence between our systems and that of nature
shows further the identity of the operations of the human and the Divine intellect ;
especially when it is remembered to what an extraordinary degree many @ priori
conceptions, relating to nature, have in the end proved to agree with the reality,
in spite of every objection at first offered by empiric observers.
SUCTION, (a Lt.
SIMULTANEOUS EXISTENCE IN THE EARLIEST GEOLOGICAL PERIODS, OF ALL THE GREAT
TYPES OF ANIMALS.
It was formerly believed by geologists and paleontologists that the lowest animals
first made their appearance upon this globe, and that they were followed by higher
and higher types, until man crowned the series.
senting at all the present state of our knowledge, may now furnish the evidence
that this is not the case. On the contrary, representatives of numerous families
of the animal kingdom, are well known to
Every geological museum, repre-
belonging to all the four great branches
have existed simultaneously in the oldest geological formations.’ Nevertheless, I well
remember when I used to hear the great geologists of the time assert, that the
Corals were the first inhabitants of our globe, that Mollusks and Articulata followed
in order, and that Vertebrates
extraordinary change the last thirty years have brought about in our knowledge, and |
the doctrines generally adopted respecting the existence of animals and plants in past
may still differ in their views regarding the origin,
ages! However much naturalists
they now all know that neither Radiata,
the gradation, and the affinities of animals,
nor Mollusks, nor Articulata,
sERLING, (Count ALEX. von,) The Geology of
Russia in Europe, and the Ural Mountains, London,
1845, 2 vols. 4to.— Hatt, (Jamxs,) Paleontology
of New York, Albany, 1847-52, 2 vols. 4to.— Bar-
Vorganisation et de leurs progrés, Paris, 1847, 3 vols.
8vo. — Poucuet, (F. A.,) Histoire des sciences na-
turelles au moyen Age, Paris, 1853, 1 vol. 8vo.
Compare, also, Chap. II., below.
1 Murcurson, (R. IL.) The Silurian System, Lon- RANDE, (J.,) Systeme silurien du centre de la Bo-
don, 1839, 1 vol. 4to.— Murcutson, (Str R. I.) heme, Prague and Paris, 1852, 2 vols. 4to.— Srpe-
Siluria. The History of the Oldest Known Rocks wick, (A.,) and McKoy, (Fr.,) British Paleozoic
containing Fossils, London, 1854, 1 vol. 8vo. — Mur- Rocks and Fossils, London, 1851, 4to. 2 fase.; not
CHISON, (R. I.) pE VERNEUIL, (Ep.,) and Kat- yet complete.
did not appear until long after these. What an }
have any priority one over the other, as to the time —
be «fe ~J
\
24 ESSAY ON CLASSIFICATION. Part I.
of their first appearance upon earth; and though some still maintain that Vertebrata
originated somewhat later, it is universally conceded that they were already in exist-
ence toward the end of the first great epoch in the history of our globe. I think
/it would not be difficult to show upon physiological grounds that their presence upon
earth dates from as early a period as any of the three other great types of the
animal kingdom, since fishes exist wherever Radiata, Mollusks, and Articulata are
found together, and the plan of structure of these four great types constitutes a
system intimately connected in its very essence. Moreover, for the last twenty
years, every extensive investigation among the oldest fossiliferous rocks has carried
the origin of Vertebrata step by step further back, so that whatever may be the
final solution of this vexed question, so much is already established by innumerable
facts, that the idea of a gradual succession of Radiata, Mollusks, Articulata, and Ver-
tebrata, is for ever out of the question. It is proved beyond doubt, that Radiata,
Mollusca, and Articulata are everywhere found together in the oldest geological for-
mations, and that very early Vertebrata are associated with them, to continue
together through all geological ages to the present time. This shows that even in
those early days of the existence of our globe, when its surface did not yet present
those diversified features which it has exhibited in later periods, and which it exhibits
in still greater variety now, animals belonging to all the great types now represented
upon earth, were simultaneously called into existence. It shows, further, that unless
the physical elements then at work could have devised such plans, and impressed
them upon the material world as the pattern upon which Nature was to build for
ever afterwards, no such general relations as exist among all animals, of all geo-
logical periods, as well as among those now living, could ever have existed.
This is not all: every class among Radiata, Mollusks, and Articulata, is known
to have been represented in those earliest days, with the exception of the Acalephs'
and Insects only. It is, therefore, not only the plan of the four great types which
must have been adopted’ then, the manner in which these plans were to be executed,
the systems of form under which these structures were to be clothed, even the ulti-
mate details of structure which in different genera pear definite relations to those of
other genera; the mode of differentiation of species, and the nature of their rela-
tions to the surrounding media, must likewise have been determined, as the character
of the classes is as well defined as that of the four great branches of the animal
kingdom, or that of the families, the genera, and the species. Again, the first rep-
resentatives of each class stand in definite relations to their successors in later
1 Acalephs have been found in the Jurassic Lime- softness of their body. Insects are known as early
stone of Solenhofen; their absence in other forma- as the Carboniferous Formation, and may have ex-
tions may be owing simply to the extraordinary isted before.
ae
PP ce —
ee ee
Cuap. I. EARLIEST TYPES OF ANIMALS. 25
periods, and as their order of apparition corresponds to the various degrees of com-
plication in their structure, and forms natural series closely linked together, this
natural gradation must have been contemplated from the very beginning. There
can be the less doubt upon this point, as man, who comes last, closes in his own
cycle a series, the gradation of which points from the very beginning to him as its
last term. I think it can be shown by anatomical evidence that man is not only
the last and highest among the living beings, for the present period, but that he is
the last term of a series beyond which there is no material progress possible upon
the plan upon which the whole animal kingdom is constructed, and that the only
| improvement we may look to upon earth, for the future, must consist in the develop-
ment of man’s intellectual and moral faculties.
The question has been raised of late how far the oldest fossils known may truly
be the remains of the first inhabitants of our globe. No doubt extensive tracts of
fossiliferous rocks have been intensely altered by plutonic agencies, and their organic
contents so entirely destroyed, and the rocks themselves so deeply metamorphosed,
that they resemble now more closely eruptive rocks even than stratified deposits.
Such changes have taken place again and again up to comparatively recent periods,
and upon a very large scale. Yet there are entire continents, North America, for
instance, in which the palzeozoic rocks have undergone little, if any, alteration, and
where the remains of the earliest representatives of the animal and vegetable king-
doms are as well preserved as in later formations. In such deposits the evidence is
satisfactory that a variety of animals belonging to different classes of the great
branches of the animal kingdom have existed simultaneously from the beginning; so
that the assumption of a successive introduction of these types upon earth is flatly
contradicted by well established and well known facts.” Moreover, the remains found
e everywhere closely allied to one another. In Russia, in
m the oldest deposits, ar
other parts of the world, where these oldest
Sweden, in Bohemia, and in various
formations have been altered upon a more 0
North America, where they have undergone little or no change, they present the
that close correspondence in their structure and in the
r less extensive scale, as well as in
same general character,
combination of their families, which shows them to have belonged to contempora-
neous fauns. It would, therefore, seem that even where metamorphic rocks prevail,
the traces of the earliest inhabitants of this globe have not been entirely obliterated.
1 AGASSIZ, (L.,) An Introduction to the Study Number of Animals in Geological Times, Amer.
of Natural History, New York, 1847, 8vo. p- 57. Journ. of Science and Arts, 2d ser. vol. 17, 1854,
2 Agassiz, (L.,) The Primitive Diversity and p. 309.
4
wo atl
ESSAY ON CLASSIFICATION.
SECTION VIII.
THE GRADATION OF STRUCTURE AMONG ANIMALS.
There is not only variety among animals and plants; they differ also as to their
standing, their rank, their superiority or inferiority when compared to one another.
But this rank is difficult to determine; for while, in some respects, all animals are
equally perfect, as they perform completely the part assigned to them in the general
economy of nature; in other respects there are such striking differences between
them, that their very agreement in certain features points at their superiority or
inferiority im regard to others.
This being the case, the question first arises, Do all animals form one unbroken
series from the lowest to the highest? Before the animal kingdom had been studied
so closely as it has been of late, many able writers really believed that all animals
formed but one simple continuous series, the gradation of which Bonnet has been
particularly industrious in trying to ascertain” At a later period, Lamarck’ has
endeavored to show further, that in the complication of their structure, all the
classes of the animal kingdom represent only successive degrees, and he is so
thoroughly convinced that in his systematic arrangement classes constitute one grad-
ual series, that he actually calls the classes “degrees of organization.” DeBlainville *
has in the main followed in the steps of Lamarck, though he does not admit quite
so simple a series, for he considers the Mollusks and Articulates as two diverging
branches ascending from the Radiata, to converge again and unite in the Vertebrata.
But since it is now known how the great branches of the animal kingdom may be
circumscribed,» notwithstanding a few doubtful poimts; since it is now known how
1 EHRENBERG, (C. G.,) Das Naturreich des Men- - 4 BLaINvILye, (H. D. px,) De Organisation des
schen, oder das Reich der willensfreien beseelten Na- Animaux, Paris, 1822, 1 vol. 8ve.
turkérper, in 29 Classen iibersichtlich geordnet, Ber- 5 Biumensacn, (J. Fr.,) Handbuch der verglei-
lin, 1835, folio, (1 sheet). chenden Anatomie, Géttingen, 1824, 1 vol. 8vo.;
2 Bonnet, (Cu.,) Considérations sur les corps Engl. by W. Lawrence, London, 1827, 1 vol. 8vo.
organisés, Amsterdam, 1762, 2 vols. 8vo. — Contem- — Cuvier, (G.,) Lecons d’ Anatomie comparée, rec.
plations de la Nature, Amsterdam, 1764-65, 2 vols. et publ. par MM. Duméril et Duvernoy, Paris,
8vo.— Palingénésie philosophique, Genéve, 1769, 2 1800-1805, 5 vols. 8vo.5 Qde édit., rev. par MM.
vols. 8vo. : F. G. Cuvier et Laurillard, Paris, 1836-89, 10 vols.
3 Lamarck, (J. B. pE,) Philosophie zoologique, 8vo.— Cuvier, (G.,) Le Regne animal distribué
Paris, 1809, 2 vols. 8vo. d@aprés son organisation, Paris, 1817, 4 vols. 8vo.3
ee
Pe EY TP
Cuap. I. GRADATION OF STRUCTURE AMONG ANIMALS. 27
most classes should be characterized, and what is their respective standing; since
every day brings dissenting views, respecting the details of classification, nearer
together, the supposition that all animals constitute one continuous gradated series,
can be shown to be contrary to nature. Yet the greatest difficulty in this inquiry,
is to weigh rightly the respective standing of the four great branches of the whole
. animal kingdom; for, however plam the inferiority of the Radiata may seem, when
| compared with the bulk of the Mollusks or Articulata, or still more evident when
. contrasted with the Vertebrata, it must not be forgotten, that the structure of most
Echinoderms is far more complicated than that of any Bryozoon or Ascidian of the
. type of Mollusks, or that of any Helminth, of the type of Articulata, and, perhaps,
. even superior to that of the Amphioxus among Vertebrata. These facts are so well
ascertained, that an absolute superiority or inferiority of one type over the other
must be unconditionally denied. As to a relative superiority or inferiority however,
determined by the bulk of evidence, though it must be conceded that the Vertebrata
rank above the three other types, the question of the relative standing of Mollusks
ther to rest upon a difference in the tendency of their whole
structure; concentration being the
and Articulata seems ra
organization, than upon a real gradation m their
prominent trait of the structure of Mollusks, while the expression ‘outward display’
would more naturally ‘ndicate that of Articulata, and so it might seem as if Mollusks
| 7 and Articulata were standing on nearly a level with one: another, and as much
Leipzic, 1843-44, 1 vol. 8vo., 2d vol. by Frey and
LeucKArDT ; Icones anatomice, Leipzig, 1841, fol.
— Grant, (R. E.) Outlines of Comparative Anat-
omy, London, 1835, 1 vol. fol. —Jonzs, (Rrmer,)
A General Outline of the Animal Kingdom, London,
1838-39, 1 vol. 8vo. fig. ; 2d edit. 1854. — Topp, (R.
B.,) Cyclopedia of Anatomy and Physiology, London,
1835-52, 4 vol. 8vo. fig—AGassiz, (L.,) and Goutn,
(A. A.,) Principles of Zodlogy, Boston, 1 vol. 8vo.,
2d edit. 1851. — Owen, (R.,) Lectures on the Inver-
tebrate Animals, London, 18438, 1 vol. fig.; 2d edit.
1855.— Lectures on the Comparative Anatomy of
the Vertebrate Animals, Fishes, London, 1846, 1 vol.
. Qde édit. 1829-30, 5 vols. 8vo.; Be édit. illustrée
1836 et suiv; Engl. Trans. by Grirriru, London,
) 1824, 9 vols. 8vo.— Mxrcxet, (J. F.,) System der
. . vergleichenden Anatomie, Halle, 1821-31, 6 vols.
| 8vo.; French Transl., Paris, 1829-38, 10 vols. 8vo.
. — Treviranus, (G. R.,) Biologie, oder Philosophie
. der lebenden Natur, Gottingen, 1802-16, 6 vols. 8vo.
3 — Die Erscheinungen und Gesetze des organischen
Lebens, Bremen, 1831-37, 5 vols. 8vo. — DELLE
Cuiase, Istituzioni d’Anatomia e Fisiologia compa-
rata, Napoli, 1832, 8vo.— Carus, (C. G.,) Lehrbuch
der vergleichenden Anatomie, Leipzic, 1834,,2 vols.,.
Ato., fig. 2d edit.; Grundsiitze der vergleichenden Ana-
. tomie, Dresden, 1828, 8vo.; Engl. by R. J. GORE, 8vo.. fig. — SrEBOLD, (C. Tu. v..) und STANNIUS,
Bath, 1827, 2 vols. 8vo. Atlas. — Carus, (C. G.,) and (Herm.,) Lehrbuch der vergleichenden Anatomie,
Orro, (A. W.) Erliuterungstafeln zur vergleichen- Berlin, 1845-46, 2 vol. 8vo.; 2d edit. 1855; Engl.
den Anatomie, Leipzic, 1826-40, fol. — WAGNER, Trans. by W. J. Burnertr, Boston, 1854. — Brerc-
(R.,) Lehrbuch der vergleichenden Anatomie, Leipzic, MANN, (C.,) und LeucKkarpt, (R.,) Vergleichende
1834-35, 2 vol. 8vo.; Engl. by A. Tux, London, Anatomie und Physiologie, Stuttgardt, 1852, 1 vol.
1844, 1 vol. 8vo.; 2d edit. Lehrbuch der Zootomie, 8vo. fig.
ill aad
Tar:
See e
hiatal
28 acu & ON CLASSIFICATION. | Part I.
above Radiata, as both stand below Vertebrata, but constructed upon plans expressing
different tendencies. To appreciate more precisely these most general relations
among the great types of the animal kingdom, will require deeper investigations into
the character of their plan of structure than have been made thus far: Let, how-
ever, the respective standing of these great divisions be what it may; let them differ
only in tendency, or in plan of structure, or in the height to which they rise,
admitting their base to be on one level or nearly so, so much is certain, that im
each type there are representatives exhibiting a highly complicated structure and
others which appear very simple. Now, the very fact that such extremes may be
traced, within the natural boundaries of each type, shows that in whatever manner
these great types are supposed to follow one another in a single series, the highest
representative of the preceding type must join on to the lowest representative of |
the following, thus bringing necessarily together the most heterogeneous forms? = It
must be further evident, that in proportion as the internal arrangement of each great
type will be more perfected, the greater is likely to appear the difference at the two
ends of the series which are ultimately to be brought into connection with those of
other series, in any attempt to establish a single series for all animals.
I doubt whether there is a naturalist now living who could object to an arrange-
ment in which, to determine the respective standing of Radiata, Polyps would be
placed lowest, Acalephs next, and Echinoderms highest; a similar arrangement of
Mollusks would bring Acephala lowest, Gasteropoda next, and Cephalopoda highest ;
Articulata would appear in the following order: Worms, Crustacea, and Insects, and
Vertebrata, with the Fishes lowest, next Reptiles and Birds, and Mammalia highest.
I have here purposely avoided every allusion to controverted points. Now if Mol-
lusks were to follow Radiata in a simple series, Acephala should join on to the
Echinoderms; if Articulata, Worms would be the connecting link. We should then
have either Cephalopods or Insects, as the highest term of a series beginning with
Radiata, followed by Mollusks or by Articulates. In the first case, Cephalopods
would be followed by Worms; in the second, Insects by Acephala. Again, the con-
nection with Vertebrata would be made either by Cephalopods, if Articulata were
considered as lower than Mollusks, or by Insects, if Mollusks were placed below
Articulata. Who does not see, therefore, that in proportion as our knowledge of the
true affinities of animals is improving, we accumulate more and more convincing
evidence against the idea that the animal kingdom constitutes one simple series ?
1 [ regret to be unable to refer here to the con- ' between Progressive, Embryonic, and Prophetic
tents of a course of lectures which I delivered upon Types, Proc. Am. Assoc. for 1849, p- 432.
this subject, in the Smithsonian Institution, in 1852. 2 Ac assiz; (5) Animal Morphology, Proc. Am.
Compare, meanwhile, my paper, On the Differences Assoc. for 1849, p. £15.
Mt a ge
Cuap. I. GRADATION OF STRUCTURE AMONG ANIMALS. 29
The next question would then be: Does the animal kingdom constitute several, —
or any number of graduated series? In attempting to ascertain the value of the less
when compared to one another, the difficulties seem to be
comprehensive groups,
It is already possible to mark out with tolerable precision,
gradually less and less.
the relative standing between the classes, though even here we do not yet perceive
in all the types the same relations. Among Vertebrata, there can be little if any
doubt, that the Fishes are lower than the Reptiles, these lower than Birds, and that
Mammalia stand highest; it seems equally evident, that in the main, Insects and
Crustacea are superior to Worms,
Echinoderms to Acalephs and Polypi.
of which over many Crustacea, would be difficult to prove; there are Worms which
Cephalopods to Gasteropods and Acephala and
But there are genuine Insects, the superiority
in every respect appear superior to certain Crustacea; the structure of the highest
Acephala seems more perfect than that of some Gasteropods, and that of the Halcyo- -
noid Polyps more perfect than that of many aes es
seem to be so limited in the range of their characters, as to justify in every type a
complete serial arrangement among them. age et)
hardly be doubted that the gradation of these natural divisions among themselves in |
each class, constitutes the very essence of this kind of groups. As a special para- !
graph is devoted to the consideration of the character - orders in ny. next chapter,
I need not dwell longer upon this point here! It will fs aide cge! for me to
remark now, that the difficulties geologists have met with, m wee attempts to com-
pare the rank of the different types of animals and plants with the order of their
succession in different geological periods,
they have expected to find a serial gradation,
same type, where it is only incomplete, but even among the types themselves,
between which such a gradation cannot be traced. Had they limited their compari-
sons to the orders which are really founded upon gradation, the result would have
been quite different; but to do thi
yology and with Zodlogy proper, than can naturally be expected
. of which are chiefly devoted to the investigation of the struct-
Hydroids. Classes / do, therefore, not
But when we come to the orders, it can |
has chiefly arisen from the circumstance, that
not only among the classes of the
s requires more familiarity with Comparative
Anatomy, with Embr
of those, the studies
ure of our globe.
To appreciate fully the importance of this question of the gradation of animals,
and to comprehend the whole extent of the difficulties involved in it, a superficial
acquaintance with the perplexing question of the order of succession of animals in
past geological ages, is by no means sufficient; a complete familiarity with the many
attempts which have been made to establish a correspondence between the two, and
with all the crudities which have been published upon this subject, might dispel
1 See Chap. II.
j 30 . ESSAY ON CLASSIFICATION. Part I.
every hope to arrive at any satisfactory result upon this subject, did it not appear
now, that the inquiry must be circumscribed within different limits, to be conducted
upon its true ground, The results to which I have already arrived, since I have
perceived the mistake under which investigators have been laboring thus far, m
this respect, satisfy me that the point of view under which I have presented the
subject here is the true one, and that in the end, the characteristic gradation
exhibited by the orders of each class, will present the most striking correspondence
with the character of the succession of the same groups in past ages, and afford
another startling proof of the admirable order and gradation which have been estab-
lished from the very beginning, and maintained through all times in the degrees of
ae NEN
complication of the structure of animals.
SHOCTION IX.
RANGE OF GEOGRAPHICAL DISTRIBUTION OF ANIMALS.
The surface of the earth being partly formed by water and partly by land, and
the organization of all living beings standing in close relation to the one or the other |
of these mediums, it is in the nature of things, that no single species, either of ani-
mals or plants, should be uniformly distributed over the whole globe. Yet there
are some types of the animal, as well as of the vegetable kingdom, which are equably
distributed over the whole surface of the land, and others which are as widely scat-
tered in the sea, while others are limited to some continent or some ocean, to some
particular province, to some lake, nay, to some very limited spot of the earth’s
surface.t
As far as the primary divisions of animals are concerned, and the nature of the
medium to which they are adapted does not interfere, representatives of the four
great branches of the animal kingdom are everywhere found together. Radiata,
Mollusks, Articulata, and Vertebrata occur together in every part of the ocean, in
the Arctics, as well as under the equator, and near the southern pole as far as man
has penetrated; every bay, every inlet, every shoal is haunted by them. So univer-
2 IER ERIE OR PAE RD IH
f 1 The human race affords an example of the wide Ocean, how fishes may be circumscribed in the sea, |
a distribution of a terrestrial type; the Herring and and that of the Goniodonts of South America in 1
| the Mackerel families have an equally wide distri-- the fresh waters. The Chaca of Lake Baikal is f
4" ; . bution in the sea. The Mammalia of New Hol- found nowhere else; this is ‘equally true of the :
i if ' land show how some families may be limited to one Blindfish (Amblyopsis) of the Mammoth Cave, and \
| continent; the family of Labyrinthici of the Indian of the Proteus of the caverns of Carinthia. "|
AE AEE Ae TIT
eee
sal is this association,
/ consider it as
GEOGRAPHICAL RANGE OF ANIMALS. 3l
Cuap.. I.
not only at present but in all past geological ages, that I
a sufficient reason to expect, that fishes will be found in those few
fossiliferous beds of the Silurian System, in which thus far they have not yet been
\ found! Upon land, we find equally everywhere Vertebrata, Articulata, and Mollusks,
but no Radiata, this whole branch being limited to the waters; but as far as terres-
trial animals extend, we find representatives of the other three branches associated,
as we find them all four in the sea. Classes have already a more limited range of
distribution. Among Radiata,
all aquatic, they are all marine,
inhabits fresh waters.
marine and partly fluviatile, the Gasterop
partly terrestrial, while all Cephalopoda are marine.
partly terrestrial, while many are internal
are partly marine, partly fluviatile, and
1 See, above, Sect. 7.
2 For the geographical distribution of Radiata,
Dana, (J. D.,) Zoophytes. United States
Exploring Expedition, under the’ command of Ch.
Wilkes, U. S. N., Philadelphia, 1846, 1 vol. Ato.
Atlas fol. —Minyz-Epwarps et Hare, (Jot)
Recherches sur les Polypiers, Ann. Sc. Nat. 8e sér.
vol. 9-18, Paris, 1848-52, 8vo. — ESCHSCHOLTZ,
(Fr.,) System der Acalephen, Berlin, 1829, 4to. fi.
— Lesson, (R. Pr.,) Histoire naturelle des Zoophy-
tes, Acaléphes, Paris, 1843, 1 vol. 8vo. fig. Soni
KER, (A.,) Die Schwimmpolypen und Siphonophoren
von Messina, Leipzic, 1853, 1 vol. fol. fig. — Mut-
Ler, (J.,) und Troscuet, (F. H.,) System der
Asteriden, Braunschweig, 1842, 8vo. fig. — AGASSIZ,
(L.,) Catalogue raisonné des familles, des genres et
des espéces de la Classe des Echinodermes, Ann. des
Se. Nat. 3e sér. vol. 6-8, Paris, 1847, 8vo.
® T need hardly say in this connection that the
so-called fresh-water Polyps, Aleyonella, Plumatella,
ete., are Bryozoa, and not true Polyps.
* For the geographical distribution of Mollusks,
consult: Lamarck, (J. B. DE,) Histoire naturelle
des Animaux sans vertebres, Paris, 1815-22, 7 vols.
8vo.; 2de édit. augmentée de notes par MM.
DusHayves and Mitne-Epwarps, Paris, 1835-48,
10 vols. 8vo.—Fervssac, (J. B. L. px,) Histoire
naturelle des Mollusques terrestres et fluviatiles.
Paris, 1819 et suiv, 4to. fig. fol., continuée par Des-
consult:
the Polypi, Acalephs, and Echinoderms’ are not only
with a single exception, the genus Hydra, which
Among Mollusks,* the Acephala are all aquatic, but partly
oda partly marine, partly fluviatile and
Among Articulata,’ the Worms
Hayes.— Fervussao, (J. B. L. pzE,) et SANDER-
Rane, (A.,) Histoire naturelle des Aplysiens, Paris,
1828, 4to. fig. fol.— Frrussac, (J. B. L. px,) et
p’Orpieny, (A.,) Monographie des Céphalopodes
eryptodibranches, Paris, 1834-48, fol. — Marrinq,
(F. H. W.,) und Curmnirz, (J. H.) Neues syste-
‘matisches Conchylien-Kabinet, Niirnberg, 1769-95,
11 vols. 4to. fig; new edit. and continuation by
Scuupert and A. WAGNER, completed by H. C.
Kuster, Niirnberg, 11 vols. 4to. fig. — Kiener, (L.
C.,) Spécies général et Icenographie des Coquilles
vivantes, Paris, 1834, et suiv, 8vo. fig.— REEvE,
(Lovell,) Conchologia Iconica; a Complete Repertory
of Species of Shells, Pictorial and Descriptive, Lon-
don, 1843, and foll., 4to. fig. — PFEIFFER, (L.,) Mon-
egraphia Heliceorum viventium, Leipzig, 1847-48,
8vo. —Preirrer, (L.,) Monographia Pneumonopo-
morum viventium, Cassel, 1852, 8vo., and all the
special works on Conchology.
5 The mode of distribution of free or parasitic
Worms, in different parts of the world and in differ-
ent animals, may be ascertained from: Grusx, (A.
Ep.,) Die Familien der Anneliden, Wiegman’s Ar-
chiv, 1850. I mention this paper in preference to
any other work, as it is the only complete list of An-
nulata; and though the localities are not given, the
references may supply the deficiency. — RupoLrut,
(Kk. <A.,) Entozoorum sive Vermium intestinalium
Historia naturalis, Amstelodami, 1808-10, 3 vols.
32 A aor’. ESSAY ON CLASSIFICATION. Pape od
parasites, living in the cavities or in the organs of other animals ; the Crustacea are
partly marine and partly fluviatile, a few are terrestrial; the Insects are mostly ter-
restrial or rather aérial, yet some are marine, others fluviatile, and a large number of
those, which in their perfect state live in the air, are terrestrial or even aquatic
during their earlier stages of growth. Among Vertebrata’ the Fishes are all aquatic,
but partly marine and partly fluviatile; the Reptiles are either aquatic, or amphibious
or terrestrial, and some of the latter are aquatic during the early part of their life ;
the Birds are all aérial, but some more terrestrial and others more aquatic; finally,
the Mammalia though all aérial live partly im the sea, partly in fresh water, but
mostly upon land. A more special review might show, that this localization in con-
nection with the elements in which animals live, has a direct reference to peculiari-
ties of structure of such importance, that a close consideration of the habitat of ani-
mals within the limits of the classes, might in most cases lead to a very natural
classification? But this is true only within the limits of the classes, and even here
8vo. fig. — Entozoorum Synopsis, Berolini, 1819, 8vo.
fiz. — Gurit, (E. F.,) Verzeichniss der Thiere, bei
welchen Entozoen gefunden worden sind, Wiegman’s
Archiv, 1845, contin. by Creplin in the following No.
—Dvusarpin, (FEL.,) Histoire naturelle des Hel-
minthes ou Vers intestinaux, Paris, 1844, 1 vol. 8vo.
— Diesine, (C. M.,) Historia Vermium, Vindob. 1850,
2 vols. 8vo. That of Crustacea from MiILNe-Ep-
warps, Histoire naturelle des Crustacés, Paris, 1834,
3 vols. 8vo. fig-—Dana, (J. D.,) Crustacea. Uni-
ted States Exploring Expedition, under the command
of Ch. Wilkes, U. S. N., vol. xiv., Philadelphia, 1852,
2 vols. 4to., atlas, fol. For the geographical distri-
bution of Insects I must refer to the general works
on Entomology, as it would require pages to enu-
merate even the standard works relating to the dif-
ferent orders of this class; but they are mentioned
in: Percueron, (Acu. R.,) Bibliographie entomo-
logique, Paris, 1837, 2 vols. 8vo.—Acassiz, (L.;)
Bibliographia Zoologie et Geologie ; a general cata-
logue of all books, tracts, and memoirs on Zodlogy
and Geology, corrected, enlarged, and edited by H.
E.STRICKLAND, London, 1848-54, 4 vols. 8vo. (Ray
Society).
1 For the -geographical distribution of Fishes,
consult: Cuvier, (G.,) and VaLenciennes, (A.,)
Histoire naturelle des Poissons, Paris, 1828-1849, 22
vols. 8vo., fig. —Mittier, (J.,) und Hentz, (J.,)
Systematische Beschreibung der Plagiostomen, Ber-
lin, 1841, fol. fig. For that of Reptiles: DuMERIL,
(A. M. C.,) et Brsron, (G.,) Erpétologie générale,
ou Histoire naturelle compléte des Reptiles, Paris,
18384-1855, 9 vols. 8vo. fig.—Tscuupi, (J. J.,)
Classification der Batrachier, Neuchatel, 1838, 4to.
Mém. Soc. Neuch. 2d. vol.— Frirzinerr, (L. J.,)
Systema Reptilium, Vindobone, 1843, 8vo. For that
of Birds: Gray, (G. R.,) The Genera of Birds, illus-
trated with about 350 plates by D. W. Mitchell, Lon-
don, 1844-1849, 3. vols. imp. 4to.— Bonaparte,
(C. L.,) Conspectus generum Avium, Lugduni-Bata-
vorum, 1850, and seq. 8vo. For that of Mammalia:
Waaener, (A.,) Die geographische Verbreitung der
Siugthiere, Verhandl. der Akad. der Wissensch.
in Miinchen, Vol. IV.— Pomprer, (Herm.,) Die
Siiugthiere, Vogel und Amphibien, nach ihrer geo-
graphischen Verbreitung tabellarish zusammenge-
stellt, Leipzig, 1841, 4to.—See, also, the annual
reports in Wiegman’s Archiv, now edited by Tro-
schell; the Catalogues of the British Museum, of
the Jardin des Plantes, ete.
2 Agassiz, (L.,) The Natural Relations between
Animals and the Elements in which they live.
Amer. Jour. of Sc. and Arts, 2d ser., vol. 9, 1850,
8vo., p. 369.
a a a en eee ae
ed
st a TP
2p AD RI OES AEE I GL A FAG ANE AEN BORE
po
Cm em
Cuap. I. GEOGRAPHICAL RANGE OF ANIMALS. 39
not absolutely, as in some the orders only, or the families only are thus closely
related to the elements; there are even natural groups, in which this connection is
not manifested beyond the limits of the genera, and a few cases in which it is actually
confined to the species. Yet, mm every degree of these connections, we find that upon
every spot of the globe, it extends simultaneously to the representatives of different
classes and even of different branches of the animal and vegetable kingdoms; a circum-
stance which shows that when called into existence, in such an association, these vari-
and plants were respectively adapted with all the peculiarities of their
those of their order, those of their genus, and those of
ous animals
kingdom, those of their class,
their species, to the home assigned to them,
of the place, or of the element, or any other physical condition. To maintain the
serting that wherever a variety of organized
and therefore, not produced by the nature
contrary, would really amount to as
beings live together, no matter how great their diversity, the physical agents prevail-
ing there, must have in their combined action, the power of producing such a
diversity of structures as exists m animals, notwithstanding the close connection in
Slieh. these annals. stand to themapeme work out an intimate relation to them-
selves in beings, the essential characteristics
in all these animals and plants, there is one side of their
of which, have no reference to their
nature. In other words,
mmediate reference to the elements in which they live,
organization which has an 1
and ‘another which has no such connection, and yet it is
structure of animals and plants, which has no direct bearing upon the conditions in
which they are placed in nature, which constitutes their essential, their typical
beyond the possibility of an objection, that the elements in
pression I mean to include all that
precisely this part of the
character. This proves
which animals and plants live (and under this ex
is commonly called physical agents, physical causes, etc.) cannot in any way be con-
sidered as the cause of their existence.
If the naturalists of past centuries have failed to im
d from the habitat of animals, it is chiefly because
prove their systems of Zodlogy
by introducing considerations derive he
they have taken this habitat as the foundation of their primary divisions; but
the study of the connection between the structure and
reduced to its proper limits,
+ fail to lead to interesting results, among which,
the natural home of animals canno
the growing conviction that these relations are not produced by physical agents,
but determined in the plan ordained from the beginning, will not be the least.
important. |
The unequal limitation of groups of a different value, upon the surface of the
earth, produces the most diversified combinations possible, when we consider the
mode of association of different families of animals and plants in different parts of
the world. These combinations are so regulated that every natural province has a
character of its own, as far as its animals and plants are concerned, and such natural
5
tn - — R h aa
34 ' ESSAY ON CLASSIFICATION. Part I.
associations of organized beings extending over a wider or narrower area are called
Fue when the animals alone are considered, and Flore when the plants alone are
regarded. Their natural limits are far from being yet ascertained satisfactorily
everywhere. As the works of Schow and Schmarda may suffice to give an approxi-
mate idea of their extent, I would refer to them for further details, and allude here
only to the unequal extent of these different faunze, and to the necessity of limiting
them in different ways, according to the point of view under which they are con-
sidered, or rather show that, as different groups have a wider or more limited range,
in investigating their associations, or the faune, we must distinguish between zodlogi-
cal realms, zodlogical provinces, zovlogical counties, zodlogical fields, as it were; that
is, between zodlogical areas of unequal value over the widest of which range the
most extensive types, while in their smaller and smaller divisions, we find more and
more limited types, sometimes overlapping one another, sometimes placed side by
side, sometimes concentric to one another, but always and everywhere impressing a
special character upon some part of a wider area, which is thus made to differ from
that of any other part within its natural limits.
These various combinations of smaller or wider areas, equally well defined in
different types, has given rise to the conflicting views prevailing among naturalists
respecting the natural limits of faune; but with the progress of our knowledge
these discrepancies cannot fail to disappear. In some respect, every island of the
Pacific upon which distinct animals are found, may be considered as exhibiting a
distinct fauna, yet several groups of these islands have a common character, which
unites them into more comprehensive faunew, the Sandwich Islands for instance, com-
pared to the Fejees or to New Zealand. What is true of disconnected islands or of
isolated lakes is equally true of connected parts of the mainland and of the ocean.
Since it is well known that many animals are limited to a very narrow range
in their geographical distribution, it would be a highly interesting subject of inquiry
to ascertain what are the narrowest limits within which animals of different types
may be circumscribed, as this would furnish the first basis for a scientific consid-
eration of the conditions under which animals may have been created. The time
is passed when the mere indication of the continent whence an animal had been
obtained, could satisfy our curiosity; and the naturalists who, having an opportunity
of ascertaining closely the particular circumstances under which the animals they
describe are placed in their natural home, are guilty of a gross disregard of the
interest of science when they neglect to relate them. Our knowledge of the geo-
graphical distribution of animals would be far more extensive and precise than it
1 J would also refer to a sketch I have pub- Types of Mankind, Philadelphia, 1854, 4to., accom-
lished of the Faune in Norr’s and Guippon’s panied with a map and illustrations.
fo
2 rs
SO RAR INES
Cuap. I. GEOGRAPHICAL RANGE OF ANIMALS. 30
is now, but for this neglect; every new fact relating to the geographical distribu-
tion of well-known species is as important to science as the discovery of a new
species. Could we only know the range of a single animal as accurately as
Alphonse DeCandolle has lately determined that of many species. of plants, we
might begin a new era in Zodlogy. It is greatly to be regretted that in most
works, containing the scientific results of explorations of distant countries, only new
species are described, when the mere enumeration of those already known might have
added invaluable information respecting their geographical distribution. The careless-
ness with which some naturalists distinguish species merely because they are found
in distant regions, without even attempting to secure specimens for comparison, is a
perpetual source of erroneous conclusions in the study of the geographical distribu-
not less detrimental to the progress of science than the
tion of organized beings,
entical, animals and plants which may resemble
readiness of others to consider as id
each other closely, without paying the least regard to their distinct origin, and
without even pointing out the differences they may perceive between specimens from
different parts of the world. The perfect identity of animals and plants living in
of the globe has s0 often been ascertained, and it is also so
very remote parts
be allied and yet differ in all the essential
well known how closely species may
relations which characterize species,
justifiable. |
This close resemblance of animals and plants in distant parts of the world is the
gation with reference to the question of the unity
that such loose investigations are no longer
most interesting subject of investi
of origin of animals, and to that of the influence of physical agents upon organized
It appears to me that as the facts point now distinctly to an
beings in general.
als of the same species in remote regions, or of
independent origin of individu .
species representing one another in distant parts of the world, one
closely allied
osition that physical agents may have
of the strongest arguments in favor of the supp
had a controlling mfluence in changing the character of the organic world, is gone
for ever.
The narrowest limits within which certain Vertebrata may be circumscribed, is
by some large and remarkable species: the Orang-
exemplified, among Mammalia,
the Chimpanzee and the Gorilla along the west-
Outangs upon the Sunda Islands,
em coast of Africa, several distinct species of Rhinoceros about the Cape of Good
Hope, and in Java and Sumatra, the Pinchaque and the common Tapir in South
America, and the eastern Tapir in Sumatra, the East Indian and the African Ele-
phant, the Bactrian Camel and the Dromedary, the Llamas, and the different kinds
of wild Bulls, wild Goats, and wild Sheep, etc.; among birds by the African Ostrich,
the two American Rheas, the Casovary (Dromicejus) of New Holland, and the Emeu
(Casuarius galeatus) of the Indian Archipelago, and still more by the different
eae
re
36 ESSAY ON CLASSIFICATION. Part I.
species of doves confined to particular islands in the Pacific Ocean; among Reptiles,
by the Proteus of the cave of Adelsberg in Carinthia, by the Gopher (Testudo Poly-
phemus Auct.) of our Southern States ; among fishes, by the Blind Fish (Amblyopsis
speleeus) of the Mammoth Cave. Examples of closely limited Articulata may not be
so striking, yet the Blind Crawfish of the Mammoth Cave and the many parasites
found only upon or within certain species of animals, are very remarkable in this
respect. Among Mollusks, I would remark the many species of land shells, ascer-
tained by Professor Adams to occur only in J amaica,' among the West India Islands,
and the species discovered by the United States Exploring Expedition upon isolated
islands of the Pacific, and described by Dr. Gould’ Even among Radiata many
species might be quoted, among Echinoderms as well as among Medusee and Polypi,
which are only known from a few localities; but as long as these animals are not
collected with the special view of ascertaining their geographical range, the indica-
tions of travellers must be received with great caution, and any generalization
respecting the extent of their natural area would be premature as long as the coun-
tries they inhabit have not been more extensively explored. It is nevertheless true
as established by ample evidence, that within definite limits all the animals occurring
in different natural zodlogical provinces are specifically distinct. What remains to
be ascertained more minutely is the precise range of each species, as well as the
most natural limits of the different faune.
DoH blcl aN 4 pda
IDENTITY OF STRUCTURE OF WIDELY DISTRIBUTED TYPES.
It is not only when considering the diversification of the animal kingdom within
limited geographical areas, that we are called upon in our investigations to admire
the unity of plan its most diversified types may exhibit; the identity of structure of
these types is far more surprising, when we trace it over a wide range of country,
and within entirely disconnected areas. Why the animals and plants of North
America should present such a strong resemblance to those of Europe and Northern
Asia, while those of Australia are so entirely different from those of Africa and South
America under the same latitudes, is certainly a problem of great interest in connec-
1 Apams, (C. B.,) Contributions to Conchology, 2 Goutp, (A. A.,) Mollusks, United States Ex-
New York, 1849-50, 8vo. <A series of pamphlets, ploring Expedition, under the command of Cu.
full of original information. Wirxrs, U. S. N., 1 vol. 4to. Philadelphia, 1854.
ee EN
Cuap. I. STRUCTURE AND GEOGRAPHICAL DISTRIBUTION. 37
tion with the study of the influence of physical agents upon the character of animals
and plants in different parts of the world. North America certainly does not resem-
ble Europe and Northern Asia, more than parts of Australia resemble certain parts
of Africa or of South America, and even if a greater difference should be conceded
between the latter than between the former, these disparities are in no way com- |
e or similarity of their organized beings, nor in any way /
mensurate with the differenc
. rationally dependent one upon the other.
. vailing in the Arctics not extend to the temperate zone, when many species of this
Why should the identity of species pre-
zone, though different, are as difficult to distinguish, as it is difficult to prove the
. identity of certain arctic species,
. and when besides, those of the two zones mingle to a great extent at their boun-
daries? Why are the antarctic species not identical with those of the arctic regions?
And why should a further increase of the average temperature introduce such com-
Arctics, there are in different continents such
in the different continents converging to the north,
pletely new types, when even in the
strikingly peculiar types (the Rhytina for instance,) combined with those that are
identical over the whole arctic area?’
. It may at first sight seem very natural that the arctic species should extend
over the three northern continents converging towards
be no insuperable barrier to the widest dissemination over this whole area for ani-
of three continents which are almost
the north pole, as there can
mals living in a glacial ocean or upon parts — .
Yet the more we trace this identity in detail, the more
as we find in the Arctics as well as everywhere else, repre-
The arctic Mammalia belonging chiefly
bound together by ice.
surprising does it appear,
sentatives of different types living together.
to the families of Whales, Seals, Bears, Weasels, Foxes, Ruminants and Rodents,
structure as the Mammalia of any other part
the arctic Fishes, the arctic Articulata, the
Se = A NEE i ETS OTE ET PT
have, as Mammalia, the same general
of the globe, and so have the arctic Birds,
arctic Mollusks, the arctic Radiata when compared to the representatives of the same
This identity extends to every degree of affinity among
types all over our globe. :
accompany them ; their orders, their families, and
these animals and the plants which
their genera as far as they have representatives elsewhere, bear everywhere the
same identical ordinal, family, or generic characters; the arctic foxes have the same
1 I beg not to be misunderstood. IT do not im- peint under consideration. Too little attention has
pute to all naturalists the idea of ascribing all the
differences or all the similarities of the organic
world to climatic influences; I wish only to remind
them that even the truest picture of the correla-
tions of climate and geographical distribution, does
not yet touch the question of origin, which is the
thus far been paid to the facts bearing upon the
peculiarities of structure of animals in connection
with the range of their distribution. Such investi-
gations are only beginning to be made, as native
investigators are studying comparatively the anatomy
of animals of different continents.
38 ESSAY ON CLASSIFICATION. Part I.
dental formula, the same toes and claws, in fact, every generic peculiarity which
characterizes foxes, whether they live in the Arctics, or in the temperate or tropical
zone, in America, in Europe, in Africa, or in Asia. This 1s equally true of the seals
or the whales; the same details of structure which characterize their genera in the
Arctics reappear in the Antarctics, and the intervening space, as far as their natural
distribution goes. This is equally true of the birds, the fishes, ete, ete. And let it
not be supposed that it is only a general resemblance. By no means. The struc-
tural identity extends to the most minute details in the most intimate structure of
the teeth, of the hair, of the scales, in the furrows of the brain, in the ramification
of the vessels, in the folds of the internal surface of the intestine, in the complica-
tion of the glands, ete. etc., to peculiarities, indeed, which nobody but a professional
naturalist, conversant with microscopic anatomy, would ever believe could present
such precise and permanent characters. So complete, indeed, is this identity, that
were any of these beings submitted to the investigation of a skilful anatomist, after
having been mutilated to such an extent that none of its specific characters could
be recognized, yet not only its class, or its order, or its family, but even its genus,
could be identified as precisely as if it were perfectly well preserved in all its parts.
Were the genera few which have a wide range upon the earth and in the ocean,
this might be considered as an extraordinary case; but there is no class of animals
and plants which does not contain many genera, more or less cosmopolite in their
geographical distribution. The number of animals which have a wide distribution is
even so great that, as far at least as genera are concerned, it may fairly be said,
that the majority of them have an extensive geographical range. This amounts to
the most complete evidence that, as far as any of these genera extends in its geo-
eraphical distribution, animals the structure of which is identical within this range of
distribution, are entirely beyond the influence of physical agents, unless these agents
have the power, notwithstanding their extreme diversity, within these very same
geographical limits, to produce absolutely identical structures of the most diversified
types. |
It must be remembered here, that there are genera of Vertebrata, of Articulata,
of Mollusks, and of Radiata, which occupy the same identical and wide geographical
distribution, and that while the structure of their respective representatives is identi-
cal over the whole area, as Vertebrata, as Articulata, as Mollusks, as Radiata, they
are at the same time built upon the most different plans. I hold this fact to be in
itself a complete demonstration of the entire independence of physical agents of the
structure of animals, and I may add that the vegetable kingdom presents a series of
tacts identical with these. This proves that all the higher relations among animals
and plants are determined by other causes than mere physical influences.
er
a
:
.
:
Cuap. I. STRUCTURE AND GEOGRAPHICAL DISTRIBUTION. 39
While all the representatives of the same genus are identical in structure,’ the
different species of one genus differ only in their size, in the proportions of their
parts, in their ornamentation, in their relations to the surrounding elements, ete.
The geographical range of these §
itself a criterion for the distinction of species. It appears further, that while some
species which are scattered over very extensive areas, occupy disconnected parts of
closely allied to one another and which are generally desig-
pecies varies so greatly, that it cannot afford in
that area, other species
nated under the name of representative species,
The question then arises, how these natural boundaries
It is now generally believed that each
occupy respectively such disconnected
sections of these. areas.
assigned to every species are established. ally
species had, in the beginning, some starting point, from which it has spread over
the whole range of the area it now occupies, and that this starting point is still
indicated by the prevalence or concentration of
of its natural area, which, on that account, is called
external limits the representatives of such species thin
and sometimes in a reduced condition.
such species in some particular part
its centre of distribution or
centre of creation, while at its
out, as it were, occurring more sparsely
It was a great progress in our science,
knowledge of the geographical distribution
cultivators the conviction, that neither animals
one and the same spot upon the surface of the earth, and hence have spread more
hole globe became inhabited. It was really an immense
of an old prejudice; for now -we have
when the more extensive and precise
of organized beings forced upon its
nor plants could have originated upon
and more widely until the w
progress which freed science from the fetters
the facts of the case before us, it 1s really diifiet cea
such a gradual dissemination from one spot, the diversity which exists in every part
of the globe could ever have seemed to be explained. But even to grant distinct
centres of distribution for each species within their natural boundaries, 1s only to
meet the facts half way, as there are innumerable relations” between the toate dee
plants which we find associated everywhere, which must be considered as primitive,
and cannot be the result of successive adaptation. And if this be so, 1t would
follow that all animals and plants have occupied, from the beginning, those natural
boundaries within which they stand to one another in such harmonious relations?
Pines have originated in forests, heaths in heathers, grasses in prairies, bees in hives,
e e e {3 fe e
buffaloes in herds, men 1m nations!® I see a striking proof that
that representative species, which,
ult to conceive how, by assuming
herrings in schools,
this must have been the case in the circumstance,
8 Acassiz, (L.,) The Diversity of Origin of the
1 See hereafter, Chap. II. Sect. 5.
: Human Races, Christian’ Examiner, Boston, 1850,
2 Acassiz, (L.,) Geographical Distribution of
Animals, Christian Examiner, Boston, 1850, 8vo. 8vo. (February.)
(March).
40) ESSAY ON CLASSIFICATION. Part I.
as distinct species, must have had from the beginning a different and distinct
geographical range, frequently occupy sections of areas which are simultaneously
inhabited by the representatives of other species, which are perfectly identical over
the whole area. By way of an example, I would mention the European and the
American Widgeon, (Anas ‘Muareca’ Penelope and A. americana,) or the American and the
European Red-headed Ducks, (A. ferina and A. erythrocephala,) which inhabit respectively
the northern parts of the Old and New World in summer, and migrate further south
in these same continents during winter, while the Mallard (A. Boschas) and the Scaup
Duck (A. marila) are as common in North America as in Europe. What do these
facts tell: That all these birds originated together somewhere, where they no longer
occur, to establish themselves in the end within the limits they now occupy ?— or
that they originated either in Europe or America, where, it is true, they do not live
all together, but at least a part of them ?—or that they really originated within the
natural boundaries they occupy? I suppose with sensible readers I need only argue
‘ the conclusions flowing from the last supposition. If so, the American Widgeon and
the American Red-headed Duck originated in America, and the European Widgeon
and the European Red-headed Duck in Europe. But what of the Mallard and the
Scaup, which are equally common upon the two continents; did they first appear in
_Europe, or in America, or simultaneously upon the two continents? Without entering
into further details, as I have only desired to lay clearly a distinct case before my
readers, from which the character of the argument, which applies to the whole animal
kingdom, may be fully understood, I say that the facts lead, step by step, to the
inference, that such birds as the Mallard and the Scaup originated simultaneously and
separately in Europe and in America, and that all animals originated m vast num-
bers, indeed, in the average number characteristic of their species, over the whole of
their geographical area, whether its surface be continuous or disconnected by sea,
lakes, or rivers, or by differences of level above the sea, etc. The details of the
geographical distribution of animals exhibit, indeed, too much discrimination to admit
for a moment that it could be the result of accident, that is, the result of the
accidental migrations of the animals or of the accidental dispersion of the seeds of
plants. The greater the uniformity of structure of these widely distributed organized
beings, the less probable does their accidental distribution appear. I confess that
nothing has ever surprised me so much as to see the perfect identity of the most
delicate microscopic structures of animals and plants, from the remotest parts of the
world. It was this striking identity of structure in the same types, this total inde-
pendence of the essential characteristics of animals and plants, of their distribution
under the most extreme climatie differences known upon our globe, which led me to
distrust the belief, then almost universal, that organized beings are influenced by
physical causes to a degree which may essentially modify their character.
LOCALIZED STRUCTURES.
SECTION XI.
COMMUNITY OF STRUCTURE AMONG ANIMALS LIVING IN THE SAME REGIONS.
The most interesting result of the earliest investigations of the fauna of Australia
was the discovery of a type of animals, the Marsupialia, prevailing upon this conti-
nental island, which are unknown im almost every other part of the world. Every
student of Natural History knows now that there are no Quadrumana in New Holland,
neither Monkeys, nor Makis: no Insectivora, neither Shrews, nor Moles, nor Hedgehogs;
no true Carnivora} neither Bears, nor Weasels, nor Foxes, nor Viverras, nor Hyenas,
nor Wild Cats; no Edentata, neither Sloths, nor Tatous, nor Ant-eaters, nor Pangolins ;
no Pachyderms, neither Elephants, nor Hippopotamuses, nor Hogs, nor Rhinoceroses,
nor Tapirs, nor Wild Horses; no Ruminantia, neither Camels, nor Llamas, nor Deers,
nor Goats, nor Sheep, nor Bulls, ete., and yet the Mammalia of Australia are
almost as diversified as those of any other continent. In the words of Waterhouse,”
who has studied them with particular care, “the Marsupialia present a remarkable |
diversity of structure, containing herbivorous, carnivorous, and insectiverous species ;
indeed, we find amongst the marsupial animals analogous representations of most of |
the other orders of Mammalia. The Quadrumana are represented by the Phelangers,
the Carnivora by the Dasyuri, the Jnsectwvora by the small Phascogales, the Rauminantia
by the Kangaroos, and the Edentata by the Monotremes. The Cheiroptera. are not.
represented by any known marsupial animals, and the Rodents are represented by a \
single Species only ; the hiatus is filled up, however, in both cases, by placental |
species, for Bats and Rodents are tolerably numerous in Australia, and, if we except
the Dog, which it is probable has been introduced by man, these are the only pla- |
cental Mammalia found in that continent.” N evertheless, all these animals have in
common some most striking anatomical characters, which distinguish them from all
other Mammalia, and stamp them as one of the most natural groups of that class;
their mode of reproduction, and the connection of the young with the mother, are
different; so, also, is the structure of their brain, etc.®
Now, the suggestion that such peculiarities could be produced by physical agents
is for ever set aside by the fact that neither the birds nor the reptiles, nor, indeed,
any other animals of New Holland, depart in such a manner from the ordinary char-
1 Doubts are entertained respecting the origin of ® See Owen, (R.,) Marsupialia in Todd’s Cyclo-
the Dingo, the only beast of prey of New Holland. — pedia of Anat. and Physiol., London, 1841, 8vo., and
* Warernouse, (G. A.,) Natural History of the several elaborate papers by himself and_ others,
Mammalia, London, 1848, 2 vols. 8vo., vol. i. p. 4 quoted there.
6
42 ESSAY ON CLASSIFICATION. Part I.
acter of their representatives in other parts of the world; unless it could be shown
that such agents have the power of discrimination, and may produce, under the same
conditions, beings which agree and others which do not agree with those of different
continents; not to speak again of the simultaneous occurrence in that same continent
of other iP yulleons types of Mammalia, Bats and Rodents, which occur there
as well as everywhere else in other continents. Nor is New Holland the only part
of the world which nourishes animals highly diversified among themselves, and yet
presenting common characters strikingly different from those of the other members
of their type, circumscribed within definite Basra ihical areas. Almost every part
of the globe exhibits some such group either of animals or of plants, and every
class of organized beings contains some native natural group, more or less extensive,
more or less prominent, which is circumscribed within peculiar geographical limits.
Among Mammalia we might quote further the Quadrumana, the representatives of
which, though greatly diversified in the Old as well as im the New World, differ and
agree respectively in many important points of their structure; also the Edentata of
South America. )
Among birds, the Humming Birds, which constitute a very natural, beautiful,
and numerous family, all of which are nevertheless confined to America only, as the
Pheasants are to the Old World? Among Reptiles, the Crocodiles of the Old World
compared to those of America. Among fishes, the family of Labyrinthici, which is
confined to the Indian and Pacific Oceans, that of Goniodonts, which is limited to the
fresh waters of South America, as that of Cestraciontes to the Pacific. The compar-
ative anatomy of Insects is not sufficiently far advanced to furnish striking examples
of this kind; among Insects, however, remarkable for their form, which are limited
to particular regions, may be quoted the genus Mormolyce of Java, the Pneumora
of the Cape of Good Hope, the Belostoma of North America, the Fulgora of China,
ete. The geographical distribution of Crustacea has been treated in such a masterly
‘manner by Dana, in his great work upon the Crustacea of the United States Explor-
ing Expedition, Vol. XTIL, p. 1451, that I can only refer to it for numerous examples
of localized types of this class, and also as a model how to deal with such subjects.
Among Worms, the Peripates of Guiana deserves to be mentioned. Among Cepha-
lopods, the Nautilus in Amboyna. Among Gasteropods, the genus Io in the western
waters of the United States. Among Acephala, the Trigonia in New Holland, certain
Naiades in the United States, the Actheria in the Nile. Among Echinoderms, the
Pentacrinus in the West Indies, the Culcita in Zanzibar, the Amblypneustes in the
Pacific, the Temnopleurus in the Indian Ocean, the Dendraster on the western coast
1 What are’ called Pheasants in America do not ants. The American, so-called, Pheasants are gen-
even belong to the same family as the eastern Pheas- uine Grouses.
Cuap. I. SERIAL CONNECTION AMONG ANIMALS. : 43
of North America. Among Acalephs, the Berenice of New Holland. Among Polypi,
the true Fungide in the Indian and Pacific Oceans, the Renilla in the Atlantic, ete.
Many more examples might be quoted, were our knowledge of the geographical
distribution of the lower animals more precise. But these will suffice to show that
whether high or low, aquatic or terrestrial, there are types of animals remarkable for
their peculiar structure which are circumscribed within definite limits, and this locali-
zation of special structures is a striking confirmation of the view expressed already
in another connection, that the organization of animals, whatever it is, may be
adapted to various’ and identical conditions of existence, and can in no way be con-
sidered as originating from these conditions.
SECT LON: X21.
SERIAL CONNECTION IN THE STRUCTURE OF AMIMALS WIDELY SCATTERED UPON THE
SURFACE OF OUR GLOBE.
ptiles inhabiting different parts
Ever since I have become acquainted with the re
of the world, I have been struck with a remarkable fact, not yet noticed by natu-
ralists, as far as I know, and of which no other class exhibits such striking examples.
This fact is that among Saurians, as well as among Betrachians, there are families, the »
representatives of which, though scattered all over the globe, form the most natural
one particular degree of development.
connected series, in which every link represents
It contains about one
The Scincoids,’ among Saurians, are one of these families.
Bibron to thirty-one genera, which, in the
hundred species, referred by Duméril and
exhibit most remarkable combinations,
development of their organs of locomotion,
illustrated in a diagram, on’ the followmg page.
Fully to appreciate the meaning of this diagram, it ought to be remembered,
that the animals belonging to this family are considered here in two different points
their zodlogical relations to one another are expressed
of view. In the first place,
re of their legs; some having four legs,
by the various combinations of the structu
and these are the most numerous, others only two legs, which are always the hind
legs, and others still no legs at all. Again these legs may have only one toe, or
two, three, four, or five toes, and the number of toes may vary between the fore
and hind legs. The classification adopted here is based upon these characters. In
1 For the characters of the family, see DUMERIL See also CoctrEau, Etudes sur les Scincoides, Paris,
et Brsron, Erpétologie générale, vol. 5, p- 511. 1836, 4to. fig.
44 ESSAY ON CLASSIFICATION. Exer I.
the second place, the geographical distribution is noticed. But it 1s at once apparent
that the home of these animals stands in no relation whatsoever to their zodlogical
arrangement., On the contrary, the most remote genera may occur in the same
country, while the most closely related may live far apart.
GENERA WITH FOUR LEGS.
Tropidophorus, 1 species, Cochin-China.
Scincus, 1 sp., Syria, North and West Africa.
Sphenops, 1 sp., Egypt.
Diploglossus, 6 sp., West Indies and Brazils.
Amphiglossus, 1 sp., Madagascar.
Gongylus, with 7 sub-genera:
Gongylus, 2 sp., Southern Europe, Egypt, Teneriffe, Isle de France.
Eumeces, 11 sp. East and West Indies, South America, Vanikoro,
New Ireland, New Guinea, Pacific Islands.
Euprepes, 13 sp., West coast of Africa, Cape of Good Hope, Egypt,
Abyssinia, Seychelles, Madagascar, New Guinea, East Indies,
Sunda Islands, Manilla.
Plestiodon, 5 sp., Egypt, Algiers, China, Japan, United States.
Lygosoma, 19 sp., New Holland, New Zealand, Java, New Guinea,
Timor, East Indies, Pacific Islands, United States.
Letolopisma, 1 sp., Mauritius and Manilla.
With five toes to the fore feet, as
well as to the hind feet:
Tropidolopisma, 1.sp., New Holland.
Oyclodus, 3 sp., New Holland and Java.
Trachysaurus, 1 sp.. New Holland.
Ablepharus, 4 sp., Southeastern Europe, New Holland, Pacific Islands.
With jive toes to the fore feet and four toes to the hind feet: Campsodactylus, 1 sp., Bengal.
With four toes to the fore feet and Heteropus, 3 sp. Africa, New Holland, Isle de France.
jive toes to the hind feet: ) Gymnophthalmus, 1 sp., W. Indies and Brazil.
With four toes to the fore feet and Tetradactylus, 1 sp., New Holland. The genus Chalcides of the allied
family Chalcidioids, exhibits another example of this combination.
four toes to the hind feet:
With four toes to the fore feet and three toes to the hind feet: No examples known of this combination.
With three toes to the fore feet and four toes to the hind feet: Not known.
With three toes to the fore feet and | Sree ehameglnte x sc eieeman
three toes to the hind feet: / eieabontiges ee a gnapeaam
( Nessta, 1 sp., Origin unknown.
With three toes to the fore feet and two toes to the hind feet: Not known.
With two toes to the fore feet and { Heteromeles, 1 sp., Algiers.
three toes to the hind feet: see 1 sp., New Holland.
With two toes to the fore feet and two toes to the hind feet: Chelomeles, 1 sp., New Holland.
With two toes to the fore feet and one toe to the hind feet: Brachymeles, 1 sp. Philippine Islands.
With one toe to the fore feet and two toes to the hind feet: Brachystopus, 1 sp., South Africa.
With one toe to the fore feet and one toe to the hind feet: Hvesia, 1 sp., Origin unknown.
SERIAL CONNECTION AMONG ANIMALS
GENERA WITH ONLY TWO LEGS.
No representatives are known with fore legs only ; -but this structural combination occurs in the allied
| he allie
family of the Chalcidioids. The representatives with hind legs only, present the following combinati
g ions : —
With two toes: Scelotes, 1 sp. Cape Good Hope.
With one toe: Propeditus, 1 sp., Cape Good Hope and New Holland.
Ophiodes, 1 sp. South America.
Hysteropus, 1 sp., New Holland.
Lialis, 1 sp.. New Holland.
Dibamus, 1 sp., New Guinea.
GENERA WITHOUT ANY LEGS.
sp., Europe, Western Asia, Northern Africa.
Ophiomorus, 1 sp., Morea, Southern Russia, and Algiers.
Acontias, 1 sp., Southern Africa, Cape Good Hope.
Typhlina, 1 sp., Southern Africa, Cape Good Hope.
Anguis, 1
Who can look at this diagram, and not recognize in its arrangement the combi
nations of thought? This is so obvious, that while considering it one might almost
overlook the fact, that while it was drawn up to classify animals preserved in the
Museum of . the Jardim. des..Plantes an Passat © in reality inscribed in Nature by
these animals themselves, and is only read off when they are brought together, and
compared side by side. But it contains
the series is not built up of equivalent representative
combinations being richly endowed, others numbering a few, or even a single genus
and still others being altogether disregarded ; sucht freedom indicates selection, oe
not the working of the law of necessity.
And if from a contemplation of this remarkable series we turn our attention to
the indications relating to the geographical distribution of these so closely linked ,
genera, inscribed after their names, we perceive at once, that they are scattered all ;
oe the globe, but not so that there could be any connection between the combina-
tions of their structural characters and their homes.
found in Europe, in Western Asia, in Northern Africa, and at the Cape of Good
Hope; the types with hind legs only, and with one single toe, at the Cape of
Good Hope, in South America, New Holland, and New Guinea; those with two toes
at the Cape of Good Hope only. Among the types with four legs the origin of those
with but one toe to each foot is unknown, those with one toe in the fore foot and
two aa the hind foot are from South Africa, those with two toes in the fore foot and
one in the hind foot occur in the Philippime Islands, those with two toes to all four
feet in New Holland, those with three toes to the hind feet and two to the fore feet
an important element for our discussion:
s in its different terms, some
The types without legs are
46 ESSAY ON CLASSIFICATION. j Part I.
in Algiers and New Holland; none are known with three toes to the fore feet and
two to the hind feet. Those with three toes to the four feet inhabit Europe, North-
ern Africa, and New Holland. There are none with three and four toes, either in
the fore feet or in the hind feet. Those with four toes to the four feet live in
New Holland; those with five toes to the fore feet and four to the hind feet, in
Bengal, and with four toes in the fore feet and five in the hind feet, in Africa,
the West Indies, the Brazils, and New Holland. Those with five toes to all four
feet have the widest distribution, and yet they are so scattered that no single zodlog-
ical province presents any thing like a complete series; on the contrary, the mixture
of some of the representatives with perfect feet with others which have them rudi-
mentary, in almost every fauna, excludes still more decidedly the idea of an influence
of physical agents upon this development.
Another similar series, not less striking, may be traced among the Batrachians,
for the characters of which I may refer to the works of Holbrook, Tschudi, and
Baird, even though they have not presented them in this connection, as the charac-
teristics of the genera will of themselves suggest their order, and further details upon
this subject would be superfluous for my purpose, the more s0, as I have already
discussed the gradation of these animals elsewhere” ,
Similar series, though less conspicuous and more limited, may be traced in every
class of the animal kingdom, not only among the living types, but also among the
representatives of past geological ages, which adds to the interest of such series in
showing, that the combinations include not only the element of space, indicating
omnipresence, but also that of time, which involves prescience. The series of Crinoids,
that of Brachiopods through all geological ages, that of the N autiloids, that of
Ammonitoids from the Trias to the Cretaceous formation inclusive, that of Trilobites
from the lowest beds up to the Carboniferous period, that of Ganoids through all
formations; then again among living animals in the class of Mammalia, the series of
Monkeys in the Old World especially, that of Carnivora from the Seals, through the
Plantigrades, to the Digitigrades; in the class of Birds, that of the Wading Birds,
and that of the Gallinaceous Birds; in the class of Fishes, that of Pleuronectide and
Gadoids, that of Skates and Sharks; in the class of Insects, that of Lepidoptera from
the Tineina to the Papilionina; in the class of Crustacea, that of the Decapods in
particular; in the class of Worms, that of the Nudibranchiata or that of the Dorsibran-
1 Hoxsroox, (J. E.,) North American Her- Acad. Nat. Science, of Philadelphia, 2d series,
petology, Philadelphia, 1842, 4to.; 5th vol. — vol. I, 1849, 4to.
Tscuup1, (J. J.) Classification der Batrachier, 2 Agassiz, (L.,) Twelve Lectures on Compara-
Neuchatel, 1838, 4to.— Barrp, (Sp. F.) Revision tive Embryology, Boston, 1849, 8vo.; p. 8.
of the North American Tailed Batrachia, Journal
a
2 ee ee RE
‘are essentially distinguished by their form,
Crap. 1.
chiata especially ; in the class of Cephalopoda, that of the Sepioids; in the class of
Gasteropoda, that of the Nudibranchiata in particular ; in the class of Acephala, that
of the Ascidians and that of the Oysters in the widest sense; in the class of Echino-
derms, those of Holothuriz and Asterioids; im the class of Acalephs, that of the
Hydroids; in the class of Polyps, that of the Halcyonoids, of the Atraoids, etc., etc.,
deserve particular attention, and may be studied with great advantage in reference
to the points under consideration. For everywhere do we observe in them, with
reference to space and to time, the thoughtful combinations of an active mind.
But it ought not to be overlooked, that while some types represent strikingly con-
nected series, there are others in which nothing of the kind seems to exist, and the
diversity of which involves other considerations.
SECTION XIII.
RELATION. BETWEEN THE SIZE OF ANIMALS, AND THEIR STRUCTURE:
structure of animals has been very little
The relation between the size and
survey of the animal kingdom may
investigated, though even the most superficial
satisfy any one, that there is a decided relation between size and structure among
them. Not that I mean to assert that size and structure form parallel series, or
that all animals of one branch, or even those of the same class or the same order,
agree very closely with one another
organization is not defined within those limits, though the Vertebrata, as a whole,
are larger than either Articulata, Mollusks, or Radiata; though Mammalia are larger
than Birds, Crustacea larger than Insects ; though Cetacea are larger than Herbivora,
these larger than Carnivora, ete. The true limit at which, in the organization of
animals, size acquires a real importance, is that of families, that 1s, the groups which
as if form and size were correlative as
far as the structure of animals is concerned. The representatives of natural families
are indeed closely similar m that respect ;
where tenfold within these limits, and frequentl |
selected among the most natural families, will show this. Omitting mankind, on
account of the objections which might be ma
consider the different families of Monkeys, of Bats, of
the extreme differences are hardly any-
y only double. A few examples,
de against the idea that it embraces
any original diversity, let us
of Rodents, of Pachyderms, of Ruminants, etc., among
the Falcons, the Owls, the Swallows, the Finches, the
the Wrens, the Ostriches, the Herons,
Insectivora, of Carnivora,
Birds, the Vultures, the Eagles,
Warblers, the Humming Birds, the Doves,
SIZE OF ANIMALS. a AT
in reference to size. This element of their
48 ESSAY ON CLASSIFICATION. Picea,
the Plovers, the Gulls, the Ducks, the Pelicans; among Reptiles, the Crocodiles, the
different families of Chelonians, of Lizards, of Snakes, the Frogs proper, the Toads,
etc.; among Fishes, the Sharks and Skates, the Herrings, the Codfishes, the Cyprin-
nodonts, the Cheetodonts, the Lophobranchii, the Ostracionts, etc.; among Insects, the
Sphingoide or the Tineina, the Longicorns or the Coccinellina, the Bomboide or the
Brachonide ; among Crustacea, the Cancroidea or the Pinnotheroide, the Limuloidee
or the Cypridoide, and the Rotifera;* among Worms, the Dorsibranchiata or the
Naioide ; among Mollusks, the Stromboide or the Buccinoide, the Helicinoide or the
Limneoide, the Chamacea or the Cycladoide; among Radiata, the Asterioide and
the Ophiuroide, the Hydroids and the Discophorew, the Astreeoide and the Actinioide.
Having thus recalled some facts which go to show what are the limits within
which size and structure are more directly connected, it is natural to infer, that
since size is such an important character of species, and extends distinctly its cycle
of relationship to the families or even further, it can as little be supposed to be
determined by physical agents as the structure itself with which it is so closely
connected, both bearing similar relations to these agents.
‘Life is regulated by a quantitative element in the structure of all organized
beings, which is as fixed and as precisely determined as every other feature depend-
ing more upon the quality of the organs or their parts. This shows the more
distinctly the presence of a specific, immaterial principle in each kind of animals
and plants, as all begin their existence in the condition of ovules of a microscopic
And yet these primitive
ovules, so identical at first in their physical constitution, never produce any thing
size, exhibiting in all a wonderful similarity of structure.
different from the parents; all reach respectively, through a succession of unvarying
changes, the same final result, the reproduction of a new bemg identical with the
parents. How does it then happen, that, if physical agents have such a powerful
influence in shaping the character of organized beings, we see no trace of it in the
innumerable instances in which these ovules are discharged in the elements in which
they undergo their further development, at a period when the germ they contain,
1 See Dana’s Crustacea, p- 1409 and 1411.
2 These remarks about the average size of ani-
mals in relation to their structure, cannot fail to
meet with some objections, as it. is well known,
that under certain circumstances, man may modify
the normal size of a variety of plants and of
domesticated animals, and that even in their natural
state occasional instances of extraordinary sizes
occur. But this neither modifies the character-
istic average, nor is it a case which has the
least bearing upon the question of origin or even
the maintenance of any species, but only upon
individuals, respecting which more will be found in
Sect. 16. Moreover, it should not be overlooked
that there are limits to these variations, and that
though animals and plants may be placed under
influences conducive to a more or less voluminous
erowth, yet it is chiefly under the agency of man,
that such changes reach their extremes.
Sect. 15.)
(See also
Cuap. I. SIZE AND THE ELEMENTS. 49
has not yet assumed any of those more determined characteristics which distinguish
the full-grown animal or the perfect plant? Do physicists know a law of the
material world which presents any such analogy to these phenomena, that it could
be considered as accounting for them?
In this connection it should be further remembered, that these cycles of size
characteristic of different families, are entirely different for animals of different types,
though living together under identical circumstances.
SECTION ALY.
RELATIONS BETWEEN THE SIZE OF ANIMALS, AND THE MEDIUMS IN WHICH THEY LIVE.
a _
+ animals of different types, even when living
It has just been remarked, tha
Yet, life is so closely combined
together, are framed in structures of different size.
with the elements of nature, that each type shows decided relations, within its own
| concerned! The aquatic Mammalia, as a |
| limits, to these elements as far as size 18
whole, are larger than the terrestrial ones;
Reptiles. In families which are essentially terrestrial, the species which take to the |
main permanently terrestrial, as for
so are the aquatic Birds, and the aquatic |
water are generally larger than those which re
instance, the Polar Bear, the Beaver, the Coypu, and the Capivara. Among the
different families of aquatic Birds, those of their representatives which are more ter-
restrial in their habits are generally smaller than those w
in the different families of Insects which
hich live more permanently
; in water. The same relation is observed
number aquatic and terrestrial species. It is further remarkable, that among aquatic
animals, the fresh water types are inferior in size to the marine ones; the marine
Turtles are all larger than the largest inhabitants of our rivers and ponds, the more
aquatic Trionyx larger than the Emyds and among these the more aquatic Chelydra
larger than the true Emys, and these generally larger than the more terrestrial
Clemmys or the Cistudo. The class of Fishes has its largest representatives in the
sea; fresh water fishes are on the whole dwarfs, in comparison to their marine
t of them, our Sturgeons and Salmons, go to the sea. The
relatives, and the larges
to be satisfied of the fact, we need only
same relations obtain among Crustacea ;
compare our Crawfishes with the Lobsters, our Apus with Limulus, etc. Among
1 Grorrroy Sr. Hiarre, (Isr.,) Recherches humaines, Paris, 1831, 4to.— See also my paper
zoologiques et physiologiques sur les variations upon the Natural Relations between Animals and the
de la taille chez les Animaux et dans les races Elements, etc., quoted above, p. 32.
7
50 ESSAY ON CLASSIFICATION. Part I.
Worms, the Earthworms and Leeches furnish a still wider range of comparisons
when contrasted with the marine types. Among Gasteropods and Acephala, this
obtains to the same extent; the most gigantic Ampullariae and Anodontae are small
in comparison to certain Fusus, Voluta, Tritonium, Cassis, Strombus, or to the
Tridacna. Among Radiata even, which are all marine, with the exception of the
single genus Hydra, this rule holds good, as the fresh water Hydroids are among the
smallest Acalephs known. 3
This coincidence, upon such an extensive scale, seems to be most favorable to
the view that animals are modified by the immediate influence of the elements;
yet I consider it as affording one of the most striking proofs that there is no causal
connection between them. Were. it otherwise, the terrestrial and the aquatic repre-
sentatives of the same family could not be so similar as they are in all their
essential characteristics, which actually stand in no relation whatsoever to these
elements. What constitutes the Bear in the Polar Bear, is not its adaptation to an
aquatic mode of existence. What makes the Whales Mammalia, bears no relation to
the sea. What constitutes Earthworms, Leeches, and Eunice members of one class,
has no more connection with their habitat, than the peculiarities of structure which
unite Man, Monkeys, Bats, Lions, Seals, Beavers, Mice, and Whales into one class.
Moreover, animals of different types living in the same element have no sort of
similarity, as to size. The aquatic Insects, the aquatic Mollusks fall in with the
average size of their class, as well as the aquatic Reptiles and the aquatic Birds, or
the aquatic Mammalia; but there 1s no common average for either terrestrial or
aquatic animals of different classes taken together, and in this lies the evidence that
organized beings are independent of the mediums in which they live, as far as their
origin is concerned, though it is plain that when created they were made to suit
the element in which they were placed.
To me these facts show, that the phemomena of life are manifested in the
physical world, and not through or by it; that organized beings are made to
conquer and assimilate to themselves the materials of the inorganic world; that
they maintain their original characteristics, notwithstanding the unceasing action of
physical agents upon them. And I confess I cannot comprehend how beings, so
entirely independent of these influences, could be produced by them.
IMMUTABILITY OF SPECIES.
CHe TT Olea a
PERMANENCY OF SPECIFIC PECULIARITIES IN ALL ORGANIZED BEINGS.
It was a great step in the progress of science when it was ascertained that
species have fixed ‘characters, and that they do not change in the course of time.
But this fact, for which we are indebted to Cuvier,, has acquired a still greater
importance since it has also been established, that even the most extraordinary
changes in the mode of existence and in the conditions under which animals may be
placed, have no more influence upon their essential characters than the lapse of time.
The facts bearing upon these two
I will, therefore, allude only to a few points, to avoid even the
That animals of different geo-
subjects are too well known now to require
special illustration.
possibility of a misapprehension of my statements.
logical periods differ specifically, en masse, from those of preceding or following forma-
tions, is a fact satisfactorily ascertained. Between two successive geological periods,
then, changes have taken place among animals and plants. But none of those pri-
mordial forms of life, which naturalists call species, are known to have changed
It cannot be denied, that the species of different
durmg any of these periods.
lists to derive their distinguishing
successive periods are supposed by some natura
features from changes which have taken place in those of preceding ages; but this
is a mere supposition, supported neither by physiological nor by geological evidence,
and the assumption that animals and plants
one and the same period, is equally gratuitous.
the evidence furnished by the Egyptian monuments, and by the most careful com-
parison between animals found in the tombs of Egypt with living specimens of the
same species obtained in the same country, that there is not the shadow of a differ-
ence between them, for a period of about five thousand years. These comparisons,
have proved, that as far as it has been possible to carry
not afford the beginning of an evidence that species
may change in a similar manner during
On the contrary, it is known by
first instituted by Cuvier,
back the investigation, it does
change in the course of time,
Geology only shows that at different periods* there have existed
if the comparisons be limited to the same great
cosmic epoch.
1 Cuvier, (G.,) Recherches sur Jes ossements great length, each of which is characterized by dif-
fossiles, ete., Nouv., édit. Paris, 1821, 5 vols., Ato., ferent animals, that the differences these animals ex-
fig., vol. i. sur PTbis, p. cxli. hibit, is in itself evidence of a change in the species.
2 I trust no reader will be so ignorant of the The question is, whether any changes take place
facts here alluded to, as to infer from the use of during one or any of these periods. It is almost
the word “period” for different eras and epochs of incredible how loosely some people will argue upon
52 ESSAY ON CLASSIFICATION.
Part I.
different species; but no transition from those of a preceding into those of the
following epoch has ever been noticed anywhere; and the question alluded to here is
to be distinguished from that of the origin of the differences in the bulk of species
belonging to two different geological eras.
The question we are now examining
involves only the fixity or mutability of species during one epoch, one era, one
period in the history of our globe.
this point from a want of knowledge of the facts,
A dis-
tinguished physicist has recently taken up this sub-
even though they seem to reason logically.
ject of the immutability of species, and called in
question the logic of those who uphold it. I will
put his argument into as few words as_ possible,
and show, I hope, that it does not touch the case.
“Changes are observed from one geological period
to another; species which do not exist at an earlier
period are observed at a later period, while the for-
mer have disappeared; and though each species may
have possessed its peculiarities unchanged for a lapse
of time, the fact that when long periods are con-
sidered, all those of an earlier period are replaced
by new ones at a later period, proves that species
change in the end, provided a sufficiently long period
of time is granted.” I have nothing to object to the
statement of facts, as far as it goes, but I maintain
that the conclusion is not logical. It is true that
species are limited to particular geological epochs;
it is equally true that, in all geological formations,
those of successive periods are different, one from
the other.
low that they have changed, and not been exchanged
But because they so differ, does it fol-
for, or replaced by others? The length of time
taken for the operation has nothing to do with the
argument. Granting myriads of years for each pe-
riod, no matter how many or how few, the question
remains simply this: When the change takes place,
does it take place spontaneously, under the action of
physical agents, according to their law, or is it pro-
duced by the intervention of an agency not in that
way at work before or afterwards? A comparison
may explain my view more fully. Let a lover of
the fine arts visit a museum arranged systematically,
and in which the works of the different schools are
placed in chronological order; as he passes from one
And nothing furnishes the slightest argument m
room to another, he beholds changes as great as those
the palzontologist observes in passing from one sys-
tem of rocks to another. But because these works
bear a closer resemblance as they belong to one or
the other school, or to periods following one another
closely, would the critic be in any way justified
in assuming that the earlier works have changed
into those of a later period, or to deny that they
are the works of artists living and active at the
time of their production? The question about the
immutability of species is identical with this sup-
posed case. It is not because species have lasted
for a longer or shorter time in past ages, that nat-
uralists consider them as immutable, but because in
the whole series of geological ages, taking the entire
lapse of time which has passed since the first intro-
duction of animals or plants upon earth, not the
slightest evidence has yet been produced that species
are actually transformed one into the other. We
only know that they are different at different periods,
as are works of art of different periods and of differ-
ent schools; but as long as we have no other data to
reason upon than those geology has furnished, to this
day, it is as unphilosophical and illogical, because
such differences exist, to assume that species do
change, and have changed, that is, are transformed,
or have been transformed, as it would be to main-
tain that works of art change in the course of time.
We do not know how organized beings have origi-
nated, it is true; no naturalist can be prepared to
account for their appearance in the beginning, or for
their difference in different periods; but enough is
known to repudiate the assumption of their transmu-
tation, as it does not explain the facts, and shuts out
further attempts at proper investigations. See Ba-
pEN Powe.t’s Essays, quoted above; p. 412, et
seq., and Essay 3d, generally. _
Cuap. I.
favor of their mutability ;
gone to confirm the results
fixed.
parison, that animals and plants
five thousand years?
existence for innumerable ages,
became inhabited cannot be counted in years.
IMMUTABILITY OF SPECIES. 53
It is something to be able to show by
have undergone no change for a period of about
This result has had the greatest influence upon the progress
of science, especially with reference to the ¢
rence in the series of geological formations
in each epoch as those of the present day ;°
viction, now universal among well informed naturalists, )
and that the length of time elapsed since it first
on the contrary, every modern investigation’ has only
first obtained by Cuvier, and his views that species are
monumental evidence, and by direct com-
onsequences to be drawn from the occur-
of organized beings as highly diversified
it has laid the foundation for the con-
that this globe has been in
Even the length of the period to
| notwithstanding the precision with which certain
which we belong is still a problem,
systems of chronology would fix the creati
circumstances which show that the animals
generally supposed. It has been possible to
period inhabitants of our globe than is
trace the formation and growth of our coral ree
cient precision to’ ascertain that it must take abou
those coral walls to rise from its foundation to th
There are, around the southernmost extremity 0
. centric with one another, which can be shown
other. This gives for the beginning of the fir
thousand years; and yet the corals by which they were |
These facts, then, furnish as direct evidence as we
Seema
identical species in all of them.
can obtain in any branch of physical inquiry,
animals now existing, have been in existence over
¢ the whole of that period.’ And yet these
not undergone the slightest change durin
1 Runtu, Recherches sur les plantes trouvées
dans les tombeaux égyptiens, Ann. des scien. nat., vol.
vili., 1826, p. 411.
2 It is not for me to discuss the degree of reli-
ability of the Egyptian chronology; but as far as it
goes, it shows that from the oldest periods ascer-
| tained, animals have been what they are now-
® See my paper upon The Primitive Diversity,
eee eo =
ete., quoted above, p. 20.
4 Norr & Guippon, Types of Mankind
Florida, soon
, p- 653.
5 See my paper upon the Reefs of
to be published in the Reports of the United States
on of man‘ There are, however, many
now living have been for a much longer
fs, especially in Florida,’ with suffi-
t eight thousand years for one of
e level of the surface of the ocean.
f Florida alone, four such reefs con-
to have grown up, one after the
st of these reefs an age of over thirty
all built up are the same
that some, at least, of the species of
thirty thousand years, and have
Coast Survey, extracts of which are already printed
in the Report for 1851, p. 140.
6 Those who feel inclined to ascribe the differ-
ences which exist between species of different geo-
logical periods to the modifying influence of physi-
cal agents, and who look to the changes now going
on among the living for the support of such an
opinion, and may not be satisfied that the facts just
mentioned are sufficient to prove the immutability
of species, but may still believe that a longer period
of time would yet do what thirty thousand years
have not done, I beg leave to refer, for further con-
54 Hee AY ON CLASSI PRCA ETON. Part I.
four concentric reefs are only the most distinct of that region; others, less exten-
sively investigated thus far, lie to the northward; indeed, the whole peninsula of
Florida consists altogether of coral reefs annexed to one another in the course of
time, and containing only fragments of corals and shells, etc., identical with those
Now, if a width of five miles is a fair average for one
coral reef growing under the circumstances under which the concentric reefs of
Florida are seen now to follow one another, and this regular succession should extend
only as far north as Lake Ogeechobee, for two degrees of latitude, this would give
about two hundred thousand years for the period of time which was necessary for
that part of the peninsula of Florida which lies south of Lake Ogeechobee to rise
now living upon that coast.
to its present southern extent above the level of the sea, and durimg which no
changes have taken place in the character of the animals of the Gulf of Mexico.
It is very prejudicial to the best imterests of science to confound questions that
are entirely different, merely for the sake of supporting a theory; yet this is con-
stantly done, whenever the question of the fixity of species is alluded to. A few
more words upon this point will, therefore, not be out of place here.
I will not enter into a discussion upon the question whether any species is found
identically the same in two successive formations, as I have already examined it at
full length elsewhere} and it may be settled finally one way or the other, without
affecting the proposition now under consideration; for it is plain, that if such identity
could be proved, it would only show more satisfactorily how tenacious species are in
their character, to continue to live through all the physical changes which have
taken place between two successive geological periods. Again, such identity once
proved, would leave it still doubtful whether their representatives in two successive
epochs are descendants one of the other, as we have already strong evidence in favor
of the separate origin of the representatives of the same species in separate geo-
graphical areas? The case of closely allied, but different species occurring im succes-
sive periods, yet limited respectively in their epochs, affords, in the course of time, a
parallel to the case of closely allied, so-called, representative species occupyimg differ-
ent areas in space, which no sound naturalist would suppose now to be derived one
from the other. There is no more reason to suppose equally allied species following
one another in time to be derived one from the other; and all that has been said
sideration, to the charming song of Chamisso, entitled
Tragishe Geschichte, and beginning as follows:
’*s war Einer dem’s zu Herzen ging.
1 Agassiz, (L.,) Coquilles tertiaires réputées
identiques avec les espéces vivantes, Nouv. Mém. de
la Soc. Helv. des se. nat. Neuchatel, 1845, vol. 7,
4to. fig. — Acassiz, (L.,) Etudes critiques sur les
Mollusques fossiles, Neuchatel, 1831-45, 4to. fig. —
Agassiz, (L.,) Monographies d’Echinodermes vivans
et fossiles, Neuchatel, 1838-42, 4 nos., 4to. fig. —
Acassiz, (L.,) Recherches sur les Poissons fossiles,
Neuchatel, 1833-44, 5 vols., 4to., atlas, fol.
' 2 See Sect. 10, where the case of representative
species is considered.
Cuar. IL. IMMUTABILITY OF SPECIES. 55
in preceding paragraphs respecting the differences observed between species occurring
in different geographical areas, applies with the same force to species succeeding
each other in the course of time.
When domesticated animals and cultivated plants are mentioned as furnishing
evidence of the mutability of species, the circumstance is constantly overlooked or
passed over in silence, that the first point to be established respecting them, in order
to justify any inference from them against the fixity of species, would be to show
that each of them has originated from one common stock, which, far from being the
case, is flatly contradicted by the positive knowledge we have that the varieties of
several of them, at least, are owing to the entire amalgamation of different species."
The Egyptian monuments show further that many of those so-called varieties which
are supposed to be the product of time,
we have no tradition, no monumental evidence
are as old as any other animals which have
been known to man; at all events,
of the existence of any wild animal older than that which represents domesticated
animals, already as different among themselves
quite possible that the different races of domesticate
the different races of men are. Moreover,
as they are now.” It is, therefore,
d animals were originally distinct
species, more or less mixed now, as
neither domesticated animals nor cultivated plants,
proper subjects for an investigation respecting the fixity or muta
all involve already the question at issue in the premises which are assumed in intro-
With reference to the different breeds of our
nor the races of men, are the
bility of species, as
ducing them as evidence in the case.
which are known to be produced by the management of man,
domesticated animals,
they must be well distinguished
as well as certain varieties of our cultivated plants,
from permanent races, which, for aught we know, may be primordial; for breeds
are the result of the fostermg care of man;
influence and. control the human mind has over org
They show, therefore, that even the least impor-
ace during one and the same cosmic period among
and do not result from
they are the product of the limited
anized beings, and not the free
product of mere physical agents.
tant changes which may take pl
animals and plants are controlled by an intellectual power,
the immediate action of physical causes.
So far, then, from disclosing the effects of physical agents, whatever changes are
known to take place in the course of time among organized beings appear as the ©
result of an intellectual power, and go, therefore, to substantiate the view that all
the differences observed among finite b
Supreme Intellect, and not determined by physical causes. This position is still
strengthened when we consider that the differences which exist between differ-
eings are ordamed by the action of the
more
ent races of domesticated animals and the varieties of our cultivated plants, as well
2 Norr & Giippon, Types of Mankind, p. 386.
1 Our fowls, for instance.
Se
56 ESSAY ON CLASSIFICATION. Part I.
as among the races of men, are permanent under the most diversified climatic influ-
ences; a fact, which the extensive migrations of the civilized nations daily proves more
extensively, and which stands in direct contradiction to the supposition that such or
similar influences could have produced them.
When considering the subject of domestication, in particular, it ought further to
be remembered, that every race of men has its own peculiar kinds of domesticated
animals and of cultivated plants, which exhibit much fewer varieties among them
in proportion as those races of men have had little or no imtercourse with other
races, than the domesticated animals of those nations which have been formed by the
mixture of several tribes.
It is often stated that the ancient philosophers have solved satisfactorily all the
great questions interesting to man, and that modern investigations, though they have
grasped with new vigor, and illuminated with new light, all the phenomena of the
material world, have added little or nothing in the field of intellectual progress. Is
this true? There is no question so deeply interesting to man as that of his own
origin, and the origin of all things. And yet antiquity had no knowledge concerning
it; things were formerly believed either to be from eternity, or to have been created
at one time. Modern science, however, can show, in the most satisfactory manner,
that all finite beings have made their appearance successively and at long intervals,
and that each kind of organized beings has existed for a definite period of time in
past ages, and that those now living are of comparatively recent origin. At the
same time, the order of their succession and their immutability during such cosmic
periods, show no causal connection with physical agents and the known sphere of
action of these agents in nature, but argue in favor of repeated interventions on
the part of the Creator. It seems really surprising, that while such an intervention
is admitted by all, except the strict materialists, for the establishment of the laws
regulating the inorganic world, it is yet denied by so many physicists, with reference
to the introduction of organized beings at different successive periods. Does this not
rather go to show the imperfect acquaintance of these investigators with the condi-
tions under which life is manifested, and with the essential difference there is between
the phenomena of the organic and those of the physical world, than to furnish any
evidence that the organic world is the product of physical causes ?
OY. ANIMALS:
HABITS
BE DOIN ae ae
RELATIONS BETWEEN ANIMALS AND PLANTS AND THE SURROUNDING WORLD.
Every animal and plant stands im certain definite relations to the surrounding
world, some however, like the domestic animals and cultivated plants, being capable
of adapting themselves to various conditions more readily than others; but even
this pliability is a characteristic feature.
systematic point of view, and deserve the m
Yet, the direction zodlogical studies have taken since comparative anat-
almost entirely the attention of naturalists,
These relations are highly important in a
ost careful attention, on the part of
naturalists.
omy and embryology began to absorb
has been very unfavorable to the investi
to the conditions under which they live, are more
gation of the habits of animals, in which
their relations to one another and ;
We have to go back to the authors of the preceding century,}
especially exhibited.
of the habits of animals, as among modern writers
for the most interesting accounts
there are few who have devoted their chief attention to this subject.2 So little,
indeed, is its importance now appreciated, that the students of this branch of natural
history are hardly acknowledged as peers by their fellow investigators, the anat-
omists and physiologists, or the systematic zodlogists. And yet, without a thorough
knowledge of the habits of animals, it will never be possible to ascertain with any
degree of precision the true limits of all those species which descriptive zodlogists
have of late admitted with so much confidence in their works. And after all, what
does it matter to science that thousands of species more or less, should be described
and entered in our systems, if we know nothing about them? A very common
defect of the works relating to the habits of animals has no doubt contributed to
detract from their value and to turn the attention in other directions: their purely
tance that they are too frequently made the
anecdotic character, or the circums
Nevertheless, the importance of this
occasion for narrating personal adventures.
5 vols. 8vo.— Kirsy, (W.,) and Spence, (W.,)
An Introduction to Entomology, London, 1818-26,
4 vols. 8vo. fig. — Lenz, (H. O.,) Gemeinniitzige
Naturgeschichte, Gotha, 1835, 4 vols. 8vo.— Rar-
1 Reaumur, (R. Ant. pDx,) ‘Mémoires pour
servir 2 Phistoire des Insectes, Paris, 1834-42, 6 vol.
4to. fig. — Rodsur, (A. J.,) Insectenbelustigungen,
Niirnberg, 1746-61, 4 vols. 4to. fig. — BUFFON,
(G. L. LeCrerc per,) Histoire naturelle générale ZENBURG, (J. Tu. Cu.,) Die Forst-Insekten, Ber-
et particulitre, Paris, 1749, 44 vols. 4to. fig. lin, 1837-44, 3 vols. 4to. fig., and supplement. —
2 AupuBon, (J. J.,) Ornithological Biography, Harris, (T. W.,) Report on the Insects injurious
or an Account of the Habits of the Birds of the to Vegetation, Cambridge, 1841, 1 vol. Svo.; the
United States of America, Edinburgh, 1831-49, most important work on American Insects.
8
58 ESSAY ON CLASSIFICATION. Part I.
kind of investigation can hardly be overrated; and it would be highly desirable that
naturalists should turn again their attention that way, now that comparative anatomy
and physiology, as well as embryology, may suggest so many new topics of inquiry,
and the progress of physical geography has laid such a broad foundation for
researches of this kind.
species described from isolated specimens are founded in nature, or how far they
Then we may learn with more precision, how far the
may be only a particular stage of growth of other species; then we shall know,
what is yet too little noticed, how extensive the range of variations is among ani-
mals, observed in their wild state, or rather how much individuality there is in each
So marked, indeed, is this individuality in many families,—and
that of Turtles affords a striking example of this kind, — that correct descriptions of
and all living beings.
species can hardly be drawn from isolated specimens, as is constantly attempted to
be done. I have seen hundreds of specimens of some of our Chelonians, among
which there were not two identical. And truly, the limits of this variability con-
stitutes one of the most important characters of many species; and without precise
information upon this point for every genus, it will never be possible to have a
solid basis for the distinction of species. Some of the most perplexing questions
in Zodlogy and Paleontology might long ago have been settled, had we had more
precise information upon this point, and were it better known how unequal in this
respect different groups of the animal kingdom are, when compared with one
another. While the individuals of some species seem all different, and might be
described as different species, if seen isolated or obtained from different regions, those
of other species appear all as cast in one and the same mould. It must be, there-
fore, at once obvious, how different the results of the comparison of one fauna with
another may be, if the species of one have been studied accurately for a long
period by resident naturalists, and the other is known only from specimens collected
by chance travellers; or, if the fossil representatives of one period are compared
with living animals, without both faune having first been revised according to the
same standard.
Another deficiency, in most works relating to the habits of animals, consists in
the absence of general views and of comparisons. We do not learn from them,
how far animals related by their structure are similar in their habits, and how far
4
* In this respect, I would remark that most of
the eases, in which specific identity has been affirmed
between living and fossil species, or between the
fossils of different geological periods, belong to
families which present either great similarity or
extraordinary variability, and in which the limits of
species are, therefore, very difficult to establish.
Such cases should be altogether rejected in the
investigation of general questions, involving funda-
mental principles, as are untrustworthy observations
always in other departments of science. Compare
further, my paper upon the primitive diversity and
number of animals, quoted above, in which this
point is specially considered.
Cuap. I. HABITS OF ANIMALS. . 59
these habits are the expression of their structure. Every species is described as if
it stood alone in the world; its peculiarities are mostly exaggerated, as if to con-
trast more forcibly with all others. Yet, how interesting would be a comparative
study of the mode of life of closely allied species; how instructive a picture might
be drawn of the resemblance there is in this respect between species of the same
genus and of the same family. The more I learn upon this subject, the more am I
struck with the similarity in the very movements, the general habits, and even in
the intonation of the voices of animals belonging to the same family; that is to say,
between animals agreeing in the main in form, size, structure, and mode of develop-
ment. A minute study of these habits, of these movements, of the voice of animals
cannot fail, therefore, to throw additional light upon their natural affinities.
While I thus acknowledge the great importance of such investigations with refer-
ence to the systematic arrangement of animals, I cannot help regretting deeply, that
they are not more highly valued with reference to the mformation they might
secure respecting the animals themselves, independently of any system. How much
is there not left to study with respect to every species, after it 1s named and classi-
fied. No one can read Nauman’s Natural History of the German Birds without
feeling that natural history would be much further advanced, if the habits of all
other animals had been as accurately investigated and as minutely recorded; and yet
that work contains hardly any thing of importance with reference to the systematic
We scarcely possess the most elementary information neces-
arrangement of birds.
stion of the instincts and in general
sary to discuss upon a scientific basis the que
the faculties of animals, and to compare them together and with those of man,'
not only because so few animals have been thoroughly investigated, but because so
much fewer still have been watched during their earlier periods of life, when their
faculties are first developing; and yet how attractive and instructive this growing
age is in every living being! Who could, for instance, believe for a moment longer
that the habits of animals are in any degree determined by the circumstances under
which they live, after having seen a little Turtle of the genus Chelydra, still
enclosed in its egg-shell, which it hardly fills half-way, with a yolk bag as large as
lower surface and enveloped in its amnios and in its allantois,
itself hanging from its
f it could bite without killing itself??
with the eyes shut, snapping as fiercely as 1
Who can watch the Sunfish (Pomotis vulgaris) hovering over its eggs and protecting
them for weeks, or the Catfish (Pimelodus Catus) move about with its young, like
1 Sonerriiy, (P.,) Versuch einer vollstindigen des animaux, par R. Flourens, Ann. Sc. Nat., 2de
Thierseelenkunde, Stuttgart und Tiibingen, 1840, sér., vol. 12.
2 vols. 8vo.— Cuvinr, (FRep.,) Résumé analyt- * See, Part IIL, which is devoted to the Em-
ique des observations sur Vinstinet et intelligence bryology of our Turtles.
EO OTN A a ARE TON RPE
60 ESSAY ON CLASSIFICATION. Part I.
a hen with her brood, without remaining satisfied that the feeling which prompts
them in these acts is of the same kind as that which attaches the Cow to her
suckling, or the child to its mother? Who is the investigator, who having once
recognized such a similarity between certain faculties of Man and those of the higher
animals can feel prepared, in the present stage of our knowledge, to trace the limit
where this community of nature ceases? And yet to ascertain the character of all
these faculties there is but one road, the study of the habits of animals, and a
comparison between them and the earlier stages of development of Man. I confess
I could not say in what the mental faculties of a child differ from those of a
young Chimpanzee. ?
Now that we have physical maps of almost every part of the globe,’ exhibiting
the average temperature of the whole year and of every season upon land and sea;
now that the average elevation of the continents above. the sea, and that of the
most characteristic parts of their surface, their valleys, their plains, their table-lands,
their mountain systems, are satisfactorily known; now that the distribution of moisture
in the atmosphere, the limits of the river systems, the prevailing direction of the
winds, the course of the currents of the ocean, are not only investigated, but mapped
down, even in school atlases; now that the geological structure of nearly all parts
of the globe has been determined with tolerable precision, zodlogists have the widest
field and the most accurate basis to ascertain all the relations which exist between
animals and the world in which they live.
Having thus considered the physical agents with reference to the share they may
have had in calling organized beings into existence, and satisfied ourselves that
they are not the cause of their origin, it now remains for us to examine more
particularly these relations, as an established fact, as conditions in which animals and
plants are placed at the time of their creation, within definite limits of action and
reaction between them; for though not produced by the influence of the physical
world, organized beings live in it, they are born im it, they grow up in it, they
multiply in it, they assimilate it to themselves or feed upon it, they have even a
modifying influence upon it within the same limits, as the physical world is sub-
servient to every manifestation of their life. It cannot fail, therefore, to be highly
interesting and instructive to trace these connections, even without any reference
to the manner in which they were established, and this is the proper sphere of
investigation in the study of the habits of animals. The behavior of each kind
towards its fellow-beings, and with reference to the conditions of existence in which
it is placed, constitutes a field of inquiry of the deepest interest, as extensive as it is
1 BerGuavs, Physikalischer Atlas, Gotha, 1838 Atlas of Natural Phenomena, Edinburgh, 1848,
et seq., fol. —Jounston, (ALEx. Kuiru,) Physical 1 vol. fol
HABITS OF ANIMALS. 61
OuAP. al.
complicated. When properly investigated, especially within the sphere which con-
stitutes more particularly the essential characteristics of each species of animals and
plants, it is likely to afford the most direct evidence of the unexpected independence
of physical influences of organized beings, if I mistake not the evidence I have
myself been able to collect. What can there be more characteristic of. different
species of animals than their motions, their plays, their affections, their sexual rela-
are of their young, the dependence of these upon their parents, their
tions, their c¢
and yet there is nothing in all this which depends in the slight-
instincts, ete., ete. ; -
est degree upon the nature or the influence of the physical conditions im which
are independent of these conditions to a
they live. Even their organic functions
of their existence which exhibits the
degree unsuspected, though this is the sphere
closest connections with the world around.
Functions have so long been considered
axiom in comparative anatomy and physiology, that
ans. Most of our general works upon
as the test of the character of organs,
that it has almost become an
identical functions presuppose identical org
comparative anatomy are divided into chapters according to this view. And yet
there never was a more incorrect principle, leading to more injurious consequences,
more generally adopted. That naturalists shoul
must have felt again and again how unsound
d not long ago have repudiated it,
is the more surprising as every one oe
ation and circulation of fishes afford a striking example.
How long have not their gills been considered as the equivalent of the lungs of
the higher Vertebrata, merely because they are breathing organs; and yet these gills
are formed in a very different way from the lungs; they bear very different rela-
and it is now known that they may exist simultane-
it is The organs of respir
tions to the vascular system ;
ously with lungs, as in some full-grown Batrachians, and,
stages of development, in all Vertebrata. There can no longer be any doubt now,
that they are essentially different organs,
their nature and cannot constitute an argument In oe
The same may be said of the vascular system of the fishes. Cuvier’ described their
ng the right auricle and the right ventricle, ahs - propels
in the same manner as the right ventricle pro-
the warm blooded animals; yet embryology has
n based upon the special relations of the heart of
in the earlier embryonic
and that their functions afford no test of
favor of their organic identity.
heart as representi
the blood it contains to the gills,
pels the blood to the lungs of
taught us that such a compariso
fishes, is unjustifiable. The air sacs
as lungs, because they perform similar respiratory functions, and yet they are only
modified traches,? which are constructed upon such a peculiar plan, and stand in
of certain spiders haye also been considered
1 Cuvier, (G.,) Regn. Anim., 2de édit., vol. 2, * LevokarpT, (R.,) Ueber den Bau und die
pe 1a Bedeutung der sogenannten Lungen bei den Arach-
= . " i <=
A i eo Wl i nai na ,
62 ESSAY ON CLASSIFICATION. P xpa- ‘I.
such different relations to the peculiar kind of blood of the Articulata,’ that no
homology can be traced between them and the lungs of Vertebrata, no more
than between the so-called lungs of the air breathing Mollusks, whose aérial respira-
tory cavity is only a modification of the peculiar kind of gills observed in other
Mollusks. _ Examples might easily be multiplied; I will, however, only allude further
to the alimentary canal of Insects and Crustacea, with its glandular appendages,
formed in such a different way from that of Vertebrata, or Mollusks, or Radiata, to
their legs and wings, etc. etc. I might allude also to what has been called the foot
in Mollusks, did it not appear like pretending to suppose that any one entertains
still an idea that such a name implies any similarity between their locomotive
apparatus and that of Vertebrata or Articulata, and yet, the very use of such a
name misleads the student, and even some of the coryphees of our science have
not freed themselves of such and similar extravagant comparisons, especially with
reference to the solid parts of the frame of the lower animals?
The identification of functions and organs was a natural consequence of the
prevailing ideas respecting the influence physical agents were supposed to have upon
organized beings. But as soon as it is understood, how different the organs may
be, which in animals perform the same function, organization is at once brought into
such a position to physical agents as makes it utterly impossible to maintain any
genetic connection between them. A fish, a crab, a mussel, living in the same
waters, breathing at the same source, should have the same respiratory organs, if the
elements in which these animals live had any thing to do with shaping their organi-
zation. I suppose no one can be so short-sighted, as to assume that the same
physical agents acting upon animals of different types, must produce, in each, peculiar
organs, and not to perceive that such an assumption implies the very existence of
these animals, independently of the physical agents. But this mistake recurs so
constantly in discussions upon this and similar topics, that, trivial as it is, it requires
to be rebuked.’ On the contrary, when acknowledging an intellectual conception,
niden, in SreBoLtp und K6.xirKer’s Zeitschrift, f. shared in the physical doctrines more or less pre-
wiss. Zool., 1849, I, p. 246.
* BLANCHARD, (Em.,) De la circulation dans les
Insectes, Compt. Rend., 1847, vol. 24, p. 870.—
AcassizZ, (L.,) On the Circulation of the Fluids in
Insects, Proc. Amer. Asso., for 1849, p. 140.
? Carus, (C. G.) Von den Ur-Theilen des
Knochen- und Schalengeriistes, Leipzig, 1828, 1 vol.,
fol., p. 61-89.
8 T hope the day is not far distant, when zodlo-
gists and botanists will equally disclaim having
vailing now, respecting the origin and existence of
organized beings. Should the time come when my
present efforts may appear like fighting against
windmills, I shall not regret having spent so much
labor in urging my fellow-laborers in a right direc-
tion; but at the same time, I must protest now
and for ever, against the bigotry spreading in some
quarters, which would press upon science, doctrines
not immediately flowing from scientific premises,
and check its free progress.
CHap. IL. RELATIONS OF INDIVIDUALS. 63
as the preliminary step in the existence not only of all organized beings, but of
every thing in nature, how natural to find that while diversity is introduced in the
plan, in the complication and the details of structure of animals, their relations to
the surrounding media are equally diversified, and consequently the same functions
may be performed by the most different apparatus !
SECTION XYVIT.
RELATIONS OF INDIVIDUALS TO ONE ANOTHER.
The relations in which individuals of the same species of animals stand to one
another are not less determined and fixed than the relations of species to the sur-
rounding elements, which we have thus far considered. The relations which individ-
ual animals bear to one another are of such a character, that they ought long ago
to have been considered as proof sufficient that no organized being could ever have
been called into existence by another agency than the direct intervention of a
reflective mind. It is in a measure conceivable that physical agents might pro-
duce something like the body of the lowest kinds of animals or plants, and that
ing may have been produced again and
but that upon closer analysis of the
under identical circumstances the same th
again, by the repetition of the same process;
should not have at once appeared how incongruous the
possibilities of the case, it
uld delegate the power of reproducing
further supposition is, that such agencies co a cae:
what they had just called into existence, to those very beings, with such limitations,
that they could never reproduce any thing but thempelv et
stand. It will no more do to suppose that from simpler structures such a pro-
on of the most perfect, as every step implies an
Such a delegation of
I am at a loss to under-
cess may end in the producti
addition of possibilities not even included in the original case.
power can only be an act of intelligence; while between the production of an
as the result of a physical law, and the repro-
indefinite number of organized beings,
by themselves, there 1s no necessary connec-
duction of these same organized beings
tion. The successive generations of any anim ,
y causal relation to physical agents, if these agents
action to the full extent to which they
al or plant cannot stand, as far as
their origin is concerned, in an
have not the power of delegating their own
have already been productive in the first appearance of these beings; for it is a
physical law that the resultant is equal to the forces applied. If any new being
has ever been produced by such agencies, how could the successive generations
enter, at the time sof their birth, into the same relations to these agents, as. their
64 ESSAY ON CLASSIFICATION. Part I,
ancestors, if these beings had not in themselves the faculty of sustaining their char-
acter, in spite of these agents? Why, again, should animals and plants at once begin
to decompose under the very influence of all those agents which have been subservi-
ent to the maintenance of their life, as soon as life ceases, if life is limited or deter-
mined by them? :
There exist between individuals of the same species relations far more complicated
than those already alluded to, which go still further to disprove any possibility of
causal dependence of organized beings upon physical agents. The relations upon
which the maintenance of species is based, throughout the animal kingdom, in the
universal antagonism of sex, and the infinite diversity of these connections in differ-
ent types, have really nothmg to do with external conditions of existence; they
indicate only relations of individuals to individuals, beyond their connections with the
material world in which they live. How, then, could these relations be the result of
physical causes, when physical agents are known to have a specific sphere of action,
in no way bearing upon this sphere of phenomena ?
For the most part, the relations of individuals to individuals are unquestionably
of an organic nature, and, as such have to be viewed in the same light as any other
structural feature; but there is much, also, in these connections that partakes of a
psychological character, taking this expression in the widest sense of the word.
When animals fight with one another, when they associate for a common purpose,
when they warn one another in danger, when they come to the rescue of one
another, when they display pain or joy, they manifest impulses of the same kind as
are considered among the moral attributes of man. The range of their passions is
even as extensive as that of the human mind, and I am at a loss to perceive a
difference of kind between them, however much they may differ in degree and in
the manner in which they are expressed. The gradations of the moral faculties
among the higher animals and man are, moreover, so imperceptible, that to deny to
the first a certain sense of responsibility and consciousness, would certainly be an
exaggeration of the difference between animals and man. There exists, besides, as
much individuality, within their respective capabilities, among animals as among men,
as every sportsman, or every keeper of menageries, or every farmer and shepherd
can testify who has had a large experience with wild, or tamed, or domesticated
animals.’
This argues strongly in favor of the existence in every animal of an immaterial
1 See J. E. Rrpimneer’s various works illustra- naturelle des Mammiferes, Paris, 1820-385, 3 vols.
tive of Game Animals, which have appeared under fol.—-Lenz, (H. O.,) Gemeinniitzige Naturgeschichte,
different titles, in Augsburg, from 1729 to 1778.— Gotha, 1835, 4 vols. 8vo.— Binetry, (W.,) Animal
Grorrroy Sr. HiLarre, et Cuvier, (FR,,) Histoire Biography, London, 1803, 3 vols. 8vo.
Cuap. I.
RETATIONS “OF TNDITVIDUALS:
65
principle similar to that which, by its excellence and superior endowments, places
man so much above animals.’
1 Tt might easily be shown that the exaggerated
views generally entertained of the difference exist-
ing between man and monkeys, are traceable to the
ignorance of the ancients, and especially the Greeks,
to whom we owe chiefly our intellectual culture, of
the existence of the Orang-Outang and the Chim-
panzee. The animals most closely allied to man
known to them were the Red Monkey, «7$os, the
Baboon, xvvoxéqpadog, and the Barbary Ape, 20x06.
A modern translation of Aristotle, it is true, makes
him say that monkeys form the transition between
man and quadrupeds; (ArisToTeLes, Naturge-
schichte der Thiere, von Dr. F. Srrack, Frankfurt-
am-Main, 1816, p. 65;) but the original says no
such thing. In the History of Animals, Book 2,
Chap. V., we read only, a 58 tar Cow emapqo-
regiles thy iow tH te avOQasty nal TOIg TETQasOOW.
There is a wide difference between “partaking of
the nature of both man and the quadrupeds,” and
“forming a transition between man and the quadru-
peds.” The whole chapter goes on enumerating the
structural similarity of the three monkeys named
above with man, but the idea of a close affinity is
not even expressed, and still less that of a transi-
tion between man and the quadrupeds. The writer,
on the contrary, dwells very fully upon the marked
differences they exhibit, and knows as well as any
modern anatomist has ever known, that monkeys have
four hands. éyeu dé nal Bouziovac, acrteg cr Pgumos,
. . . « bdiove 88 tobe mbdag. slot yao o1oy KEiQes
weycho. Ket of Sdxrvaor were 01 TOY YEIQar, O weyas
lanodrarog* nat tO xdtw Tov modoS YEIQl Go1or, Tehav
émlt TO pixog TO The yewwog emt Ta ~oyaca Teor nae-
aso Dévag. Torro d& in’ dugov oxlygdregor, xux0s
oes auvdows pmovpevoy MTEoVIY.
It is strange that these clear and precise dis-
tinctions should have been so entirely forgotten in
the days of Linneus that the great reformer in
Natural History had to confess, in the year 1746,
that he knew no character by which to distinguish
man from the monkeys. Fauna Suecica, Preefat. p. 2.
“Nullum characterem adbue eruere potul, unde
9
Yet the principle exists unquestionably, and whether
homo a simia internoscatur.” But it is not upon
structural similarity or difference alone that the re-
lations between man and animals have to be con-
sidered. The psychological history of animals shows
that as man is related to animals by the plan of his
structure, so are these related to him by the char-
acter of those very faculties which are so tran-
scendent in man as to point at first to the necessity
of disclaiming for him completely any relationship
with the animal kingdom. Yet the natural history
of animals is by no means completed after the so-
matic side of their nature has been thoroughly in-
vestigated ; they, too, have a psychological individ-
uality, which, though less fully studied, is neverthe-
less the connecting link between them and man. I
cannot, therefore, agree with those authors who would
disconnect mankind from the animal kingdom, and
establish a distinct kingdom for man alone, as
Ehrenberg (Das Naturreich des Menschen, Berlin,
1835, fol.) and lately I. Geoffroy St. Hilaire, (Hist.
nat. générale, Paris, 1856, Tome 1, Part 2, p. 167,)
have done. Compare, also, Chap. II., where it is
shown for every kind of groups of the animal kingdom
that the amount of their difference one from the
other never affords a sufficient ground for removing
any of them into another category. A close study
of the dog might satisfy every one of the similarity
of his impulses with those of man, and those im-
pulses are regulated in a manner which discloses
psychical faculties in every respect of the same kind
as those of man; moreover, he expresses by his
voice his emotions and his feelings, with a precision
which may be as intelligible to man as the articu-
lated speech of his fellow men. His memory is so
retentive that it frequently baffles that of man. And
though all these faculties do not make a philosopher
of him, they certainly place him in that respect
upon a level with a considerable proportion of poor
humanity. The intelligibility of the voice of ani-
mals to one another, and all their actions connected
with such calls are also a strong argument of their
perceptive power, and of their ability to act. spon-
wer
66 ESSAY ON CLASSIFICATION. Paar .L
it be called soul, reason, or instinct, it presents in the whole range of organized
beings a series of phenomena closely linked together; and upon it are based not
only the higher manifestations of the mind, but the very permanence of the specific
differences which characterize every organism. Most of the arguments of philosophy
in favor of the immortality of man apply equally to the permanency of this principle
May I not add, that a future life, in which man should be
deprived of that great source of enjoyment and intellectual and moral improvement
in other living beings.
which result from the contemplation of the harmonies of an organic world, would
involve a lamentable loss, and may we not look to a spiritual concert of the com-
bined worlds and all their inhabitants in presence of their Creator as the highest
conception of paradise ?
SECTION: 2 Vigda;
METAMORPHOSES OF ANIMALS.
The study of embryology is of very recent date; the naturalists of the past
century, instead of investigating the phenomena accompanying the first formation and
growth of animals, were satisfied with vague theories upon reproduction.’
taneously and with logical sequence in accordance
with these perceptions. There is a vast field open
for investigation in the relations between the voice
and the actions of animals, and a still more inter-
esting subject of inquiry in the relationship between
the cycle of intonations which different species of
animals of the same family are capable of uttering,
which, as far as I have as yet been able to trace
them, stand to one another in the same relations as _
the different, so-called, families of languages (SCHLE-
GEL, (FR.,) Ueber die Sprache und Weisheit der
Indier, Heidelberg, 1808, 1 vol. 8vo. —HumBoiprt,
(W. v.,) Ueber die Kawi-Sprache, auf der Insel
Java, Berlin, 1836-39, 3 vols. 4to. Abh. Ak. d. Wis-
sensch. — STEINTHAL, (H.,) Grammatik, Logik und
Psychologie, Berlin, 1855, 1 vol. 8vo.) in the human
family. All the Canina bark; the howling of the
wolves, the barking of the dogs and foxes, are
only different modes of barking, comparable to one
another in the same relation as the monosyllabic,
It is true
the agglutinating, and the inflecting languages. The
Felide mew: the roaring of the lion is only ano-
ther form of the mewing of our cats and the other
species of the family. The Agwina neigh or bray:
the horse, the donkey, the zebra, the dow, do not differ
much in the scale of their sounds. Our cattle, and the
different kinds of wild bulls, have a similar affinity
in their intonations; their lowing differs not in kind;
but only in the mode of utterance. Among birds,
Who does not
distinguish the note of any and every thrush, or of
this is, perhaps, still more striking.
the warblers, the ducks, the fowls, etc., however nu-
merous their species may be, and who can fail to
And does
this not indicate a similarity also in their mental
perceive the affinity of their voices?
faculties ?
1 Burron, (G. L. LeCrerc pe,) Discours sur
la nature des Animaux, Geneve, 1754, 12mo.; also
in his Oeuvres completes, Paris, 1774-1804, 36 vols.
Ato.
Cuap. I. METAMORPHOSES OF ANIMALS. 67
the metamorphoses of Insects became very early the subject of most remarkable
observations; but so little was it then known that all animals undergo great changes
from the first to the last stages of their growth, that metamorphosis was considered
a distinguishing character of Insects. The differences between Insects, in that
respect, are however already so great, that a distinction was introduced between
those which undergo a complete metamorphosis, that is to say, which appear in
three successive different forms, as larvae, pup2, and perfect insects, and those with
an incomplete metamorphosis, or whose larve differ little from the perfect insect.
The range of these changes is yet so limited in some insects, that it is not only
not greater, but is even much smaller than in many representatives of other classes.
We may, therefore, well apply the term metamorphosis to designate all the changes
2
which animals undergo, in direct and immediate succession,” during their growth,
whether these changes are great or small, provided they are correctly qualified for
each type.
The study of embryology, at fir
which the chicken undergoes in the egg;
o diligent and thorough has been the study, that
upon an extensive illustration of the whole field,
st limited to the investigation of the changes
has gradually extended to every type
of the animal kingdom; and s
‘ the first author who ventured
C. HE. von Baer, has already pre
curate and so comprehensive, that all subsequent
sented the subject in such a clear manner, and
drawn general conclusions so ac
researches in this department of our science, may be considered only as a further
first noticed by him and of the results he has already
development of the facts
s he who laid the foundation for the most extensive
deduced from them.’ It. wa
bli oh a j mF’s article “ Entwickelunosges-
1 SWAMMERDAM, (J.,) Biblia Natura, sive His- others in Brscuor esces
toria Insectorum, ete., Lugduni-Batavorum, 1737-88,
8 vols. fol. fig. — Rraumur, (R. Ant. DE,) Mémoires
pour servir & Histoire des Insectes, Paris, 1734-42,
6 vol. 4to. fig. —Rorset von Rosenuor, (A. J»)
Insectenbelustigungen, Niirnberg, 1746-61, 4 vols.
Ato. fig.
2 T say purposely, “in direct and immediate suc-
cession,” as the phenomena of alternate generation
are not included in metamorphosis, and consist chiefly
in the production of new germs, which have their
own metamorphosis; while metamorphosis _ proper
relates only to the successive changes of one and
chichte,” in Waener’s Handworterbuch der Physio-
logie, vol. 1, p. 860, I shall mention hereafter, chiefly
those published since, under the influence of Déllin-
ger, this branch of science has assumed a new char-
acter: — Baur, (C. E. v.,) Ueber Entwickelungs-
geschichte der Thiere, Konigsberg, 1828-37, 2 vols.
4to. fig. The most important work yet published.
The preface is a model of candor and truthfulness,
and sets the merits of Dollinger in a true and beauti-
ful light. As text-books, I would quote, Burpacu,
(C. F.,) Die Physiologie als Erfahrungswissenschaft,
Leipzig, 1829-40, 6 vols. 8vo.; French, Paris,
1837-41, 9 vols. 8vo.— MUturr, (J.,) Handbuch der
Physiologie des Menschen, Coblenz, 1848, 2 vols. 8vo.
4th edit.; Engl. by W. Bary, London, 1837, 8vo.
— Waener, (R.,) Lehrbuch der Physiologie, Leip-
the same germ.
8 Without referring to the works of older writers,
such as DeGraaf, Malpighi, Haller, Wolf, Meckel,
Tiedemann, etc., which are all enumerated with many
68 ESSAY ON CLASSIFICATION.
Parr I.
generalizations respecting the mode of formation of animals; for he first discovered,
in 1827, the ovarian ege of Mammalia, and thus showed for the first time, that
there is no essential difference in the mode of reproduction of the so-called vivip-
arous and oviparous animals, and that man himself is developed in the same manner
as the animals. The universal presence of eggs in all animals and the unity of their
structure, which was soon afterwards fully ascertained, constitute, in my opinion, the
greatest discovery of modern times in the natural sciences.’
It was, indeed, a gigantic step to demonstrate such an identity in the material
basis of the development of all animals, when their anatomical structure was already
From that
time a more and more extensive investigation of the manner in which the first
known to exhibit such radically different plans in their full-grown state.
germ is formed in these eggs, and the embryo develops itself; how its organs
grow gradually out of a homogeneous mass; what changes, what complications, what
connections, what functions they exhibit at every stage; how in the end the young
animal assumes its final form and structure, and becomes a new, independent being,
could not fail to be the most interesting subject of inquiry. To ascertain all this,
in as many animals as possible, belonging to the most different types of the animal
kingdom, became soon the principal aim of all embryological investigations; and it
can truly be said, that few sciences have advanced with such astonishing rapidity,
and led to more satisfactory results.
For the actual phases of the mode of development of the different types of the
animal kingdom, I must refer to the special works upon this subject,’ no general
zig, 1839-42, 2 vols. 8vo.— VaLEnTIN, (G.,) Hand-
buch der Entwickelungsgeschichte, ete., Berlin, 1835,
1 vol. 8vo.— Lehrbuch der Physiologie des Men-
schen, Braunschweig, 1843, 2 vols. 8vo. — Loneet,
(F. A.,) Traité de Physiologie, Paris, 1850, 2 vols.
8vo.— KéuiiKer, (ALB.,) Microscopische Anatomie
des Menschen, Leipzig, 1840-54, 2 vols. 8vo. fig. —
See also Owen’s Lectures, etc., SrEBOLD und Sran-
nius’s Lehrbuch, and Carus’s Morphologie, q. a.
p- 27, and p. 18.
modern text-book on physiology, but most of them
I might further quote almost every
are so evidently mere compilations, exhibiting no
acquaintance with the subject, that I omit purposely
to mention any other elementary works.
1 Baer, (C. E. a,) De Ovi Mammalium et
Hominis Genesi, Konigsberg, 1827, 4to., fig. —
PurkinJE, (J. E.) Symbole ad ovi avium historiam
ante incubationem, Lipsie, 1830, 4to. fig. — Wac-
NER, (R.,) Prodromus Historiz generationis Hominis
atque Animalium, etc., Lipsie, 1836, 1 vol., fol., fig.
—Icones physiologice, Lipsix, 1839, 4to. fig.
2 The limited attention, thus far paid in this
country to the study of Embryology, has induced
me to enumerate more fully the works relating to
_ this branch of science, than any others, in the hope
There
exist upon this continent a number of types of ani-
of stimulating investigations in that direction.
mals, the embryological illustration of which would
add immensely to the stock of our science; such
are the Opossum, the Ichthyoid Batrachians, the
Lepidosteus, the Amia, etc. not to speak of the
opportunities which thousands of miles of sea-coast,
everywhere easily accessible, afford for embryologi-
cal investigations, from the borders of the Arectics
to the Tropics. In connection with Embryology
the question of Individuality comes up naturally.
Onan. “1. METAMORPHOSES OF ANIMALS. 69
treatise embracing the most recent investigations having as yet been published; and
I must take it for granted, that before forming a definite opinion upon the com-
parisons instituted hereafter between the growth of animals, and the structural grada-
tion among full-grown animals, or the order of succession of the fossils characteristic
of different geological periods, the necessary information respecting these changes has
been gathered by my readers, and sufficiently mastered to enable them to deal with
it freely.
The embryology of Polypi has been very little studied thus far; what we know
of the embryonic growth of these animals relates chiefly to the family of Actinoids.!
When the young is hatched, it has the form of a little club-shaped or pear-shaped
body, which soon assumes the appearance of the adult, from which it differs only by
The mode of ramification and the multiplication by buds
have, however, been carefully and minutely studied in all the families of this class?
peculiar, that they are discussed hereafter in a
having few tentacles.
Acalephs present phenomena s0
special section. Their young® are either polyplike or resemble more immediately
See upon this subject: — Levoxart, (Rup.,) Ueber _—_4to. p. 29. — Loven, (8. L.) Beitrag zur Kenntniss
den Polymorphismus der Individuen oder die
Erscheinung der Arbeitstheilung in der Natur,
Giessen, 1851, 4to. — Rercuert, (C. B.,) Die mono-
gene Fortpflanzung, Dorpat, 1852. — Huxey, (TH.
H.,) Upon Animal Individuality, Ann. and Mag.
Nat. Hist. 2d ser., 1852, vol. 9, p. 507. — ForBEs,
(Ep.,) On the supposed Analogy between the Life
of an Individual and the Duration of a Species, Ann.
and Mag.” Nat. Hist, 2d ser, 1859) vob 16 poe sone eh ee Generationen, Uebers,,
— Braon, (At.,) Das Individuum der Pflanze, q- a = - Von Lorenzen, Kopenh. 1842, 8vo., fig.; Engl.
— Betrachtungen iiber die Erscheinung der Ver- by G. Busx, (Ray RAY) An n08; + eS
jiingung in der Natur, Freiburg, 1849, 4te. fig.
1 Sars, (M.,) Beskrivelser og Jagttagelser over
nogle maerkelige eller nye i Havet ved den Ber-
genske Kyst levende Dyr, ete., Bergen, 1835, 4to.
— Fauna littoralis Norvegie, Christiania, 1846, fol.
fig. — Ratuxe, (H.,) in Burdach’s Physiologie, vol.
2d, 2d edit. p. 215. — Zur Morphologie, Reisebemer-
kungen aus Taurien, Riga und Leipzig, 1837, 4to.,
fig. — Acassiz, (L.,) Twelve Lectures, ete. p. 40,
et seq. |
der Gattungen Campanularia und Syncoryne, Wiegm.
Arch., 1837, p. 249 and 821; French Ann. Se. n.
Qde sér., vol. 15, p. 157.— Sars, (M.,) Beskrivelser,
q. a. — Fauna littoralis, q. a. — NorpMAnn, (AL. v.,)
Sur les changements que lage apporte dans la
maniere d’étre des Campanulaires, Comptes-Rendus,
1834, p. 709. — Steunstrup, (J.,) Ueber den Gene-
rations-Wechsel oder die Fortpflanzung und Ent-
VanBENEDEN, (P. J.,) Mémoire sur les Campanu-
laires de la cdte d’Ostende, etc. Mém. Ac. Brux.
1843, vol. 17, 4to. fig. — Recherches sur l’Embry-
ogénie des Tubulaires, etc., Mém. Ac. Brux. 1844,
Ato. fig. —DusarpINy, (FEL.,) Observations sur un
nouveau genre de Médusaires (Cladonema,) pro-
venant de la métamorphose des Syncorynes, Ann. Se.
n. 2de sér. 1843, vol. 20, p. 370.— Mémoire sur le
développement des Médusaires et des Polypes
Hydraires, Ann. Se. n. 8e sér., 1845, vol. 4, p. 257.
2 See Dana’s Zoophytes, and Mrtnz-EDWARDS —Wut, (J. G. Fr.) Hore tergestine, Leipzig,
et Harm, Recherches, etc., q. a p- 31, note 2. 1844, 4to. fig. — Frey, (H.,) und Leucxarr, (R.,)
8 SreBoxp, (C. Tu. E. v.,) Beitrage zur Natur- Beitrige zur Kenntniss wirbelloser Thiere, Braun-
geschichte der wirbellosen Thiere, Dantzig, 1839, schweig, 1847, 4to. fig. — DALYELL, (Sir J. G.,) Rare
70 ESSAY ON CLASSIFICATION.
Part I.
the type of their class. Few multiply in a direct, progressive development. As to
Echinoderms, they have for a long time almost entirely escaped the attention of
Embryologists, but lately J. Miiller has published a series of most important investi-
gations upon this class,! disclosing a wonderful diversity in the mode of their develop-
and Remarkable Animals of Scotland, etc., London,
1847, 2 vols. 4to. fig. — Forses, (Ep.,) Monograph
of the British Naked-eyed Meduse, London, 1847,
1 vol. fol. fig. (Ray Society.) —On the Morphology
of the Reproductive System of Sertularian Zoophytes,
etc. Ann. and Mag. Nat. Hist., 1844, vol. 14, p. 380.
—Acassiz, (L.,) Twelve Lectures, etc, gq. a.—
Desor, (Ep.,) Lettre sur la génération médusipare
des Polypes Hydraires, Ann. Se. Nat., 3e sér., 1849,
vol. 12, p. 204. — Kroun, (A.,) Bemerkungen tiber
die Geschlechtsverhiltnisse der Sertularinen, Miil-
ler’s Arch. 1848, p. 174.— Ueber die Brut des
Cladonema radiatum und deren Entwickelung zum
Stauridium, Miiller’s Arch., 1853, p. 420.— Ueber
Podocoryne carnea Sars und die Fortpflanzungsweise
ihrer medusenartigen Sprésslinge, Wiegm. Arch.,
1851, I, p. 263.— Ueber einige niedere Thiere,
Miiller’s Arch., 1853, p. 187. — Ueber die friihesten
Entwickelungsstufen der Pelagia noctiluca, Miiller’s
Arch., 1855, p. 491. — KOxuikeEr, (A.,) Die Schwimm-
polypen, ete., q. a.— Buscn, (W.,) Beobachtungen
iiber Anatomie und Entwickelungsgeschichte einiger
wirbelloser Seethiere, Berlin, 1851, 4to. fig. pp. 1,
25 and 30.— GEGENBAUER, KOLLIKER und MUL-
LuR, Bericht iiber einige im Herbste 1852 in Messina
angestellte anatomische Untersuchungen, Zeitsch. f.
wiss. Zool. vol. 4, p. 299.— GueEnBavER, (C.)
Ueber die Entwickelung von Doliolum, der Schei-_
benquallen und von Sagitta, Zeitsch. f. wiss. Zool.,
1853, p. 18.— Beitrige zur nihern Kenntniss der
Schwimmpolypen (Siphonophoren,) Zeitsch. f. wiss.
Zool., 1858, vol. 5, p. 285. — Ueber Diphyes turgida,
etc., Zeitsch. f. wiss. Zool., 1853, vol. 5, p. 442.—
Ueber den Entwickelungscyclus von Doliolum, ete.,
Zeitsch.’ f. wiss. Zool. 1855, vol. 7, p. 283. —
Frantzivs, (AL. v.,) Ueber die Jungen der Cephea,
Zeitsch. f. wiss. Zool., vol. 4, p. 118. — MU tier, (J.,)
Ueber eine eigenthiimliche Meduse des Mittelmeeres
und ihren Jugendzustand, Miiller’s Arch., 1851, p. 272.
— ScuvuLtze, (M..) Ueber die minnlichen Geschle-
chtstheile der
Arch., 1850, p. 53.— Hincxks, (Tu.,) Notes on the
Reproduction of the Campanulariadz, etc., Ann. and
Mag. Nat. Hist., 2d ser., 1852, vol. 10, p. 81. — Fur-
ther Notes on British Zoophytes, Ann. and Mag. Nat.
Hist., 1853, vol. 15, p. 127. — Atiman, (G. J.,) On
Hydroids, Rep. Brit. Ass. Adv. Se., 1852, p. 50.—
Derpes, (A.,) Note sur les organes reproducteurs et
Campanularia geniculata, Miiller’s
Yembryogénie du Cyanea chrysaora, Ann. Sc. Nat.,
8e sér., 1850, vol. 138, p. 8377.— Voer, (C.,) Ueber
die Siphonophoren, Zeitsch. f. wiss. Zool., 1852,
vol. 3, p. 522.— Huxtey, (Tu. H.,) On the Anat-
omy and Affinities of the Family of the Meduse,
Philos. Trans. Roy. Soc. 1849, IL, p. 418.— An
Account of Researches into the Anatomy of the
Hydrostatic Acalephw, Proc. Brit. Ass. Adv. Se.
1851, p. 78. — Leucxarpt, (R.,) Zoologische Unter-
suchungen, Giessen, 1853-04, 4to. fig. Ist Fase. —
Zur nihern Kenntniss der Siphonophoren von Nizza,
Wieem. Arch., 1854, p. 249. — Srimpson, (W..,).
Synopsis of the Marine Invertebrata of Grand Manan,
Smithson. Contrib., 1858, 4to. fig. — Lerpy, (Jos.,)
Contributions towards a Knowledge of the Marine
Invertebrate Fauna, ete, Journ. Acad. Nat. Sce.,
Philad., 2d ser. 1855, vol. 8, 4to. fig. —See also
below, Sect. 20.
? Beskrivelser, ete., p. 87.— Ueber die Ent-
wickelung der Seesterne, Wiegm. Arch. 1844, L.,
p- 169, fig. — Fauna littoralis, etc., p. 47. — MULLER,
(J..) Ueber die Larven u. die Metamorphose der
Ophiuren u. Seeigel, Akad. d. Wiss., Berlin, 1848. —
Ueber die Larven u. die Metamorphose der Echino-
dermen, 2te Abh., Ak. d. Wiss., Berlin, 1849. —
Ueber die Larven u. die Metamorphose der Holo-
thurien u. Asterien, Ak. d. Wiss., Berlin, 1850.—
Ueber die Larven u. die Metamorphose der Echino-
dermen, 4te Abh. Ak. d. Wiss., Berlin, 1852.—
Ueber die Ophiurenlarven des Adriatischen Meeres,
Cuap. I. METAMORPHOSES OF ANIMALS. ut
ment, not only in the different orders of the class, but even in different genera
of the same family. The: larvee of many have a close resemblance to diminutive
Ctenophore, and may be homologized with this type of Acalephs.
As I shall hereafter refer frequently to the leading divisions of the animal king-
dom, I ought to state here, that I do not adopt some of the changes which have
been proposed lately in the limitation of the classes, and which seem to have been
pretty generally. received with favor. The undivided type of Radiata appears to
me as one of the most natural branches of the animal kingdom, and I consider
its subdivision into Coelenterata and Echinodermata, as an exaggeration of the ana-
tomical differences observed between them. As far as the plan of their structure
is concerned, they do not differ at all, and that structure is throughout homologi-
cal. In this branch I recognize only three classes, Polypi, Acalephe, and Echinoder-
mata. The chief difference between the two first lies in the radiating partitions of
the main cavity of the Polypi, supporting the reproductive organs; moreover, the
digestive cavity in this class consists of an inward fold of the upper aperture of
the common sac of the body, while in Acalephs there exist radiating tubes, at least
in the proles medusina, which extend to the margin of the body where they anas-
tomoze, and the digestive cavity is hollowed out of the gelatinous mass of the
body. This is equally true of the Hydroids, the Medusx proper, and the Cteno-
phore; but nothing of the kind is observed among Polypi. Siphonophorz, whether
their proles medusina becomes free or not, and Hydroids agree in having, in the proles
medusina, simple radiating tubes, uniting into a single circular tube around the mar-
gin of the bell-shaped disk. These two groups, constitute together, one natural
order, in contradistinction from the Covered-eyed Medusze, whose radiating tubes
ramify towards the margin and form a complicated net of anastomoses. Morpho-
logically, the proles polypoidea of the Acalephs, is as completely an Acaleph, as their
Ak. d. Wiss. Berlin, 1852. — Ueber den allge- Seen Cs) Twelve Lectures, ete., p. 13.—
meinen Plan in der Entwickelung der Echinodermen,
Ak. d. Wiss., Berlin, 1853. — Ueber die Gattungen
der Seeigellarven, 7te Abh., Ak. d. Wiss., 1855.—
Ueber den Canal in den Eiern der Holothurien,
Miiller’s Arch., 1854, p. 60.— French abstracts of
these papers may be found in Ann. Sc. Nat., 3e
sér., 1852 and ’58, vols. 17, 19, and 20; An English p- 817.— Ueber die Entwickelung einer lebendig
account is published by Huxiey, (Tu. H.,) Report gebihrenden Ophiure, Miiller’s Arch., 1851, p. 338.
upon the Researches of Prof. Miiller into the Anat- — Ueber die Larve des Echinus brevispinosus, Miil-
omy and Development of the Echinoderms, Ann. and ler’s Arch., 1853, p. 361.— Beobachtungen iiber
Mag. Nat. Hist., 2d ser., vol. 8, 1851, p. 1. — KorEN Echinodermenlarven, Miiller’s Arch., 1854, p. 208. —
Derses, (A.,) Sur la formation de Pembryon chez
Yoursin comestible, Ann. Sc. Nat., 8e sér., vol. 8,
p. 80.— Busu, (W.,) Beobachtungen, ete. q. a.—
Ueber die Larve der Comatula, Miiller’s Arch. 1849,
p- 400. — Kroun, (A.,) Ueber die Entwickelung der
Seesterne und Holothurien, Miiller’s Arch., 1853,
und DanreLssEn in Nyt Magazin for Naturvid, vol. 5, Scuvtze, (M.,) Ueber die Entwickelung von Ophio-
p. 253, Christiania, 1847; Ann. Se. Nat. 1847, p. 347, lepis squamata, Miiller’s Arch., 1852, p. 37.
72 ESSAY ON CLASSIFICATION. Part I.
proles medusina, and whether they separate or remain connected, their structural
relations are everywhere the same.
most common and the most polymorphous Hydroid, with our common Portuguese
Man-of-War (Physalia,) may at once show the homology of their most polymorphous
individuals. )
The embryology of Mollusks has been very extensively investigated, and some
types of this branch are among the very best known in the animal kingdom. The
natural limits of the branch itself appear, however, somewhat doubtful. I hold that
it must include the Bryozoa? which lead gradually through the Brachiopods? and
Tunicata to the ordinary Acephala, and I would add, that I have satisfied myself
of the propriety of uniting the Vorticellide with Bryozoa. On the other hand, the
Cephalopods can never be separated from the Mollusks proper, as a distinct branch ;
the partial segmentation of their yolk no more affords a ground for their separation,
than the total segmentation of the yolk of Mammalia would justify their separation
from the other Vertebrata. Moreover, Cephalopods are in all the details of their
structure homologous with the other Mollusks.
esting, inasmuch as the simple Ascidians have pedunculated young, which exhibit the
most striking resemblance to Boltenia, and form, at the same time, a connecting link
with the compound Ascidians* The development of the Lamellibranchiata seems to
A comparison of Hydractinia, which is the
The Tunicata are particularly imter-
_ 17 shall show this fully in my second volume.
Meanwhile, see my paper on the structure and
homologies of Radiata, q. a. p. 20.
2 Arian, (G. J.) On the Present State of our
Knowledge of the Fresh Water Polyzoa, Proc. Brit.
Asso. Adv. Sc., 20th Meet., Edinburgh, 1850, p. 309.
— Proe. Irish Ac. 1850, vol. 4, p. 470. — Ibid., 1853,
vol. 5, p. 11.—VanBenepen, (P. J.,) Recherches
sur VAnatomie, la physiologie et le développement
des Bryozoaires qui habitent la céte d’Ostende, Nouv.
Mém. Ac. Brux., 1845, vol. 18.— Dumortier, (B. C.,)
et VanBenepen, (P. J.,) Histoire naturelle des
Polypes composés @eau douce, Mém. Ac. Brux.,
1850, vol. 16, 4to. fig. —Hincxs, (Tu.,) Notes on
British Zoophites, with Descriptions of some New
Species, Ann. and Mag. Nat. Hist., 2d ser., 1851,
vol. 8, p. 853. — Enrenserc, (C. G.,) Die Intu-
sionsthiere als vollkommene Organismen, Leipzig,
1838, 2 vols. fol. fig. —Srur, (F.,) Infusionsthiere
auf ihre Entwickelungsgeschichte untersucht, Leip-
zig, 1854, 1 vol. 4to. fig. — FRANTzIUS, (AL. Y.,)
Analecta ad Ophrydii versatilis historiam naturalem,
Vratislav, 1849. — Lacumann, (C. F. J.,) Ueber die
Organization der Infusorien, besonders der Vorticel-
len, Miiller’s Arch., 1856, p. 840. Having satisfied
myself that the Vorticellide are Bryozoa, I would
also refer here to all the works on Infusoria in which
these animals are considered.
8 T see from.a short remark of Leuckart, Zeitsch.
f. wiss. Zool., vol. 7, suppl., p. 115, that he has also
perceived the close relationship which exists between
Brachiopods and Bryozoa.
4 Savieny, (J. C.,) Mémoires sur les Anim. sans
Vertébres, etc. gq. a.—Cuamisso, (Ap. A.,) De
animalibus quibusdam e classe Vermium Linnezana,
Fase. 1, De Salpa, Berol, 1819, 4to., fig. — Muyern,
(F. J.) Beitrige zur Zoologie, etc., Ist Abth., iiber
Salpen, Nov. Act. Nat. Cur. 1832, vol. 16.—
Epwarps, (H. Mitye,) Observations sur les Asci-
dies composées des cdtes de la Manche, Paris, 1841,
4to., fig. — Sars, (M.,) Beskrivelser, q. a.— Fauna
litt., q. a. — VANBENEDEN, (P. J.,) Recherches sur
Cuap. I. METAMORPHOSES OF ANIMALS. 73
be very uniform, but they differ greatly as to their breeding, many laying their
egos before the germ is formed, whilst others carry them in their gills until the
young are entirely formed. This is observed particularly among the Unios, some of
which, however, lay their eggs very early, while others carry them for a longer
or shorter time, in a special pouch of the outer gill, which presents the most diversi-
fied forms in different genera of this family. Nothing is as yet known of the
development of Brachiopods.
lembryogénie, ’anatomie et la physiologie des Asci-
dies simples, Mém. Ac. Brux., 1847, vol. 20.—
Kroun, (A.,) Ueber die Entwickelung der Ascidien,
Miiller’s Arch., 1852, p. 312.— Kérirer, (A.,)
et Léwic, De la composition et de Ja structure
des enveloppes des Tuniciers, Ann. Se. Nat. 3e sér.,
vol. 5, p. 193.— Huxiey, (Tu. H.,) Observations
upon the Anatomy and Physiology of Salpa and
Pyrosoma, Philos. Trans. R. Soc., 1851, IL, p. 567.
— Escuricut, (D. F.,) Anatomisk-physiologiske
Underségelser over Salperne, Kidb. 1840, fig. —
STEENSTRUP, (J.,) Ueber den Generationswechsel,
q. a.—Voer, (C.,) Bilder aus dem Thierleben,
Frankfurt a. M., 1852, 8vo.— MU tier, (H.,) Ueber
Salpen, - Zeitsch.. f., wiss., Zool. vol.. 4, p. 3829.—
Leucxart, (R.,) Zoologishe Untersuchungen, Gies-
sen, 1853-54, 4to., fig., 2d Fase.
1 Carus, (C. G.,) Entwickelungsgeschichte unse-
rer Flussmuschel, Leipzig, 1832, 4to., fig. — QUATRE-
races, (Arm. pE,) Sur Yembryogénie des Tarets,
Ann. Se. Nat., 8e sér., 1849, vol. 2, p. 202.—Sur
la vie interbranchiale des petites Anodontes, Ann. Se.
Nat., 2de sér., vol. 5, p. 821. — Loven, (S. L.,) Om
Utvecklingen of Mollusca Acephala, Overs. Vet.
Akad. Férhandl. Stockholm, 1849.— Germ. Miiller’s
Arch., 1848, p. 531, and Wiegman’s Arch., 1849,
p- 812. — Prevost, (J. L.,) De la génération chez la
moule des peintres, Mém. Soc. Phys. Genéve, 1825,
vol. 8, p. 121.—Scumupz, (O.,) Ueber die Entwicke-
lung von Cyclas calyculata Drap. Miiller’s Arch.,
1854, p. 428. — Luyp1e, (F.,) Ueber Cyclas cornea,
Miiller’s Arch., 1855, p. 47.
2 Carus, (C. G.,) Von den dussern Lebensbe-
dingungen der weiss- und kaltbliitigen Thiere, Leip-
zig, 1824, 4to. fig. — Prevost, (J. L.) De la
génération chez. le Lymnée, Mém. Soe. Phys.,
10
The Gasteropods? exhibit a much greater diversity
Geneve, vol. 5, p. 119.— Sars, (M.,) Zur Entwicke-
lungsgeschichte der Mollusken und Zoophyten,
Wieem. Arch., 1837, L, p. 402; 1840, I, p. 196.—
Zusiitze zu der von mir gegebenen Dartstellung
der Entwickelung der Nudibranchien. Wiegm. Arch.
1845, I. p. 4. — QUATREFAGES, (ARM. DE,) Mémoire
sur ’Embryogénie des Planorbes et des Lymnées,
Ann. Se. Nat., 2de sér., vol. 2, p. 107. — VanBrENeE-
DEN, (P. J.,) Recherches sur le développement des
Aplysies, Ann. Sc. Nat. 2de sér., vol. 15, p. 123. —
VanBenepen, (P. J.,) et Wrypiscuman, (Cu.,)
Recherches sur Embryogénie des Limaces, Mém.
Ac. Brux., 1841. — Jacquemiy, (Em.,) Sur le
développement des Planorbes, Ann. Se. Nat., vol. 5,
p. 117; Nov. Act. Nat. Cur. vol. 18.— Dumor-
vier, (B. C.,) Mémoire sur les évolutions de
Yembryon dans les Mollusques Gastéropodes, Mém.
Ac, Brux., 1836, vol. 10.— Laurent, (J. L. M.,)
Observations sur le développement de Voeuf des
Limaces, Ann. Sc. Nat., vol. 4, p. 248.— Poucuer,
(F. A.) Sur le développement de Yembryon des
Lymnées, Ann. Se. Nat., 2de sér., vol. 10, p. 63.—
Voer, (C.,) Recherches sur ’Embryologie de l’Ac-
teon, Ann. Se. Nat., 3e sér., 1846, vol. 6, p. 5.—
Beitrag zur Entwickelungsgeschichte eines Cepha-
lophoren, Zeitsch. f wiss. Zool., 1855, vol. 7, p. 162.
— ScuuttzE, (M.,) Ueber die Entwickelung des
Tergipes lacinulatus, Wiegm. Arch., 1849, L., p- 268.
— Warneck, (N. A.) Ueber die Bildung und
Entwickelung des Embryo bei Gasteropoden, Bull.
Soc. Imp., Moscou, 1850, vol. 28, I, p. 90.—
Scumipt, (O.,) Ueber die Entwickelung von Limax
agrestis, Miiller’s Arch., 1851, p- 278. — Lrypie,
(F.,) Ueber Paludina vivipara, ein Beitrag zur
nihern Kenntniss dieses Thieres in embryologischer,
anatomischer und histologischer Beziehung, Zeitsch.
74 ESSAY ON CLASSIFICATION.
Part I.
in their development than the Lamellibranchiata. Even among the terrestrial and
aquatic Pulmonata there are striking differences.
Some of the Pectinibranchiata are
remarkable for the curious cases in which their eggs are hatched and the young
developed, to an advanced state of growth.
The cases of Pyrula and Strombus are
among the most extraordinary of these organic nests. The embryology of Cepha-
lopods! has been masterly illustrated by Kolliker. )
There is still much diversity of opinion among naturalists, respecting the limits
of Articulata; some being inclined to separate the Arthropoda and Worms as dis-
f. wiss. Zool, 1850, vol. 2, p. 125.— KOLiiKeER,
(A.,) q. a, Zeitsch. f. wiss. Zool. vol. 4, p. 333 and
369. — Mixer, (J.,) Ueber verschiedene Formen
von Seethieren, Miiller’s Arch., 1854, p. 69. — Ueber
Synapta digitata und tiber die Erzeugung von
Schnecken in Holothurien, Berlin, 1852, 4to. fig. —
The remarkable case described in this paper, admits
of an explanation which Miiller has not considered.
It is known, that fishes penetrate into the cavity of
the body of Holothurie, through its posterior open-
ing. (De Bosset, Notice, etc., Mém. Soc. Sc. Nat.,
Neuch., 1839, vol. 2, 4to.) The similarity of Ento-
concha mirabilis with the embryonic shell of various
species of Littorine, such as Lacuna vincta, the
development of which I had an opportunity of study-
ing, suggests the possibility, that some species of this
family, of which there are many very small ones,
select the Synapta as their breeding place and leave
it after depositing their eggs, which may become con-
nected with the Synapta, as our Mistletoe or the
Orobanche and many other parasitic plants, with the
plants upon which they grow. — GEGENBAUER, (C.,)
Beitrige zur Entwickelungsgeschichte der Landgas-
teropoden, Zeitsch. f. wiss. Zool., 1852, vol. 3, p.371.— |
Untersuchungen iiber Pteropoden und Heteropoden,
Leipzig, 1855, 1 vol., 4to. fig.— Koren, (J.,) und
DANIELSSEN, (D. C.,) Bitrag til Pectinibranchiernes
Udviklingshistorie, Bergen, 1851, 8vo. ;, French Ann.
Se. Nat., 1852, vol. 18, p. 257, and 1853, vol. 19,
p- 89; also Germ. in Wiegm. Arch., 18538, p. 173. —
Norpmany, (At. V.,) Versuch einer Monographie
von Tergipes Edwardsii, St. Petersburg, 1844, 4to. —
Levcxkart, (R.,) Zoologische Untersuchungen, Gies-
sen, 1853-54, 4to., fig., 3d Fase. — Huxuey, (Tu. H.,)
On the Morphology of the Cephalous Mollusca, ete.,
Phils. Trans. R. Soc. 1853, L, p, 29.— Hoge,
-(JABEZ,) On the Development and Growth of the
Watersnail, Quart. Micr. Journ., 1854, p. 91.— Rerp,
(J.,) On the Development of the Ova of the Nudi-
branchiate Mollusca, Ann. and Mag. Nat. Hist., 1846,
vol. 17, p. 877.— Carpenter, (W. B.,) On the
Development of the Embryo of Purpura Lapillus,
Quart. Micr. Journ., 1848, p. 17.
1 KOLLER, (ALB.,) Entwickelungsgeschichte
der Cephalopoden, Zurich, 1844, 4to., fig.— VaN-
BeneveEN, (P. J.,) Recherches sur l’Embryogénie
des Sépioles, N. Mém. Acad. Brux., vol. 14, 1841.
— Corpstream, (Z.,) On the Ova of Sepia, Lond.
and Ed., Phil..Mag., Oct., 1833.— Duces, (ANT.,)
Sur le développement de ’embryon chez les Mollus-
ques Céphalopodes,. Ann. Sc. Nat., vol. 8, p. 107. —
RaruKeE, (H.,) Perothis, ein neues genus der Cepha-
lopoden, Mém. Ac. St. Petersb., 1834, vol. 2, p.
149. (Is the young of some Loligoid Cephalopod.) |
Mitne-Epwarps, (H.,) Observations. sur les sper-
matophores des Mollusques Céphalopodes, ete., Ann.
Se., n., 2de sér., vol.-3, p. 193. — KOLLixer, (A.,)
' Hectocotylus Argonaute Delle Chiaje und Heect.
Tremoctopodis K., die Minnchen .von Argonauta
Argo und Tremoctopus violaceus, Ber. Zool. Anst.
Wiirzburg, 1849, p. 69.—Mizver, (H.,) Ueber
das Miinnchen von Argonauta Argo und die Hecto-
eotylen, Zeitsch. f. wiss. Zool., vol. 4, p. 1.— VerRA-
ny, (J. B.,) et Voat, (C.,) Mémoire sur les Hec-
tocotyles et les males de quelques Céphalopodes,
Ann. Se. n., 8e sér., 1852, vol. 17, p. 147.— Rov-
LIN, (F. D.,) De la connaissance qu’ont. eue les
anciens du bras copulateur chez certains Céphalo-
podes, Ann. Sc. n., 3e sér., 1852, vol. 17, p. 188.—
Leucxart, (R.,) Zool. Unters. q. a.
Cron, METAMORPHOSES OF ANIMALS. 75
tinct branches, while others unite them into one. I confess I cannot see the ground
for a distinction. The worm-like nature of the larve of the majority of Arthropods
and the perfect homology of these larvae with the true Worms, seem to me to
show beyond the possibility of a doubt, that all these animals are built upon one
and the same plan, and belong, therefore, to one branch, which contains only three
classes, if the principles laid down in my second chapter are at all correct, namely,
the Worms, Crustacea, and Insects. As to the Protozoa, I have little confidence
in the views generally entertained respecting their nature. Having satisfied myself
that Colpoda and Paramecium are the brood of Planarie, and Opalina that of Dis-
toma, I see no reason, why the other Infusoria, included in Ehrenberg’s division
Enterodela? should not also be the brood of the many lower Worms, the develop-
ment of which has thus far escaped our attention. Again, a comparison of the early
stages of development of the Entomostraca with Rotifera might be sufficient to show, —
what Burmeister, Dana, and Leydig have proved in another way, that Rotifera are
The vegetable character of most of the Anen-
genuine Crustacea, and not Worms.
I have not yet been able to arrive at a
tera has been satisfactorily illustrated.
definite result respecting the Rhizopods, though they may represent, in the type of
Mollusks, the stage of yolk segmentation of Gasteropods. From these remarks it
should be inferred, that I do not consider the Protozoa as a distinct branch of the
animal kingdom, nor the Infusoria as a natural class.”
Taking the class of Worms, in the widest sense, it would thus embrace the
1 That Vorticellide are Bryozoa, has already
been stated above.
2 Scuuttze, (M.,) Beitriige zur Naturgeschichte
den Turbellarien, Greifswald, 1851, 4to., fig. — Zoo-
logische Skizzen, Zeitsch. f. wiss. Zool. 1852, vol. 4,
p. 178.— Mixer, (J.,) Ueber eine eigenthiimliche — trage Zur
Wurmlarve, ete. Archiv, 1850, p. 485.— DEsor, Zeitsch. f. wiss. Zool. 1851, vol. 3, p. 257.— Bei-
(E.) On the Embryology of Nemertes, with an Ap-
pendix on the Embryonic Development of Polynoe,
Boston Journ. Nat. Hist. 1850, vol. 6, p. 1; Miiller’s
Archiv, 1848, p. 511.— Agassiz, (L.,) Colpoda and
Paramecium are larve of Planaria, Proc. Am. Ass.
Adv. Sc., Cambridge, 1849, p. 489. — Girarp, (CH.,)
Embryonic Development of Planocera elliptica, Jour. 165.— AverBacn, (L.,) Ueber die Einzelligkeit
Ac. Nat. Se. Phil., 2d ser. 1854, vol. 2, p. 807.— der Amoeben Zeitsch. f. wiss. Zool. 1855, vol. 7,
Enrenzere, (C. G.,) Die Infusionsthierchen, ete., p- 3865. — Ueber Eneystirung von Oxytricha Pellio-
q. a.—Kirzine, (F. T.,) Ueber die Verwandlung nella, Zeitsch. f. wiss. Zool. 1854, vol. 5, p. 430.—
Crenkowsky, Ueber Cystenbildung bei Infusorien,
1849, vol. 1, p. 270.—Naxert, (C.,) Gattungen
einzelliger Algen, Zurich, 1849, 4to. fig.— Braun,
(A.,) Algarum unicellularium genera nova et minus
cognita, Leipzig, 1855, 4to. fig. — Coun, (F.,) Bei-
Entwickelungsgeschichte der Infusorien
triige zur Kenntniss der Infusorien, Zeitsch. f. wiss.
Zool. 1854, vol. 5, p. 420.— Ueber Encystirung von
Amphileptus fasciola, ibid. p. 434.—Scnuntzs, (M.,)
Ueber den Organismus der Polythalamien, Leipzig,
1854, 1 vol. fol. fig. — Beobachtungen iiber die Fort-
pflanzung der Polythalamien, Miiller’s Archiv, 1856,
der Infusorien in niedere Algenformen, Nordhausen,
1844, 4to. fig. —Srepozip, (C. Tx. i; *v.,) Ueber Zeitsch. f. wiss. Zool. 1855, vol. 6, p- 301.
einzellige Pflanzen und Thiere, Zeitsch. f. wiss. Zool. »
"6 ESSAY ON CLASSIFICATION. Parr I.
Helminths, Turbellarie, and Annulata.
The embryology of these animals still requires
careful study, notwithstanding the many extensive investigations to which they have
been submitted; the intestinal Worms especially continue to baffle the zeal of
naturalists, even now when the leading features of their development are ascertained.
The Nematoids undergo a very simple development, without alternate generations,
The Cestods and
Cystici, which were long considered as separate orders of Helminths, are now known
and as some are viviparous their changes can easily be traced.
to stand in direct genetic connection with one another, the Cystici being only
earlier stages of development of the Cestods? The Trematods exhibit the most
‘complicated phenomena of alternate generations; but as no single species has thus
far been traced through all the successive stages of its transformations, doubts are
1 Gren, (F.,) Beitriige zur Entwickelungsges-
chichte der Eingeweidewiirmer, Zeitsch. f. wiss. Zool.,
1852, vol. 4, p. 196.—Nexson, (H.,) On the Re-
production of the Ascaris Mystax, Philos. Trans.
R. Soc, 1852, IL, p. 563.— Gruse, (E.,) Ueber
einige Anguillulen und die Entwickelung von Gor-
dius aquaticus, Wiegmann’s Archiv, 1849, I., p. 358.
— Sresoxp, (C. Tu. E. v.,) Ueber die Wanderung
der Gordiaceen, Uebers. d. Arb. und Ver. schles.
Ges. f. vaterl. Kultur., 1850, p. 38.— MEISSNER,
(G.,) Beitrige zur Anatomie und Physiologie von
Mermis albicans, Zeitsch. f. wiss. Zool., 1853, vol. 5,
p- 207.— Beobachtungen iiber das Eindringen der :
Saamenelemente in den Dotter, Zeitsch. f. wiss.
Zool., 1855, vol. 6, p. 208, und 272. — Beitriige zur
Anatomie und Physiologie der Gordiaceen, Zeitsch. f.
wiss. Zool., 1855, vol. 7, p. 1.—K6x1tixer, (A.,)
Beitriige zur Entwickelungsgeschichte wirbelloser
Thiere, Miiller’s Archiv, 1843, ‘p. 68. — BaGeEr,
(H.,) Dissertatio inaug. de evolutione Strongyli au-
ricularis et Ascaridis acuminate, Erlangen, 1841,
Ato. fig. — Lerpy, (Jos.,) A Flora and Fauna within
living Animals, Smithson. Contrib. 1853, 4to. fig. —
Luscuxa, (H.,) Zur Naturgeschichte der Trichina
spiralis, Zeitsch. f. wiss. Zool. 1851, vol. 8, p. 69.—
Biscuorr, (Tx.,) Ueber Ei- und Samenbildung und
Befruchtung bei Ascaris Mystax, Zeitsch. f. wiss.
Zool., 1855, vol. 6, p. 377. — Widerlegung, des von
Dr. Keser bei den Najaden und Dr. Nevson bei
den Ascariden behaupteten Eindringens der Sper-
matozoiden in das Ei, Giessen, 1854, Ato. fig. —
Bestiitigung des von Dr. Newrort bei den Batra-
chiern und Dr. Barry bei den Kaninchen behaupte-
ten Eindringens der Spermatozoiden in das Ei, Gies-
sen, 1854, Ato.
* Van Benepen, (P. J.,) Les Helminthes Ces-
toides, etc., Bullet. Ac. Belg., vol. 16, et seq.; Mdém.
Ac. Brux., 1850, vol. 17, et seq. — KétirKer, (A.,)
Beitriige, etc., q.a.3 p. 81.— Sresoip, (C. Tu. E.
v.,) Ueber den Generationswechsel der Cestoden, ete.,
Zeitsch. wiss. Zool., 1850, vol. 2, p. 198.— Ueber
die Umwandlung von Blasenwiirmer in Bandwiirmer,
Uebers. d. Arb. und Ver. d. schles. Ges. f vaterl.
Kultur, 1852, p. 48.— Ueber die Verwandlung des
Cysticercus pisiformis in Tenia serrata, Zeitsch. f.
wiss. Zool., 1853, vol. 4, p. 400.—Ueber die Ver-
wandlung der Echinococcus-Brut in Tenien, Ibid.,
1853, p. 409. — Ueber die Band-und Blasenwiirmer,
nebst einer Einleitung iiber die Entstehung der Ein-
geweidewiirmer, Leipzig, 1854, 8vo. fig. — Hux ey,
(Tu. H.,) On the Anatomy and Development of
Echinococcus veterinorum, Ann. and Mag. Nat. Hist.
2d ser., vol. 14, p. 879. — KUCHENMEISTER, (FR.,)
Ueber die Umwandlung der Finnen (Cysticerci) in
Bandwiirmer (Tanie) Prag. Vierteljahrssch, 1852,
p- 106. — Wacener, (R. G.,) Die Entwickelung der
Cestoden, Bonn, 1855, 1 vol. 4to. fig. — MrIssNEr,
(G.,) Zur Entwickelungsgeschichte und Anatomie
der Bandwiirmer, Zeitsch. f. wiss. Zool., 1854, vol.
5, p. 880. — Levoxart, (R.,) Erziehung des Cysti-
cercus fasciolaris aus den Eiern der Tenia crassi-
collis, Zeitsch. f. wiss. Zool. 1854, vol. 6, p..139.
Guapy. Tf METAMORPHOSES OF ANIMALS. var
still entertained respecting the genetic connection of many of the forms which
appear to belong to the same organic cycle” It is also still questionable, whether
Gregarinze and Psorospermia are embryonic forms or not, though the most recent
investigations render it probable that they are” The development of the Annv-
lata, as they are now circumscribed, exhibits great variety ;? some resemble more
the Nematods, in their metamorphoses, Ww
1 NorpMANN, (AL. v.,) Micrographische Beitrage
zur Naturgeschichte der wirbellosen Thiere, ‘Berlin,
1832, 4to. tig. — Bosanus, (L.,) Zerkarien und ibr
Fundort, Isis 1818, vol. 4, p. 729. — Enthelmin-
tica Isis 1821, p. 162. Carus, Beobachtungen tiber
einen merkwiirdigen Eingeweidewurm, Leucochlori-
dium paradoxum, Nov. Act. Ac. Nat. Cur., vol. 17;
p. 85.— Sresozp, (C. Tu. E. v.,) Helminthologische
Beitriige, Wiegman’s Archiv, 1835, vol. 1, p. 49.—
Ueber die Conjugation des Diplozoon paradoxum,
etc., Zeitsch. f. wiss., Zool., 1851, vol. 8, p. 62.—
Gyrodactylus, ein ammendes Wesen. Zeitsch. f. wiss.
Zool., 1849, vol. 1, p. 847. — SrrenstRvP, (J.,) Ge-
nerationswechsel, etc., q. a. —Brruarz, (TH.,) Ein
Beitrig zur Helminthographia humana, Zeitsch. 1
wiss. Zool., 1852, vol. 4, p. 59. — AGASSIZ, (L.,) Zo6-
logical Notes, etc., Amer. Journ. Sc. and A. 1852, vol.
13, p. 425. — Barr, (K. E. v.,) Beitriige zur Kennt-
niss der niedern Thiere, Act. Nov. Nat. Cur. 1827,
vol. 13.— AvBErt, (H.,) Ueber das Wassergeftiss-
system, die Geschlechtsverhiltnisse, die Hibildung
und: die Entwickelung von Aspidogaster conchicola,
Zeitsch. f. wiss: Zool. 1855, vol. 6, p. 349. — LEIDY,
(Jos.,) Description of two new Species of Distoma,
with the partial History of one of them, Jour. Ac
Nat. Se. Phil. 1850, vol. 1, p. 301, fig.
2 Mutter, (J.,) Ueber eine eigenthiimliche
krankhafte parasitische Bildung, ete. _Miiller’s
Archiv, 1841, p. 477.— Ueber parasitische Bildun-
gen ete., Miiller’s Archiv, 1842, p. 193. —DuFrour,
(L.,) Note sur la Grégarine, etc., Ann. Se. Nat.,
1828, vol. 13, p. 366, fig. — Ibid., Qde sér., 1837,
vol. 7, p. 10.—Srepoxp, (C. Tu. E. v.,) Beitrage
ete., q. a3 p. 56-71. — HAMMERSCHMIDT, (C. Ep.,)
Helminthologische Beitriige, Isis 1838, p- 351.—
Kouirker, (A.,) Die Lehre von der thierischen
Zelle, etc., Zeitsch. wiss. Botanik. 1845, vol. i, p- 46,
while others, the Leeches for instance,
and p. 97.— Beitriige zur Kenntniss niederer Thiere,
Zeitsch. f. wiss. Zool. 1848, vol. i. p. 1.— HENLE,
(J.,) Ueber die Gattung Gregarina, Miiller’s Archiv,
1845, p. 369. — Franrzivs, (At. v.,) Observationes
quedam de Gregarinis, Berolini, 1846.—Srxtn, (F.,)
Ueber die Natur der Gregarinen, Miiller’s Archiv,
1848, p. 182, fig.—Brucu, (C.,) Einige Bemer-
kungen tiber die Gregarinen, Zeitsch. f. wiss. Zool.
1850, vol. 2, p. 110.— Luypie, (F.,) Ueber Proro-
spermien und Gregarinen, Miiller’s Archiv, 1851,
p- 221. — Lewy, (Jos.,) On the Organization of the
Genus Gregarina, Trans. Amer. Phil. Soc. 1851, vol.
10, p. 233. — Some Observations on Nematoidea im-
perfecta and Descriptions of three parasitic Infusoria,
Trans. Amer. Phil. Soc. 1851, vol. 10, p. 241.—
Lreperktinn, (N.,) Ueber die Psorospermien, Miil-
ler’s Archiv, 1854, p. 1.
8 Weber, (E. H.,) Ueber die Entwickelung von
Hirudo medicinalis, Meckel’s Archiv, 1828, p. 366,
fig. — Fiiieri, (Fit. pe,) Sopra Panatomia e lo svi-
luppo delle Clepsine, Pavia, 1839, 8vo. fig. — Loven,
(J.,) Beobachtungen iiber die Metamorphose einer
Annelide, K. Vet. Ac. Handl. 1840, Wiegmann’s
Archiv, 1842, vol. i, p. 302.— Oxrstep, (A. S.,)
Ueber die Entwickelung der Jungen bei einer Anne-
lide, ete., Wiegmann’s Archiv, 1845, vol. i., p. 20.—
Sars, (M.,) Zur Entwickelung der Anneliden, Wieg-
mann’s Archiv, 1845, vol. i, p. 11.— Mernes, (A..)
Zur Roth-Wiirmer Gattung Euaxes, Wiegmann’s
Archiv, 1845, vol. i, p. 24.— Grouse, (A. E.,). Zur
Anatomie und Entwickelung der Kiemenwiirmer,
Konigsberg, 1838, 4to.—Actinien, Echinodermen und
Wiirmer, etc., K6nigsberg, 1840, 4to. fig. — Unter-
suchungen tiber die Entwickelung der Clepsine, Dor-
pat, 1844.— Epwarps, (H. Mrine,) Observations
sur le développement des Annélides, Ann. Se. Nat.
3e sér. 1845, vol. 3, p. 145.— Kocu, (H.,) Einige
in gnats
Se
A Re TS
78 ESSAY ON CLASSIFICATION.
Part I.
approximate more the type of the Trematods. The Sipunculoids appear to be more
closely related to the Annulata than to the Holothurioids!
The class of Crustacea, on the contrary, may be considered as one of the best
known, as far as its zoUlogical characters and embryonic growth are concerned; the
only point still questioned being the relationship of the Rotifera2 In their mode
of development the Lernzans, the Entomostraca proper, and the Cirripeds agree as
closely with one another as they differ from the higher Crustacea.
This con-
formity* is the more interesting, as the low position the Entomostraca hold in the
Worte zur Entwickelungsgeschichte der Eunice, mit
einem Nachworte von Kdélliker, N. Denksch. Schw.
Gesell., 1847, vol. 8, 4to. fig. — QuaTREFAGES, (A.
DE,) Mémoire sur ?Embryogénie des Annélides, Ann.
Se. Nat. 3e sér., 1848, vol. 10, p. 153, fig. —DEsor,
(Ep.,) On the Embryology, ete, gq. a.— Lerpy,
(Jos.,) Descriptions of some American Annelida
abranchia, Journ. Ac. Nat. Se. Phil. 1850, vol. 2,
p- 48, fig., (Lumbricillus contained several thousand
large Leucophrys. The case related here by Leidy
seems to me to indicate rather the hatching of Opali-
nas from the eggs of Lumbricillus, than the presence
of parasitic Leucophrys.) —Scuuntze, (M.,) Ueber
die Fortpflanzung durch Theilung bei Nais probosci-
dea, Wiegman’s Archiv, 1849, I., p. 293; id. 1852,
I., p. 8.— Zoologische Skizzen (Arenicola piscat.)
Zeitsch. f. wiss. Zool. 1852, yol. 4, p. 192. — Buscu,
(W.,) Beob. iiber Anat. und Entw. q. a. (p. 55.) —
MUuuer, (M.,) Observationes anatomice de Vermi-
bus quibusdam maritimis, Berolini, 1852, 4to.; Miil-
ler’s Archiv, 1852, p. 323.—Ueber die weitere
_ Entwickelung von Mesotrocha sexoculata, Miiller’s
Archiv, 1855, p. 1.—Ueber Sacconereis helgolandica,
Miiller’s Archiv, 1855, p. 13. — Krouy, (A.,) Ueber |
die Ercheinungen bei der Fortpflanzung von Syllis,
Wiegman’s Archiv, 1852, I., p. 66.— Ueber die
Sprésslinge von Autolytus prolifer Gr., Miiller’s Ar-
chiv, 1855, p. 489.— LuucxKart, (R.,) Ueber die
ungeschlechtliche Vermehrung bei Nais proboscidea,
Wiegman’s Archiv, 1851, p. 134.— Ueber die Ju-
gendzustiinde einiger Anneliden, Wiegman’s Archiv,
1855, I., p. 63. ,
1 Peters, (W.) Ueber die Fortpflanzungsorgane
des Sipunculus, Miiller’s Archiv, 1850, p. 382.—
Miter, (M.,) Ueber eine den Sipunculiden ver-
wandte Wurmlarve, Miiller’s Archiv, 1850, p. 439.
— Krouy, (A.,) Ueber die Larve des Sipunculus
Miiller’s Archiv, 1851, p. 368.—
Scumarpa, (L.,) Zur Naturgeschichte der Adria
(Bonellia viridis) Denksch. Wien. Akad. 1852, vol.
4, p. 117, fig. — Geaenpaver, (C.,) Ueber die Ent-
wickelung von Doliolum, der Scheibenquallen und
nudus, etc.,
von Sagitta, Zeitsch. f. wiss. Zool. vol. 5, p. 13.
? EBRENBERG, (C. J.,) Die Infusionsthierchen,
etc., q. a. — DALRYMPLE, (J..) Description of an In-
fusory Animalcule allied to the Genus Notommata.
Philos. Trans. 1844, IL, p. 3381.— Narcei, (H.,)
Beitrige zur Entwickelungsgeschichte der . Rader-
thiere, inaug. Diss., Zurich, 1852, 8vo. fig. — Lrypie,
(Fr.,) Ueber den Bau und die systematische Stel-
lung der Riiderthiere, Zeitsch. f. wiss. Zool. 1854,
vol. 6, p. 1.— Zur Anatomie und Entwickelungsges-
chichte der Lacinularia socialis, Zeitsch. f. wiss. Zool.
1852, vol. 3, p. 452.— Coun, (F.,) Ueber die Fort-
pflanzung der Riiderthiere, Zeitsch. f. wiss. Zool.,
1855, vol. 7, p. 431. — Huxuey, (Tu. H.,) Lacinula-
ria socialis, Trans. M. Soc., Micr. Journ. 1852, p. 12.
— Wittiamson, (W. C.,) On the Anatomy of Meli-
certa ringens. Quart. Micr. Journ. 1852, p. 1.
* Jurine, (L.,) Histoire des Monocles qui se
trouvent aux environs de Geneve, Paris, 1806, 4to.
fig. — Epwarps, (H. Mitwne,) in Cuvier, Réen. An.
édit. illustr. q. a. Crustacés; represents young Li-
mulus.— ZappacH, (E. G.,) De Apodis cancrifor-
mis Anatome et Historia evolutionis Bonne, 1841,
Ato. fig. —Norpmann, (AL. v.,) Microgr. Beitr. q.
a.— Leypic, (FR.,) Ueber. Argulus foliaceus, ein
Beitrag zur Anatomie, Histologie und Entwickelungs-
geschichte dieses Thieres, Zeitsch. f. wiss. Zool. 1850,
vol. 2, p. 323.—- Ueber Artemia salina und Branchi-
Cuap. I. METAMORPHOSES OF ANIMALS. 79
class of Crustacea, agrees strikingly with their early appearance in geological times,
while the form of the adult Cirripeds' and that of the Lerneans would hardly
lead one to suspect their near relationship, which has, indeed, been quite overlooked
‘ until Embryology showed that their true position is among Crustacea. In the
development of the higher Crustacea,’ their superior rank is plainly exhibited, and
few types show more directly a resemblance, in their early stages of development,
to the lower members of their class, than the Brachyura.
I include Myriapods, Arachnoids, and the true Insects,
as, according to the views expressed hereafter, these natural groups constitute only
plication of the same combination of organic systems, and
In the class of Insects,
different degrees of com
must, therefore, be considered as natural orders of one and the same class. This
class, though very extensively studied im a zoological and anatomical point of view,
and as far as the habits of its representatives are concerned, still requires, however,
much patient work, as the early embryonic development of these animals has been
much less studied than their later transformations.’ The type of the Arachnoids
pus stagnalis, Zeitsch. f. wiss. Zool. 1851, vol. 3, ps 1829, 1 vol. fol. fig. — Beitriige zur Fauna Norve-
280. — VanBENxDEN, (P. J.,) Recherches sur quel-
ques Crustacés inférieurs Ann. Se. Nat. 3e sér. 1851,
vol. 16, p. 71.— Mémoire sur le développement et
Vorganisation des Nicothoés, Ann. Se. Nat. 3e sér.
1850, vol. 13, p. 354. — Barranpe, (J.,) Syst. sil. q-
a.; contains the first observations upon the transfor-
gica, Act. Nov. Ac. Leop. Ces. vol. 20. — Beitriige
zur vergleichenden Anatomie und Physiologie, Rei-
sebemerkungen aus Skandinavien, Dantzig, 1842,
Ato. — Zur Morphologie, Reisebemerkungen aus Tau-
rien, Riga und Leipzig, 1837, dto. fig. — Ueber die
Entwickelung der Decapoden, Miiller’s Archiv, 1836,
mations of Trilobites. p. 187, Wiegman’s Archiv, 1840, I, p. 241.—
1 THompson, (W. V.,) Zodlogical Researches
and Illustrations, or Natural History of nondescript
or imperfectly known Animals, Cork, 1828-34, 8vo.,
fig. — Burmeister, (H.,) Beitrige zur Naturge-
schichte der Rankenfiisser, (Cirripedia,) Berlin, 1834,
1 vol. 4to. fig—Goonsir, (H. D. S.,) On the Sexes,
Organs of Reproduction, and Development of Cirri-
peds, Ed. N.. Phil. J.. 1843, No. 35, p. 88, fig. —
Martin St. Ance, (G. J.,) Mémoire sur Vorganisa-
tion des Cirripédes et sur leurs rapports naturels
avec les animaux articulés, Ann. Se. Nat. 1831,
p- 366, fig. —Darwiy, (Cu.,) A Monograph of the
sub-class Cirripedia, with Figures of all the Species,
London, 1851, 2 vols. 8vo. (Ray Society.) — BATE,
(Srencr,) On the Development of the Cirripedia,
Ann. and Mag. Nat. Hist. 2d ser. vol. 8, p- 324,
2 RatuKe, (H.,) Untersuchungen iiber die Bil-
dung und Entwickelung des Flusskrebses, Leipzig,
Beobachtungen und Betrachtungen iiber die Entwi-
ekelung der Mysis vulgaris, Wiegman’s Archiv, 1839,
p. 195, fig.—Erpi, (M. P.,) Entwickelung des
Hummereies, Miinchen, 18438, 4to. fig. — Epwarps,
(H. Mixye,) sur la génération des Crustacés, Ann.
Sc, Nat. 1829.— Observations sur les changements
de forme que divers Crustacés éprouvent dans le
jeune Age, Ann. Sc. Nat. 2de sér. vol. 8, p. 821.
— Agassiz, (L.,) Zodlogical Notes, ete, Am. Jour.
Se. and A., 1852, p. 426.— Recent Researches, ete.,
Am. Journ. Se. and A., 1852, vol. 16, p. 136.
8 Heroxp, (M.,) Entwickelungsgeschichte der
Schmetterlinge, etc., Kassel und Marburg, 1815, 4to.
fig. — Disquisitiones de animalium vertebris caren-
tium in ovo formatione, Frankfurt a. M., 1835, fol.
fig. — Raruxe, (H.,) Entwickelungsgeschichte der
Blatta germanica, Meckel’s “Archiv, 1832. —. Zur
Entwickelungsgeschichte der Maulwurfsgrille (Gryl-
'
lint
gee eee OSES Ee
80 ESSAY ON CLASSIFICATION.
Part I.
embraces two groups, the Acari and the Arachnoids proper, corresponding respec-
tively in this class to the Entomostraca and the higher Crustacea. The embryo
of the Acari resembles somewhat that of the Entomostraca, whilst that of the true
On the ground of the
similarity of their young, some animals, formerly referred to the class of Worms?
Spiders’ recalls the metamorphosis of the higher Crustacea.
are now considered as Arachnoids; but the limits between the aquatic Mites and
the Pycnogonums are not yet quite defined.
In the branch of Vertebrata, all classes have been extensively studied, and as
far as the principal types are concerned, the leading features of their development
are satisfactorily known. Much, however, remains to be done to ascertain the minor
modifications characteristic of the different families. It may even be, that further
investigations will greatly modify the general classification of the whole branch.
The class of Fishes*? may require subdivision, since the development of the Plagios-
lotalpa- vulgaris,) Miiller’s Archiv, 1844, p..27.—
KoxiiKer, (A.,) Observationes de prima Insecto-
rum Genesi, Turici, 1842, 4to. fig. — Zappacu, (G.,)
Die Entwickelung des Phryganiden Kies, Berlin,
1 vol. 4to. 1854.— Levoxarpt, (R.,) Ueber die
Micropyle und den feinern Bau der Schalenhaut bei
den Insekteneiern, Miiller’s. Arch., 1855, p. 90.—
Newrort, (Gro.,) On the Organs of Reproduction
and the Development of Myriapoda, Phil. Trans. R.
Soe., 1842, II. p..99.—Srem, (FR.,) Vergeichende
Anatomie und Physiologie der Insecten, 1ste Monogr.,
Die weiblichen Geschlechtsorgane der Kifer, Berlin,
1847, fol. fig. —SreBoip, (C. Tu. E. v.,) Ueber die
Fortpflanzung von Psyche, Zeitsch. f. wiss. Zool.,
1848, vol..1, p.93.— Leypic, (FR.,) Einige Remer-
kungen iiber die Entwickelung der Blattliuse, Zeitsch.
f. wiss: Zool., 1850, vol. 2, p. 62. — Meyer, (H.,)
Ueber die. Entwickelung des Fettkérpers, der Tra-_
cheen: und der keimbereitenden Geschechtstheile bei
den Lepidopteren, Zeitsch. f. wiss. Zool., 1849, vol. 1-
— Burnett, (W. J.) Researches on the Develop-
ment of viviparous Aphides, Amer. Journ. Sci. and
Arts, 1854, vol. 17, p. 62 and 261.—.As far as the
metamorphoses of Insects, after the eclosion of the
larva, are concerned, I must refer to the works of
Reaumer and Roesel already quoted, and to almost
every modern book upon Entomology. The meta-
morphoses of North American Insects are minutely
described in Harris’s Report, q. a.
* Heroxp, (M.,) De generatione Aranearum in
ovo, Marburgi, 1824, fol. fig. — Raruxe, (H.,)
Zur Mor-
phologie, q. a. — VANBENEDEN, (P. J.,) Recherches
sur l’Histoire naturelle et le développement de l Atax
ypsilophora, Mém. Ac. Brux., 1850, vol. 24, p. 444.
— Wirticu, (W. H. v.,) Observationes quedam de
Ueber die Entwickelung des Scorpions;
aranearum ex ovo evolutione, Diss. inaug. Halis
Sax., 1845. — Die Entstehung des .Arachnideneies
im Eierstock, Miiller’s Arch., 1849, p. 113. — Carus,
(J. V.,) Ueber die Entwickelung des Spinneneies,
Zeitseh. f. wiss. Zool., 1850, vel. 2, p. 97. — Dusar-
DIN, (F.,) Mémoire sur des Acariens sans bouches,
dont ona fait le genere Hypopus et qui sont le
premier Age des Gamaoses, Ann. Se. Nat., 1849,
vol. 12, p. 248 et 259.
2 Kaurmann, (Jos.,) Ueber die Entwickelung
und zoologische Stellung der Tardigraden, Zeitsch.
f. wiss. Zool. 1851, vol. 8, p. 220.— VANBENEDEN,
(P. J.,) Recherches sur Vorganisation et le dévelop-
pement des Linguatules (Pentastoma,) Mém. Ac.
Brux. vol. 15, IL, p. 188.—Scuuserr, (T. D.,)
Ueber Entwickelung von Pentastomum tenioides
Zeitsch. f. wiss. Zool. 1852, vol. 4, p. 117.— Wir-
son, (E.,) Researches into the Structure and De-
velopment of a newly discovered Parasitic Animal-
cule of the. Human Skin, Phil. Trans. R. Soe. 1844,
p- 805.
§ ForcuHamMER, (G.,) De Blennii vivipari
Cuap. I. METAMORPHOSES OF ANIMALS.
81
toms differs greatly from that of the ordinary fishes. As it now stands in our sys-
tems, the class of Fishes is certainly the most heterogeneous among Vertebrata.
formatione et evolutione observationes, Kiel, 1819,
4to. — Prevost, (J. L.,) De la génération chez le
Séchot (Cottus Gobio), Mém. Soc. Phys. et Hist. Nat.,
Geneve, vol. 4, 1828, 4to. — Raruke, (H.,) Beitriige
zur Geschichte der Thierwelt, Halle, 1820-27, 4 vols.
4to. fig. — Abhandlungen zur Bildungs- und Ent-
wickelungsgeschichte des Menschen und der Thiere.
Leipzig, 1832-33, 2 vols. 4to. fig.— Ueber das Ki
einiger Lachsarten, Meckel’s Archiv, 1832, p. 392.—
Barr, (K. E. v.,) Untersuchungen iiber die Ent-
wickelungsgeschichte der Fische, Leipzig, 1835, 4to.
— Also Entw. der Thiere, q. a. vol. 2d.— DAvyY,
(J.,) On the Development of the Torpedo, Philos.
Trans. R. Soc., 1834. — Fiuiert, (Fix. pe,) Memoria
sullo sviluppo del Gobius fluviatilis, Anna. Medic.,
Milano, 1841, 8vo. fig. — Ruscont, (M.,) Sopra la
fecondatione artificiale nei pesci, Giorn. delle Se.
Med.-chir., Pavia, vol. 9; tranls. in Miiller’s Archiv,
1840, p. 185.— Lettre sur les changements que les
ceufs de Poissons éprouvent avant qu’ils aient pris la
forme d’embryon, Ann. Sc. Nat., 2de sér. vol. 55
transl. Mag. Zool. and Bot., L, p. 586.— AGAssiZ,
(L.,) Histoire naturelle des Poissons d’eau douce de
lV Europe centrale, vol. 1. Embryologie des Salmones,
par C. Voer, Neuchatel, 1842, 8vo. atlas fol. These
investigations were made under my direction and
supervision. — Mtuer, (J.,) Ueber den glatten Hai
des Aristoteles, und iiber die Verschiedenheiten unter
den Haifishen und Rochen in der Entwickelung des
Kies, Berlin, 1842, fol. fig. —LeucKart, (F. S.,)
Untersuchungen iiber die iiussern Kiemen der Em-
bryonen von Rochen und Haien, Stuttgardt, 1836,
8vo. fig. — Leypié, (FR.,) Beitriige zur microscopis-
chen Anatomie und © Entwickelungsgeschichte der
Rochen und Haie, Leipzig, 1852, 1 vol. 8vo. fig er
Carus, (C. G.,) Erliuterungstafeln, ete., No. 3, Leip-
zig, 1831, fol. fig. —Suaw, (J.,) Account of some
Experiments and Observations on the Parr, ete.,
Edinb. New Phil. Journ., vol. 21, p. 99. —On the
Development and Growth of the Fry of the Salmon,
ete., Ibid. vol. 24, p. 165; also Ann. Nat. Hist., I.
p- 75, and IV. p. 352.— YarReLy, (W.) Growth
; 11
of the Salmon in Fresh Water, Ann. and Mag. Nat.
Hist. IV. p. 884.—Duvernoy, (G. L.) Observa-
tions pour servir & la connaissance du développement
de la Pécilie de Surinam, An. Se. Nat., 1844, 8e sér.
I. p. 8138, fig.— Costr, (P.,) Histoire générale et
particuliere du développement des corps organisés,
Paris, 1847-53, 4to., Atl. fol., 2d Fase., Epinoche. —
QUATREFAGES, (ARM. DE,) Mémoire sur les Embry-
ons des Syngnathes, Ann. Se. Nat., 2de sér. vol. 18,
p- 193, fig. —Sur le développement embryonaire des
Blennies, etc., Comptes-Rendus, vol. 17, p. 320. —
VALENCIENNES, (A.,) Anableps in Cuvier et VALEN-
creNNES, Histoire naturelle des Poissons, Paris, 1846,
vol. 18, p. 245. — Wyman, (J.,) Observations on the
Development of Anableps Gronovii, Journ. Bost. Nat.
Hist., 1854, vol. 6, fig. — Acassiz, (L.,) Extra-
ordinary Fishes from California, constituting a new
family, Amer. Journ. Se. and A., 1853, vol. 16, p. 380.
— Embryology of Lophius americanus, Proc. Am. Ac.
1855.— LeREBOULLET, (A.,) Recherches sur l Ana-
tomie des organes génitaux des animaux Vertébrés,
N. Act. Ac. Nat. Cur., vol. 23, p. 1.— Ann. Se. Nat.,
4e sér. vol. 1.—Avsert, (H.,) Beitrage zur Ent-
wickelungsgeschichte der Fische, Zeitsch.. f. wiss.
Zool., 1853, vol. 5, p. 94; 1855, vol. 7.— VaLen-
vin, (G.,) Zur Entwickelungsgeschichte der Fische,
Zeitsch. f. wiss. Zool., 1850, vol. 2, p. 267. — Lrucx-
art, (R.,) Ueber die allmihlige Bildung der Korper-
gestalt bei den Rochen, Zeitsch. f. wiss. Zool., 1850,
vol. 2, p. 258. — Harcke, (E.,) Ueber die Eier der
Scomberesoces, Miiller’s Arch., 18955, p. 23. — Rer-
zius, (A.,) Ueber den grossen Fetttropfen in den
FEiern der Fische, Miiller’s Arch., 1855, pe o4, 6
Brucu, (C.,) Ueber die Micropyle der Fische,
Zeitsch. f. wiss. Zool., 1855, vol. 7, p. 172.— Rer-
cueRrt, (K. B.,) Ueber die Micropyle der Fischeier,
etc., Miiller’s :Arch., 1856, p. 83. — DowLer, (B.,)
Discovery of a Viviparous Fish in Louisiana, Amer.
Jour. Sc. and Arts, 1835, vol. 19, p. 183, with Remarks
by L. Acassiz, p. 186.—Scnutrzx, (M.,) Note sur le
développement des Pétromyzons, Comptes-Rendus,
1856, p. 836; Ann. and Mag. Nat. Hist., 2d. ser.
82 ESSAY ON CLASSIFICATION.
Parr I.
The disagreement of authors as to the limits and respective value of its orders and
families may be partly owing to the unnatural circumscription of the class itself?
As to the. Reptiles, it is already. certain, that the Amphibia and Reptiles proper, so
long united as one class, constitute two. distinct classes.
In the main, the develop-
ment of the true Reptiles? agrees very closely with that of the Birds, while the
Amphibians? resemble more the true fishes.
1856, vol. 17, p. 443.— Mixer, (A.,) Ueber die
Entwickelung der Neunaugen, Miiller’s Ach., 1856,
p- 803. The unexpected facts mentioned here, render
it highly probable, that Amphioxus is the immature
state of some marine Cyclostom.
1 The peculiarities. of the development of the
Plagiostoms consist not so much in the few large
eggs they produce, and the more intimate connection
which the embryo of some of them assumes with the
parent, than in the development itself, which, not-
withstanding the absence of an amnios and an allan-
tois, resembles closely, in its early stages, that of the
Reptiles proper and of the Birds, especially in the
formation of the vascular system, the presence of a
sinus terminalis, ete. Again, besides the more ob-
vious anatomical differences existing between the
Plagiostoms and the bony Fishes, it should be remem-
bered that, as in the higher Vertebrata, the ovary is
separated from the oviducts in the Sharks and Skates,
and the eggs are taken up by a wide fallopian tube:
That the Plagiostoms can hardly be considered sim-
ply as an order in the class of Fishes, could already
be inferred from the fact, that they do not constitute
I would,
therefore, propose the name of SeLacurans for a
a natural series with the other Fishes.
distinct class embracing the Sharks, Skates, and —
Chimeras. Recent investigations upon the Cyclos-
toms, show them also to differ widely from the
Fishes proper, and they too ought to be separated as
a distinct class, for which the name of MyzontTrs
may be most appropriate.
* Vorkmann, (G. W.,) De Colubri Natricis
Generatione, Lipsie, 1834, 4to.— RaruKe, (H.,)
Entwickelungsgeschichte der Natter, (Coluber Na-
trix,) Konigsberg, 1839, 4to. fig. — WrInLAND, (D..,)
Ueber den Eizahn der Ringelnatter, Wiirt. Nat.
Hist. Jahreshefte, 1855.— Timpemann, (F.,) Ueber
In no class are renewed embryological
das Ei und den Feetus der Schildkrite, Heidelberg,
1828, 4to. fig. — Barr, (K. E. v.,) Beitriige zur
Entwickelungsgeschichte der Schildkréten, Miiller’s
Archiv, 1834, p. 544.— RatuKe, (H.,) Ueber die
Entwickelung der Schildkréten, Braunschweig, 1848,
4to. fig.
* Roser vy. Rosennor, (A. J.,) Historia natu-
ralis Ranarum nostratium, ete., Norimb., 1758, fol.
fig. — Funx, (A. F.,) De Salamandre terrestris vita,
evolutione, formatione, etc., Berlin, 1826, fol. fig. —
Ratuxe, (H.,) Diss. de Salamandrarum corporibus
adiposis eorumque evolutione, Berol, 1818.— Ueber
die Entstehung und Entwickelung der Geschlechts-
theile bei den Urodelen, N. Schr., Dantz. Naturf. Ges.,
1820.—Sremuem, (L.,) Die Entwickelung der
Frésche, Hamburg, 1820, 8vo. fig. — Hassext, (J.
Conr., vAN,) Dissert. exhibens Observationes de
metamorphosi quarumdam partium Rane temporarie,
Gottinge, 1820, 8vo.— Prevost, (J. L.,) et Leserr,
Mémoire sur la formation des organes de la circula-
tion et du Sang dans les Batraciens, Ann. Se. Nat., 3e
sér. I. p. 198, fig. — Ruscont, (M.,) Développement
de la Grenouille commune, depuis le moment de sa
naissance jusqu’ & son état parfait, Milan, 1828, Ato.
fig. — Amours des Salamandres aquatiques et déve-
loppement du Tétard de ces Salamandres, ete., Milan,
1822, 4to. fig. — Barr, (K. E. v.,) Die Metamor-
phose des Eies der Batrachier vor der Erscheinung
des Embryo, ete. Miiller’s Archiv, 1834, p. 481.
— Entwickelungsgeschichte, etc., vol. 2d, p. 280. —
REICHERT, (K. B.,) Das Entwickelungsleben im Wir-
belthierreich, Berlin, 1840, 4to. fig. — Vergleichende
Entwickelungsgeschichte des Kopfes der nackten
Amphibien, etc., Kénigsberg, 1838, 4to. fig. — Ueber .
den Furchungsprocess der Batrachier-Kier, Miiller’s
Archiv, 1841, p. 523. — Voer, (C.,) Untersuchungen
iiber die Entwickelungsgeschichte der Geburtshelfer-
kréte, Solothurn, 1841, 4to. fig. — Quelques observa-
tions sur l’embryologie des Batraciens, Ann. Se. 1,
3e sér. vol. 2, p. 45. — Remak, (R.,) Untersuchungen
tiber die Entwickelung der Wirbelthiere, Berlin, 1855,
fol. — Newrort, (G.,) On the Impregnation of the
Ovum in the Amphibia, Philos. Trans. R. Soc., 1851,
I, p. 169.— Wirricn, (W. H. v.,) Beitriige zur mor-
phologischen und histologischen Entwickelung der
Harn- und Geschlechtswerkzeuge der nackten Amphi-
bien, Zeitsch. f. wiss. Zool., 1852, vol. 4, p.- 125.—
WEINLAND, (D.,) Ueber den Beutelfrosch, Miiller’s
Archiv, 1854, p. 449.— Wyman, (J.,) Observations
on Pipa americana, Am. Jour. Se. and Arts, 2d ser.
1854, vol. 17, p. 369. oe
1 PanpER, (Cur. H.,) Diss. sistens historiam
metamorphoseos quam ovum incubatum prioribus
quinque diebus subit, Wirceb. 1817, 8vo. — Beitrage
zur Entwickelungsgeschichte des Hiihnchens im Hie,
Wiirzb. 1817, fol. fig. — Barr, (K. E. v.,) Entwicke-
lungsgeschichte, etc. vol. 1.— Durrocuet, (H.,)
Histoire de lPceuf des Oiseaux avant la ponte, Bull.
Soc. Philom., 1819, p. 38. — Hunter, (Joun,) Obser-
vations on Animal Development, edited and his Ilus-
trations of that process in the Bird described by R.
Owen, London, 1841, fol. fig. — Prevost, (J. L.,)
Ann. Se. Nat., 1827, vol. 12, p. 415. — PREVOST, (J.
L.,) et Lesert, Mémoires sur la formation des
organes de la circulation et du sang dans l’embryon
du Poulet, Ann. Se. Nat. 3e sér. I. p. 265; II. p. 222,
fig. ; III. p. 96. — Bauprimonr, (A.,) et Marrin St.
ANGE, (G. J.) Recherches anatomiques et physiolo-
giques sur le développement du fetus, Paris, 1850,
4to. — Mecxet v. Hemspacn, (H.,) Die Bildung der
fiir partielle Furchung bestimmten Kier der Vogel,
ete., Zeitsch. f. wiss. Zool., 1852, vol. 3, p- 420. —
In no class are embryological investigations extend-
ing over a variety of families more needed than
in that of Birds, if we should ever derive any
Mémoire sur le développement du poulet dans Pout, »
Cuap. I. METAMORPHOSES OF ANIMALS. 83
investigations, extending over a variety of families, so much needed, as in that of
_ Birds, though the general development of these animals is, perhaps, better known
, than that of any other type;+ while the class of Mammalia? has found in Bischoff
Ce oi 3
a most successful and thorough investigator.
assistance from the knowledge of their development
for their natural classification.
2 For the papers relating to the foetal envelopes
and the placenta and also to the different systems
of organs or any organ in particular and for human
_ embryology generally, see Bischoff’s article “ Ent-
wickelungsgeschichte,” in R. Wagner’s Handworter-
buch der Physiologie, p. 867, where every thing that
has been done in this direction, up to the year 1843,
is enumerated. For more recent researches upon
these topics consult, also, MUtier’s Archiv, Wree-
man’s Archiv, SIEBOLD und KOLLIKER’s Zeitsch.
f. wiss. Zool., Mitne-Epwarps, Ann. Sc. Nat., and
the Annals and Magazine of Nat. Hist., ete.
8 Biscuorr, (Tu. L. W.,) Entwickelungsges-
chichte des Kaninchen-Eies, Braunschweig, 1842.
Ato. fig. — Entwickelungsgeschichte des Hunde-Kies,
Braunschweig, 1845, 4to. fig. — Entwickelungsges-
chichte des Meerschweinchens, Giessen, 1852, 4to. fig.
—Entwickelungsgeschichte des Rehes, Giessen, 1854,
Ato. fig. — Prevost, (J. L.,) et Dumas, (J. A.,) De
Ja génération chez les Mammiferes, etc., Ann. Sc. Nat.
1824, vol. 3, p. 113, fig. — Bosanus, (L.,) Observatio
~anatomica de foetu canino 24 dierum, ete, Act. Ac.
Nat. Cuv., vol. 10, p. 189, fig. — Costs, (P.,) Embry-
ogénie comparée, Paris, 1837, 8vo. Atlas 4to. — His-
toire particuliére et générale du développement des
corps organisés, q. a — Recherches sur le génération
des Mammiféres et le développement de la brebis,
Ann. Se. Nat., 1835, III. p. 78.— Recherches sur
la génération des Mammiftres, Paris, 1834, 4to. fig.
— Bernuarnt, (C. A.) Symbole ad Ovi Mamma-
lium historiam ante pregnationem, Vratisl., 4to., Miil-
ler’s Arch., 1835, p. 228. — Barry, (M.,) Researches
in Embryology, Phil. Trans. R. Soc. 1838, p. 801;
1839, p. 307; 1840, p. 529; 1841, p. 195. — Barr,
(H. E. v.,) q. a.— Owen, (R.,) On the Ova of
the Ornithorhynchus paradoxus, Phil. Trans. 1834,
p- 555.— On the Young of the Ornithorhynchus para-
84 ESSAY ON CLASSIFICATION. Parr I.
Embryology has, however, a wider scope than to trace the growth of individual
animals, the gradual building up of their body, the formation of their organs, and all
the changes they undergo in their structure and in their form; it ought also to
embrace a comparison of these forms and the successive steps of these changes
between all the types of the animal kingdom, in order to furnish definite standards
of their relative standing, of their affinities, of the correspondence of their organs in
all their parts. Embryologists have thus far considered too exclusively, the gradual
transformation of the egg into a perfect animal; there remains still a wide field of
investigation to ascertain the different degrees of similarity between the successive
forms an animal assumes until it has completed its growth, and the various forms of
different kinds of full-grown animals of the same type; between the different stages
of complication of their structure in general, and the perfect structure of their
kindred; between the successive steps in the formation of all their parts and the
various degrees of perfection of the parts of other groups; between the normal
course of the whole development of one type compared with that of other types, as
well as between the ultimate histological differences which all exhibit within certain
limits. Though important fragments have been contributed upon these different
points, I know how much remains to be done, from the little I have as yet been
able to gather myself, by systematic research in this direction.
I have satisfied myself long ago, that Embryology furnishes the most trustworthy
standard to determine the relative rank among animals. A careful comparison of
the successive stages of development of the higher Batrachians furnishes, perhaps, the
most striking example of the importance of such investigations. The earlier stages
of the Tadpole exemplify the structure and form of those Ichthyoids which have
either no legs, or very imperfect legs, with and without: external gills; next it
assumes a shape reminding us more of the Tritons and Salamanders, and ends with
the structure of the Frog or Toad. A comparison between the two latter families
might prove further, that the Toads are higher than the Frogs, not only on account
of their more terrestrial habits (see Sect. 16), but because the embryonic web, which,
to some extent, still unites the fingers in the Frogs, disappears entirely in the Toads,
and may be also, because glands are developed in their skin, which do not exist in
Frogs. A similar comparison of the successive changes of a new species of Comatula
discovered by Prof. Holmes, in the harbor of Charleston, in South Carolina, has
shown me in what relation the different types of Crinoids of past ages stand to
doxus, Trans. Zool. Soc., i. p. 221; Proe. Zodl. Soc., (Cu.,) Observations on the Reproductive Organs and
nu. p. 438;*Ann. Se: Nat., 2d ‘ser. ii. p. 303; iii. on the Foetus of Delphinus Nesarnak, Journ. Ac.
p- 299. — On the Generation of the Marsupial Ani- Nat. Sc. Phil, new ser. 1849, vol. 1, p. 267.
mals, ete, Phil. Trans. 1824, p. 333. — Meias, . 1 Aaassiz, (L.,) Twelve Lectures, etc., page 8.
Cuap. -I. METAMORPHOSES OF ANIMALS. 85
these changes, and has furnished a standard to determine their relative rank; as
it cannot be doubted, that the earlier stages of growth of an animal exhibit a |
condition of relative inferiority, when contrasted with what it grows to be, after |
it has completed its development, and before it enters upon those phases of its
existence which constitute old age, and certain curious retrograde metamorphoses
observed among parasites.
Comatula there exists a stem, by which the little animal is
In the young
or to the cirrhi of the parent; the stem is at first
attached, either to sea weeds,
simple and without cirrhi, supporting a globular head, upon which the so-called arms
are next developed and gradually completed by the appearance of branches; a few
cirrhi are, at the same time, developed upon the stem, which increase in number
until they form a wreath between the arms and the stem. At last, the crown
having assumed all the characters
from the stem, and the Comatula moves freely a
The classes of Crustacea and of Insects,’ are particularly instructive in this
has described the transformations of so many Crustacea,
upon this subject,’ for
of a diminutive Comatula, drops off, freeing itself
s an independent animal.’
respect. Rathke, however,
that I cannot do better than to refer to his various papers
details relating to the changes these animals undergo during their earlier stages of
that while the embryo of the highest Crustacea, the
structure the lowest types of this class, as the
shape of those of a higher order,
growth. I would only add,
Brachyura, resembles by its form and
Entomostraca and Isopoda, it next assumes the
the Macroura, before it appears with all the characteristics of the Brachyura.
the . best measure of the true affinities existing
that the affinities of animals can only be
the history of Zodlogy shows, on the con-
Embryology furnishes, also,
between animals. I do not mean to say,
ascertained by embryonic investigations ;
e study of the formation and growth of animals had
trary, that even before th
al relationship of most animals had
become a distinct branch of physiology, the gener
already been determined, with a remarkable d
tigations. It is, nevertheless, true, that in some remarkable instances, the knowledge
of the embryonic changes of certain animals
ties, while, in other cases, it has furnished a very ,
ships, which, before, could appear probable, but were still very problematical. Even
Cuvier considered, for instance, the Barnacles as a distinct class, which he placed
gave the first clue to their true affini-
welcome confirmation of relation-
1 A condensed account of the transformations of 2 See Acassiz’s Twelve Lectures, p. 62, and
the European Comatula, may be found in E.
Forsers’s History of the British Starfishes, p. 10.
3 will be illustrated taining the relative standing of every family.
Classification of Insects, etc., gq. a. It is expected
that Embryology may furnish the means of ascer-
The embryology of our specie
3
e La OV oO
in one of my next volumes. See above, page 79, note 2.
eoree of accuracy, by anatomical inves-
86 ESSAY ON CLASSIFICATION: Part I.
among Mollusks, under the name of Cirripeds. It was not wntil. Thompson! had
shown, what was soon confirmed by Burmeister and Martin St. Ange, that the
young Barnacle has a structure and form identical with that of some of the most
common Entomostraca, that their true position in the system of animals could be
determined; when they had to be removed to the class of Crustacea, among Articu-
lata. The same was the case with the Lerneans, which Cuvier arranged with the
Intestinal Worms, and which Nordmann has shown upon embryological evidence to
belong also to the class of Crustacea? Lamarck associated the Crmoids with Polypi,
and though they were removed to the class of Echinoderms by Cuvier, before the
metamorphoses of the Comatula were known, the discovery of their pedunculated
young furnished a direct proof that this was their true position.
Embryology affords further a test for homologies in contradistinction of analogies.
It shows that true homologies are limited respectively within the natural boundaries
of the great branches of the animal kingdom. |
The distinction between homologies and analogies, upon which the. English natu-
ralists have first. insisted,* has removed much doubt respecting the real affinities of
animals which could. hardly have been so distinctly appreciated before. It has
taught us to distinguish between real affinity, based upon structural conformity, and
similarity, based upon mere external resemblance in form and habits. But even after
this distinction had been fairly established, it remained to determine within what
limits homologies may be traced. The works of Oken, Spix, Geoffroy, and Carus,
show to what extravagant comparisons. a preconceived idea of unity may lead. It
was not until Baer had shown that the development of the four great branches of
the animal kingdom is essentially different,’ that it could even be suspected that
organs performing identical functions may be different in their essential relations to
one another, and not until Rathke’ had demonstrated that the yolk is im open
communication with the main cavity of the Articulata, on the dorsal side of the
animal, and not on the ventral side, as in Vertebrata, that a solid basis was ob-
tained for the natural limitation of true homologies. It now appears more and
more distinctly, with every step of the progress Embryology is making, that the
structure of animals is only homologous within the limits of the four great branches
1 Tuompson’s Zool. Researches, ete.; BurMEts- 5 See, above, Sect. IV., notes 1 and 2.
TER’S Beitriige, etc.; Martin St. Ancr, Mém. sur 6 Barr’s Entwickelungsgeschichte, vol. 1, p. 160
Porganisation, etc., quoted above, page 79, note 1. and 224, The extent of Baer’s information and the
2 NorpMANn’s Micrographische Beytriige, q. a. comprehensiveness of his views, nowhere appear so
3 THompson and Forpzs, q: a. page 79. strikingly as in this part of his work.
4 Swainson’s Geography and Classification, ete. 7 Raruxkr’s Unters. iiber Bild., etc., see, above, p.
See above, Sect. V., p. 20. . 79, note 2. ;
Cuap. I. METAMORPHOSES. OF ANIMALS 87
of the animal kingdom, and that general homology strictly proved, proves also
typical identity, as special homology proves class identity.
The results of all embryonic investigations, of modern times go-to show more
and more extensively, that animals are entirely independent of external causes in
their development. The identity of the metamorphoses of oviparous and viviparous
animals belonging to the same type, furnishes the most convincing evidence to that
effect... Formerly it was supposed that the embryo could be affected directly by
external influences to such an extent, that monstrosities, for instance, were ascribed to
the influence of external causes. Direct observation has shown, that they are
founded upon peculiarities of the normal course of their development? The snug
berth in which the young undergo their first transformation in the womb of their
mother in all Mammalia, excludes so completely the immediate influence of any
external agent, that it is only necessary to allude to it, to show how independent
their growth must be of the circumstances in which even the mother may be placed.
This is equally true of all other viviparous animals, as certain snakes, certain sharks,
the uniformity of temperature in the nests of birds,
and the viviparous fishes. Again,
of influences which might otherwise reach
and the exclusion, to a certain degree,
them, in the various structures animals build for the protection of their young or of
8 that the instinct of all animals leads them to remove
their eggs,’ show distinctly,
or to make these agents sub-
their progeny from the: influence of physical agencies,
servient to their purposes, as in the case of the ostrich.
Mollusks bury their eggs to subtract them from varying influences; fishes deposit
them in localities where they are exposed to the least changes. Insects secure theirs
Reptiles and terrestrial
1 This seems the most appropriate place to re- based, is, of course, the mode of development of the
mark, that the distinction made between viviparous Sor
ther oviparous or viviparous, agree with one another ;
In this respect we find that Selachians, whe-
and oviparous animals is not only untenable as far as
their first origin in the egg is concerned, but also un- this is also the case with the bony fishes and the rep-
physiological, if it is intended, by this designation, to tiles, whether they are respectively oviparous or vivi-
convey the idea of any affinity or resemblance in their parous; even the placentalian and non-placentalian
‘ , i ith one another i i i
respective modes of development. Fishes show more Mammalia agree with o er in what is essential
distinctly than any other class, that animals, the devel- in their development. Too much importance has thus
opment of which is identical, in all its leading feat-
ures, may-either be viviparous or oviparous; the dif-
far been attached to the connections in which the germ
of the transformations of the germ itself.
2 Bisuorr, (Tu. L. W.,) in R. Waener’s Hand-
ference here arising only from the connection in
which the egg is developed, and not from the devel-
opment itself. Again, viviparous and oviparous ani- wérterbuch der Physiologie, Article “ Entwickelungs-
Fé ° 59 4 :
mals of different classes differ greatly in their devel- geschichte,” p. 885.
gos ® Burpacu’s Physiologie, ete., q. a. vol. 2, 2d ed.
Sect. 8334-38. See, also, Kirpy and Spencr’s Intro-
duction, ete., q. a
opment, even though they may agree in laying €
or bringing forth living young. The essential feature
upon which any important generalization may be
is developed, to the exclusion of the leading features -
88 ESSAY ON CLASSIFICATION. Part I.
in various ways. Most marine animals living in extreme climates, lay their eggs in
winter, when the variations of external influences are reduced to a minimum.
Everywhere we find evidence that the phenomena of life, though manifested in. the
midst of all the most diversified physical influences, are rendered independent of
them to the utmost degree, by a variety of contrivances prepared by the animals
themselves, in selfprotection, or for the protection of their progeny from any influ-
ence of physical agents not desired by them, or not subservient to their own ends.
SECTION XIX.
DURATION OF LIFE.
There is the most extraordinary inequality in the average duration of the life of
different kinds of animals and plants. While some grow and reproduce themselves
and die in a short summer, nay, in a day, others seem to defy the influence of
time.
Who has thus apportioned the life of all organized beings? To answer this
question, let us first look at the facts of the case. In the first place, there is no
conformity between the duration of life and either the size, or structure, or habitat
of animals; next, the system, in which the changes occurring during any period are
regulated, differs in almost every species, there being only a slight degree of unt
formity between the representatives of different classes, within certain limits.
In most Fishes and the Reptiles proper, for instance, the growth is very gradual
and uniform, and their development continues through life, so much so that their
size is continually increasing with age.
In others, the Birds, for instance, the growth is rapid during the first period of
their life, until they have acquired their full size, and then follows a period of equl-
librium, which lasts for a longer or shorter period in different species.
In others still, which also acquire within certain limits a definite size, the Mam-—
malia, for instance, the growth is slower in early life, and maturity is attained, as in
man, at an age which forms a much longer part of the whole duration of life.
In Insects, the period of maturity is, on the contrary, generally the shortest,
while the growth of the larva may be very slow, or, at least, that stage of develop-
ment last for a much longer time than the life of the perfect Insects. There is no
1 ScHUBLER, (Gust.,) Beobachtungen tiber jahr- Thier- und Pflanzenreich, Tiibingen, 1831, 8vo.—
liche periodisch wiederkehrende Erscheinungen im QueETELET, (A.,) Phénoménes périodiques, Ac. Brux,
Cuap. I. DURATION OF LIFE.
more striking example of this peculiar mode of growth than the seventeen years
locust, so fully traced by Miss M. H. Morris’
While all longlived animals continue, as a matter of course, their existence
through a series of years, under the varying influence of successive seasons, there
are many others which are periodical in their appearance; this is the case with most
insects? but perhaps in a still more striking manner with Meduse.*
The most interesting point in this subject is yet the change of character which
takes place in the different stages of growth of one and the same animal. Neither
Vertebrata, nor Mollusks, nor even Radiata exhibit im this respect any thing so
remarkable in the continuous changes which an individual animal may undergo, as
_ the Insects, and among them those with so-called complete metamorphoses, in which
the young (the larva) may be an active, wormlike, voracious, even carnivorous
being, which in middle life (the chrysalis) becomes a mummylike, almost motionless
maggot, incapable of taking food, ending life as a winged and active insect. Some
of these larvee may be aquatic and very voracious, when the perfect insect is aérial
and takes no food at all. |
Is there any thing in this regulation of the duration of life in animals which
recalls the agency of physical forces? Does not, on the contrary, the fact, that
while some animals are periodical and bound to the seasons in their appearance,
and others are independent of the course of the year, show distinctly their independ-
ence of all those influences which, under a common expression, are called physical
causes? Is this not further illustrated in the most startling manner by the extraor-
dinary changes, above alluded to, which one and the same animal may undergo
Does this not prove directly the immediate
during different periods of its life?
ling all these external influences, as well
intervention of a power capable of control
as regulating the course of life of every being, and establishing it upon such an
immutable foundation, within its cycle of changes, that the uninterrupted action of
these agents shall not interfere with the regular order of their natural existence?
There is, however, still another conclusion to be drawn from these facts: they
point distinctly at a discriminating knowledge of time and space, at an appreciation
of the relative value of unequal amounts of time and an unequal repartition of
small, unequal periods over longer periods, which can only be the attribute of a
thinking being.
1 Harrrs’s Insects injurious to Vegetation, p. 184. 4 BurMEIsTer’s Handb. d. Entom. ete. —Lacor-
2 Herotp, (E.,) Teutscher Raupen-Kalender, DAIRE, Introd. & ’Entomologie, etc. — Kirpy and
Nordhausen, 1845. SpeNCcE, Introd. to Entomol., ete., q. a., give accounts
8 Acassiz’s Acalephs of North America, p. 228. of the habits of Insects during their metamorphosis.
12
89
ESSAY ON CLASSIFICATION.
© ECT LON. : 26.85
ALTERNATE GENERATIONS.
While some animals go on developing gradually from the first formation of their
germ to the natural end of their life, and bring forth generation after generation, a
‘progeny which runs with never varying regularity through the same course, there
are others which multiply in various ways, by division and by budding, or by a
strange succession of generations, differing one from the other, and not returning, by
a direct course, to their typical cycle.
The facts which have led to the knowledge of the phenomena now generally
known under the name of alternate generation, were first observed by Chamisso and
Sars, and afterwards presented in a methodical connection by Steenstrup, in his
famous pamphlet on that subject? As a brief account of the facts may be found in
almost every text-book of Physiology, I need not repeat them here, but only refer
to the original investigations, in which all the details known upon this subject may
be found? These facts show, in the first place with regard to Hydroid Meduse, that
the individuals born from eggs, may be entirely different from those which produced
the eggs, and end their life without ever undergoing themselves such changes as
would transform them into individuals similar to their parents;* they show further,
1 Much information useful to the zodlogist, may
be gathered from Braun’s paper upon the Budding
of Plants, q. a., p. 18, note 8. The process of multi-
plication by budding or by division, and that of sexual
reproduction, are too often confounded by zodlogists,
and this confusion has already led to serious mis-
constructions of well known facts.
2 STEENSTRUP, (J.,) Ueber den Generationswech-
sel, q. a., p. 69, note 3.
® See the works quoted above, page 69, note 3,
and p. 70, note 1, also Carus, (V.,) Zur nihern Kennt-
niss des Generationswechsels, Leipzig, 1849, 8vo. —
Einige Worte iiber Metamorphose und Generations-
wechsel, Zeitsch. f. wiss. Zool., 1851, vol. 3, p. 39.
— OweEN, (R.,) On Parthenogenesis, or the Succes-
sive Production of Procreating Individuals from a.
single Ovum, London, 1849, 8vo.—On Metamor-
phosis and Metagenesis, Ann. and Mag. Nat. Hist.,
2d ser. vol. 8, 1857, p. 59.— Proscn, (V.,) Om
Parthenogenesis og Generationsvexel et Bidrag til
Generationsleren, Kidbenhavn, 1851.— LeucKart,
(R.,) Ueber Metamorphose, ungeschlechtliche Ver-
mehrung, Generationswechsel, Zeitsch. f. wiss. Zool,,
vol. 8, 1851.— Dana, (J. D.,) On-the Analogy
between the Mode of Reproduction in Plants and the
observed in some
Radiata, Amer. Journ. A. and Se., 2d ser. vol. 10,
p. 341. — EnrensBere, (C. G.,) Ueber die Formen-
“ Alternation of Generations”
bestiindigkeit und den Entwickelungskreis der orga-
nischen Formen, Monatsber. der Akad., Berlin, 1852,
8yvo.
4 Polymorphism among individuals of the same
species is not limited to Acalephs ; it is also observed
among genuine Polyps, the Madrepores, for example,
and among Bryozoa, Ascidians, Worms, Crustacea
(Lupea), and even among Insects (Bees).
Cuap. I. ALTERNATE GENERATIONS. 91
that this brood originating from eggs, may increase and multiply by producing new
individuals like themselves (Syncoryne), or of two kinds (Campanularia), or even indi-
viduals of various kinds, differing all to a remarkable extent, one from the other,
(Hydractinia,) but in neither case resembling their common parent. None of these
new individuals have distinct reproductive organs, any more than the first indi-
viduals born from eggs, their multiplication taking place chiefly by the process of
budding; but as these buds remain generally connected with the first individual
Geniiothons Wareastancanice compound communities, similar to some polypstocks.
Now some of these buds produce, at certain seasons, new buds of an entirely differ-
ent kind, which generally drop off from the parent stock, at an early period of their
development, (asin Syncoryna, Campanularia, etc.) and then undergo a succession of
changes, which end by their assuming the character of the previous egg-laying
individuals, organs of reproduction of the two sexes developmg meanwhile in them,
which, when mature, lead to the production of new eggs; In others (as in Hydrac-
tinia,) the buds of this kind do not drop off, but fade away upon the parent. stock,
after having undergone all their transformations, and also produced in due time, a
number of eggs! —
In the case of the Meduse proper,’ the parent lays eggs, from which originate
polyplike individuals; but here these individuals divide by transverse constrictions
into a number of disks, every one of which undergoes a succession of changes, which
end in the production of as many individuals, each identical with the parent, and
capable in its turn, of laying eggs, (some, however,
But the polyplike individuals born from eggs may also multiply by budding and
the first, the base of which does not die, but
ting the same process.
being males and others females. )
each bud undergo the same changes as
is also capable of growing up again and of repea
In other classes other phenomena of a similar character have been observed,
which bear a similar explanation. J. Miiller? has most fully illustrated the alter-
nate generations of the Echinoderms; Chamisso, Steenstrup, Eschricht, Krohn, and
Sars, those of the Salps;* von Siebold, Steenstrup, and others, those of certain Intes-
tinal Worms
This alternate generation differs essentially from metamorphosis, though some
1 I have observed many other combinations of a Siphonophora, see the works quoted above, p. 69,
similar character among the Hydroid Medusx, which
I shall describe at full length in my second volume ;
and to which I do not allude here, as they could not ® Mitier, (J.,) Ueber den allgemeinen Plan,
etc., q. a, p. 70, note I.
note 3.
2 See SIEBOLD, and Sars, q. a., p. 69, note 3.
be understood without numerous drawings. The
case of Hydractinia is not quite correctly repre-
sented in the works in which that animal has been 5 See the works, q. a. page 76, note 2, and 77,
described. Respecting Physalia and the other _ note 1.
* See the works, q. a., page 72, note 4.
|
al
snes i a: Al. Mes iit a tla i i os
TR EAE. itt lin es: iti A Re MaRS eae em one “d
92 | ESSAY ON CLASSIFICATION. Part I.
writers have attempted to identify these two processes. In metamorphosis, as
observed among Insects, the individual born from an egg goes on undergoing change
after change, in direct and immediate succession, until it has reached its final trans-
formation; but however different it may be at different periods of its life, it is
always one and the same individual. In alternate generations, the individual born
from an egg never assumes through a succession of transformations the character of
its parent, but produces, either by internal or external budding or by division, ‘a
number, sometimes even a large number of new individuals, and it is this progeny
of the individuals born from eggs, which grows to assume again the characters of
the egg-laying individuals.
There is really an essential difference between the sexual reproduction of most
animals, and the multiplication of individuals in other ways. In ordinary sexual
reproduction, every new individual arises from an egg, and by a regular succession
of changes assumes the character of its parents. Now, though all species of animals
reproduce their kind by eggs, and though in each there is at least a certain number
of individuals, if not all, which have sprung from eggs, this mode of reproduction 1s
not the only one observed among animals. We have already seen how new individ-
uals may originate from buds, which in their turn may produce sexual individuals ;
we have also seen how, by division, individuals may also produce other individuals
differing from themselves quite as much as the sexual buds, alluded to above, may
differ from the individuals which produce them. There are yet, still other com-
binations in the animal kingdom. In Polyps, for instance, every bud, whether it
is freed from the parent stock or not, grows at once up to be a new sexual
individual; while in many animals which multiply by division, every new individual
thus produced assumes at once the characters of those born from egos.' There
is, finally, one mode of reproduction which is peculiar to certain Insects, in which
several generations of fertile females follow one another, before males appear again?
What comprehensive views the physical agents must be capable of taking, and
what a power of combination they must possess, to be able to ingraft all these
complicated modes of reproduction upon structures already so complicated !— But
if we turn away from mere fancies and consider the wonderful phenomena just
alluded to, in all their bearings, how instructive they appear with reference to this
very question of the influence of physical agents upon organized bemgs! For here
we have animals endowed with the power of multiplying in the most extraordinary
ways, every species producing new individuals of its own kind, differing to the utmost
from their parents. Does this not seem, at first, as if we had before us a perfect
1 MitnE-Epwarps, Rech. anat. et zool. faites pen- 2 Owen, Parthenogenesis, etc., q. a., p. 90.—Bon-
dant un Voyage sur les cétes de Sicile, 3 vols. Ato. fig. NET, (Cu.,) Traité d’Insectologie, ete., Paris, 1745.
Cuap. I. SUCCESSION OF ANIMALS AND PLANTS. 93
exemplification of the manner in which different species of animals may originate, one
from the other, and increase the number of types existing at first? And yet, with all
this apparent freedom of ‘transformation, what do the facts finally show? That all
these transformations are the successive terms of a cycle, as definitely closed within
precise limits, as in the case of animals, the progeny of which resembles for ever
the immediate parent, in all successive generations. For here, as everywhere in
the organic kingdoms, these variations are only the successive expressions of a
well regulated cycle, ever returning to its own type.
SECTION “XA
SUCCESSION OF ANIMALS AND PLANTS IN GEOLOGICAL TIMES.
Geologists hardly seem to appreciate fully, the whole extent of the intricate
relations exhibited by the animals and plants whose remains are found in the
different: successive geological formations.
ting the zodlogical and botanical characters of these remains
I ‘do not mean to say, that the mvesti-
gations we possess respec : ;
are not remarkable for the accuracy and for the mgenuity with which they have
having myself thus far devoted the better part of
been traced. On the contrary,
I have learned early, from the difficul-
my life to the investigation of fossil remains, 3
ties inherent in the subject, better to appreciate the wonderful skill, the high
the vast erudition displayed in the investigations of Cuvier
intellectual powers
ages! But I cannot refrain
and his successors upon the faune and florz of past
1 Cuvier, (G.,) Recherches sur les Ossemens 2 vols. 8vo. — Histoire des Végétaux fossiles, Paris,
fossiles de Quadrupédes, etc., Paris, 1812, 4 vols.
Ato.; nouv. édit. Paris, 1821-23, 5 vols. 4to.; 4e
édit. 10 vols. 8vo. and 2 vols. pl. 4to. — SOWERBY,
(JameEs,) The Mineral Conchology of Great Britain,
London, 1812-19, 6 vols. 8vo. fig. —SCHLOTTHEIM,
(E. F. v.,) Die Petrefactenkunde, ete., Gotha, 1820,
8vo. fig. — Lamarck, (J. B. pz,) Mémoires sur les
fossiles des environs de Paris, Paris, 1823, 4to. fig. —
Go.tpruss, (G. A.,) Petrefacta Germanie, Diissel-
dorf, 1826-33, fol. fig. — STERNBERG, (Kaspar, M.
Gr. v.,) Versuch einer geognostisch-botanischen Dar-
stellung der Flora der Vorwelt, Leipzig und Prag,
1820-88, fol. tig. — Broneniart, (AD.,) Prodrome
@une Histoire des Végétaux fossiles, Paris, 1818, description of species may be found in Brown,
1828-43, 2 vols. 4to. fig. — Linpiey, (J.,) and Hur-
ton, (W.,) The Fossil Flora of Great Britain, Lon-
don, 1831-87, 3 vols. 8vo.—GopprrT, (H. R.,)
Systema Filicum fossilium, Vratisl. et Bonne, 1836,
Ato. fig. — Die Gattungen der fossilen Pflanzen, ver-
glichen mit denen der Jetztwelt, etc., Bonn, 1841-
48, 4to. fig. — Monographie der fossilen Coniferen.
Diisseldorf, 1850, 4to. fig. — More special works are
quoted hereafter, but only such works shall be men-
tioned, which have led on, in the progress of Geology
and Paleontology, or contain full reports of the pres-
ent state of our science, and also such as have
special reference to America. References to the
94 ESSAY ON CLASSIFICATION. Part I.
from expressing my wonder at the puerility of the discussions in which some geol-
ogists allow themselves still to indulge, in the face of such a vast amount of well
digested facts as our science now possesses. They have hardly yet learned to see
that there exists a definite order in the succession of these innumerable extinct
begs; and of the relations of this gradation to the other great features exhibited
by the animal kingdom, of the great fact, that the development of life is the promi-
nent trait in the history of our globe,’ they seem either to know nothing, or to
look upon it only as a vague speculation, plausible perhaps, but hardly deserving
the notice of sober science.
It is true, Paleontology as a science is very young; it has had to fight its
course through the unrelenting opposition of ignorance and prejudice. What amount
of labor and patience it has cost only to establish the fact, that fossils are really
the remains of animals and plants that once actually lived upon earth? only those
Then it had to be proved,
that they are not the wrecks of the Mosaic deluge, which, for a time, was the
prevailing opinion, even among scientific men?
know, who are familiar with the history of science.
After Cuvier had shown, beyond
question, that they are the remains of animals no longer to be found upon earth,
among the living, Paleontology acquired for the first time a solid basis. Yet what
an amount of labor it has cost to ascertain, by direct evidence, how these remains
are distributed in the solid crust of our globe, what are the differences they exhibit
in successive formations what is their geographical distribution, only those can
(H. G.,) Index palzontologicus, Stuttgart, 1848-49,
3 vols. 8vo. — See also, KEFERSTEIN, (CHR.,) Ge-
schichte und Literatur der Geognosie, Halle, 1840,
1 vol. 8vo.— Arcuiac, (Vic. D’,) Histoire des pro-
gres de la Géologie, Paris, 1847, et suiv, 4 vols.
8vo.; and the Transactions, Journals, and Proceed-
ings of the Geological Society of London, of Paris,
of Berlin, of Vienna, ete.; also, Leonyarp and
Bronn’s Neues Jahrbuch, ete.
1 Acassiz’s Geological Times, ete., q. a, p- 29,
note 2. — Dana’s Address to the Amer. Ass. for Adv.
Se. 8th Meeting, held at Providence, 1855.
? Scirita, (Ae.,) La vana speculazione desin-
Napoli, 1670, 4to. fig.
° Scueucuzer, (J. J.,) Homo Diluvii testis et
Seooxonos, Tiguri, 1726, 4to.—BucKxianp, (W.,)
Reliquiz diluviane, or Observations on the Organic
Remains attesting the Action of an Universal Deluge,
London, 1826, 4to. fig.
gannata dal senso.
4 For references respecting the fossils of the
oldest geological formations, see the works, quoted
above, p. 23, note 1. Also, McCoy, (F.,) Synopsis
of the Silurian Fossils of Ireland, Dublin, 1846, 4to.
fig. — Grernitz, (H. D.,) Die Versteinerungen der
Grauwackenformation, Leipzig, 1850-53, 4to. fig. —
And for local information, the geological reports of
the different States of the Union, a complete list of
which, with a summary of the Geology, may be found
‘in Marcov’s (J.,) Résumé explicatif d’une carte
géologique des Etats-Unis, Bull. Soc. Géol. de
France, Paris, 1855, 2de sér. vol. 12.—For the
Devonian system: Puitures, (Joun,) Figures and
Descriptions of the Palwozoic Fossils of Cornwall,
Devon, and Westsomerset, etc., London, 1841, 8vo. —
ARCHIAC, (Vic. D’,) and VERNEUIL, (Ep. DE,) Me-
moir on the Fossils of the Older Deposits in the
Rhenish Provinces, Paris, 1842, 4to. fig. — Sanp-
BERGER, (G. UND FR.,) Systematische Beschreibung
Cap. I.
SUCCESSION OF ANIMALS AND PLANTS. 95
fully appreciate, who have had a hand in the work* And even now, how many
important questions still await an answer !
und Abbildung der Versteinerungen des Rheinischen
Schichtensystems in Nassau, Wiesbaden, 1850-54,
— Ato. fig. — For the Carboniferous period: PHILLIPS,
(J.,) Illustrations of the Geology of Yorkshire, Lon-
don, 1836, 2d vol. 4to. fig. — DeKoyrnox, (L.,)
Descriptions des animaux fossiles qui se trouvent
dans le terrain houiller de la Belgique, Lidge, 1842,
2 vols. Ato. fig.; suppl., ete. — McCoy, (FR.,) Synop-
sis of the Carboniferous Fossils of Ireland, Dublin,
1844, 4to. fig. — Germar, (E. Fr.,) Die Versteine-
rungen des Steinkohlengebirges, Halle, 1844-53,
fol. fig. — Gernitz, (H. B.,) Die Versteinerungen
der Steinkohlenformation, Leipzig, 1855, fol. fig. —
For the Permian system: QUENSTEDT, (A.,) Ueber
die Identitiit der Petrificate des Thiiringischen und
Englischen Zechsteins, Wiegman’s Archiv, 1839, I,
p. 75. — Gernirz, (H. B.,) und Gutsier, (A.,) Die
Versteinerungen des Zechsteingebirges, etce., Dres-
den, 1849, 4to. fig. — Kiva, (W.,) Monograph of
the Permian Fossils of England, (Paleont. Soe.,)
London, 1850, 4to. fig. — For the Triasic system:
Arzerti, (FR. v.,) Beitrag zur einer Monographie
des bunten Sandsteins, Mushelkalks, und Keupers,
Stuttgart und Tiibingen, 1834, 8vo. — For the Jura,
Pures, (J.,) Illustrations of the Geology of York-
shire, York, 1829, vol. 1, 4to. fig. — Puscn, (G. G.,)
Polens Paleontologie, etc., Stuttgart, 1836, 4to. fig.—
Romer, (Fr. A.,) Die Versteinerungen des nord-
deutschen Oolithen-Gebirges, Hannover, 1836, 4to.
fic. — ZinreN, (C. H. v.,) Die Versteinerungen Wir-
tembergs, Stuttgart, 1830-34, fol. fig. — ORIBGNY,
(Axo. @,) Paléontologie frangaise, Paris, 1840-53,
8vo. fig. — Morris, (J.,) and Lycertt, (J.,) Mollusca
from the Great Oolite, (Paleont. Soc.,) London,
1850-55, 4to. fig. — For the Cretaceous pertod: Mor-
TON, (S. G.,) Synopsis of the Remains of the Creta-
ceous Group of the United States, Philadelphia, 1834,
8vo. fig. — Orpreny, (ALC. d’,) Paldont. frang., q- a
— Gernirz, (H. Br.,) Charakteristik der Schichten
und Petrefakten des Kreidegebirges, Dresden, 1839-
42, Ato. fic. —Proret, (F. J.) et Roux, (W.)
Description des fossiles qui se trouvent dans les gres
verts des environs de Genéve, Mém. Soc. Phys., ete.,
Genéve, 1847-52, vol. 12 et 13.— Romer, (F. A.,)
Die Versteinerungen des norddeutschen Kreidege-
birges, Hannover, 1841, 4to. fig. — Die Kreide-
bildungen von Texas, Bonn, 1852, 4to. fig. — Reuss,
(A. E.,) Die Versteinerungen der béhmischen Kreide-
formation, Stuttgart, 1845-46, 4to. fig. — MU ier,
(Jos.,) Monographie der Petrefacten der Aachener
Kreideformation, Bonn, 1851, 4to. fig. — SHARPE,
(D.,) Fossil Remains of Mollusca found in the Chalk
of England, (Palxont. Soc.,) London, 1854, 4to. fig. —
Hart, (James,) Cretaceous Fossils of Nebraska,
Trans. Amer. Acad., 1856, vol. 5.— For the Zer-
taries: Broecut, (G. B.,) Conchiologia fossile sub-
appennina, etc., Milano, 1814—48, 2 vols., 4to. fig. —
DesHayes, (G. P.,) Description des coquilles fossiles
des environs de Paris, 1824-37, 3 vols. 4to. Atl. —
Broyn, (H. G.,) Italiens Tertiiirgebilde, Heidelberg,
1831, 8vo.— Lea, (I.,) Contributions to Geology,
Philadelphia, 1833, 8vo. fig. — Conran, (T. A.)
Fossil Shells of the Tertiary Formations of North
America, Philadelphia, 1832-86, 8vo. fig. — GRATE-
Loup, (Dr.,) Conchyliologie fossile du bassin de
Y Adour, ete., Bordeaux, 1837, 8vo. fig. — MATHERON,
(PH.,) Catalogue méthodique et descriptif des corps
organisés fossiles, etc., Marseilles, 1842, 8vo. —
Berenpt, (G. C.,) Organische Reste im Bernstein,
Berlin, 1845-54, fol.. fig.— Woop, (S. V.,) A
Monograph of the Crag Mollusks, (Paleont. Soc.,)
1848-50, 4to. fig. — Epwarps, (F. E.,) Eocene
Mollusca, (Paleont. Soe.,) London, 1849-52, 4to. fig.
_ _ Horvess, (M.,) Die fossilen Mollusken des Ter-
tiir-Beckens von Wien, Wien, 1851, 4to. fie. —
Berricu, (E.,) Die Conchylien des norddeutschen
Tertiiirgebirges, Berlin, 1854-56, 8vo. fig.—Twvo-
MEY, (M.,) and Hormes, (Fr. S.,) Fossils of South
Carolina, Charleston, 1855-56, 4to. fig.
1 Bucu, (L. v.,) Pétrifications recueillies en
Amérique par Mr. Alex. de Humboldt et par Mr.
Ch. Degenhard, Berlin, 1838, fol. fig. — Orpreny,
(Atc. p’,) Voyage dans l Amérique Méridionale, etc.,
Paris, 1834-43, 7 vols. 8vo. Atl. 4to. — ARCHIAC,
ESSAY ON CLASSIFICATION. Part I.
One result, however, stands now unquestioned: the existence during each great
geological erat of an assemblage of animals and plants differing essentially for each
period. And by period I mean those minor subdivisions in the successive sets
of beds of rocks, which constitute the stratified crust of our globe, the number of
which is daily increasing, as our investigations become more extensive and more
precise” What remains to be done, is to ascertain with more and more precision,
the true affinities of these remains to the animals and plants now living, the rela-
tions of those of the same period to one another, and to those of the preceding
and following epochs, the precise limits of these great eras in the development
of life, the character of the successive changes the animal kingdom has undergone,
the special order of succession of the representatives of each class,’ their combina-
(Vic. d’,) et Harmer, (J.,) Description des animaux
fossiles du groupe nummulitique de l’Inde, Paris,
18538, 4to. fig. — Levoxart, (F. S.,) Ueber die
Verbreitung der iibriggebliebenen Reste einer vor-
weltlichen Schépfung, Freiburg, 1835, 4to.
1 Geological text-books: DeLaBrcukg, (Sir H. T.,)
Geological Manual, London, 1833, 1 vol. 8ve.; Ger-
man Trans. by Dechen; French by Brochant de Vil-
lers.— The Geological Observer, London, 1851, 8vo.
— Lye tt, (Sir C.,) Manual of Elementary Geology,
London, 1851, 1 vol. 8vo.— Principles of Geology,
etc., London, 1830, 2 vols. 8vo.; 8th edit., 1850,
1 vol. 8vo.— Naumann, (C. Fr.,) Lehrbuch der
Geognosie, Leipzig, 1850-54, 2 vols. 8vo. Atl. 4to.—
Voart, (C.,) Lehrbuch der Geologie und Petrefakten-
kunde, Braunschweig, 1854, 8vo. 2 vols., 2d edit. —
Text-books on Fossils: Bronn, (H. G.,) Lethea
Geognostica, Stuttgart, 1835-37, 2 vols., 8vo. Atl.
fol.; 3d edit. with Fr. Raemer, 1846, et seq. —
Piorut, (F. J.,) Traité élémentaire de Paléontologie, _
ete., Paris, 1844-45, 4 vols., 8vo. fig.; 2de édit. 1853
et seq., 8vo. Atl. 4to.—OrBieny, (Atco. d’,) Cours
élémentaire de Paléontologie, Paris, 1852, 3 vols.,
12mo. — Giese, (E. G.,) Fauna der Vorwelt, Leip-
zig, 1852, 2 vols. 8vo.— Allgemeine Paleontologie,
Leipzig, 1852, 1 vol., 8vo.— Quenstept, (F. A.,)
Handbuch der Petrefaktenkunde, Tiibingen, 1852,
8vo. fig. Unfortunately, there exists not a single
English text-book of Paleontology. A translation
of Pictet’s and Bronn’s works would be particularly
desirable.
_? At first, only three great periods were distin-
guished, the primary, the secondary, and the tertiary ;
afterwards, six or seven, (DelaBéche); later, from
ten to twelve; now, the number is almost indefinite,
at least undetermined in the present stage of our
knowledge, when many geologists would only con-
sider as subdivisions of longer periods, what some
paleontologists are inclined to consider as distinct
periods.
8 The principal Monographs relating to special
classes or families, are the following; Polyps and
Infusoria: Micuewin, (H.,) Iconographie Zoophy-
tologique, Paris, 1841-45, 4to. fig. — Epwarps, (H.
Mixye,) et Hamme, (J.,) Recherches, ete., q. a., p. 31.
— Polypiers fossiles des terrains paléozoiques, Arch.
Mus., vol. 5.— Monograph of the British Fossil
Corals, Paleont. Soc., London, 1850-55, 4to. fig. —
Lonspa.e, (W.,) On the Corals from the Tertiary
Formations of North America, Journ. Geol. Soc., I,
p- 495; Sill. Journ., 2d ser. IV., p. 857. — McCoy,
(Fr.,) Contributions to British Paleontology, Cam-
bridge, 1854, 1 vol. 8vo. fig. — References to all
minor papers may be found in Edwards and Haime’s
Recherches. — Enrenbere, (C. G.,) Mikrogeologie,
Leipzig, 1854, fol. fig. — Echinoderms: MILER, (J.
C.,) A Natural History of the Crinoidea, Bristol,
1821, 4to. fig. — Orpiany, (Ac. D’,) Histoire
naturelle générale et particuliére des Crinoides vivans
et fossiles, Paris, 1840, 4to. fig. — Austin, (TH. and
Tu. Jr.,) Monograph on Recent and Fossil Crinoidea,
Bristol, 4to. fig. (without date.) — Hatz, (J.,)
Cuap. I. SUCCESSION OF ANIMALS AND PLANTS. OF
tions into distinct faunse during each period, not to speak of the causes, or even
the circumstances, under which these changes may have taken place.
Paleont. of New York, q. a.— Goipruss, (G. A.,)
Petref. Germ., q. a. — DeKontncx, (L.,) et LeHon,
(H.,) Recherches sur les Crinoides, etc., Bruxelles,
1854, 4to. fic. —Owen, (D. D.,) and SHUMARD, (B.
F.,) Description of New Species of Crinoidea, Journ.
Ac. Nat. Se., Philad. 1850, 4to. fig. — SISMONDA,
(E.,) Monographia degli Echinidi fossili del Pie-
monte, Torino, 1840, 4to. fig.— DzsMovutins, (C)
Etude sur les Echinides, Bordeaux, 1835-37, 8vo.
fic. — Acassiz, (L.,) Monogr. Echin., q. a., p- 94.—
Catalogue raisonné, ete., q. a. p. 31. I quote this
paper under my name alone, because that of Mr.
Desor, which is added to it, has no right there. It
was added by him, after I had left Europe, not only
without authority, but even without my learning it,
for a whole year. The genera Goniocidaris, Mespi-
Jia, Boletia, Lenita, Gualteria, Lovenia, Breynia,
which bear his name, while they should bear mine,
as I have established and named them, while Mr.
-Desor was travelling in Sweden, were appropriated
-by him, without any more right, by a mere dash of the
pen, while he was carrying my manuscript through
the press. How many species he has taken to him-
self, in the same manner, I cannot tell. As the
printed work, and a paper presented by me to the
Academy of Sciences of Paris, in 1846, exhibit, for
every one acquainted with zodlogical nomenclature,
internal evidence of my statement, such, for instance,
as my name left standing as authority for the species
of Mespilia, Lenita, Gualteria, and Breynia, while
the genus bears his, I need not allude further to the
subject. This is one of the most extraordinary cases
of plagiarism I know of. — Dzsor, (E.,) Synopsis des
Echinides fossiles, Paris, 1854-56, 8vo. fig.; partly
reprinted from my Catalogue, with additions and
figures. — Bucn, (L. v.,) Ueber die Cystideen, Ber-
lin, 1844, 4to. fie.; Ak. d. wiss.—Mixrer, (J.,)
Ueber den Bau der Echinodermen, Berlin, 1854, 4to.
fig. — Rormer, (F.,) Ueber Stephanocrinus, etc.,
Wiegm. Arch., 1850, p. 865. — Monographie der
fossilen Crinoidenfamilie der Blastoideen, ete., Wiegm.
Arch., 1851, p. 323.—Forsus, (Ep.) Echino-
13
dermata of the British Tertiaries, (Paleont. Soc.,)
1852, 4to. fig.—Mem. of the Geol. Surv. of the
Unit. Kingdom, London, 1849, 8vo. fig., Dec. 1st, 3d,
and 4th.— Mollusks: DesHayes, (G. P.,) Traité
élémentaire de Conchyliologie, etc., Paris, 1835-39,
2 vols. 8vo. fig. — Description des coquilles carac-
téristique des terrains, Paris, 1831, 8vo. fig. — Woop-
warp, (S. P.,) A Manual of the Mollusca, ete.,
London, 1851-54, 12mo. fig.— Hacrnow, (Fr..v.,)
Die Bryozoen der Maastrichter Kreideformation,
Cassel, 1851, 4to. fig. — DesMourins, (C.,) Essai
sur les Sphérulites, Bull. Soc. Lin., Bordeaux, 1827.
—Roguan, (O. R. pu,) Description des Coquilles
fossilles de la famille des Rudistes, etce., Carcassonne,
1841, 4to. fig.—Hoxrnrnenaus, (Fr. W.,) Mono-
graphie der Gattung Crania, Diisseldorf, 1828, 4to.
fic. — Bucu, (L. v.,) Ueber Terebrateln, etc., Berlin,
1834, Ato. fig. ; Ak. d. wiss. — Ueber Productus und
Leptena, Berlin, 1842, 4to. fig.; Ak. d. wiss. —
Davipson, (TuH.,) British Brachiopoda, (Paleont.
Soc.,) London, 1851-55, 4to. fig. — DeKonincx, (L.,)
Recherches sur les animaux fossiles, Liége, 1847, 4to.
fig.— Agassiz, (L.,) Etudes crit. q. a., p. 54.— Favre,
(A.,) Observations sur les Dicerates, Genéve, 1843,
4to. fig. — Brrtarpi, (L.,) e Micuerorrs, (G.,)
Saggio orittografico sulla classe dei Gasteropodi fossili,
Torino, 1840, 4to. fig. — DrHaan, (W.,) Mono-
graphie Ammoniteorum et Goniatiteorum Specimen,
Lugduni-Batav., 1825, 8vo.— Bucn, (L. v.,) Ueber
Ammoniten, tiber ihre Sonderung in Familien, etc.,
Berlin, 1832, 4to. fig. Ak. d. wiss.— Ueber Gonio-
titen und Clymenien in Schlesien, Berlin, 1839, 4to.
fig.; Ak. d. wiss. — Munster, (Gr. v.,) Ueber
Goniatiten und Planuliten im Uebergangskalk, ete.,
Baireuth, 1832, 4to. fig.— Vourz, (Pu. L.,) Obser-
vations sur les Bélemnites, Paris, 1830, 4to. fig. —
Quenstevr, (F. A.) De Notis Nautileorum pri-
mariis, ete., Berolini, 1834, 8vo. — Crustacea: Bron-
@NIART, (AL.,) et Dusmarest, (A. G.,) Histoire
naturelle des Trilobites, etc., Paris, 1822, 4to. fig. —
Datman, (J. W.,) Ueber die Palwaden oder die
sogenannten Trilobiten, a. d. Schwed., Niirnberg,
Se
oa a ne rn mene
—
RR ec
98 ESSAY ON CLASSIFICATION.
Part I.
In order to be able to compare the order of succession of the animals of past
ages with some other prominent traits of the animal kingdom, it is necessary for
1828, 4to. fig. — Green, (J.,) A Monograph of the
Trilobites of North America, ete., Philadelphia, 1833,
8vo. fig. — Emmertcn, (H. F.,) De Trilobitis, Bero-
lini, 1839, 8vo. fig. — Zur Naturgeschichte der Trilo-
biten, Meiningen, 1844, 4to. — Burmeister, (H.,)
Die Organisation der Trilobiten, Berlin, 1843,
Ato. fig.; (Ray Society.) — Bryricu, (E.,) Ueber
einige béhmische Trilobiten, Berlin, 1845, 4to.; 2d
part, 1846, 4to.— Corpa, (A. J. C.,) und Haw _e,
(Ie.,) Prodrom einer Monographie der bohmischen
Trilobiten, Prag, 1848, 8vo. fig. — BARRANDE, (J.,)
Syst. Sil., q. a. p. 238. — Satter, (J. W.,) In Mem.
Geol. Surv., ete., Dec. 2d. — Mtnster, (Gr. G. v.,)
Beitriige zur Petrefaktenkunde, Beyreuth, 1839, 4to.
2d Fase., fig. — Meyer, (H. v.,) Neue Gattungen
fossiler Krebse, etce., Stuttgart, 1840, 4to. fig. — DE
Konrnck, (L.,) Mémoire sur les Crustacés fossiles
de Belgique, Liége, 1841, 4to. fig. — Cornvrt, (J.,)
Description des Entomostracés fossiles, ete., Mém. Soe.
Géol. de France, 2de sér., vol. 1, part 2d, Paris,
1846, 4to. fig. — Bosqurr, Description des Ento-
mostracés fossiles de la Craie de Mestricht, Mém.
Soc. Roy. de Liege, 1847, 8vo.—Jonezs, (T. R.,)
The Entomostraca of the Cretaceous Formation of
England, (Palzont. Soc.,) London, 1848, 4to. fig. —
Darwin, (Cu.,) Fossil Cirripedia, (Paleont. Soc.,)
London, 1851 and 1854, 4to. fig. — Insects: Bropre,
(P. B.,) History of the Fossil Insects of the Second-
ary Rocks of England, London, 1845, 8vo.— Her,
(O.,) Die Insektenfauna der Tertiiirgebilde von
Oeningen und von Radeboy, Leipzig, 1853, 4to..
fig.; N. Denx., helv. Gessellsch.— Heer, (O.,) et
Escuer v. DER Lintu, (A.,) Zwei geologische Vor-
trage, etc, Ziirich, 1852, 4to.— PMishes: AGassiz,
(L.,) Rech. s. les poiss. foss., q. a., p. 54. — EGERTON,
(Str Puit.,) A Systematic and Stratigraphical Cata-
logue of the Fossil Fishes, etc., London, 1837, 4to.
2d edit.— On some new Ganoid Fishes, Proc. Geol.
Soc. London, IV., p. 188. — On some New Species of
Chimeroid Fishes, Ibid., p. 153 and 211,.and several
other papers in Trans. Geol. Soc. Lond.; Journ.
Geol. Soc.; Ann. and Mag. Nat. Hist., and Memoirs
of the Geol. Surv. of the United Kingdom, Dec. 6th.
— Picret, (F. J.,) Poissons fossiles du Mt. Liban,
Genéve, 1850, 4to. fig. — Hecxet, (J. J.,) Beitrige
zur Kenntniss der fossilen Fische Oesterreichs, Wien,
1849, 4to. fig. — Gippes, (R. W.,) Monograph of the
Fossil Squalide of the United States, Journ. Ac. Nat.
Se. Philadelphia, 1848 and 1849, 4to. fig. — New
Species of Myliobates, Ibid., 1849, p. 299. — McCoy,
(F.,) In Sedgwick and McCoy’s British Paleoz.
Rocks, q. a., p. 23. — NewBerRY, (J. 8.,) Fishes of
the Carbonif. Deposits of Ohio, Proc. Ac. Nat. Se.,
Philadelphia, 1856. — Reptiles: Cuvier, (G.,) Rech.
Oss. foss., q. a, p. 93.—JaEcER, (G. Fr.,) Ueber
die fossilen Reptilien welche in Wiirtemberg aufge-
funden worden sind, Stuttgart, 1828, 4to. fig. —
Grorrroy Sr. Hivaree, (Er.,) Recherches sur les
grands Sauriens, ete., Paris, 1831, 4to. fig. — Drs-
LONGCHAMPS, (Eup.,) Mém. sur le Poecilopleuron —
Bucklandi, Caen, 1837, 4to. fig. — Bronn, (H. G.,)
und Kavp, (J. J.,) Abhandlungen iiber die Gavial-
artigen Reptilien, Stuttgart, 1842, fol. fig. —Goxp-
Fuss, (A.,) Der Schiadelbau des Mosasaurus, N. Act.
Ac. Nat. Car., 1844, 4to. fig. — Auton, (E. p’,) und
Burmeister, (H.,) Der fossile Gavial von Boll,
Halle, 1854, fol. fig. — Burmeister, (H.,) Die
‘Labyrinthodonten, Berlin, 1850, 4to. fig. — QuEN-
stept, (A.,) Die Mastodonsaurier sind Batrachier,
Tiibingen, 1850, 4to. fig. — Gippes, (R. W.,) A
Memoir on Mosasaurus and three New Genera, etc.,
Smithson. Contrib. 1851, 4to. fig. — Meyer, (H. v.,)
Zur Fauna der Vorwelt, Die Saurier des Muschel-
-kaikes, ete, Frankfurt a. M., 1845-52, fol. — Mryrr,
(H. v.,) und Piienincer, (Te.,) Beitrige zur Pale-
ontologie Wiirtembergs, Stuttgart, 1844, 4to. fig.— ©
Owen, (R.,) Report on British Fossil Reptiles, Brit.
Ass. 1839, p. 43; 1841, p. 60.— Fossil Reptilia of
the London Clay, (Paleont. Soc.,) London, 1849, 4to.
fiz. (the Chelonia with T. Bei.) — Fossil Reptilia
of the Cretaceous Formation, (Palzont. Soc.,) Lon-
don, 1851, 4to. fig. — Fossil Reptilia of the Wealden
Formation, (Palzont. Soc.,) London, 1852-55, 4to.
fig. — Lea, (1.,) On a Fossil Saurian of the New
Cuap. I. SUCCESSION OF ANIMALS AND PLANTS. 99
me to make a few more remarks upon. this topic. I can, fortunately, be very
brief, as we possess a text-book of Paleontology, arranged in zodlogical order, in
which every one may at a glance see how, throughout all the classes of the animal
kingdom, the different representatives of each, in past ages, are distributed in the
e % ° 1
successive geological formations.
From such a cursory survey, it must appear, that
while certain types prevail durmg some periods, they are entirely foreign to others.
This limitation is conspicuous,
while, in other types,
frequently only to the genera or the species. |
we shall see presently, that all these types bear, as far as
ned, the closest relation to the relative rank
their range in time,
the order of their succession is concer
of living animals
with reference to entire classes among Vertebrata,
it relates more to the orders, or to the families, and extends
But, whatever be the extent of
of the same types compared with one another, to-the phases of
the embryonic growth of these types in the present day, and even to their geo-
graphical distribution upon the present surface of our globe. I will, however, select
Red Sandstone, etc., Philadelphia, 1852, 4to. fig. —
Lerpy, (Jos.,) Description of Extinct Mammalia and
Chelonia from Nebraska Territory, in D. D. OWEN,
Geol. Surv. of Wisconsin, Iowa, Minesota, etc.,
Philadelphia, 1852, 4to. fig. — On Bathygnathus
borealis, an extinct Saurian, Journ. Ac. Nat. Se.,
Philad., 1854, 4to. fig. — Description of a New Species
of Crocodile, ete., Ibid., 1851. — Birds: Owen, (B.,)
History of British Fossil Mammalia and Birds, Lon-
don, 1844-46, 1 vol. 8vo. fig. — Fossil Birds from the
Wealden, Journ. Geol. Soc., II., p. 96. — Memoir on
the Dinornis, Trans. Zool. Soc., vol. 3, p. 8,. London,
1844, 4to. fig. — Mammalia: Cuvimr, (G.,) Oss. foss.,
q. a. — Bucxianp, (W.,) Rel. Diluv., q. a, p- 94. —
DeEBLarnvit_e, (Ducr.,) Ostéographie ou Descrip-
tion iconographique comparée du Squelette, etc,
Paris, 1841, et suiv. 4to., Atlas fol. —Kavp, (J. J.;)
Descriptions d’ossemens fossiles de Mammiferes incon-
nus, Darmstadt, 1832-39, 4to. fig. —Owern, (R.,).
Odontography, or a Treatise on the Comparative
Anatomy of the Teeth, London, 1840-41, 3 vols. 8vo.
fig. — Brit. foss. Mam. and Birds, q. a. —The Fossil
Mammalia of the Voyage of H. M. S. BEAGLE,
London, 1838, 4to. fig. — Description of the Skeleton
of an extinct gigantic Sloth, Mylodon robustus, Lon-
don, 1842, 4to. fig.; and many papers in Journal
of Geological Society; Trans. Zool. Society, etc. —
ScumERLING, (P. C.,) Recherches sur les ossemens
fossiles des cavernes de Liege, Liege, 1833-36,
2 vols. 4to. fig. — CroizeT et Jopert, Recherches
sur les ossemens fossiles du département du Puy-de-
Dome, Paris, 1828, fol. fig. — Meyer, (H. v.,) Zur
Fauna, etc., q. a — Die fossilen Zahne und Knochen,
in der Gegend von Georgensgmiind, Frankfurt a. M.,
1834, Ato. fig. —JAEGER, (G. FR.,) Die fossilen
Siugethiere Wiirtembergs, Stuttgardt, 1835-39, fol.
fig. — Farcoyer, (H.,) and Cavriey, (P. T.,)
Fauna antiqua sivalensis, etc., London, 1846, fol. fig.
-— Gervais, (P.,) Zoologie et Paléontologie fran-
caises, Paris, 1848-52, to. fig. — MUier, (J.,)
Ueber die fossilen Reste der Zeuglodonten, ete.,
Berlin, 1849, fol. fig. —LeConre, (J.,) On Platy-
gonus compressus, Mem. Amer. Acad. Arts and Se.,
1848, 4to. fig. — Wyman, (J.,) Notice of the Geo-
logical Position of Castoroides ohioensis, by J. Haut,
and an Anatomical Description of the same, Boston
Journ. Nat. Hist., 1847, vol. 5, p. 385, 8vo. fig. —
Warren, (J. C.,) Description of a Skeleton of the
Mastodon giganteus, Boston, 1852, 4to. fol. — Leipy,
(J.,) The Ancient Fauna of Nebraska, Smith. Contr.,
Washington, 1852, 4to. fig. See also Sect. 22.
1 T allude to the classical work of Picrnt, Traité
élémentaire de Paléontologie, q. a., a second edition
of which is now publishing.
100 ESSAY ON CLASSIFICATION.
‘Part I.
a few examples for further discussion. Among Echinoderms the Crinoids are, for
a long succession of periods, the only representatives of that class; next follow
the Starfishes, and next the Sea-Urchins, the oldest of which belong to the type
of Cidaris and Echinus, followed by Clypeastroids and Spatangoids. No satisfactory
evidence of the existence of Holothurizs has yet been found. Among Crustacea,
a comparison of the splendid work of Barrande* upon the Silurian System of
Bohemia, with the paper of Count Miinster upon the Crustacea of Solenhofen? and
with the work of Desmarest upon fossil Crabs will at once show that while
Trilobites are the only Crustacea of the oldest paleozoic rocks, there is found in
the jurassic period a carcinological fauna entirely composed of Macrura, to which
Brachyura are added in the tertiary period. The formations intermediate between
the older paleozoic rocks and the Jura contain the remains of other Entomostraca,
and later of some Macroura also. In both classes the succession of their repre-
sentatives, in different periods, agrees with their respective standing, as determined
by the gradation of their structure.
Among plants, we find in the Carboniferous period prominently, Ferns and
Lycopodiacew ;* in the Triassic period Equisetaceee® and Coniferee prevail; in the
Jurassic deposits, Cycadex,’ and Monocotyledonex; while later only Dicotyledonex
take the lead.’
of late advanced beyond the attempts to represent the characteristic features of
The iconographic illustration of the vegetation of past ages has
the animal world in different geological periods.’
Without attempting here to characterize this order of succession, this much follows
already from the facts mentioned, that while the material world is ever the same
|) through all ages in all its combinations, as far back as direct investigations can
' > yials into ever new forms and new combinations.
trace its existence, organized beings, on the contrary, transform these same mate-
The carbonate of lime of all
ages is the same carbonate of lime in form as well as composition, as long as it
is under the action of physical agents only. Let life be introduced upon earth,
1 BaRRANDE’s Syst. Silur., q, a., p. 23.
2 Gr. G. v. Minster, Beitriige zur Petrefacten-
kunde, q. a., p. 98.
® DesmareEsT, see Brongniart and Desmarest’s
Hist. Nat. d. Tril. et Crust., q. a., p. 97.
* See, above, p. 93.
5 Scuimper, (W. P.,) et Movexrot, (A.,) Mono-
graphie des Plantes Fossiles du Grés-bigarré de la
chaine des Vosges, Strasb. et Paris, 1840-43, 4to.
fig. .
6 BucKLAND, (W.,) On the Cycadeoide, a Family
of Plants found in the Oolite, ete., Trans. Geol. Soc.
Lond. 2d ser. IL, p. 395.
” Uncer, (Fr.,) Chloris protogea, Beitrige zur
Flora der Vorwelt, Leipzig, 1841, 4to. fig. — Herr,
(O.,). Flora tertiaria Helvetie, Wintherthur, 1855,
fol. fig.
‘8 Landscapes of the different geological periods
are represented in Unenr, (FR.,) Die Vorwelt in
ihren vershiedenen Bildungsperioden, Wien, fol. (no
date.) These landscapes are ideal representations of
the vegetation of past ages.
Cuar. L SUCCESSION OF ANIMALS AND PLANTS. 101
and a Polyp builds its coral out of it, and each family, each genus, each species
a different one, and different ones for all successive geological epochs. Phosphate
of lime in paleozoic rocks is the same phosphate, as when prepared artificially by
Man; but a Fish makes its spines out of it, and every Fish in its own way, a
Turtle its shield, a Bird its wings, @ Quadruped its legs, and Man, like all. other
Vertebrates, its whole skeleton, and during each successive period in the history
of our globe, these structures are different for different species. What similarity is
there between these facts! Do they not plainly idicate the working of different
agencies excluding one another? Truly the noble frame of Man does not owe its
origin to the same forces which combine to give a definite shape to the crystal.
And what is true of the carbonate of lime, is equally true of all Inorganic sub-
stances; they present the same characters
Let us look upon the subject in still another light, and we shall see that the
same is also true of the influence of all
the only one to which, though erroneously, the
The effects it may now
in all ages past, as those they exhibit now.
physical causes. Among these agents, the
most powerful is certainly electricity ;
formation of animals has ever been directly ascribed.
produce, it has always produced, and produced them in the same manner. It has
various earthy minerals and deposited them in crystalline
reduced metallic ores and
it has transported these and other
form, in veins, during all geological ages;
substances from one point to another, in times past, as we may do now in our
Evaporation upon the surface of the earth has
which after accumulating have been
Rain drop marks in the carbonifer-
laboratories, under its influence.
always produced clouds in the atmosphere,
condensed in rain showers in past ages aS NOW.
ght to us this testimony of the identity of the
to remind us that what these agents may
the oldest geological times, and have
ous and triassic rocks have brou
operation of physical agents in past ages,
do now, they already did in the same way, in
Who could, in presence of such facts, assume any causal con-
the one of which is ever obeying the
successive period new relations, an
done at all times.
nection between two series of phenomena,
same laws, while the other presents at every
ever changing gradation of new combinations, dean
Who does not see, on the contrary, that this identity of the
totally disproves any influence on their part
leading to a final climax with the
appearance of Man?
products of physical agents in all ages, :
‘in the production of these ever changing beings, which constitute the organic world,
and which exhibit, as a whole, such striking evidence of connected thoughts!
ESSAY ON CLASSIFICATION.
SECTION XXII.
LOCALIZATION OF TYPES IN PAST AGES.
The study of the geographical distribution of the animals now living upon
earth has taught us, that every species of animals and plants has a fixed home, and
even that peculiar types may be circumscribed within definite limits, upon the
surface of our globe. But it is only recently, since geological investigations have
been carried on in remote parts of the world, that it has been ascertained that
this special localization of types extends to past ages. Lund for the first time
showed that the extinct Fauna of the Brazils during the latest period of a past
age, consists of different representatives of the very same types now prevalent in
that continent; Owen has observed similar relations between the extinct Fauna
of Australia? and the types now living upon that continent. .
If there is any naturalist left who believes that the Fauna of one continent
may be derived from another portion of the globe, the study of these facts, in
all their bearing, may undeceive him.
It is well known how characteristic the Edentata are for the present Fauna
of the Brazils, for there is the home of the Sloths, (Bradypus,) the Tatous,
(Dasypus,) the Ant-eaters, (Myrmecophaga); there also have been found those
extraordinary extinct genera, the Megatherium, the Mylodon, the Megalonyx, the
Glyptodon, and the many other genera described by Dr. Lund and Professor
Owen, all of which belong to this same order of Hdentata. Some of these
extinct genera of Edentata had also representatives in North America, during the
same geological period? thus showing that though limited within similar areas, the
range of this type has been different in different epochs.
Australia, at present almost exclusively the home of Marsupials, has yielded
also a considerable number of equally remarkable species, and two extinct genera
of that type, all described by Owen in a report to the British Association, in
1844, and in Michell’s Expeditions into the Interior of Australia. |
1 Lunp, (Dr.,) Blik paa Brasiliens Dyreverden of Extinct Mammalia, Ann. and Mag. Nat. Hist., 1846,
for sidste Jordomveltning. K. Danske Vidensk. vol. 17, p. 197. -
Selsk. Afhandl. VIII., Kidbenhavn, 1841, 4to. fig., p. ® Lerpy, (Jos.,) A Memoir on the Extinct Sloth
61, etc.; Engl. Abstract, Ann. and Mag: vol. 3, p. Tribe of North America, Smithson. Contrib. 1855, 4to.
422. fig. — Wyman, (J.,) Notice of Fossil Bones, ete., Am.
2 Owen, (R.,) On the Geographical Distribution Journ. Se. and A., 2d ser., 1850, vol. 10.
Cuap. I. EARLY LOCALIZATION OF TYPES. 108
How far similar facts are likely to occur in other classes, remains to be ascer-
tained. Our knowledge of the geographical distribution of the fossil remains is
yet too fragmentary to furnish any further data upon this pomt. It is, however,
worthy of remark, that though the types of the oldest geological periods had a
much wider distribution than most recent families exhibit now, some families of
fishes largely represented in the Devonian system of the Old World have not
yet been noticed among the fossils
the Cephalaspids, the Dipteri, and the Acanthodi. Again, of the many gigantic
d Oolitic periods, none are known to occur elsewhere
of that period in America, as, for instance,
Reptiles of the Triasic an
: it can hardly be simply owing to the less extensive dis-
except in Europe, and
of the world, since other fossils of
tribution of these formations in other parts .
the same formations are known from other continents. It is more likely that
some of them, at least, are peculiar to limited areas of the surface of the globe,
as, even in Europe, their distribution 1s not extensive. .
Without, however, entering upon debatable ground, it remains evident, that
before the establishment of the present state of things, peculiar types of animals,
which ead formerly circumscribed within definite limits, have continued to occupy
present period, even though no genetic. con-
their representatives in these different forma-
Such facts are in the most direct
the same or similar grounds in the
nection can be assumed between them,
tions not even belonging to the same genera.
contradiction with any assumption that physical agents could have any thing to
do with their origin; for though their occurrence within
might at first seem to favor such a view, it must be borne in mind gee these
her types which have a much wider range,
similar geographical areas
so localized beings are associated with ot
ore significant, they belong to different geological periods,
have undoubtedly taken place. Thus the
at the theory assumes; they prove a
and, what is still m |
between which great physical changes
facts indicate precisely the reverse of wh
organized beings during successive geological periods, not-
continued similarity of ye
sical conditions, which the
withstanding the extensive changes, in the prevailing phy
country they inhabited may have undergone, at different periods. In whatever direc-
tion this theory of the origin of animals and plants, —
stand a critical examiation. Only the delib-
under the influence of physical
agents, is approached, it can nowhere
erate intervention of an Intellect, acti
account for phenomena of this kind.
ng consecutively, according to one plan, can
ESSAY ON CLASSIFICATION.
SHOT LO Beak seb
LIMITATION OF SPECIES TO PARTICULAR GEOLOGICAL PERIODS.
Without entering into a discussion respecting the precise limits within which this
fact is true, there can no longer be any doubt, that not only species, but all other
groups of animals and plants, have a definite range of duration, as well as individ-
uals! The limits of this duration, as far as species are concerned, generally coin-
cide with great changes in the physical conditions of the earth’s surface ;* though,
strange to say, most of those investigators who would ascribe the origin of organ-
ized beings to the influence of such causes, maintain also, that species may extend
from one period to another, which implies that these are not affected by such
changes.’
When considering, in general, the limitation of species to particular geological
periods, we might very properly disregard the question of the simultaneity of the
successive appearance and disappearance of Faune, as in no way affecting the
result of the investigation, as long as it is universally conceded, that there is no
species, known among the fossils, which extends through an indefinite series of
geological formations. Moreover, the number of the species, still considered as
identical in several successive periods, is growing smaller and smaller, in proportion
as they are more closely compared. I have already shown, long ago, how widely
many of the tertiary species, long considered as identical with living ones, differ
from them} and also. how different the species of the same family may be, in
successive subdivisions. of the same great geological formation.” Hall has come to
' the same result in his investigations of the fossils of the State of New York.
Every monograph reduces: their number, in every formation. Thus Barrande, who
has devoted so many years to the most minute investigation of the Trilobites of
+ Compare Sect. XTX.
2 Evie DE Beaumont, Recherches sur quelques-
unes des Révolutions de la surface du Globe, Paris,
1830, 1 vol. 8vo.
§ For indications respecting the occurrence of all
species of fossil organized beings now known, consult,
Brown, (H. G.,) Index palxontologicus, Stuttgardt,
1848-49, 3 vols. 8vo. — Orpreny, (A. D’,) Prodrome
de Paléontologie stratigraphique universelle etc.,
Paris, 1850, 2 vols. 12mo. — Morris, (J.,) Catalogue
of the British Fossils, London, 1854, 1 vol. 8vo.
* Acassiz, (L.,) Coquilles tertiaires reputées
identiques avec les espéces vivantes, Neuchatel, 1845,
Ato. fig.
5 Acassiz, (L.,) Etudes critiques sur les Mollus-
ques fossiles, Neuchatel, 1840-45, 4to. fig.
6 Hart, (J.,) Paleontology of the State of New
York, q.'a.,'p. 23, note 1.
Cuap. I. LIMITATION OF SPECIES (IN TIME. | 105
Bohemia?! has come to the conclusion that their species do not extend from one
formation to the other; D’Orbigny* dnd Pictet® have come to the same conclusion
for: the fossil: remains ‘of all classes: “It. may well be, said that, as. fossil remaimse
are studied more carefully, in a zoUlogical point of view, the supposed identity of
species, in different geological formations, vanishes gradually more and more; so
that the limitation of species in time, already ascertained in a general way, by the
earlier investigations of their remains in successive geological formations, is circum-
scribed, step by step, within narrower, more definite, and also more equable periods.
Species are truly limited in time, as they are limited in space, upon the surface of.
the globe. The facts do not exhibit a gradual disappearance of a limited number of
species, and an equally gradual introduction of an equally limited number of new
creation and the simultaneous destruc-
ones; but, on the contrary, the simultaneous
tion of entire faune, and a coincidence betwe
and the great physical changes our earth has undergone.
to attempt to determine the extent of the geographical range of these changes, and
still more questionable to assert their synchronism upon the whole surface of the
en these changes in the organic world
Yet it would be premature
globe, in the ocean and upon dry land.
To form adequate ideas of the great physical changes the surface of our globe
has undergone, and the frequency of these modifications of the character of the
earth’s surface, and of their coincidence with the changes observed among the organ-
ized beings, it is necessary to study attentively the works of Ele de Beaumont.
He, for the first time, attempted to determine the relative age of the different sys-
tems of mountains, and showed first, also, that the physical disturbances occasioned
by their upheaval coincided with the successive disappearance of entire faune, and
the reappearance of new ones. In his earlier papers he recognized seven, then
twelve, afterwards fifteen such great convulsions of the globe, and now he has
traced more or less fully and conclusively the evidence that the number of these
disturbances has been at least sixty, perhaps one hundred. But while the genesis
and genealogy of our mountain systems were thus illustrated, paleontologists, extend-
ing their comparisons between the fossils of different formations more carefully to
all the successive beds of each great era, have observed more and more marked
differences between them, and satisfied themselves that faunz also have been more
frequently renovated, than was formerly supposed; 80 that the general results of
1 BaRRANDE, Systeme silurien, etc., q. a.3; see, 4 Eire pe Beaumont, Notice sur les systemes de
Montagnes, Paris, 1852, 3 vols. 12mo.; see, also,
Bucu, (Lor. v.,) Ueber die geognotischen Systeme
von Deutschland, Leonhard’s Taschenb., 1824, IL., p.
also, my Monographies d’Echinodermes, q. a., p. 54.
2 D’Orzieny, Paléontologie Frangaise, q. a., p. 95.
8 Piotet, Traité de Paldéontologie, etc., q. a., p.
96, note 1. O01.
14
106 | ESSAY ON CLASSIFICATION. Part I.
geology proper and of paleontology concur in the main to prove, that while the
globe has been at repeated intervals, and indeed frequently, though after immensely
long periods, altered and altered again, until it has assumed its present condition,
so have also animals and plants, living upon its surface, been again and again extin-
guished and replaced by others, until those now living were called into existence
with man at their head. The investigation is not in every case sufficiently com-
plete to show everywhere a coincidence between this renovation of animals and
plants and the great physical revolutions which have altered the general aspect of
the globe, but it is already extensive enough to exhibit a frequent synchronism and
correlation, and to warrant the expectation that it will, im the end, lead to a com-
plete demonstration of their mutual dependence, not as cause and effect, but as steps
in the same progressive development of a plan which embraces the physical as well
as the organic world. :
In order not to misapprehend the facts, and perhaps to fall back upon the
idea, that these changes may be the cause of the differences observed between the
fossils of different periods, it must be well understood that, while organized beings
exhibit through all geological formations a regular order of succession, the character
of which will be more fully illustrated hereafter, this succession has been from
time to time violently interrupted by physical disturbances, without any of these
altering in any way the progressive character of that succession of organized beings.
Truly this shows that the important, the leading feature of this whole drama is
the development of life’ and that the material world affords only the elements for
its realization. The simultaneous disappearance of entire faune, and the following
simultaneous appearance of other faune, show further that, as all these faunz con:
sist of the greatest variety of types, in all formations, combined everywhere into
natural associations of animals and plants, between which there have been definite
relations at all times, their origin can at no time be owing to the limited influence
of monotonous physical causes, ever acting im the same way. Here, again, the
intervention of a Creator is displayed in the most striking manner, in every stage
of the history of the world. |
1 Dana, (J. D.,) Address, q. a., p. 94, note 1. ° Acassiz, (L.,) Geol. Times, q. a., p. 25.
Cuap. I. SUCCESSION AND STANDING OF ANIMALS.
SECTION: XLV.
PARALLELISM BETWEEN THE GEOLOGICAL SUCCESSION OF ANIMALS AND PLANTS AND
THEIR PRESENT RELATIVE STANDING.
The total absence of the highest representatives of the animal kingdom in the
oldest deposits forming part of the crust of our globe, has naturally led to the
very general belief, that the animals
of the history of our earth were inferior to those now living, nay, that there is
d lowest animals to the highest now in exist-
which have existed during the earliest period
a natural gradation from the oldest an
ence! To some extent this is true;
form one simple series from the earliest times,
of animals would have been represented, to the last period, when Man appeared
at the head’ of the animal creation? Jt has already been shown (Sect. VII). that -
representatives of all the great types of the animal kingdom have existed from the
beginning of the creation of organized beings. Ie ESI a AOR EA Msi
sive appearance of the great branches of the animal kingdom, that we may expect |
succession in geological times and their relative
pondence be observed between the
but it is certainly not true that all animals
during which only the lowest types
to trace a parallelism between their
standing at present. Nor can any such corres
appearance of classes, at least not among Radiata, Mollusks, and Articulata, as their
respective classes seem to have been introduced simultaneously upon our earth, with
perhaps the sole exception of the Insects, which are not known to have existed
mong Vertebrata, however, there appears already a
before the Carboniferous period. A
of the classes, between the time of their
certain coincidence, even within the limits
introduction, and the rank their representatives h
But upon this point more hereafter.
It is only within the limits of the different orders of each class, that the paral-
lelism between the succession of their representatives in past ages and their respec-
decidedly characteristic. But if this is true, it
old, in comparison to one another.
tive rank, in the present period, is
must be at the same time obvious
spondence may be influenced by the state of our
and natural gradation of living animals, and that until our classifications have become
the correct expression of these natural relations,
with the succession of their representatives in past ages may be entirely overlooked.
On that account it would be presumptuous on my part to pretend, that I could
to what extent the recognition of this corre-
knowledge of the true affinities
even the most striking coincidence
1 See the paleontological works quoted in Sect. 21. 2 AcassizZ, (L.,) Twelve Lect., ete, p. 25 and 69.
= ~
“ — ~~ Sree
acl cc is Sans A nis. ODS ani. IAA thas" illic ME ain ati i ot atti Ss
Sr OARS naar anOTNAAD DORR — a os Sean See = — : : .
Sica eet aie Ls a deco a eee ll stile wt 2 a
SS ——— = —- - 7 — "
i oan
a ie
108 ESSAY ON CLASSIFICATION. Part IL
illustrate this proposition, through the whole animal kingdom, as such an attempt
would involve the assertion that I know all. these relations, or that where there
exists a discrepancy between the classification and the succession of animals, the
classification must be incorrect, or the relationship of the fossils incorrectly appre-
ciated. I shall therefore limit myself here to a general comparison, which may,
however, be sufficient to show, that the improvements which have been introduced
in our systems, upon purely zodlogical grounds, have nevertheless tended to render
more apparent the coincidence between the relative standimg among living animals
and the order of succession of their representatives in past ages. I have lately
attempted to show, that the order of Halcyonoids, among Polyps, is superior to that
of Actinoids;* that, in this class, compound communities constitute a higher degree of
development, when contrasted with the characters and mode of existence of single
Polyps, as exhibited by the Actinia; that top-budding is superior to lateral budding ;
and that the type of Madrepores, with their top-animal, or at least with a defi-
nite and limited number of tentacles, is superior to all other Actinoids.. If this be
so, the prevalence of Actinoids in older geological formations, to the exclusion of
Halcyonoids, the prevalence of Rugosa and Tabulata in the oldest deposits,” the
later prevalence of Astreeoids, and the very late introduction of Madrepores, would
already exhibit a correspondence between the rank of the living Polyps and the
representatives of that class in past ages, though we may hardly expect a very close
coincidence in this respect between animals the structure of which is so simple.
The gradation among the orders of Echinoderms is perfectly plam. Lowest
stand the Crinoids, next the Asterioids, next the Echinoids, and highest the Holo-
thurioids. Ever since this class has been circumscribed within its natural limits,
this succession has been considered as expressing their natural relative standing, and
modern investigations respecting their anatomy and embryology, however extensive,
have not led to any important change in their classification, as far as the estimation
of their rank is concerned. This is also precisely the order in which the representa-
tives of this class have successively been introduced upon earth in past geological ages.
Among the oldest formations we find pedunculated Cinoids? only, and this order
remains prominent for a long series of successive periods; next come free Crinoids
and Asterioids; next Echinoids,’ the successive appearance of which since the triasic
* For classification of Polypi, see DANA, q. 2, p- * See the works q. a. p.96; also: Mixier, (J.,)
31, note 2; also Minnn-Epwarps and Hare, q. a., and TroscHeL, (F. H.,) System der Asteriden,
and Acassiz, (L.,) Classification of Polyps, Proc. Braunschweig, 1842, 4to. fig. — Mitiuer, (J.,) Ueber
Am. Acad. Se. and Arts, 1856, p. 187. : den Bau der Echinodermen, Berlin, 1854, 4to. — T1n-
* See Mitne-Epwarps and Ham, q. a., p. 31. DEMAN, (FR.,) Anatomie der Réhren-Holothurie, des
® Mitier, Crinoids, q. a. — D’ORBIGNY, q. a. — Seeigels, etc., Landshut, 1817, fol. fig. — VALENTIN,
J. HA, q. a.— Austin, q. - p- 96. (G.,) Anat. du gerne Echinus, Neuchatel, 1842, 4to.
Cuap. I. SUCCESSION AND STANDING OF ANIMALS. 109
period to the present day, coincides also with the gradation of their subdivisions,
as determined by their structure ; and it was not until the present period, that the
highest Echinoderms, the Holothurioids, have assumed a prominent position in their
class. |
Among Acephala there is not any more uncertainty respecting the relative rank
of their living representatives, than among Echinoderms. Every zodlogist acknowl-
edges the inferiority of the Bryozoa and the Brachiopods* when compared with the
Lamellibranchiata, and among these the inferiority of the Monomyaria in compari-
son with the Dimyaria would hardly be denied. Now if any fact is well established
in Paleontology, it is the earlier appearance and prevalence of Bryozoa and_Bra-
chiopods in the oldest geological formations, and their extraordinary development
for a long succession of ages, until Lamellibranchiata assume the ascendency which
they maintain to the fullest extent at present. :
oht further show how close this correspondence is
‘s)
A closer comparison of the differ-
ent families of these orders m
through all ages. ee
Of Gasteropoda I have nothing special to say, as every paleontologist is aware
have been investigated in comparison with what has
how imperfectly their remains
Yet the Pulmonata are known to be
been done for the fossils of other classes.
of more recent origin than the Branchifera, -
than the Holostomata, and this exhibits already a general
and among these the Siphonostomata
to have appeared later
coincidence between their succession in time and their respective rank.
Our present knowledge of the anatomy of the Nautilus, for = science is
indebted to the skill of Owen? may satisfy everybody that among Cephalopods the
Tetrabranchiata are inferior to the Dibranchiata; and it is not too much to say,
that one of the first points a collector of fossils may ascertain for oe is the
exclusive prevalence of the representatives of the first of ibate types in the oldest
formations, and the later appearance, about the middle ee sain of represent-
atives of the other type, which at present 1s the most widely i eimns
Of Worms, nothing can be said of importance with reference to our inquiry ;
Sicilie, eorumque Historia et Anatomia, Parma,
1791-93, 2 vols. fol. fig., continued by Delle Chiaje.
2 OwEN, (R.,) Memoir on the Pearly Nautilus,
London, 1832, 4to. fig. — VALENCIENNES, (A.,) Nou-
velles Recherches anatomiques sur le Nautile. C. R.,
Paris, 1841, 4to.— Cuvier, (G.,) Mémoires pour
servir 4 lHistoire et 4 ’ Anatomie des Mollusques,
Paris, 1817, 4to. fig. — Epwarps, (H. M.,) QuaTRE-
races, (AR. DE,) et Brancnarp, (Em.) Voyage en
Sicile, Paris, 3 vols. 4to. fig. (without date.)
1 Orpreny, (A. d’,) Bryozoires, Ann. Se. Nat., 3e
sér. 1851, vol. 16, p. 292. — Cuvier, (G.,) Mémoire
sur l’animal de la Lingule, Ann. Mus. I. p. 69, fig. —
Voer, (C.,) Anatomie der Lingula anatina, N. Mém.
Soc. Helv. 1848, VIL, 4to. fig. — OWEN, (R.,) On the
Anatomy of the Brachiopoda, Trans. Zool. Soe. I.
Ato., p. 145, fig — On the Anatomy of the Terebratula,
1853, dto. fig. (Palwont. Soc.)—Bucu, (L. v.,) Ueber
Terebrateln, q. a., p. 97.—Davipson, (TH.,) Monogr.
ete. q. a, p. 97.— Port (Xav.,) Testacea utriusque
ie ET a alt dae, A Potten 4
110 ESSAY ON CLASSIFICATION. Part I.
but the Crustacea exhibit, again, the most striking coincidence. Without entering
into details, it appears from the classification of Milne-Edwards that Decapods, Sto-
mapods, Amphipods, and Isopods constitute the higher orders, while Branchiopods,
Entomostraca, Trilobites, and the parasitic types, constitute, with Limulus, the lower
orders of this class‘ In the classification of Dana,’ his first type embraces Deca-
pods and Stomapods, the second Amphipods and Isopods, the third Entomostraca,
including Branchiopods, the fourth Cirripedia, and the fifth Rotatoria. Both acknowl-
edge in the main the same gradation; though they differ greatly in the combina-
tion of the leading groups, and also the exclusion by Milne-Edwards of some types,
as the Rotifera, which Burmeister first, then Dana and Leydig, unite justly, as I
believe, with the Crustacea? This gradation now presents the most perfect coinci-
dence with the order of succession of Crustacea in past geological ages, even down
to their subdivisions into minor groups. Trilobites and Entomostraca are the only
representatives of the class in paleozoic rocks; in the middle geological ages appear
a variety of Shrimb, among which the Macrouran Decapods are prominent, and later
only the Brachyoura, which are the most numerous in our days.
The fragmentary knowledge we possess of the fossil Insects, does not justify
us, yet, in expecting to ascertain with any degree of precision, the character of
their succession through all geological formations, though much valuable information
has already been obtained respecting the entomological faunse of several geological
periods.*
The order of succession of Vertebrata in past ages, exhibits features in many
respects differing greatly from the Articulata, Mollusks, and Radiata. Among these
we find their respective classes appearing simultaneously in the oldest periods of
the history of our earth. Not so with the Vertebrata, for though Fishes may be
as old as any of the lower classes, Reptiles, Birds, and Mammalia are introduced
successively in the order of their relative rank in their type. Again, the earliest
representatives of these classes do not always seem to be the lowest; on the con-
trary, they are to a certain extent, and in a certain sense, the highest, in as far
| as they embody characters, which, in later periods, appear separately in higher
classes, (See Sect. 26,) to the exclusion of what henceforth constitutes the special
character -of “the lower class. For instance, the oldest Fishes known partake of
the characters, which, at a later time, are exclusively found in Reptiles, and no
longer belong to the Fishes of the present day. It may be said, that the earliest
Fishes are rather the oldest representatives of the type of Vertebrata than of. the
1 Mitng-Epwarps, Hist. Nat. des Crustacés, ° Lrypie, (FR.,) Raderthiere, etc., Zeitsch. f.
Paris, 1834-40, 3 vols. 8vo. wiss. Zool. 1854, vol. 6, p. 1.
2 Dana, (J. D.,) Crustacea, q. a., p. 32. 4 HeER, q.a.; Bropix, q. a., p. 98.
Guar. L SUCCESSION AND STANDING OF ANIMALS. Vi
class of Fishes, and that this class assumes only its proper characters after the
introduction of the class of Reptiles upon earth. Similar relations may be traced
between the Reptiles and the classes of Birds and Mammalia, which they precede.
I need only allude here to the resemblance of the Pterodactyli and the Birds, and
to that of Ichthyosauri and certain Cetacea. Yet, through all these intricate rela-
tions, there runs an evident tendency towards the production of higher and higher
types, until at last, Man crowns the whole series. Seen as it were at a distance,
so that the mind can take a general survey of the whole, and perceive the con-
nection of the successive steps, without bemg bewildered by the details, such a
series appears like the development of a great conception, expressed in such har-
that every link appears necessary to the full comprehension
monious proportions, to |
dent and perfect in itself, that it might be
of its meaning, and yet, so indepen
mistaken for a complete whole, and again,
ceding and following members of the series, ,
out of the other. What is universally acknowledged as characteristic of the highest
. : , : ‘ s, a richness, a magnificen
conceptions of genius, is here displayed im a fulness, ol ae aint aren
a complication of relations, which baffle our
so intimately connected with the pre-
that one might be viewed as flowing
an amplitude, a perfection of details,
skill and our most persevering efforts t
inciding to such an extent, and not read in them the
0 appreciate all its beauties. Who can
look upon such series, co : ; : |
successive manifestations of a thought, expressed at different -— im ever new
forms, and yet tending to the same end, onwards to the SiGe ‘seedings senda
in the first appearance of the earliest Fishes!
advent is already prophesied ; |
a somewhat different character from that
The relative standing of plants presents
of animals. Their great types are not built upon so strictly different plans of
structure; they exhibit, therefore, a more uniform gradation from their lowest to
their highest types, which are not personified in one highest plant, as the highest
animals are in Man. ee
ed respecting the limitation of the most compre-
Again, Zodlogy is more advanc 3
while Botany is in advance respecting the
hensive general divisions, than Botany,
limitation and characteristics of families and genera. :
s respecting the number, and the relative rank
There is, on that account, more
diversity of opinion among botanist
of the vegetable kingdom, than among zovlogists respecting
of the primary divisions
While most writers+ agree in admitting
the great branches of the animal kingdom.
among plants, such primary groups as Acotyledones, Monocotyledones, and Dicotyle-
co}
dones, under these or other names, others would separate the Gymnosperms from
the Dicotyledones? ee a
It appears to me, that this pomt in the classification of the livmg plants cannot
2
1 GorreERT, etc, q. a, p- 93. Ap. BRONGNrAR?, ete, q. a, p. 93.
At SOT eA A a cA. ~ a Bi eb seus em oe _— i "
mace bee eas ce S
112 | ESSAY ON CLASSIFICATION. Part I.
be fully understood without a thorough acquaintance with the fossils and their
distribution in the successive geological formations, and that this case exhibits
one of the most striking examples of the influence classification may have upon
our appreciation of the gradation of organized beings in the course of time. As
long as Gymnosperms stand among Dicotyledones, no relation can be traced between
the relative standing of living plants and the order of succession of their repre-
sentatives in past ages. On the contrary, let the true affinity of Gymnosperms
with Ferns, Equisetacese, and especially with Lycopodiaceze be fully appreciated, and
at once we see how the vegetable kingdom has been successively introduced upon
earth, in an order which coincides with the relative position its primary divisions
bear to one another, in respect to their rank, as determined by the complication
of their structure. Truly, the Gymnosperms, with their imperfect flower, their open
carpels, supporting their polyembryonic seeds in their axis, are more nearly allied
to the anathic Acrophytes, with their innumerable spores, than to either the Mono-
cotyledones or Dicotyledones; and, if the vegetable kingdom constitutes a graduated
series beginning with Cryptoganes, followed by Gymnosperms, and ending with
Monocotyledones and Dicotyledones, have we not in that series the most striking
coincidence with the order of succession of Cryptogams in the oldest geological forma-
tions, especially with the Ferns, Equisetacee, and Lycopodiacese of the Carboniferous
period, followed by the Gymnosperms of the Trias and Jura and the Monocoty-
ledones of the same formation and the late development of Dicotyledones? Here,
as everywhere, there is but one order, one plan im nature.
SECTION [es ¥.
PARALLELISM BETWEEN THE GEOLOGICAL SUCCESSION OF ANIMALS AND THE EMBRYONIC
. GROWTH OF THEIR LIVING REPRESENTATIVES.
Several authors have already alluded to the resemblance which exists between
the young of some of the animals now living, and the fossil representatives of the
same families in earlier periods! But these comparisons have, thus far, been traced
only in isolated cases, and have not yet led to a conviction, that the character
of the succession of organized beings in past ages, is such, in general, as to show
1 Acassiz,(L.,) Poiss.. foss., q. a, p-54.—Em- ques _principes relatifs & la Classification naturelle
bryonic Types, q. a., p. 11.— Twelve Lect., ete., p. 8. des animaux, An. Sc. Nat., 3e sér., 1844, 1 vol.
— Epwarps, (H. Mizne,) Considérations sur quel- p- 69.
‘ Crap. TL. SUCCESSION AND DEVELOPMENT OF ANIMALS. 113
a remarkable agreement with the embryonic growth of animals; though the state
of our knowledge in Embryology and Palzontology justifies now such a conclusion.
The facts most important to a proper appreciation of this point, have already been
considered in the preceding paragraph, as far as they relate to the order of suc-
cession of animals, when compared with the relative rank of their living repre-
sentatives. In examining now the agreement between this succession and the phases
of the embryonic growth of living animals, we may, therefore, take for granted,
that the order of succession of their fossil representatives is sufficiently present
to the mind of the reader, to afford a satisfactory basis of comparison. Too
few Corals have been studied embryologically, to afford extensive means of. com-
parison; yet so much is known, that the young polyp, when hatched, is an inde-
pendent, simple animal, that it is afterwards incased in a cup, secreted by the foot of
the actinoid embryo, which may be compared to the external wall of the Rugosa,
and that the polyp gradually widens until it has reached its maximum diameter,
prior to budding or dividing, while in ancient corals this stage of enlargement seems
to last during their whole life, as, for example, in the Cyathophylloids. None of the
ancient Corals form those large communities, composed of myriads of united individ-
uals, so characteristic of our coral reefs; the more isolated and more independent
character of the individual polyps of past ages presents a striking resemblance to
the isolation of young corals, in all the living types. In no class is there, however,
so much to learn still, as in Polypi, before the correspondence of their embryonic
erowth, and their succession in time, can be fully appreciated. In this connection
I would also remark, that among the lower animals, it is rarely observed, that
any one, even the highest type, represents in its metamorphoses all the stages of
the lower types, neither in their development, nor in the order of their succession;
and that frequently the knowledge of the embryology of several types of differ-
ent standing, is required, to ascertain the connection of the whole series in both
spheres.
No class affords, as yet, a more complete and more beautiful evidence of the
correspondence of their embryonic changes, with the successive appearance of their
representatives in past ages, than the Echinoderms, thanks to the extensive and
patient investigations of J. Miiller upon the metamorphoses of these animals? Prior
to the publication of his papers, the metamorphosis of the European Comatula alone
was known. (See Sect. XVIIL, p. 85.) This had already shown, that the early stages i
myself seen further, that the successive stages of the embryonic growth of Comatula
typify, as it were, the principal forms of Crinoids which characterize the successive
1 Mitne-Epwarps et Hamme, q. 4, p. 31. * Murxer, (J.,) Seven papers, q. a., p. 71.
15
\
of growth of this Echinoderm exemplify the peduncated Crinoids of past ages. I have
r 7 . = : : — =
‘
A ar ae hin i. BOB ee ee ee ee
<a : “ ie Ses ‘asin rs. wed 2 “ . \
ume =e ca _—— -” _ - ~— : Ca
a = Sr eee === ‘
" acme stim
a en a ES me
Yaaro
114 ESSAY ON CLASSIFICATION. | Parr I.
geological formations; first, it recalls the Cistoids of the paleeozoic rocks, which are
represented in its simple spheroidal head, next the few-plated Platyermoids of the
Carboniferous period, next the Pentacrinoids of the Lias and Oolithe, with their whorls
of cirrhi, and finally, when freed from its stem, it stands as the highest Crinoid,
as the prominent type of the family, in the present period. The investigations of
Miiller upon the larvee of all the families of living Asterioids and Echinoids enable
us to extend these comparisons to the higher Echinoderms also. The first poimt
which strikes the observers in the facts ascertained by Miiller, is the extraordinary
similarity of so many larve, of such different orders and different families as the
Ophiuroids and Asterioids, the Echinoids proper and the Spatangoids, and even the
Holothurioids, all of which end, of course, in reproducing their typical peculiarities.
It is next very remarkable, that the more advanced larval state of Echinoids and
Spatangoids should continue to show such great similarity, that a young Amphidetus
hardly differs from a young Kchinus." Finally, not to extend these remarks too far,
I would only add, that these young Echinoids (Spatangus, as well as Echinus proper)
have rather a general resemblance to Cidaris, on account of their large spines,
than to Echinus proper. Now, these facts agree exactly with what is known
of the successive appearance of Echinoids in past ages ;”
their earliest representa-
tives belong to the genera Diadema and Cidaris, next come true Echinoids, later
only Spatangoids. When the embryology of the Clypeastroids is known, it will,
no doubt, afford other links to connect a larger number of the members of this
series. |
What is known of the embryology of Acephala, Gasteropoda, and Cephalopoda,
affords but a few data for such comparisons. It is, nevertheless, worthy of remark,
that while the young Lamellibranchiata are still in their embryonic stage of growth,
they resemble, externally at least, Brachiopods*? more than their own parents, and
the young shells of all Gasteropods* known in their embryonic stage of growth,
being all holostomate, recall the oldest types of that class. Unfortunately, nothing
is yet known of the embryology of the Chambered Cephalopoda, which are the only
ones found in the older geological formations, and the changes which the shield of
the Dibranchiata undergoes have not yet been observed, so that no comparisons can
be established between them and the Belemnites and other representatives of this
order in the middle and more recent geological ages.
Respecting Worms, our knowledge of the fossils is too fragmentary to lead to
any conclusion, even should our information of the embryology of these animals
1 Compare J. Miiller’s 1st paper, pl. W1., with 8 See the works, q. a. p. 73, note 1.
pls. IV.—VIL, and with pls. VI. and VIL., 4th paper. 4 See the works, q. a., p. 73, note 2, especially
2 AcassiZ, (L.,) Twelve Lectures, q. a., etc. p. 25. those relating to Nudibranchiata.
Cuap. I. SUCCESSION AND DEVELOPMENT OF ANIMALS. 115
be sufficient as a basis for similar comparisons. The class of Crustacea, on the
contrary, is very instructive in this respect; but, to trace our comparisons through
the whole series, it is necessary that we should consider simultaneously the em-
bryonic growth of the higher Entomostraca, such as Limulus, and that of the highest
order of the class,! when it will appear, that as the former recall in early life |
the form and character of the Trilobites, so does the young Crab passing through \
the form of the Isopods, and that of the Macrouran Decapods, before it assumes its |
typical form as Brachyouran, recall the well-known succession of Crustacea through |
the geological middle ages and the tertiary periods to the present day. The early |
appearance of Scorpions, in the Carboniferous period, is probably also a fact to the
point, if, as I have attempted to show, Arachnidians may be considered as exemplify-
ing the chrysalis stage of development of Insects; but, for reasons already. stated
(Sect. XXIV.) it is hardly possible to take Insects into consideration in these inquiries.
In my researches upon fossil Fishes,’ I have pointed out at length the embryonic
character of the oldest fishes, but much remains to be done in that direction. |
arned of late, is that the young Lepidosteus, _
The only fact of importance I have le
long after it has been hatched, exhibits in the form of its tail, characters, thus
far only known among the fossil fishes of the Devonian system.* It is to be hoped,
that the embryology of the Crocodile will throw some light upon the succession
of the gigantic Reptiles of the middle geological ages, as I shall show, that the |
embryology of Turtles throws light upon the fossil Chelonians. It is already plain,
that the embryonic changes of Batrachians coincide with what is known of their
succession in past ages.® The fossil Birds are too little known, and the fossil
Maminalin®-.dio Riis picicidl thoes sufficiently long series of geological formations
to afford many striking points of comparison ; yet, the characteristic peculiarities
of their extinct genera exhibit everywhere indications,
tives in early life resemble them more than they do their own parents. A minute
comparison of a young elephant, with any mastodon, will show this most fully, |
of their teeth, but even in the proportion of their ,
that their living representa-
not only in the peculiarities
limbs, their toes, ete.
l( It may, therefore, be considered as
illustrated as investigations cover a wider ground, that the phases of development
i Rapacae order of succession of their extinct. repre-
a general fact, very likely to be more fully
of “all living animals correspond oe
sentatives in past geological times.’ As far as this goes, the oldest representatives
5 See the works, q. a. p. 82, note 3.
® Cuv., Oss. foss., q. a.: also, Agassiz, (L.,)
Zodlogical Character of Young Mammalia, Proc. Am.
Ass. Ady. Se, Cambridge, 1849, p. 85,
1 Agassiz, (L.,) Twelve Lectures, ete., p. 66.
2 Classif. of Insects, q. a. p- 89.
8 Poiss. fossiles, q. a. p. 54.
* Agassiz, (L.,) Lake Superior, etc., p- 254.
a ae
“ said - ent be 7 ae ee a YI
a ju. Cia i in Haw < = a wr pr ili < ~
Mra A ce ac NAR OES ANT RK Sy A A Si mt etc sce ur meme IS a ’
ieee .
7 ah
a
nec anal “a
116 ESSAY ON CLASSIFICATION. Part I.
of every class may then be considered as embryonic types of their respective orders
or families among the living. Pedunculated Crinoids are embryonic types of the
Comatuloids, the oldest Echinoids embryonic representatives of the higher living
families, Trilobites embryonic types of Entomostraca, the Oolitic Decapods embryonic
types of our Crabs, the Heterocercal Ganoids embryonic types of the Lepidosteus,
the Andrias Scheuchzeri an embryonic prototype of our Batrachians, the Zeuglodonts
embryonic Sirenide, the Mastodonts embryonic Elephants, ete.
To appreciate, however, fully and correctly all these relations, it is further neces-
sary to make a distinction between embryonic types in general, which represent
in their whole organization early stages of growth of higher representatives of the
same type, and embryome features prevailing more or less extensively in the charac-
ters of allied genera, as in the case of the Mastodon and Elephant, and what I
would call hypembryonic types, in which embryonic features are developed to extremes
in the further periods of growth, as, for instance, the wings of the Bats, which
exhibit the embryonic character of a webbed hand, as all Mammalia have it at
first, but here grown out and developed into an organ of flight, or assuming in
other families the shape of a fin, as in the Whale, or the Sea-turtle, in which the
close connection of the fingers is carried out to another extreme. |
Without entering into further details upon this subject, which will be fully
illustrated in this work, enough has already been said to show, that the leading
thought which runs through the succession of all organized beings in past ages, is
manifested again in new combinations, in the phases of the development of the
living representatives of these different types. It exhibits everywhere the working
of the same creative Mind, through all times, and upon the whole surface of the
globe.
SECTION. %-%.V-1;
PROPHETIC TYPES AMONG ANIMALS.
We have seen in the preceding paragraph, how the embryonic conditions of
higher representatives of certain types, called into existence at a later time, are
typified, as it were, in representatives of the same types, which have existed at
an earlier period. These relations, now they are satisfactorily known, may also be
considered as exemplifying, as it were, in the diversity of animals of an earlier
period, the. pattern upon which the phases of the development of other animals
Cuap. I. PROPHETIC TYPES AMONG ANIMALS. 117
of a later period were to be established. They appear now, like a prophecy in
those earlier times, of an order of things not possible with the earlier combina-
tions then prevailing in the animal kingdom, but exhibiting in a later period, in a
striking manner, the antecedent considerations of every step in the gradation of
animals. ;
This is, however, by no means the only, nor even the most remarkable case,
of such prophetic connections between facts of different dates.
Recent investigations in Paleontology have led to the discovery of relations
between animals of past ages and those now living, which were not even suspected
by the founders of that science. It has, for instance, been noticed, that certain types
which are frequently prominent among th
in their structure, peculiari
in different, distinct types.
Ichthyosauri_before Dolphins, ete.
There are entire families, among the representatives of older periods, of nearly
every class of animals, which, in the state of their perfect development exemplify
such prophetic relations, and afford, within the limits of the animal kingdom, at
least, the most unexpected evidence, that the plan of the whole creation had been
maturely considered long before it was executed.
time past, been in the habit of calling prophetic types. The Sauroid! Fishes of the
These Fishes, which have pre-
Such types, I have for some
past geological ages, are an example of this kind.
ceded the appearance of Reptiles, :
characters, not to be found in the true members of this class, which form its bulk
at present. Y
Ichthyosauri* which have preceded the appearance of the Crastacea, are other exam-
ples of such prophetic types. These cases suffice for the present, to show that
there is a real difference between embryome types and prophetic types. Embryonic
types are in a measure also prophetic types, but they exemplify only the pecu-
higher representatives of their own types; while
liarities of development of the
ations observed at a later period, in two
prophetic types exemplify structural comb
and are, moreover, not necessarily embryonic in their
or several distinct types,
the Monkeys in comparison to Man; while they may be
character, as for example, ee
so, as in the case of the Pinnate, Plantigrade, and Digitigrade Carnivora, or still
more so in the case of the pedunculated Crinoids.*
Another combination is also frequently observed among animals, when a series
exhibits such a succession as exemplifies a natural gradation, without. immediate
1 Acassiz, (L.,) Poiss. foss., vol. 2, part 2. ° Cuvier, (G.,) Oss. foss., as q. Qe
2 Cuvier, (G.,) Oss. foss., vol. 5, p- 2. * See above, Sect. 25.
e representatives of past ages, combine \
ties which at later periods are only observed separately |
Sauriod Fishes before Reptiles, Pterodactyles before Birds,
7)
ae Ey 4
4
SS
present a combination of ichthyic and reptilian \
The Pterodactyles? which have preceded the class of Birds, and the :
118 ESSAY ON CLASSIFICATION. Part I.
or necessary reference to either embryonic development or succession in time, as the
Chambered Cephalopods. Such types I call progressive types+
Again, a distinction ought to be made between prophetic types proper and
what I would call synthetic types, though both are more or less blended in nature.
Prophetic types proper, are those which in their structural complications lean towards
other combinations fully realized in a later period, while synthetic types, are those
which combine, in a well balanced measure, features of several types occurring as
distinct, only at a later time. Sauroid Fishes and Ichthyosauri are more distinctly
synthetic than prophetic types, while Pterodactyles have more the character of
prophetic types; so are also Echinocrinus with reference to Echini, Pentremites with
reference to Asterioids, and Pentacrinus with reference to Comatula. Full illustra-
tions of these different cases will yet be needed to render obvious the importance
of such comparisons, and I shall not fail, in the course of this work, to present
ample details upon this subject. Enough, however, has already been said to show,
that the character of these relations among animals of past ages, compared with those
of later periods or of the present day, exhibits more strikingly than any other
feature of the animal kingdom, the thoughtful connection which unites all living
beings, through all ages, into one great system, intimately linked together from
beginning to end.
SECTION XXVII.
PARALLELISM BETWEEN THE STRUCTURAL GRADATION OF ANIMALES AND THEIR
EMBRYONIC GROWTH.
So striking is the resemblance of the young of higher animals to the full-grown
individuals of lower types, that it has been assumed by many writers that all the
higher animals pass, during the earlier stages of their growth, through phases cor-
responding to the permanent constitution of the lower classes. These suppositions,
the results of incomplete investigations, have even become the foundation of a
system of philosophy of Nature, which represents all animals as the different degrees
of development of a few primitive types.” These views have been too generally
circulated of late, in an anonymous work, entitled “Vestiges of Creation,” to require
1 AGassiz, (L.,) On the Difference between ~ don. TrELIAmeD,) Entretiens d’un Philosophe indien
Progressive, Embryonic, and Prophetic Types, etc., avec un missionaire francais, Amsterdam, 1748, 2
Proc. Am. Ass. Adv. Sc., Cambridge, 1849, p. 482. vols. 8vo. —OKEN, (Lor.,) Lehrbuch der Natur-Phi-
? LAMARCK, q. a. p. 26.— DuMaiLier, (Pseu- losophie, q. a., p. 18. — The Vestiges of Creation, ete.
Cuap. I. RANK AND DEVELOPMENT OF ANIMALS. 419
further mention here. It “ie also been shown above (Sect. VIII.) that animals do
not form such a simple series as would result from a successive development.
There remains, therefore, only for us to show now within what limits the natural
oradation which may be traced in the different types of the animal kingdom; cor-
responds to the changes they undergo during their growth, having already considered
the relations which exist between these metamorphoses and the successive appear-
ance of animals upon earth, and between the latter and the structural gradation or
relative standing of their living representatives.
of structure of all animals is sufficiently advanced to enable us to select, almost at
random, our examples of the correspondence between the structural gradation of
in all those classes the embryologic develop-
Our knowledge of the complication
animals and their embryonic growth,
ment of which has been sufficiently investigated. rh
distinctly how closely all the leading features of the anima , a
whether we consider the complication of their structure, or their succession in time,
or their embryonic development, I shall refer by pre .
which I have chosen before for the illustration of the other relations.
Among Echinoderms, we find in the order of Crinoids the pedunculated types
standing lowest, Comatule highest, and it is well ees that = young ass
is a pedunculated Crinoid, which only becomes free in later si 9 J. Miiller has*
shown that among the Echinoids, even the highest representatives, the Spatan-
goids, differ but slightly in early youth from
can doubt that these are inferior to the former.
al gradation which may be traced between the
urally from the highest Bruchyoura,
Yet, in order to show more
1 kingdom are combined,
ference to the same types
the Echinoids, and no zodlogist \
Among Crustacea, Dana* has
insisted particularly upon the seri
different types of Decapods, their order bemg nat
through the Anomoura, the Macroura, the Tetradecapods, etc. to the Entomostraca ;
the Macrouran character of the embryo of our Crabs
by Rathke, in his beautiful investigations upon the embryology of Crustacea. I
have further shown that the young of ;
having been described as representatives of that
has been fully illustrated
Macroura represents even Entomostraca
forms, some of these young
order.£ The correspondence between the
growth, I have illustrated fully in a special paper.’ 1“
made in the class of Fishes;* among Reptiles, we find the most striking examples
gradation of Insects and their embryonic
Similar comparisons have been
4 Dana, q. a, p. 32.— BurMEIsTER, Cirripeds,
1 See the works quoted from p. 67-87, also MILNE-
q. a, p. 79.— THOMPSON, q. a., p. 79.
Epwarps, q. a., p. 112. —Tuompson, Crinoids, q- a
2 MUier, (J.,) Ueber Pentacrinus Caput-Me-
dus, Berlin, 1833, 4to., Ak. d. Wiss.
® Forses, (Ep.,) History of British Starfishes,
London, 1851, 1 vol. 8vo., p. 10.
5 RATHKE, q. a., p. 79.
6 Twelve Lectures, ete., p. 67.
7 Classification of Insects, q. a.
§ Poissons fossiles, q. a.
120 ESSAY ON CLASSIFICATION. Part I.
of this kind among Batrachians?! (see, above, Sect. XII); among Birds,’ the uniformly
webbed foot, in all young, exhibits another correspondence between the young
of higher orders and the permanent character of the lower ones. In the order
of Carnivora, the Seals, the Plantigrades, and the Digitigrades exemplify the same
comcidence between higher and higher representatives of the same types, and the
embryonic changes through which the highest pass successively.
No more complete evidence can be needed to show that there exists throughout
the animal kingdom the closest correspondence between the gradation of their types
and the embryonic changes their respective representatives exhibit throughout. And
yet. what genetic relation can there exist between the Pentacrinus of the West
Indies and the Comatule, found in every sea; what between the embryos of Spatan-
goids and those of Echinoids, and between the former and the adult Echinus;
what between the larva of a Crab and our Lobsters; what between the Caterpillar
of a Papilio and an adult Tinea, or an adult Sphinx; what between the Tadpole
of a Toad and our Menobranchus; what between a young Dog and our Seals,
unless it be the plan designed by an intelligent Creator? —
SHC TLO N: 2 XV LIT,
RELATIONS BETWEEN THE STRUCTURE, EMBRYONIC GROWTH, GEOLOGICAL SUCCESSION, AND
THE GEOGRAPHICAL DISTRIBUTION OF ANIMALS.
It requires unusual comprehensiveness of view to perceive the order prevailing
in the geographical distribution of animals. We should, therefore, not wonder that
this branch of Zodlogy is so far behind the other divisions of that science. Nor
should we wonder at the fact that the geographical distribution of plants is so much
better known than that of animals, when we consider how marked a feature the
vegetable carpet which covers the surface. of our globe is, when compared with the
little show animals make, almost everywhere. And yet it will, perhaps, some day,
be easier to understand the relations existing between the geographical distribution
of animals and the other general relations prevailing among animals, because the
range of structural differences is much greater among animals than among plants.
Even now, some curious coincidences may be pointed out which go far to show
that the geographical distribution of animals stands in direct relation to their rela-
* Twelve Lectures, ete., p. 8. 2 Acassiz, (L.,) Lake Superior, ete., p. 194.
Cuar. IL GRADATION; GROWTH, SUCCESSION, DISTRIBUTION. 121
tive standing in their respective classes, and to the order of their. succession in
past geological ages, and more indirectly, also, to their embryonic growth.
Almost every class has its tropical families, and these stand generally highest f =
in their respective classes; or, when the contrary is the case, when they stand!
evidently upon a lower level, there is some prominent relation between them and
The class of Mammalia affords striking examples,
the prevailing types of past ages.
In the first place, the Quadrumana, which, next
of these two kinds of connection.
to Man, stand highest in their class, are all tropical animals; and it is worthy of
remark, that the two highest types of Anthropoid Monkeys, the Orangs of Asia and
the Chimpanzees of Western Africa bear, in the coloration of their skin, an. addi-
tional similarity to the races of Man inhabiting the same regions, the Orangs being
yellowish red, as the Malays, and the Chimpanzee blackish, as the Negroes. The
stand low in their class, though chiefly tropical; but
Pachyderms, on the contrary,
prominent among the earliest representatives of
they constitute a group of animals
that class in past ages. Among Chiroptera, the larger frugivorous representatives are
on the contrary, occur everywhere. Among
essentially tropical; the more omnivorous, ith:
Carnivora, the largest, most powerful, and also highest types, the Digitigrade, prevail
in the tropics, while among the Plantigrades, the most powerful, the Bears, belong
to the temperate and to the arctic zone, and the lowest, the Pinnate, are marine
species of the temperate and arctic seas. Among Ruminants, we find the Giraffe
and the Camels in the warmer zones, the others everywhere. In the class of Birds
s in other classes, and yet the aquatic types form
class in temperate and cold regions, and
the higher land birds prevail in
the gradation is not so obvious a
by far the largest representation of this
are almost the only ones found in the arctic, while
the warm regions. Among Reptiles, the Crocodilians are entirely tropical; the largest
land Turtles are also only found in the tropics, and the aquatic representatives of
this order, which are evidently inferior to their land kindred, extend much further
The Rattlesnakes and Vipers extend further north and higher up the moun-
north.
The same is true of Sala-
tains than the Boas and the common harmless snakes. :
The Sharks and Skates are most diversified in the tropics. It
st brilliant diurnal Lepidoptera are found, and
Among Crustacea the highest order, the Bra-
but Dana has shown, what was not
manders and Tritons.
is also within the tropics that the mo
this is the highest order of Insects.
chyoura, are most numerous in the torrid zone; bu Binh
at all expected, that they nevertheless reach their highest perfection in the middle
temperate regions! The Anomoura and Macroura, on the contrary, are nearly
equally divided between the torrid and temperate zones; while the lower Tetrade-
capods are far more numerous in extra tropical latitudes than in the tropical. The
1 Dana, Crustacea, p. 1501.
16
*
\
\
|
| ie
|
y
:
' 18
ae
{ {
Tea
i}
1
Wa
HG
Pit
. i
| Ti
| RG
ian
;
a; 1
:
| i
| |
- r
:
|
ha
ay
7 |
|
i
ia
|
id
a
ti
|
i
i
aii
122 ESSAY ON CLASSIFICATION. Part I.
Cephalopods are most diversified within the tropics; yet the Nautilus is a reminis-
cence of past ages. Among Gasteropods, the Stromboids belong to the tropics; but
among the lamellibranchiate Acephala, the Naiades, which seem to me to stand very
high in their class, have their greatest development in the fresh waters of North
America. The highest Echinoderms, the Holothurians and Spatangoids are most diver-
sified within the tropics, while Echini, Starfishes, and Ophiuree extend to the arctics.
The presence of Pentacrinus in the West Indies has undoubtedly reference to the
prevalence of Crinoids in past ages. The Madrepores, the highest among the Acti
noid Polypi, are entirely tropical, while the highest Halcyonoids, the Renilla, Vere-
tillum, and Pennatula, extend to the tropics and the temperate zone.
Another interesting relation between the geographical distribution of animals and
their representatives in past ages, is the absence of embryonic types in the warm
regions. We find in the torrid zone no true representatives of the oldest geo-
logical periods; Pentacrinus is not found before the Lias; among Cephalopods we
find the Nautilus, but nothing like Orthoceras; Limulus, but nothing like Trilobites.
This study of the relations between the geographical distribution of animals, and
their relative standing, is rendered more difficult, and in many respects obscure, by
the circumstance that entire types, characterized by peculiar structures, are so
strangely limited in their range; and yet, even this shows how closely the geographi-
cal distribution of animals is connected with their structure. Why New Holland
should have no Monkeys, no Carnivora, no Ruminants, no Pachyderms, no Edentata,
is not to be explained; but that this is the case, every zodlogist knows, and is
further aware, that the Marsupials? of that continental island represent, as it were,
the other orders of Mammalia, under their special structural modifications. New
Holland appears thus as a continent with the characters of an older geological age.
No one can fail, therefore, to perceive of how great an interest for Classification
will be a more extensive knowledge of the geographical distribution of animals in
general, and of the structural peculiarities exhibited by localized types.
SECTEON. £20 x
MUTUAL DEPENDENCE OF THE ANIMAL AND VEGETABLE KINGDOMS.
Though it had long been known, by the experiments of De Saussure, that the
breathing process of animals and plants are very different, and that while the for-
1 See Sect. 11.
Cuap. IL - - PARASITIC ANIMALS. 123
mer inhale atmospheric air, and exhale carbonic acid gas, the latter appropriate
carbon and exhale oxygen, it was not until Dumas and Bousingault! called partic-
ularly the attention of naturalists to the subject, that it was fully understood how
direct the dependence is of the animal and vegetable kingdoms one upon the other,
in that respect, or rather how the one consumes what the other produces, and vice
versd, thus tending to keep the balance which either of them would singly disturb
to a certain degree. The common agricultural practice of manuring exhibits from
another side the dependence of one kingdom upon the other: the undigested
particles of the food of animals return to the ground, to fertilize it for fresh pro-
duction? Again, the whole animal kingdom is either directly or indirectly dependent
upon the vegetable kingdom for its sustenance, as the herbivorous animals afford
the needful food for the carnivorous tribes. We are too far from the time when
it could be supposed that Worms originated in the decay of fruits and other vege-
table substances, to need here repetition of what is known respecting the repro-
duction of these animals. Nor can it be necessary to show how preposterous the
assumption would be that physical agents produced plants first, in order that from
Who could have taught the physical agents to
these, animals might spring forth.
pon the vegetable kingdom?
make the whole animal world dependent u
ral facts as those above alluded to, show, more directly
On the contrary, such gene
could do, the establishment of a well-
than any amount of special disconnected facts a
regulated order of things, considered in advance; for they exhibit well-balanced
conditions of existence, prepared long beforehand, such as only an intelligent being
could ordain.
SECTION <a.
PARASITIC ANIMALS AND PLANTS.
However independent of each other some animals may appear, there are yet
many which live only in the closest connection with their fellow-creatures, and
which are known only as parasites upon or within them. Such are the intestinal
Worms, and all the vermin of the skin? Among plants, the Mistletoe, Orobanche,
1 and 2; see also Rupotpui, (K. A.,) Entozoorum
sive Vermium, etc., q. a., p. 31.— Bremsmr, (J. G.,)
Ueber lebende Wiirmer im lebenden Menschen,
Wien, 1819, 4to.— Dusarpin, (F.,) Hist. Nat. des
Helminthes, etc., q. a., p. 32. — Dixssine, (C. M.,)
Historia Vermium, etc., q. a. p. 32.
1 Dumas, Legon sur la statique chimique des
étres organisés, Ann. Se. Nat. 2de sér. vol. 6, p. 335
vol. 17, p. 122.
2 Lresie, Agricultural Chemistry ; Animal Chem-
istry.
® See above, p. 76, notes 1 and 2, and p. 77, notes
adie th Senet ieadal Sdn dicen ena
ae
a
‘
2
-
Bt
:
a 7 i
\
v
j }
;
4 }
|
i
4
4
| ; @ 1
| 1
i
i i}
:
i
| i
i
i
‘ ;
| |
. {
it a
a3
3)
“f i
|
ig
Wy
Bit wat}
Tay
: t |
: :
| N ia
| ia}
PBiah
}
| :
|
i +
‘1
| q
|
ame
: aa
q it
| al
q |
a 7
} a
{ EE tT
aii
i
Baal
a ij
Ve || |
‘i ih
PETE F
| :
} H
| y | ial
fia t
q hy i ;
Y i ‘
TR
{ }
| aa i
tai)
| | ‘
aaa |
|
a} |
|
| |
j
a
Re a mt
aa RN RAR aL
PNET Ta Se ET
124 ESSAY ON CLASSIFICATION. Part I.
Rafflesia, and many Orchidese may be quoted as equally remarkable examples of
parasitism.
There exists the greatest variety of parasites among animals. It would take
volumes to describe them and to write their history, for their relations to the
animals and plants upon which they are dependent for their existence are quite
as diversified as their form and their structure.
It is important, however, to remark, at the outset, that these parasites do not
constitute for themselves one great division of the animal kingdom. They belong,
on the contrary, to all its branches; almost every class has its parasites, and in
\. none do they represent one natural order. This fact is very significant, as it shows
at once that parasitism is not based upon peculiar combinations of the leading
structural features of the animal kingdom, but upon correlations of a more specific
character. Nor is the degree of dependence of parasites upon other organized
beings equally close. There are those which only dwell upon other animals, while
others are so closely connected with them that they cannot subsist for any length
of time out of the most intimate relation to the species in which they grow and’
multiply. Nor do these parasites live upon one class of animals; on the contrary,
they are found in all of them.
Among Vertebrata there are few parasites, properly speaking. None among
Mammalia. Among Birds, a few species depend upon others to sit upon their
egos and hatch them, as the European Cuckoo, and the North American Cowbird.
Among Fishes, some small Ophidiums (Fierasfers) penetrate into the cavity of the
body of large Holothurie in which they dwell’ cheneis attach themselves -to
other fishes, but only temporarily. Among Articulata, the number of parasites is
largest. It seems to lie in the very character of this type, so remarkable for the
outward display of their whole organization, to include the greatest variety of
parasites. And it is really among them, that we observe the most extraordinary
combinations of this singular mode of existence. |
Insects, in general, are more particularly dependent upon plants for their sus-
tenance than herbivorous animals usually are, masmuch as most of them are
limited to particular plants for their whole life, such as the Plant-lice, the Coccus,
the Gall Insects. In others, the larve only are so limited to particular plants, while
the larve of others still, such as the Bots, grow and undergo their development
under the skin or in the intestines, or in the nasal cavities of other animals. The
Ichneumons lay their eggs in the larve of other insects, upon which the young
larvee prey until hatched. Among perfect Insects, there are those which live only
in community with others, such as the Ant-Hill Insects, the Clavigers, the Clerus,
* See above, p.'74, note.
Cuap. I. PARASITIC ANIMALS. 4125
and Bees. Different kinds of Ants live together, if not as parasites one upon another,
at least in a kind of servitude. Other Insects live upon the bodies of warm
blooded animals, such as the Fleas and Lice, and of these the number is legion.
Some Hydrachnas are parasitic upon aquatic Mollusks.’
Among Crustacea, there are Crabs constantly living in the shell of Mollusks, |
such as the Pinnotheres of the Oyster and Mussel. I have found other species upon
Sea-Urchins, (Pinnotheres Melitte, a new species, upon Melitta quinquefora). The
Paguri take the shells of Mollusks to protect themselves ; while a vast number of
Amphipods live upon Fishes, attached to their gills, upon their tongue, or upon their
The Cyamus Ceti lives upon the Whale. Some Cirripeds
skin, or upon Starfishes’
are parasites upon the Whales, others upon Corals. In the family of Lerneans,
or fins or upon the body of Fishes,
the females are mostly parasites upon the gills
while the males are free.
Among Worms this mode of
dwell only among Corals, entire families
but here again we find the most diversi
- stantly parasitic, others depend only for a
The young Gordius is a free animal; it then creeps
them again to propagate; the young Distoma
livés free in the: water as Cercaria, and spends the remainder of its life im other
animals; the Txnia, on the contrary, is @ parasite through life, and only its eggs
But what is most extraordinary in this,
he fact, that while they undergo their first
they do not reach their complete develop-
ther higher type, bemg swallowed up by
Such is the case with many Filaria,
habit lower Fishes, and these Fishes
existence is still more frequent, and while some
of others consist only of genuine parasites ;
fied relations; for, while some are con-
certain period of their life upon other
animals for their existence.
into the body of Insects, and leaves
pass from one animal into the other.
as in many other intestinal Worms, is t
transformations in some kind of animals,
ment until they pass into the body of ano
this while in the body of their first host.
the Txenie and Bothrocephali. These at first in
being swallowed by Sharks or Water Birds, or Mic ;
up by Cats, the parasites living +n them undergo their final transformation in the
latter. Many Worms undertake extensive migrations through the bodies of other
animals, before they reach the proper P
e with their Worms being eaten
lace for their final development.
Die Pflanzen-Liuse, Aphiden, Niirnberg, 1846, 8vo.
fig. — Dueks, (Ant.,) Recherches sur Vordre des
Acariens, Ann. Se. Nat., 2de sér., 1834, L., p. 5, IL,
p- 18, fig.
2 J have found a new genus of this family upon
Asterias Helianthoides.
1 Nirzscu, (Cur. L.,) Darstellung der Familien
und Gattungen der Thierinsekten, Halle, 1818, 8vo.
— Haypen, (C. v.,) Versuch einer systematischen _
Eintheilung der Acariden, Isis, 1826, p- 608. —
Ratzensure, (J. S. C.,) Die Ichneumonen der
Forstinsekten, Berlin, 1844-52, 3 vols. 4to. Toa
Ciark, (Br.,) Observations on the Genus Oestrus, 8 See above, p. 76, note 1; SreBoLp, Wanderung,
Trans: Lin, Boe. Wis g 389, HOO OLY paley pa Tonolets ‘SreeNernue, cre
ESSAY ON CLASSIFICATION. Part I.
Among Mollusks, parasites are very few, if any can properly be called true
parasites, as the males of some Cephalopods living upon their own females;! as the
Gasteropods growing buried in Corals? and the Lithodomus and a variety of Arcas
found in Corals. Among Radiata there are no parasites, properly speaking; some
of them only attaching themselves by preference to certain plants, while the young
of others remain connected with their parent, as in all Corals, and even among
Crinoids, as in the Comatula of Charleston.
In all these different cases, the chances that physical agents may have a share
in producing such animals are still less than in the cases of independent animals,
for here we have superadded to the very existence of these beings all the com-
plicated circumstances of their peculiar mode of existence and their various con-
nections with other animals. Now, if it can already be shown from the mere
connections of independent animals, that external circumstances cannot be the cause
of their existence, how much less could such an origin be ascribed to parasites !
It is true, they have been supposed to originate in the body of the animals upon
which they live. What then of those who enter the body of other animals at
a somewhat advanced stage of growth, as the Gordius? Is it a freak of his?
Or, what of those which only live upon other animals, such as lice; are they the
product of the skin? Or, what of those which have to pass from the body of
a lower into that of a higher animal, to undergo their final metamorphosis and
in which this succession is normal? Was such an arrangement devised by the first
animal, or imposed upon the first by the second, or devised by physical agents
for the two? Or, what of those in which the females only are parasites? Had
the two sexes a different origin? Did perhaps the males and females originate
in different ways? |
I am at a loss to conceive how the origin of parasites can be ascribed to
physical causes, unless, indeed, animals themselves be considered as physical causes,
with reference to the parasites they nourish; and if so, why can they not get
rid of them, as well as produce them, for it cannot be supposed, that all this
is not done consciously, when parasites bear such close structural relations to the
various types to which they. belong?
The existence of parasitic animals belonging to so many different types of the
animal as well as the vegetable kingdom, is a fact of deep meaning, which Man
himself cannot too earnestly consider, and, while he may marvel at the fact, take
it as a warning for himself, with reference to his boasted and yet legitimate inde-
1 See above, p. 74, note 1, KOLLIKER, MULtEr, ? Rtprert, (Ep.,) Mémoire sur le Magilus
VERANY and Voer, ete. antiquus, Trans. Soc. Strasb., 1832, I, fig.
Cuap. I. COMBINATION OF RELATIONS. 127
pendence. All relations im nature are regulated by a superior wisdom. May we
only learn in the end to conform, within. the limits of our own sphere, to the
laws assigned to each race!
SOT TON Ras
GOMBINATION IN TIME AND SPACE OF VARIOUS KINDS OF RELATIONS AMONG ANIMALS.
It must occur to every reflecting mind, that the mutual relation and respective
parallelism of so many structural, embryonic,
teristics of the animal kingdom are the most conclusive proof, that they were
ordained by a reflective mind, while they present at the same time the side of
to our intelligence, when seeking to penetrate the relations
geological, and geographical charac-
nature most. accessible
between finite beings and the cause of their existence. :
The phenomena of the inorganic world are all simple, when compared to those
of the organic world. There is not one of the great physical agents, electricity,
magnetism, heat, light, or chemical affinity, which exhibits, in its sphere, as com-
plicated phenomena as the simplest organized beings; and we need not look for
the highest among the latter, to find them presenting the same physical phenomena
as are manifested inthe material world pesmes sere which are exclusively pecu-
liar to them. When, then, organized beings include every thing the material world
contains, and a great deal more that is peculiarly their own, how could they be
produced by physical causes, and how can the physicists, acquainted with the laws
of the material world, and who acknowledge that these laws must have been
established at the beginning, overlook that a fortiori the more complicated laws
which regulate the organic world, of the existence of which there is no trace for
a long period upon the surface of the earth, must have been established, later
and successively, at the time of the creation of the successive types of animals
and plants ? say
Thus far, we have been considerimg chiefly the contrasts existing between the
organic and inorganic worlds! At this stage of our investigation it may not be
ake a glance at some of the . coincidences which may be traced
! they afford direct evidence that the physical world
th laws which obtain .also among living beings,
out of place to t
between them, especially as
has been ordained in conformity wl
h spheres equally: plainly, the workings of a reflective mind.
and disclose, in bot
1 Compare Sects. 24, 25, 26, 27, 28, 29, and 30.
7 -
eg
crease
a
rogers sree sarees
ck: belies
ene Sa sate
128 ESSAY ON CLASSIFICATION. Parr I.
It is well known, that the arrangement of the leaves in plants! may be expressed
he SE: AR al etl 5 AR atte ee Satine | mons et _
nt RN i ARR <a Nl an a it
by very simple series of fractions, all of which are gradual approximations to, or
the natural means between 4 or 4, which two fractions are themselves the maxi-
a isle
ee ee ane
mum and the minimum divergence between two single successive leaves. The
es.
normal series of fractions which expresses the various combinations most frequently
observed among the leaves of plants, is as follows: 4, 4, 2, 8, 3, 8, 23, 24, ete.
elms ll Eh lt
Now, upon comparing this arrangement of the leaves in plants with the revolu-
tions of the members of our solar system, Peirce has discovered the most perfect
identity: between the fundamental laws which regulate both, as may be at once
seen by the following diagram, in which the first column gives the names of the
planets, the second column indicates the actual time of revolution of the successive
planets, expressed in days, the third column the successive times of revolution of
the planets, which are derived from the hypothesis that each time of revolution
should have a ratio to those upon each side of it, which shall be one of the
ratios of the law of phyllotaxis; and the fourth column, finally, gives the normal
series of fractions expressing the law of the phyllotaxis.
Neptune, . ‘ 60,129 , . 62,000
Uranus, . , “) BO MOTE” « ‘ . 981,000
Saturn, . mi 10,759 F ; 10,333
Jupiter, . °. . 4,333. : e aloo
Asteroids, . . 1,200 to 2,000 . 1,550
Mars, ‘ ‘ : Sd. ‘ ‘ 596
Earth, i P 365 ‘ ; 366
Venus, . , " PI ie ere 227
Mercury, P 88 . rt 87 43
In this series the Earth forms a break; but this apparent irregularity admits
of an easy explanation. The fractions 3, 3, 2, 3, qs, a, $$ etc, as expressing the
position of successive leaves upon an axis, by the short way of ascent along the
spiral, are identical, as far as their meaning is concerned, with the fractions express-
ing these same positions, by the long way, namely, 4, 2, 3, 5, 38, 3, 24, ete.
Let us, therefore, repeat our diagram in another form, the third column giving
the theoretical time of revolution.
Neptune, ‘ ‘ ee : 62,000
ES ah pages 52 - - 62,000
Uranus, ‘ : ‘ : 31,000
« Be: See ee Faye MM | Cost a
1 See the works quoted above, p. 18, note 3.
- Cuar. L COMBINATION OF RELATIONS. 129
Saturn, % LOZBIB oo EN 10,759
‘“ 2 6889) 5 ; d
Jupiter, 3 4,133 . . 4,333
ee: 3 2,480 e . 5 —_
Asteroids, 5 pL ica ae 1,200
&“ & PO ON Pease tS!
Mars fs 596 . j Peer Sioa
ALS,
Earth, 85 366. . ‘ ; 365
Venus, 43 227 . : ~ 225
&< 12 140 . ; _o—_—
Mercury, 34 87 : : es
It appears from this table, that two intervals usually elapse between two suc-
: (CRP RO Re
cessive planets, so that the normal order of actual fractions is 4, 4, 2, %, 355, etc,
or the fractions by the short way in phyllotaxis, from which, however, the Earth
is excluded, while it forms a member of the series by the long way. The explana-
tion of this, suggested by Peirce, is that although the tendency to set off a planet
is not sufficient at the end of a single interval, By
end of the second interval, that the planet is found exterior to the limit of this
o far from the Sun relatively to Neptune,
it becomes so strong near the
second interval. Thus, Uranus is rather to
Saturn relatively to Uranus, and Jupiter relatively to Saturn, and the planets thus
formed engross too large a proportionate share of material, and this is especially
Hence, when we come to the Asteroids, the disposition is
‘ |
the case with Jupiter. a aie ;
nole interval, that the outer Asteroid is but just within
g |
so strong at the end of a si Aes Sa
this interval, and the whole material of the Asteroids 1s dispersed in separate masses
over a wide space, instead of being concentrated into a single planet. A conse-
. forming agents is, that a small proportionate
quence of this dispersion of the
Hence, Mars is ready for formation so
material is absorbed into the Asteroids.
far exterior to its true place, that when the nex
he Earth, after which the normal law is resumed
without any further disturbance. Under this law, there can be no planet exterior
to Neptune, but there may be one interior to Mereury.
Let us now look back upon some of the leading features alluded to before,
of organized beings to. the world around, or those of
+ interval elapses the residual force
becomes strong enough to form t
omitting the simpler relations
individuals to individuals, to consider only the different parallel series we have been
in their respective great types, the phenomena of
comparing when showing that, ;
whether we compare their rank as deter-
animal life correspond to one another,
mined by structural complication with the phases of their growth, or with their
succession in past geological ages; whether we compare this succession with their
embryonic growth, or all these different relations with each other and with the geo-
ee 17
d
eareenen -%
a ——— | ,
“a TRE:
CN CARR EDP REY TENS rae
aha
seamen as
aoe ee
Sa i a a MT Ti i RR tT
a : - ae
nin . a
a ee ee ee ee poner
ETT
. , . ‘ ‘ 6 shin és Ponca taitenisiibinhianacntin, \
ae nl he MM a athe
130 ESSAY ON CLASSIFICATION. Parr L
graphical distribution of animals upon earth. The same series everywhere!! These
facts are true of all the great divisions of the animal kingdom, so far as we have
pursued the investigation; and though, for want of materials, the train of evidence
is incomplete in some instances, yet we have proof enough for the establishment
of this law of a universal correspondence im all the leading features which . binds
all organized beings, of all times, into one great system, intellectually and intelligibly
linked together,'even where some links of the chain. are missing. It requires con-
siderable familiarity with the subject even to keep in mind the evidence, for,
though yet imperfectly understood, it is the most brilliant result of the combined
intellectual efforts of hundreds of investigators during half a century. The connec-
tion, however, between the facts, it is easily seen, is only intellectual; and implies,
therefore, the agency of Intellect as its first cause.’
And if the power of thinking connectedly is the privilege of cultivated minds
only; if the power of combining different thoughts, and of drawing from them new
thoughts, is a still rarer privilege of a few superior minds; if the ability to trace
simultaneously several~trains of’ thought is such an extraordinary gift, that the few
cases in which evidence of this kind has been presented have become a matter
of historical record (Cesar dictating several letters at the same time), though they
exhibit only the capacity of passing rapidly, in quick succession, from one topic to
another, while keeping the connecting thread of several parallel thoughts: if all
this is only possible for the highest intellectual powers, shall we by any false
argumentation allow ourselves to deny the intervention of a Supreme Intellect in
calling into existence combinations im nature, by the side of which, all human
conceptions are child’s play? |
If I have succeeded, even very imperfectly, in showing that the various rela-
tions observed between animals and the physical world, as well as between them-
selves, exhibit thought, it follows, that the whole has an Intelligent Author, and it
may not be out of place to attempt to point out, as far as possible, the difference
there may be between Divine thinking and human thought.
Taking nature as exhibiting thought for my guide, it appears to me, that while
human thought is consecutive, Divine thought is simultaneous, embracing at the same
time and for ever, in the past, the present, and the future, the most diversified
relations among hundreds of thousands of organized beings, each of which may
present. complications agam, which, to study and understand even imperfectly, as
for instance, Man himself, Mankind has already spent thousands of years. And
yet, all this has been done by one Mind, must be the work of one Mind only, of
* Compare all the preceding sections, where every 2 AGassiz, (L.,) Contemplations of God in the
topic is considered separately. - Kosmos, Christian Examiner, January, 1851, Boston.
Cuap. I. COMBINATION OF RELATIONS. 131
Him before whom Man can only bow in grateful acknowledgment of the pre-
rogatives he is allowed to enjoy im this world, not to speak of the promises of a
future life. .
I have intentionally dismissed many points In my argument with mere questions,
in order not to extend unduly a discussion which is after all only accessory to
the plan of my work. I have felt justified in doing so because, from the point
of view under which my subject is treated, those questions find a natural solution
which must present itself to every reader. We know what the intellect of Man
may originate, we know its creative power, its power of combination, of foresight,
of analysis, of concentration; we are, therefore, prepared to recognize a similar
action emanating from a Supreme Intelligence to a boundless extent. We need,
therefore, not even attempt to show that such an Intellect may have originated all
the Universe contains; it is enough to demonstrate, that the constitution of the
physical world, and more particularly the organization of living beings in their connec-
tion with the physical world prove, in general, the existence of a Supreme Being,
as the Author of all things. The task of science is rather to mvestigate what has
been done, to inquire, if possible, how it has been done, than to ask what is possible
for the Deity, as we can know that only by what actually exists. To attack such
a position, those who would deny the intervention in nature of a creative mind,
must show, that the cause to which they refer the origin of finite bemgs is by
its nature a possible cause, which cannot be denied of a being endowed with the
attributes we recognize in God. Our task is therefore completed, as soon as we
It would, nevertheless, be highly desirable that every
have proved his existence.
should go over the subject anew,
naturalist, who has arrived at similar. conclusions,
from his point of view and with particular reference to the special field of his
investigations; for so only can the whole evidence be brought out.
I foresee already that some of the most striking illustrations may be drawn —
from the morphology of the vegetable kingdom, especially from the characteristic
succession and systematical combination of different kinds 3
tion of the foliage and the flowers of so many plants, ‘il of Which end their
development by the production of an endless variety of fruits. The inorganic world,
‘considered in the same light, would not fail to exhibit also unexpected evidence
of thought, in the character of the laws regulating the chemical combinations, the
action of physieal forces, the universal attraction, etc, etc. Even the history of
o be investigated from this point of view. But I must
of leaves in the forma-
human culture ought t
leave it to abler hands to discuss suehk topics.
ESSAY ON CLASSIFICATION.
SECTION 2A AE.
RECAPITULATION.
i reenalalciline the: preceding statements, we may present the followimg con-
clusions : — |
~~ Ast! Phe ‘Senhention of all these known features of nature into one system ex-
hibits thought, the most comprehensive thought, m limits transcending the highest
wonted powers of man.
2d. The simultaneous existence of the most diversified types under identical
circumstances exhibits thought, the ability to adapt a great variety of structures to
the most uniform conditions. ine ;
3d. The repetition of similar’ types, under the: most diversified circumstances,
shows an immaterial connection between them; it exhibits thought, proving directly
how completely the. Creative Mind is independent of the influence of a material
world. |
Ath. The unity of plan in otherwise highly diversified types of animals, exhibits
thought; it exhibits more immediately premeditation, for no plan could embrace such
a diversity of beings, called into existence at such long intervals of time, unless it
had. been framed in the beginning with immediate reference to the end.
oth. The correspondence, now generally known as special homologies, in the details
of structure in animals otherwise entirely disconnected, down to the most minute
peculiarities, exhibits thought, and more immediately the power of expressing a
general proposition in an indefinite number of ways, equally complete in themselves,
though differmg in all their details.
6th. The various. degrees and different kinds of relationship among animals which
can have no genealogical connection, exhibit thought, the power of combining dif-
ferent categories into a permanent, harmonious whole, even though the material
basis of this harmony be ever changing.
7th. The simultaneous existence, in the earliest geological periods in which ani-
mals existed at all, of representatives of all the great types of the animal kingdom,
exhibits most. especially thought, considerate thought, combining power, premeditation,
prescience, omniscience.
8th. The gradation based upon complications of structure which may be traced
* The numbers inscribed here correspond to the —_ reader may at once refer back to the evidence, when
preceding sections, in the same order, so that the needed.
Cuap. I. RECAPITULATION. . 133
among animals built upon the same plan, exhibits thought, and especially the power
of distributing harmoniously unequal gifts.
9th. The distribution of some types over the most extensive range of the sur-
while others are limited to particular geographical areas, and the
of these types mto zodlogical provinces of unequal extent,
distribution of the earth’s surface among
face of the globe,
various combinations
exhibit thought, a close control in the
its inhabitants. 7
10th. The identity of structure of these types, notwithstanding their wide geo-
graphical distribution, exhibits thought, that deep thought which, the more it is
scrutinized, seems the less capable. of being exhausted, though its meaning at the
n and intelligible to every one.
surface appears at once plai
of animals otherwise en-
“11th. The community of structure in certain respects
tirely different, but living within the same geographical area, exhibits thought, and
more particularly the power of adapting most diversified types with peculiar struc-
tures to either identical or to different conditions
12th.. The connection, by series, of special structures od |
scattered over the surface of the globe, exhibits thought, unlimited comprehension,
and more directly omnipresence of mind, and also prescience,
extend through a succession of geological ages. .
13th. The relation there is between the size of animals and their structure and
Gam, exhibits thought; it shows that m nature the quantitative differences are as
fixedly determined as the qualitative ones.
14th. The independence, in the size of animals, ! 7
live, exhibits thought, in establishing such close connection between elements so influ-
ential in themselves and organized beings so little affected by the nature of these
elements.
of. existence.
observed in animals widely
as far as such series
of the mediums in which they
e of specific peculiarities under every variety of external
d, and under the present state of things upon
that limitation in time is an essential element
15th. The permanenc
influences, during each geological perio
earth, exhibits. thought: it shows, also,
of all finite beings, while eternity is an attribute of the Deity only.
16th. The definite relations in which animals stand to the surrounding world,
exhibit thought; for all animals living together stand respectively, on account of
their very differences, in different. relations 2a
a considerate adaptation of their varied organization to these
to identical conditions of existence, in a
manner which implies
uniform conditions.
17th. The relations in whi a
other, exhibit thought, and go far to prove the existence in all living beings of an
similar to that which is generally conceded to man
ch individuals of the same species stand to one an-
immaterial, imperishable principle,
only.
ae ee ee EE ee eeaeceeetina ch acieteennyeshaneaeliiindmsecntbeaaiod
pt A I ee ———
: — — . 2 2 vt Sinise -
yg a
'
:
ie
i
:
i te
| i A,
vil
Will
ai
i
|)
bly |
134 ESSAY ON CLASSIFICATION. Part I.
18th. The limitation of the range of changes which animals undergo during their
growth, exhibits thought; it shows most strikingly the independence of these changes
of external influences, and the necessity that they should be - determined by a
power superior to these influences.
19th. The unequal limitation in the average. duration of the life of individuals
in different species of animals, exhibits thought; for, however uniform or however
diversified the conditions of existence may be under which animals live together,
the average duration of life, in different species, is unequally limited. It points, there-
fore, at a knowledge of time and space, and of the value of time, since the phases
of life of different animals are apportioned according to the part they have to per-
form upon the stage of the world.
20th. The return to a definite norm of animals which multiply in various ways,
exhibits thought. It shows how wide a cycle of modulations may be included in
the same conception, without yet departing from a norm expressed more directly in
other combinations.
21st. The order of succession of the different types of animals and plants charac-
teristic of the different geological epochs, exhibits thought. I shows, that while
the material world is identical in itself in all ages, ever different types of organized
beings are called into existence in successive periods.
22d. The localization of some types of animals upon the same pelts of the sur-
face of the globe, during several successive geological periods, exhibits thought,
consecutive thought; the operations of a mind acting in conformity with a plan
laid out beforehand and sustained for a long period.
23d. The limitatiom of closely allied species to different geological periods, exhibits
thought; it exhibits the power of sustaining nice distinctions, notwithstanding the
interposition of great disturbances by physical revolutions.
24th. The parallelism between the order of suecession of animals and plants
in geological times, and the gradation among their living representatives, exhibit
thought ; consecutive thought, superintending the whole development of nature from
beginning to end, and disclosing throughout a gradual progress, ending with the
introduction of mam at the head of the animal creation.
25th. The parallelism between the order of succession of animals in geological
times and the changes their living representatives undergo during their embryological
growth, exhibits thought; the repetition of the same train of thoughts in the phases
of growth of living animals and the successive appearance of their representatives
im past ages.
26th. The combination, in many extinct types, of characters which, in later ages,
appear disconnected in different types, exhibits thought, prophetic thought, mabe ck
combinations of thought preceding their manifestation’ in living forms.
Cuap. I. RECAPITULATION. | 135
27th. The parallelism between the gradation among animals and the changes
they undergo during their growth, exhibits thought, as it discloses everywhere the
most intimate connection between essential features of. animals which have no
necessary physical relation, and can, therefore, not be understood otherwise than
as established by a thinking being.
28th. The relations existing between these different series and the geographical
distribution of animals, exhibit thought; they show the omnipresence of the Creator.
29th. The mutual dependence of the animal and vegetable kingdoms for their
maintenance, exhibits thought; it displays the care with which all conditions of
existence, necessary to the maintenance of organized beings, have been balanced.
30th. The dependence of some animals upon others or upon plants for Been
existence, exhibits thought; it shows to what degree the most complicated com-
binations of structure and adaptation can be rendered independent of the physical
conditions which surround them.
We may sum up the results of this discussion, up to this point, in still fewer
ivords : —
All organized beings exhibit in themselves all those categories of structure and
of existence upon which a natural system may be founded, in such a manner
that, in tracing it, the human mind is only translating into human language the
Divine thoughts expressed in nature in living realities.
All these beings do not exist in consequence of the continued agency of physical
causes, but have made their successive appearance upon earth by the immediate
intervention of the Creator. As proof, I may sum up my argument im the fol-
lowing manner: _
The products of
same, (that is, upon the whole surface of the glo
same (that is, during all geological periods) ; while organized beings are everywhere
different and have differed in all ages. Between two such series of phenomena
there can be no causal or genetic connection. }
31st. The combination in time and space of all these thoughtful conceptions
+t shows also premeditation, power, wisdom, great-
In one word, all. these facts in their
lina are commonly called physical agents are everywhere the
be,) and have always been the
exhibits not only thought,
ness, prescience, ommiscience, providence.
natural connection proclaim aloud the One God, whom man may know, adore,
and love; and Natural History must, in good time, become the analysis of the
thoughts of the Creator of the Universe, as manifested in the animal and vegetable
kingdoms.
It may appear strange that I should have imeluded the preceding disquisition
in that part of my work which is headed Classification. Yet, it has been done
ee oe eee
ate CA ee Se i ee ll ANCE aN a een
—_ - —e . — .
cere Pt
136 | ESSAY ON CLASSIFICATION. Part 1.
deliberately. In the beginning of this chapter, I have already stated that Classi-
fication seems to me to rest upon too narrow a foundation when it is chiefly based
upon structure. Animals are linked together as closely by their mode of develop-
ment, by their relative standing in their respective classes, by the order in which
they have made their appearance upon earth, by their geographical distribution, and
generally by their connection with the world in which they live, as by their
anatomy. All these relations should, therefore, be fully expressed in a natural
classification; and though structure furnishes the most direct indication of some of
these relations, always appreciable under every circumstance, other considerations
should not be neglected, which may complete our insight into the general plan
of creation. |
In characterizing the great branches of the animal kingdom, it is not enough
to indicate the plan of their structure, in all its peculiarities; there are possibilities
of execution which are at once suggested to the exclusion of others, and which
should also be considered, and so fully analyzed, that the various modes in which
such a plan may be carried out shall at once be made apparent. The range and
character of the general homologies of each type should also. be illustrated, as
well as the general conditions of existence of its representatives. In characterizing
classes, it ought to be shown why such groups constitute a class and not merely
an order, or a family; and to do this satisfactorily, it is indispensable to trace the
special homologies of all the systems of organs which are developed in them. It
is not less important to ascertain the foundation of all the subordinate divisions
of each class; to know how they differ, what constitutes orders, what families, what
genera, and upon what characteristics species are based in every natural division.
This we shall examine in the next chapter. . ae
ee
SATII ST TS : SNEED A ENC N TR i i o . ‘ : é -
Tythetehyetacter ts acta ey ; : * : ne aahaacriy tyetegtean estat ttattinetig tent Petit pSRSUSSSESA Stan ADS aT CONTENDING ad SOLD TA OGL GTA TASER GL
ny i ) ¥ t Shahar aas! mata het ih tia rabieg thas Tha tans Mae thastiasttaltt ra es
n > MINI
' atu tts,
tage, Soa om, Me, . pebesy .. + *
SA hantnttg! Nerbeattes Suitec tiene Soe ta ; saiitatise tees tarhieetaeeton Das acehatacting inc etats Shae
PRET S
EERE
a
abe AS I RO eminem trstaan neem Ae EY A SENT NRA st
Re A CAROLO DARWIN
*FRANCISCVS DARWIN +
larry Soane, 1882.
ner
PART I. OF THE FIRST VOLO 2 2277 ae
CONTRIBUTIONS
TO THE
NATURAL HISTORY OF THE UNITED STATES
OF
NORTH AMERICA.
Ne
i Be Bo ae.
|
—
Sais ade
}
1)
}
I
I
7}
q
|
iB
|
i)
|
| i
i!
|
4
'
}
i
Hy
iW
fe RR ST a acer reeet
° ae tet
BRANCHES OF THE ANIMAL KINGDOM,
CHAT] EK." ae ON Ds
LEADING GROUPS OF THE EXISTING SYSTEMS OF ANIMALS,
SECTION 1.
GREAT TYPES OR BRANCHES OF THE ANIMAL KINGDOM.
Tur use of the terms types, classes, orders, families, genera, and species in the
systems of Zovlogy and Botany is so universal, that it would be natural to suppose
that their meaning and extent are well determined and generally understood; but
this is so far from being the case, that it may, on the contrary, be said, there is
no subject in Natural History respecting which there exists more uncertainty and
Indeed, I have failed to find anywhere a definition
a greater want of precision.
of the character of most of the more comprehensive of these divisions, while the
current views respecting genera and species are very conflicting. Under these cir-
cumstances, it has appeared to me particularly desirable, to inquire into the founda-
tion of these distinctions, and to ascertain, if possible, how far they have a real
And while I hope the results of this inquiry may be welcome and—
existence.
satisfactory, I am free to confess that it has cost me years of labor to arrive at
a clear conception of their true character.
It is such a universal fact in every sphere of intellectual activity, that prac-
tice anticipates theory, that no philosopher should be surprised to find zovlogists
have adopted instinctively natural groups, in the animal and vegetable kingdoms,
even before the question of the character and of the very existence of such
groups in nature was raised. Did not nations speak, understand, and write Greek,
Latin, German, and Sanscrit before it was even suspected that these languages
and so many others were kindred? Did not painters produce wonders with
colors before the nature of light was understood? Had not men been thinking
about themselves and the world before logic and metaphysics were taught in schools?
18
| :
|
4 :
. = =: en = — = y. ene = ——— = -- - — : > <= ~ —= —e ree :
mopman Soe 8 a en ST a ipiosnerens errr een — = M “- - z = a a mate — - ma - oe ee = a - . met (ae ; -
eee oe = Se OE ee iene ete cesta ae — —— a a en _ _ wis nts naan tint alah i <= —_ » oe
; < a eae anne as ans | d
— 2 —— Se eee = ———— ee = — : . 4 bee
eS vee = RE ee
158 ESSAY ON CLASSIFICATION. — Part I.
Why, then, should not observers of nature have appreciated rightly the relationship
between animals or plants before getting a scientific clue to the classifications they
were led to adopt as practical? ;
Such considerations, above all others, have guided and encouraged me while I
was seeking for the meaning of all these systems, so different one from the other in
their details, and yet so similar in some of their general features. The history
of our science shows how ‘early some of the principles, which obtain to this day,
have been acknowledged by all reflecting naturalists. Aristotle, for instance, knew
already the principal differences which distinguish Vertebrata from all other animals,
and his distinction of Eneima and Aneima+ corresponds exactly to that of Vertebrata
and Inwertebrata of Lamarck? or to that of Flesh- and Gut-Ammals of Oken? or to that
of Myeloneura and Ganglionewra of Ehrenberg ; 4 and one who is at all familiar
with the progress of science at different periods, can but smile at the claims to
novelty or originality so frequently brought forward for views long before current
among men. Here, for instance, is one and the same fact presented in different
aspects; first, by Aristotle with reference to the character of the formative fluid,
next by Lamarck with reference to the general frame, for I will do Lamarck
the justice to believe, that he did not unite the Invertebrata simply because they
have no skeleton, but because of that something, which even Professor Owen fails
to express° and which yet exists, the one cavity of the body in Invertebrata con-
taining all organs, whilst Vertebrata have one distinct cavity for the centres of the
nervous system and another for the organs of the vegetative life. This acknowledg-
ment is due to Lamarck as truly as it would be due to Aristotle not to accuse
him of having denied the Invertebrata any fluid answering the office of the blood,
though he calls them Aneima; for he knew nearly as well as we now know,
that there moves a nutritive fluid in their body, though that information 1s
generally denied him, because he had no correct knowledge of the circulation of
the blood.
- Again, when Oken speaks of Flesh-Animals he does not mean that Vertebrates
consist of nothing but flesh, or that the Invertebrates have no muscular fibres;
but he brings prominently before us the presence, in the former, of those masses,
forming mainly the bulk of the body, which consist of flesh and bones, as well
as blood and nerves, and constitute another of the leading features distinguishing
Vertebrata and Invertebrata. Ehrenberg presents the same relations between the
same beings as expressed by their nervous system. If we now take the expressions
1 Histor. Anim., Lib. I., Ch. 5 and 6. 4 Das Naturreich des Menschen; a diagram, upon
2 Anim. Vert., 2d édit., vol. 1,. p. 313. a large sheet, folio.
8 Naturphilosophie, 3d edit., p. 400. 5 Comparat. Anat. of Inv., 2d edit., p. 11.
Cuap. II. BRANCHES OF THE ANIMAL KINGDOM. 139
of Aristotle, Lamarck, Oken, and Ehrenberg together, have we not, as characteristic
of their systems, the very words by which every one distinguishes the most promi-
nent features of the body of the higher animals, when speaking of blood relations,
of blood and bones, or of having flesh and nerve? |
Neither of these observers has probably been conscious of the identity of his
classification with that of his predecessors; nor, indeed, should we consider either
of them as superfluous, inasmuch as it makes prominent, features more or less differ-
ent from those insisted upon by the others; nor ought any one to suppose that
with all of them the field is exhausted, and that there is no more room for new
systems upon that very first distinction among animals." As long as men inquire
they will have opportunities to know more upon these topics than those who have
gone before them, so inexhaustibly rich is nature in the innermost diversity of her
treasures of beauty, order, and intelligence.
So, instead of discarding all the systems which have thus far had little or no
influence upon the progress of science, either because they are based upon _prin-
ciples not generally acknowledged or considered worthy of confidence, I haye care-
fully studied them with the view of ascertaining whatever there may be true in
them, from the stand-point from which their authors have considered the animal
kingdom; and IT own that I have often derived more information from such a careful
consideration than I had at first expected.
It was not indeed by a lucky hit, nor by one of those unexpected apparitions
which, like a revelation, suddenly break upon us and render at once clear and
comprehensible what had been dark and almost inaccessible before, that I came to
understand the meaning of those divisions called types, classes, orders, families, gen-
era, and species, so long admitted mm Natural History as the basis of every system,
: generally considered as mere artificial devices to facilitate our studies.
and yet so
I had been laboring under the impression that they are founded in
For years
nature, before I succeeded in finding out upon what principle they were really based.
I soon perceived, however, that the greatest obstacle in the way of ascertaining
their true significance lay in the discrepancies among different authors in their use
and application of these terms. Different naturalists.do not call by the same name
groups of the same kind and the same extent: some call genera what others call
subgenera; others call tribes, or even families, what are called genera by others;
1 By way of an example, I would mention the different from what is observed in any of the Inver-
mode of reproduction. The formation of the egg in __ tebrata, that the animal kingdom, classified according
Vertebrata; its origin, in all of them, in a more or to these facts, would again be divided into two great
less complicated Graafian vesicle, in which it is groups, corresponding to the Vertebrata and Inverte-
nursed ; the formation and development of the embryo brata of Lamarck, or the Flesh- and Gut- Animals of
up to a certain period, etc., ete., are So completely Oken, or the Hneima and Aneima of Aristotle, ete.
140 ESSAY ON CLASSIFICATION. Part I.
even the names of tribe and family have been applied by some to what others
call sub-genera; some have called families what others have called orders; some
consider as orders what others have considered as classes; and there are even genera
of some authors which are considered as classes by others. Finally, in the number
and limitation of these classes, as well as in the manner in which they are grouped
together, under general heads, there is found the same diversity of opinion. It is,
nevertheless, possible, that under these manifold names, so differently applied, groups
may be designated which may be natural, even if their true relation to one another
have thus far escaped our attention.
It is already certain that most, if not all investigators agree in the limitation,
of some groups at least, under whatever name they may call them, and however
much they would blame one another for calling them so, or otherwise. I can there-
fore no longer doubt that the controversy would be limited to definite ques-
tions, if naturalists could only be led to an agreement respecting the real nature
of each kind of groups. I am satisfied, indeed, that the most insuperable obstacle
to any exact appreciation of this subject lies in the fact, that all naturalists, with-
out exception, consider these divisions, under whatever name they may designate
them, as strictly subordinate one to the other, in such a manner, that their differ-
ence is only dependent upon their extent; the class being considered as the more
comprehensive division, the order as the next extensive, the family as more limited,
the genus as still more limited, and the species as the ultimate limitation in a
natural arrangement of living beings, so that all these groups would differ only by
the quantity of their characters, and not by the quality, as if the elements of
structure in animals were all of the same kind; as if the form, for instance, was
an organic element of the same kind as the complication of structure, and as if
the degree of complication implied necessarily one plan of structure to the exclu-
sion of another. I trust I shall presently be able to show that it is to a neglect
of these considerations that we must ascribe the slow progress which has been
made in the philosophy of classification.
- Were it possible to show that all these eroups do not differ in quantity, and
are not merely divisions of a wider or more limited range, but are based upon
different categories of characters, genera would be called genera by all, whether
they differ much or little one from the other, and so would families be called fam-
ilies, orders be called orders, ete. Could, for instance, species be based upon absolute
size, genera upon the structure of some external parts of the body, families upon
the form of the body, orders upon the similarity of the internal structure, or the
like, it is plain that there could not be two opinions respecting these groups in
any class of the animal kingdom. But as the problem is not so simple in nature,
it was not until after the most extensive investigations, that I seized the clue to
Cuap. II. BRANCHES OF. THE ANIMAL KINGDOM, 141
guide me through this labyrinth. I knew, for instance, that though naturalists have
been ‘disputing, and are still disputing, about species and genera, they all distin-
guished the things themselves in pretty much the same manner. What A would
call a species, B called only a variety or a race; but then B might call a sub-
genus the very same aggregate of individuals which A called a species; or what
A called a genus was considered by B as a family or an order. Now it was this
something called no matter how, for which I tried to find out characters which would
lead all to call it by the same name; thus limiting the practical difficulty in the
application of the name to a question of accuracy in the observations, and no longer
allowing it to be an eternal contest about mere nomenclature.
At this stage of my investigation it struck me, that the character of the writ-
ings of eminent naturalists might throw some light upon the subject itself, There
are authors, and among them some of the most celebrated contributors to our
knowledge in Natural History, who never busied themselves with classification, or
paid only a passing notice to this subject, whilst they are, by universal consent,
considered as the most successful biographers of species; such are Buffon, Reau-
mur, Roesel, Trembley, Smeathman, the two Hubers, Bewick, Wilson, Audubon,
Naumann, etc. Others have applied themselves almost exclusively to the study of
genera. Latreille is the most prominent zodlogist of this stamp; whilst Linnezeus
and Jussieu stand highest among botanists for their characteristics of genera, or at
least for their early successful attempts at tracmg the natural limits of genera. Bota-
nists have thus far been more successful than zodlogists in characterizing natural
families, though Cuvier and Latreille have done a great deal in that same direction
in Zodlogy, whilst Linnzeus was the first to introduce orders in the classification of
animals. As to the higher groups, such as classes and types, and even the orders,
we find again Cuvier leading the procession, in which have followed all the natu-
ralists of this century. 7
Now let us inquire what these men have done in particular to distinguish them-
selves especially, either as biographers of species, or as characterizers of genera, of
families, of orders, of classes, and of types. And should it appear that in each case
they have been considering their subject from some particular point of view, it strikes
me that what has been acknowledged unconsciously as constituting the particular emi-
nence or distinction of these men, might very properly be proclaimed, with grate-
ful consciousness of their services, as the characteristic of that kind of groups which
each of them has most successfully illustrated; and I hope every unprejudiced natu-
ralist will agree with me in this respect.
As to the highest divisions of the animal kingdom, first introduced by Cuvier
under the name of embranchements, (and which we may well render by the good old
English word éranch,) he tells us himself that they are founded upon distinct plans
142 ESSAY ON CLASSIFICATION. Part I.
of structure, cast, as it were, into distinct moulds or forms. Now there can certainly
be no reason why we should not all agree to designate as types or branches
all such great divisions of the animal kingdom as are constituted upon a special
plan? if we should find practically that such groups may be traced in nature.
Those who may not see them may deny their existence; those who recognize
them may vary in their estimation of their natural limits; but all can, for the
greatest benefit of science, agree to call any group which seems to them to be
founded upon a special plan of structure, a type or branch of the animal kingdom;
and if there are still differences of opinion among naturalists respecting their limits,
let the discussion upon this point be carried on with the understanding that types
are to be characterized by different plans of structure, and not by special anatomical
peculiarities. Let us avoid confounding the idea of plan with that of complication
of structure, even though Cuvier himself has made this mistake here and there in
his classification.
The best evidence I can produce that the idea of distinct plans of structure
is the true pivot upon which the’ natural limitation of the branches of the animal
kingdom is ultimately to turn, lies in the fact that every great improvement,
acknowledged by all as such, which these primary divisions have undergone, has
consisted in the removal from among each, of such groups as had been placed
with them from other considerations than those of a peculiar plan, or in conse-
Let us
Neither Infusoria nor
Intestinal Worms are any longer arranged by competent naturalists among Radiata.
Why they have been removed, may be considered elsewhere; but it was certainly
not because they were ) supposed to agree in the plan of their structure with the
quence of a want of information respecting their true plan of structure.
examine this point within limits no longer controvertible.
1 It would lead me too far were I to consider
here the characteristics of the different kingdoms of
old expressions, in a somewhat modified sense, is found
preferable to framing new ones. I trust the value of
Nature. I may, however, refer to the work. of I. the following discussion will be appreciated by its
Gerorrroy St. Hizarre, Histoire naturelle générale
des régnes organiques, Paris, 18956, 8yvo., who has dis-
cussed this subject recently, though I must object to
the admission of a distinct kingdom for Man alone.
2 It is almost superfluous for me to mention here
that the terms plan, ways and means, or manner in
which a plan is carried out, complication of structure,
form, details of structure, ultimate structure, relations
of individuals, frequently used in the following pages,
are taken in a somewhat different sense from their
usual meaning, as is always necessary when new
views are introduced in a science, and the adoption of
intrinsic merit, tested with a willingness to understand
what has been my aim, and not altogether by the rela-
tive degree of precision and clearness with which I
may have expressed myself, as it is almost impossible,
in a first attempt of this kind, to seize at once upon
I wish
also to be understood as expressing my views more
the form best adapted to carry conviction.
immediately with reference to the animal kingdom,
as I do not feel quite competent to extend the inquiry
and the discussion to the vegetable kingdom, though
I have occasionally alluded to it, as far as my in-
formation would permit.
Cuap. II. BRANCHES OF THE ANIMAL KINGDOM. 148
true Radiata, that Cuvier placed them in that division, but simply because he
allowed himself to depart from his own principle, and to add another consideration,
besides the plan of structure, as characteristic of Radiata, the supposed absence of
a nervous system, and the great simplicity of structure of these animals; as if
simplicity of execution had any necessary connection with the plan of structure.
Another remarkable instance of the generally approved removal of a class from
one of the types of Cuvier to another, was the transfer of the Cirripeds from
among the Mollusks to the branch of Articulata. Imperfect knowledge of the plan
of structure of these animals was here the cause of the mistake, which was cor-
rected without any opposition, as soon-as they became better known.
From a comparison of what is stated here respecting the different plans of
structure, characteristic of the primary divisions of the animal kingdom, with what
I have to say below about classes and orders, it will appear more fully, that it
is important to make a distinction, between the plan of a structure and the man-
ner in which that plan is carried out, or the degrees of its complication and _ its
relative perfection or simplicity. But even after it is understood that the plan of
structure should be the leading characteristic of these primary groups, it does not
yet follow, without further examination, that the four great branches of the animal
kingdom, first distinguished by Cuvier, are to be considered as the primary divisions
which Nature points out as fundamental. It will still be necessary, by a. careful
and thorough investigation of the subject, to ascertain what these primary groups
are; but we shall have gained one poimt with reference to our systems, that what-
ever these primary groups, founded upon different plans, which exist in nature, may
be, when they are once defined, or whilst they are admitted as the temporary ex-
pression of our present knowledge, they should be called the branches of the animal
kingdom, whether they be the Vertebrata, Articulata, Mollusca, and Radiata of Cuvier,
or the Artiozoaria, Actinozoaria, and Amorphozoaria of Blainville, or the Vertebrata
and Invertebrata of Lamarck. The special inquiry into this pomt must be left for
a special paper. I will only add, that I am daily more satisfied, that, in their
general outlines, the primary divisions of Cuvier are true to nature, and that never
did a naturalist exhibit a clearer and deeper insight into the most general relations
of animals than Cuvier, when he perceived, not only that these primary groups are
founded upon differences in the plan of their structure, but also how they are
essentially related to one another.
Though the term type is generally employed to designate the great fundamental
divisions of the animal kingdom, I shall not use it in future, but prefer for it the
term branch of the animal kingdom, because the term type is employed in too
many different acceptations, and quite as commonly to designate any group of any
kind, or any peculiar modification of structure stamped with a distinct and marked
144 | ESSAY ON CLASSIFICATION. Part I.
character, as to designate the primary divisions of the animal kingdom. We
speak, for instance, of specific types, generic types, family types, ordinal types,
classic types, and also of a typical structure. The use of the word type in this
sense is so frequent on almost every page of our systematic works, in Zodlogy
and in treatises of comparative anatomy, that it seems to me desirable, in order
to avoid every possible equivocation in the designation of the most important great
primary divisions among animals, to call them branches of the animal kingdom,
rather than types. ;
That, however, our systems are more true to nature than they are often sup-
posed to be, seems to me to be proved by the gradual approximation of scientific
men to each other, in their results, and in the forms by which they express those
results. The idea which lies at the foundation of the great primary divisions
of the animal kingdom is, the most general conception possible in connection with
the plan of a definite creation; these divisions are therefore the most comprehensive
of all, and properly take the lead in a natural classification, as representing the
first and broadest relations of the different natural groups of the animal kingdom,
the general formula which they each obey. What we call branches expresses, in
fact, a purely ideal connection between animals, the intellectual conception which
unites them in the creative thought. It seems to me that the more we examine
the true significance of this kind of groups, the more we shall be convinced that
they are not founded upon material relations. The lesser divisions which succeed
next are founded upon special qualifications of the plan, and differ one from the
other by the character of these qualifications. Should it be found that the features
in the animal kingdom which, next to the plan of structure, extend over the largest
divisions, are those which determine their rank or respective standing, it would
appear natural to consider the orders as the second most important category in the
organization of animals. Experience, however, shows that this is not the case;
that the manner in which the plan of structure is executed leads to the distinction
of more extensive divisions (the classes) than those which are based upon the com-
plication of structure (the orders). As a classification can be natural only as far
it expresses real relations observed in nature, it follows, therefore, that classes take
the second position in a system, immediately under the branches. We shall see
below that orders follow next, as they constitute naturally groups that are more
comprehensive than families, and that we are not at liberty to invert their respec-
tive position, nor to transfer the name of one of these divisions to the other, at
our own pleasure, as so many naturalists are constantly doing.
Cuap. IL. . CLASSES OF ANIMALS.
SROTITON Tf.
CLASSES OF ANIMALS.
Before Cuvier had shown that the whole animal kingdom is constructed upon
four different plans of structure, classes were the highest groups acknowledged in
the systems of Zodlogy, and naturalists very early understood upon what this kind
of division should be founded, in order to be natural, even though in practice
they did not always perceive the true value of the characters upon which. they
established their standard of relationship. Linneeus, the first. expounder of the
system of animals, already distinguishes, by anatomical characters, the classes he
has adopted, though very imperfectly; and ever since, systematic writers have aimed
at drawing a more and more complete picture of the classes of animals, based
upon a more or less extensive investigation of their structure. |
Structure, then, is the watchword for the recognition of classes, and an accurate
knowledge of their anatomy the surest way to discover their natural limits. And
yet, with this standard before them, naturalists have differed, and differ still greatly,
in the limits they assign to classes, and in the number of them they adopt. It
is really strange, that, applying apparently the same standard to the same objects,
the results of their estimation should so greatly vary; and it was this fact. which
led me to look more closely into the matter, and to inquire whether, after all,
the seeming unity of standard was not more a fancied than a real one. Structure
may be considered from many points of view: first, with reference to the plan
adopted in framing it; secondly, with reference to the work to be done by it, and
to the ways and means employed in building it up; thirdly, with reference to the
degrees of perfection or complication it exhibits, which may differ greatly, even
though the plan be the same, and the ways and means employed in carrying out
such a plan should not differ in the least; fourthly, with reference to the form
of the whole structure and its parts, which bears no necessary relation, at all events
no very close relation, to the degree of perfection of the structure, nor to the
manner in which its plan is executed, nor to the plan itself, as a comparison
between Bats and Birds, between Whales and Fishes, or between Holothurians and
Worms, may easily show; fifthly and lastly, with reference to its last finish, to
the execution of the details in the individual parts. |
It would not ‘be difficult to show, that the differences which exist among
naturalists in their limitation of classes have arisen from an indiscriminate con-
sideration of the structure of Sait in all these different points of view, and an
oes
t
= . an :
= a om
es i
=. See eg e eo :
SE,
Aan ae A a BE at
RRA rch So erabe sn ae
¥e8 Pe * “ va
146 ESSAY ON CLASSIFICATION. Part I.
equally indiscriminate application of the results obtained, to characterizing classes.
Those who have not made a proper distinction between the plan of a structure
and the manner in which that plan is actually executed, have either overlooked
the importance of the great fundamental divisions of the animal kingdom, or they
have unduly multiplied the number of these primary divisions, basing their dis-
tinctions upon purely anatomical considerations, that is to say, not upon differences
in the character of the general plan of structure, but upon the material develop-
ment of that plan. Those, again, who have confounded the complication of the
structure with the ways and means by which life is maintained through any given
combination of systems of organs, have failed in establishing a proper difference
between class and: ordinal characters, and have again and again raised orders to
the rank of classes. For we shall see presently, that natural orders must be based
upon the different degrees of complication of structure, exhibited within the limits
of the classes, while the classes themselves are characterized by the manner in
which the plan of the type is carried out, that is to say, by the various com-
binations of the systems of organs constituting the body of the representatives of
any of the great types of the animal kingdom ; or perhaps, still more distinctly,
the classes are characterized by the different ways in which life is maintained, and
the different means employed in establishing these ways. An example will suffice
to show that this distinction implies a marked difference between class and ordinal
characters. |
Let us compare the Polyps and Acalephs as two classes, without allowing our-
selves to be troubled by the different limits assigned to them by different authors.
Both are constructed upon the same plan, and belong, on that account, to the type
of Radiata. In establishing this fact, we do not consider the actual structure of
these animals, whether they have a nervous system or not, whether they have
organs of senses or not, whether their muscles are striated or smooth, whether
they have a solid frame or an entirely soft body, whether their alimentary cavity
has only one opening or two opposite openings, whether it has glandular annexes
or not, whether the digested food is distributed m the body one way or another,
whether the undigested materials are rejected through the mouth or not, whether
the sexes are distinct or not, whether they reproduce themselves only by eggs, or
by budding also, whether they are simple or not: all we need know, in order to
refer them to the branch of Radiata, is whether the plan of their structure exhibits
a general radiated arrangement or not. But, when we would distinguish Polypi,
Acalephs, and Echinoderms as classes, or rather, when we would ascertain what
are the classes among Radiata, and how many there are, we must inquire into the
manner in which this. idea of radiation, which lies at the foundation of their plan.
of structure, is actually expressed in all the animals exhibiting such a plan, and
Cuap. II. | CLASSES OF ANIMALS. 147
we find easily, that while in some (the Polypi) the body exhibits a large cavity,
divided by radiating partitions into a number of chambers, into which hangs a sac,
(the digestive cavity,) open below, so as to pour freely the digested food into
the main cavity, whence it is circulated to and fro in all the chambers, by the
agency of vibrating cilia; in others, (the Acalephs,) the body is plain and full
not to be compared to a hollow sac, traversed only in its thickness by radiating
tubes, which arise from a central cavity, (the digestive cavity,) without a free com-
munication with one another for their whole length, etc, etc. while in others still,
(the Echinoderms,) there is a tough or rigid envelope to the body, inclosing a large
cavity in which are contained a variety of distinct systems of organs, ete.
Without giving here a full description of these classes, I only wish to show,
that what truly characterizes them, is not the complication of their structure, (for
Hydroid Meduse are hardly more complicated in their structure than Polyps,) but
the manner in which the plan of Radiata is carried out, the ways in which life
is maintained in these animals, the means applied to this end; in one word, the
combinations of their structural elements. But the moment we would discern
what are the orders of these classes, these considerations no longer suffice; their
structure has to be viewed in a different light; it is now the complication of
these apparatus which may guide us. Actinarians and Halcyonarians among Polypi,
as orders, differ, the first by having a larger and usually indefinite number of
simple tentacles, an equally large number of internal partitions, etc. while in
Halcyonarians the eight tentacles are lobed and complicated, and all the parts are
combined in pairs, in definite numbers, etc, differences which establish a dis-
tinct standing between them in their class, assigning the latter a higher rank than
the former.
It follows, then, from the preceding remarks, that classes are to be distinguished
by the manner in which the plan of thew type is executed, by the ways and
means by which this is done, or, in other words, by the combinations of their
structural elements, that is to say, by the combinations of the different systems of
organs building up the body of their representatives. We need not consider here
the various forms under which the structure is embodied, nor the ultimate details,
nor the last finish which this structure may exhibit, as a moment’s reflection will
convince any one that neither form nor structural details can ever be characteristic
of classes.
There is another pomt to which I would call attention, respecting the charac-.
teristics of classes. These great divisions, so important in the study of the animal
kingdom, that a knowledge of their essential features is rightly considered as the
primary object of all investigations im comparative anatomy, are generally repre-
sented as exhibiting each some essential modification of the type to which they
148 ESSAY ON CLASSIFICATION. Part I.
belong. . This view, again, I consider to be a mistaken appreciation of the facts,
to which Cuvier has already called attention, though his warning has remained
unnoticed! There is in reality no difference in the plan of animals belonging to
different classes of the same branch. The plan of structure of Polypi is no more
a modification of that of Acalephe, than that of Acalephze or Echinoderms is a
modification of the plan of Polyps; the plan is exactly the same in all three;
it may be represented by one simple diagram, and may be expressed in one single
word, radiation; it is the manifestation of one distinct, characteristic idea. But
this idea is exhibited’ in nature under the most different forms, and expressed in
different ways, by the most diversified combinations of structural modifications and
in the most varied relations. In the innumerable representatives of each branch
of the animal kingdom, it is not the plan that differs, but the manner in which
this plan is executed. In the same manner as the variations played by a skilful
artist upon the simplest tune are not modifications of the tune itself, but only
different expressions of the same fundamental harmony, just so are neither the classes,
nor the orders, nor the families, nor the genera, nor the species of any great type,
modifications of its plan, but only. its different expressions, the different ways in
which the fundamental thought embodied in it is manifested in a variety of living
beings. ae
In studying the characteristics of classes we have to deal with structural features,
while in investigating their relations to the branches of the animal kingdom to
which they belong, we have only to consider the general plan, the framework,
as it were, of that structure, not the structure itself. This distinction leads to
an important practical result. Since, in the beginning of this century, naturalists
have begun, under the lead of the German physiophilosophers, to compare more
closely the structure of the different classes of the animal kingdom, points of
resemblance have been noticed between them which had entirely escaped the atten-
tion of earlier investigators, structural modifications have been identified, which, at
first, seemed to exhibit no similarity, so much so, that step by step these com-
parisons have been extended over the whole animal kingdom, and it has been
_ asserted, that, whatever may be the apparent differences in the organization of ani-
mals, they should be considered as constructed of parts essentially identical. This
assumed identity of structure has been called homology But the progress of —
science is gradually restricting these comparisons within narrower limits, and it
appears now, that the structure of animals is homologous only as far as they belong
to the same branch, so much so, that the study of homologies is likely to afford
one of the most trustworthy means of testing the natural limits of any of the
1 Cuvier, Regn. An., 2d edit., p. 48. 2 See Chap. I., Sect. 5.
Cuap. II. CLASSES OF ANIMALS. | 149
great types of the animal kingdom. While, however, homologies show the close
similarity of apparently different structures and the perfect identity of their plan,
within the same branches of the animal kingdom, yet, they daily exhibit more:
and more striking differences, both in plan and structure, between the branches
themselves, leading to the suspicion that systems of organs which are generally.
considered as identical in different types, will, in the end, prove essentially different,
as, for instance, the so-called gills in Fishes, Crustacea, and Mollusks.
It requires no great penetration to see already that the gills of Crustacea are
homologous with the tracheze of Insects and the so- -called lungs of certain spiders, in
the same manner as the gills of aquatic Mollusks are homologous with the so-called.
lungs of our air-breathing snails and slugs. Now, until it can be shown that all
these different respiratory organs are truly homologous, I hold it to be more natural
to consider the system of respiratory organs in Mollusks, m Articulates, and in Verte-
brates, as essentially different among themselves, though homologous within the limits
of each type; and this remark I would extend to all their systems of organs, to their
solid frame, to their nervous system, to their muscular system, to their digestive
apparatus, to their circulation, and to their reproductive organs, etc. It would not
be difficult to show now that the alimentary canal with its glandular appendages,
in Vertebrata, is formed in an entirely different way from that of Articulates or
Mollusks, and that it cannot be considered as homologous in all these types. And
if this be true, we must expect soon an entire reform of our methods of illustrating
comparative anatomy.
Finally, it ought to be remembered, in connection with the study of classes as
well as that of other groups, that the amount of difference existing between any
two divisions is nowhere the same. Some features in nature seem to be insisted
upon with more tenacity than others, to be repeated more frequently and more
widely, and to be impressed upon a_ larger number of representatives. This
unequal weight of different groups, so evident everywhere in the animal kingdom,
ought to make us more cautious in estimating their natural limits, and prevent. us
from assigning an undue value to the differences observed between living beings,
never overrating apparently great discrepancies, nor underrating seemingly trifling
variations. The right path, however, can only be ascertained ve extensive inves-
tigations, made with special reference to this point.
Everybody must know that the males and females of some species differ much
more one from the other than many species do, and yet the amount of difference
observed between species is constantly urged, even without a preliminary investi=
gation, as an argument for distinguishing them. These differences, moreover, are
not only quantitative, they are to a still greater extent also qualitative. In the
state NAN 2 RN GO ATTA A i I Ra al aR AICI RR tena
150 ESSAY ON. CLASSIFICATION. Part I.
same manner do genera differ more or less one from the other, even in the same
family; and such inequality, and not an equable apportionment, is the norm through-
out nature. In classes, it is not only exhibited in the variety of their forms, but
also, to an extraordinary extent, in their numbers, as, for instance, in the class of
Insects compared to that of Worms or Crustacea. The primary divisions of the ani-
mal kingdom differ in the same manner one from the other. Articulata are by far
the most numerous branch of the whole animal kingdom; their number exceeding
greatly that of all other animals put together. Such facts are in themselves sufficient
to show how artificial classifications must be which admit only the same number
and the same kind of divisions for all the types of the animal kingdom.
SECTION III.
ORDERS AMONG ANIMALS.
Great as is the discrepancy between naturalists respecting the number and limits
of classes in the animal kingdom, their disagreement in regard to orders and families
is yet far greater. These conflicting views, however, do not in the least shake
my confidence in the existence of fixed relations between animals, determined by
thoughtful considerations. I would as soon cease to believe in the existence of
one God, because men worship Him in so many different ways, or because they
even worship gods of their own making, as distrust the evidence of my own senses
respecting the existence of a preéstablished and duly considered system in nature,
the arrangement of which preceded the creation of all things that exist.
From the manner in which orders are generally characterized and introduced
into our systems, it would seem as if this kind of groups were interchangeable
with families. Most botanists make no difference even between orders and families,
and take almost universally the terms as mere synonyms. Zodlogists have more
extensively admitted a difference between them, but while some consider the orders
as superior, others place families higher; others admit orders without at the same
time distinguishing families, and vice versé introduce families into their classification
without admitting orders; others still admit tribes as intermediate groups between
orders and families. A glance at any general work on Zodlogy or Botany may
satisfy. the student how utterly arbitrary the systems are in this respect. The
Régne animal of Cuvier exhibits even the unaccountable feature, that while orders
Cuap. IL. ORDERS AMONG ANIMALS. 151
and families are introduced in some classes, only orders are noticed in others?
‘and even some exhibit only a succession of genera under the head of their class,
: : Other classi-
fications exhibit the most pedantic. uniformity of a regular succession in each class,
of sub-classes, orders, sub-orders, families, sub-families, tribes, sub-tribes, genera, sub-
without any further grouping among them into orders or families?
genera, divisions, sections, and sub-divisions, sub-sections, etc. but bear upon. their
face, that they are made to suit preconceived ideas of regularity and symmetry in
the system, and that they are by no means studied from nature.
To find out the natural characters of orders from that which really exists in
nature, I have considered attentively the different systems of Zodlogy in which
orders are admitted and apparently considered with more care than elsewhere, and
in particular the Systema Nature of Linneus, who first introduced in Zodlogy that
kind of groups, and the works of Cuvier, in which orders are frequently charac-
terized with unusual precision, and it has appeared to me that the leading idea
prevailing everywhere respecting orders, where these groups are not admitted at
random, is that of a definite rank among them, the desire to determine the rela-
tive standing of these divisions, to ascertain their relative superiority or inferiority,
as the name order, adopted to designate them, already implies. The first order
in the first class of the animal kingdom, according to the classification of Linnzeus,
is called by him Primates, expressing, no doubt, his conviction that these beings,
among which Man is included, rank uppermost in their class. Blainville uses here
and there the expression of “ degrees of organization,” to designate orders. It is
true Lamarck uses the same expression to designate classes. We find, therefore,
here as everywhere, the same vagueness in the definition of the different kinds of
groups adopted in our systems. But if we would give up any arbitrary use of
these terms, and assion to them a definite scientific meaning, it seems to me’ most
natural, and in accordance with the practice of the most successful investigators
of the animal kingdom, to call orders such divisions as are characterized by differ-
ent degrees of complication of their structure, within the limits of the classes.
As such I would consider, for instance, the Actinoids and Halcyonoids in the class
of Polypi, as circumscribed by Dana; the Hydroids, the Discophore, and the Cte-
1 In the classes Mammalia, Birds, Reptiles, and * The classes Echinoderms, Acalephs, and Infu-
soria, are divided into orders, but without families
* Such are his classes of Cephalopods, Pteropods
9
Brachiopods, and Cirripeds (Cirrhopods.) Of the Ce-
Fishes, Cuvier distinguishes mostly families as well
as orders. In the.class of Mammalia, some orders
number no families, whilst others are divided into
Tn the class of Gasteropods, phalopods, he says, however, they constitute but one
order (Regn. An. vol. 3, p- 11), and, p- 22, he calls
tribes instead of families.
Annelids, Intestinal Worms, and Polyps, some of the
orders only are divided into families, while the larger _
number are not.
them a family, and yet he distinguishes them as a
class, p. °8. .
152 ESSAY ON CLASSIFICATION. Part I.
noids. among Acalephs; the Crinoids, Asterioids, Echinoids, and Holothurie among
Echinoderms; the Bryozoa, Brachiopods, Tunicata, Lamellibranchiata among Acephala ;
the Branchifera and Pulmonata among Gasteropods; the Ophidians, the Saurians,
and the Chelonians among Reptiles; the Ichthyoids and the Anoura among Amphi-
-bians, ete. | |
Having shown in the preceding paragraph that classes rank next to branches,
it would be proper I should show here that orders are natural groups which stand
above families in their respective classes; but. for obvious reasons I have deferred
this discussion to the following paragraph, which relates to families, as it will be
easier for me to show what. is the respective relation of these two kinds of groups
after their special character has been duly considered.
From the preceding remarks respecting orders it might be inferred that I deny
-all gradation among all other groups, or that I assume that orders constitute neces-
sarily one simple series in each class. Far from asserting any such thing, I hold
on the contrary, that neither is necessarily the case. But to explain fully my
views upon this point, I must imtroduce here some other considerations. It will
be obvious, from what has already been said, (and the further illustration of this
subject will only go to show to what extent this is true,) that there exists an
unquestionable hierarchy between. the different kinds of groups admitted in our
systems, based upon the different kinds of relationship observed among animals,
that branches are the most comprehensive divisions, including each several classes,
that orders are subdivisions of the classes, families subdivisions of orders, genera
subdivisions of families, and species subdivisions of the genera; but not in the
sense that each type should necessarily include the same number of classes, nor
even necessarily several classes, as this must depend upon the manner in which
the type is carried out. A class, again, might contain no orders,’ if its represent-
atives presented no different degrees characterized by the greater or less compli-
cation of their. structure; or it may contain many, or few, as these gradations are
more or less numerous and well marked; but as the representatives of any and
every class have of necessity a definite form, each class must contain at least one
family, or many families, indeed, as many as there are systems of forms under
which its representatives may be combined, if form can be shown to be charac-
teristic of families) The same is the case with genera and species; and nothing
is more remote from the truth than the idea that a genus is better defined in
proportion as it contains a greater number of species, or that it may be necessary
to know .several species of a genus before its existence can be fully ascertained.
A. genus may be more satisfactorily characterized, its peculiarity more fully ascer-
1-See Chap. I. Sect. 1.
Cuap. IL ORDERS AMONG ANIMALS. 153
tained, its limits better defined, when we know all its representatives; but I am
satisfied that any natural genus may be at least pointed out, however numerous
its species may be, from the examination of any single one of them. Moreover,
the number of genera, both in the animal and vegetable kingdom, which contain
but a single species, is so great that it is a matter of ae in all these cases
to ascertain their generic characteristics from that one species. Again, such species
require to be characterized with as much precision, and their specific characters to
be described with as much minuteness, as if a host of them, but not yet known,
existed besides. It is a very objectionable practice among zodlogists and_ botanists,
to remain satisfied in such cases with characterizing the genus, and perhaps to -
believe, what some writers have actually stated distinctly, that in such cases generic
and specific characters are identical.
Such being the natural relations and the subordination of types, classes, orders,
families, genera, and species, I believe, névertheless, that neither types, nor classes,
(orders of course not at all,) nor families, nor genera, nor species have the same
standing when compared among themselves. But this does not in the least inter-
fere with the prominent features of orders, for the relative standing of types, or
classes, or families, or genera, or species does not depend upon the degrees of
complication of their structures as that of orders does, but upon other features,
as I will now show. The four great types or branches of the animal kingdom,
characterized as they are by four different plans of structure, will each stand higher
or lower, as the plan itself bears a higher or lower character, and that this may
be the case we need only compare Vertebrata and Radiata! The different classes
of one type will stand higher or lower, as the ways in which and the means with
which, the plan of the type to which they belong is carried out, are of a higher
or lower nature. Orders in any or all classes are of course higher or lower
according to the degree of perfection of their representatives, or according to the
complication or simplicity of their structure. Families may stand higher or lower
as the peculiarities of their form are determined by modifications of more or less
important systems of organs. Genera may stand higher or lower as the structural
peculiarities of the parts constituting the generic characteristics exhibit a higher
or lower grade of development. Species, lastly, may stand one above the other,
in the same genus, according to the character of their relations to the surrounding
world, or that of their representatives to one another. These remarks must
make it plain that the respective rank of groups of the same kind among . them-
selves must be determined by the superior or inferior grade of those features upon
1 I must leave out the details of such comparisons, moreover, any text-book of comparative anatomy
as a mere mention of the point suffices to suggest them ; may furnish the complete evidence to that effect.
20
‘154 ESSAY ON CLASSIFICATION. Parr Lh
which they are themselves founded; while orders alone are strictly ‘defined by the
natural degrees of structural complications exhibited within the limits of the
classes. |
As to the question, whether orders constitute necessarily one simple series in
their respective classes, I would say, that this must depend upon the character
of the class itself, or the manner in which the plan of the type is carried out
within the limits of the class. If the class is homogeneous, that is, if it is not
primarily subdivided into sub-classes, the orders will, of course, form a single Series ;
but if some of its organic systems are developed in a different way from the others,
there may be one or several parallel series, each subdivided into gradated orders.
This can, of course, only be determined by a much more minute study of the
characteristics of classes than has been made thus far, and mere guesses at such
an internal arrangement of the classes into series, as those proposed by Kaup or
Fitzinger, can only be considered as the first attempts towards an estimation of
the relative value of the intermediate divisions which may exist between the classes
and their orders. |
Oken and the physiophilosophers generally have taken a different view of orders.
‘Their idea is, that orders represent, in their respective classes, the characteristic
features of the other types of the animal kingdom. As Oken’s Intestinal or Gelatin-
ous animals are characterized by a single system of organs, the intestine, they
contain no distinct orders, but each class has three tribes, corresponding to the
three classes of this type, which are Infusoria, Polypi, and Acalephs. The tribes of
the class of Infusoria, are Infusoria proper, Polypoid Infusoria, and Acalephoid Infu-
soria; the tribes of the class of Polypi, are Infusorial Polypi, Polypi proper, and
Acalephoid Polypi; the tribes of the class Acalephs, are Infusorial Acalephs, Polypoid
‘Acalephs, and Acalephs proper. But the classes of Mollusks which are said to be
characterized by two systems of organs, the intestine and the vascular system,
contain each two orders, one corresponding to the Intestinal animals, the other to
the type of Mollusks, and so Acephala are divided into the order of Gelatinous
Acephala and that of Molluscoid Acephala, and the Gasteropods and Cephalopods
in the same manner into two orders each. The Articulata are considered as repre-
senting three systems of organs, the intestinal, the vascular, and the respiratory
systems; hence their classes are divided each into three orders. For instance, the
Worms contain an order of Gelatinous Worms, one of Molluscoid Worms, one of
Annulate Worms, and the same orders are adopted for Crustacea and Insects. Verte-
prata are said to represent five systems, the three lower ones being the intestine, the
vessels, and the respiratory organs, the two higher the flesh (that is, bones, muscles,
and nerves) and the organs of senses; hence, five orders in each class of this
type, as, for example, Gelatinous Fishes, Molluscoid Fishes, Entomoid Fishes, Carnal
ch
Cuap. IIL. FAMILIES. 155
Fishes, and Sensual Fishes, and so also in the classes of Reptiles, Birds, and
Mammalia. 3
I have entered into so many details upon these vagaries of the distinguished
German philosopher, because these views, however crude, have undoubtedly been
suggested by a feature of the animal kingdom, which has thus far been too little
studied: I mean the analogies which exist among animals, besides their true affinities,
and which cross and blend, under modifications of strictly -homological structures,
other characters which are only analogical. But it seems to me that the subject
of analogies is too little known, the facts bearmg upon this kind of relationship
being still too obscure, to be taken as the basis of such important groups in the
animal kingdom as the orders are, and I would insist upon considering the complica-
tion or gradation of structure as the feature which should regulate their limitation,
if under order we are to understand natural groups expressing the rank, the relative
standing, the superiority or inferiority of animals in their respective classes. Of
course, groups thus characterized cannot be considered as mere modifications of the
classes, being founded upon a special category of features.
SHCOTION “TY.
FAMILIES.
Nothing is more indefinite than the idea of form, as applied by systematic
writers, in characterizing animals. Here, it means a system of the most different
figures having a common character, as, for instance, when it is said of Zoophytes
that they have a radiated form; there, it indicates any outline which circumscribes
the body of animals, when, for mstance, animal forms are alluded to in general,
instead of designating them simply as animals; here, again, it means the special
figure of some individual species. There is in fact no group of the animal king-
dom, however extensive or however limited, from the branches down to the species,
in which the form is not occasionally alluded to as characteristic. Speaking of Articu-
lates, C. E. v. Baer characterizes them as the type with elongated forms; Mollusks
are to him the type with massive forms; Radiates that with peripheric symmetry ;
Vertebrates that with double symmetry, evidently taking their form in its widest
sense as expressing the most general relations of the different dimensions of the
1 See further developments upon this subject in Naturgeschichte, vol. 4, p. 582. Compare also the
Oxen’s Naturphilosophie, and.in his Allgemeine following chapter.
156 ESSAY ON CLASSIFICATION. Part I.
body to one another. Cuvier speaks of form in general with reference to these
four great types as a sort of mould, as it were, in which the different types
would seem to have been cast. Again, form is alluded to in characterizing orders ;
for instance, in the distinction between the Brachyourans and the Macrourans among
Crustacea, or between the Saurians, the Ophidians, and the Chelonians. It is men-
tioned as a distinguishing feature in many families, ex. gr. the Cetacea, the Bats,
etc. Some genera are separated from others in the same family. on the ground
of differences of form; and in almost every description of species, especially when
they are considered isolatedly, the form is described at full length. Is there not,
in this indiscriminate use of the term of form, a confusion of ideas, a want of
precision in the estimation of what ought to be called form and what might be
designated by another name? It seems to me to be the case. In the first place,
when form is considered as characteristic of Radiata or Articulata, or any other
of the great types of the animal kingdom, it is evident that it is not a definite
outline and well-determined figure which is meant, but that here the word form
is used as synonym for plan. Who, for instance, would describe the tubular body of |
an Holothuria as characterized by a form similar to that of the Euryale, or that of
an Echinus as identical with that of an Asterias? And who does not see that, as
far as the form is concerned, Holothuria resemble Worms much more than they
resemble any other Echinoderm, though, as far as the plan of their structure is
concerned, they are genuine Radiates, and have nothing to do with the Articu-
lates ? | |
Again, a superficial glance at any and all the classes of the animal kingdom
is sufficient to show that each contains animals of the most diversified forms.
What can be more different than Bats and Whales, Herons and Parrots, Frogs and
Sirens, Eels and Turbots, Butterflies and Bugs, Lobsters and Barnacles, Nautilus:
and Cuttlefishes, Slugs and Conchs, Clams and compound Asidians, Pentacrinus and
Spatangus, Beroe and Physalia, Actinia and Gorgonia? And yet they belong respec-
tively to the same class, as they are coupled. here: Bats and Whales together,
etc. It must be obvious, then, that form cannot be a characteristic element of
classes, if we would understand any thing definite under that name.
But form has a definite meaning understood everywhere, when applied to well-
known animals. We speak, for instance, of the human form; an allusion to the
form of a horse or that of a bull conveys at once a distinct idea; everybody would.
acknowledge the similarity of form of the horse and ass, and knows how to distin-
guish them by their form from dogs or cats, or from seals and porpoises. In this
definite meaning, form corresponds also to what we call figure when speaking of
men and women, and it is when taken in this sense, that I would now consider
the value of forms as characteristic of different animals. We have seen that form
Cuap. II. FAMILIES. - 157
cannot be considered as a character of branches, nor of classes; let us now
examine, further, whether it is a character of species. A rapid review of some of
the best known types. of the animal kingdom, embracing well-defined genera with
many species, will at once show that this cannot be the case, for such species do
not generally show the least difference in their forms. Neither the many species
of Squirrels, nor the true Mice, nor the Weasels, nor the Bears, nor the Eagles,
nor the Falcons, nor the Sparrows, nor the Warblers, nor the genuine Woodpeckers,
‘nor the true Lizards, nor the Frogs, nor the Toads, nor the Skates, nor the Sharks
proper, nor the Turbots, nor the Soles, nor the Eels, nor the Mackerels, nor the
Sculpins, nor the genuine Shrimps, nor the Crawfishes, nor the Hawkmoths, nor
the Geometers, nor the Dorbugs, nor the Spring-Beetles, nor the Tapeworms,
nor the Cuttlefishes, nor the Slugs, nor the true Asterias, nor the Sea-Anemones,
could be distinguished among themselves, one from the other, by their form only.
There may be differences in the proportions of some of their parts, but the pattern
of every species belonging to well-defined natural genera is so completely identi-
cal that it will never afford specific characters. There are genera in our system
‘hich as they now stand, might be alluded to as examples contrary to this state-
ment ; but such genera are still based upon very questionable features, and’ are
likely to be found in the end to consist of unnatural associations of heterogeneous
species: at all events, all recent improvements in Zodlogy have gone to limit
genera gradually more and more in such a manner, that the species belonging to
each have shown successively less and less difference in form, until they have
assumed, in that respect, the most homogeneous appearance. Are natural genera
any more to be distinguished by their form one from the other? Is there any
appreciable difference in the general form,—I say purposely general form, because
a more or less prominent nose, larger or smaller ears, longer or shorter claws,
ete. do not essentially modify the form,—is there any real difference in the general
form between the genera of the most natural families? Do, for instance, the
genera of Ursina, the Bears, the Badger, the Wolverines, the Raccoons, differ in form ?
‘Do the Phocoidx, the Delphinoide, the Falconine, the Turdine, the Fringilline,
the Picine, the Scolopacinz, the Chelonioide, the Geckonina, the Colubrina, the
Sparoide, the Elateride, the Pyralidoide, the Echinoide, etc., differ any more among
themselves? Certainly not; though to some extent, there are differences in the
form of the representatives of one genus when compared to those of another genus ;
but when rightly considered, these differences appear only as modifications of the
same type of forms. Just as there are more or less elongated ellipses, so do we
find the figure of the Badgers somewhat more contracted than that of either the
Bears, or the Raccoons, or the Wolverines, that of the Wolverimes somewhat more
elongated than that of the Raccoons; but the form is here as completely ay
158 ESSAY ON CLASSIFICATION. Part I.
as it is among the Viverrina, or among the Canina, or among the Bradypodide,
or among the Delphinoide, etc., ete. We must, therefore, exclude form from the
characteristics of natural genera, or at least introduce it only as a modification of
the typical form of natural families.
Of all the natural groups in the animal kingdom there remain then only families
and orders, for the distinction of which form can apply as an essential criterion.
But these two kinds of groups are just those upon which zodlogists are least
agreed, so that it may not be easy to find a division which all naturalists
would agree to take as an example of a natural order. Let us, however, do our
best to settle the difficulty and suppose, for a moment, that what has been said
above respecting the orders is well founded, that orders are natural groups charac-
terized by the degree of complication of their structure, and expressing the respec-
tive rank of these groups in their class, then we shall find less difficulty in
pointing out some few groups which could be generally considered as orders. I
suppose most naturalists would agree, for instance, that among Reptiles the Chelo-
nians constitute a natural order; that among Fishes, Sharks and Skates constitute
an order also; and if any one would urge the necessity of associating also the
Cyclostomes with them, it would only the better serve my purposes. Ganoids, even
circumscribed. within narrower limits than those I had assigned to them, and
perhaps reduced to the extreme limits proposed for them by J. Miiller, I am
equally prepared to take as an example, though I have in reality still some objec-
tions to this limitation, which, however, do not interfere with my present object.
Decapods, among Crustacea, I suppose everybody would also admit as an order,
and I do not care here what other families are claimed besides Decapods to com-
plete the highest order of Crustacea. Among Acephala, I trust Bryozoa, Tunicata,
Brachiopods, and Lamellibranchiata would be also very generally considered to be
natural orders. Among Echinoderms, I suppose Crinoids, Asterioids, Echinoids, and
Holothurioids would be conceded also as such natural orders; among Acalephs the
Beroids, and perhaps also Discophore and Hydroids; while among the Polypi, the
Haleyonoids constitute a very natural order when compared with the Actinoids.
Let us now consider these orders with reference to the characteristic forms they
include. The forms of the genuine Testudo, of Trionyx, and of Chelonia are very
different, one from the other, and yet few orders are so well circumscribed as that
of Chelonians. The whole class of Fishes scarcely exhibits greater differences than
those observed in the. forms of the common Sharks, the Sawfishes, the common
Skates, and the Torpedo, not to speak of the Cyclostomes and Myxinoids, if these
families were also considered as members of the order of Placoids. Ganoids cannot
be circumscribed within narrower limits than those assigned to them by J. Miiller,
and yet this order, thus limited, contains forms as heterogeneous as the Sturgeons,
—Cuap. IL. FAMILIES. 159
the Lepidosteus, the Polypterus, the Amia, and a host of extinct genera and families,
not to speak of those families I had associated with them and which Prof. Miiller
would have removed, which, if included among Ganoids, would add_ still more
heteromorphous elements to this order. Among Decapods, we need only remember
the Lobsters and Crabs to be convinced that it is not similarity of form which
holds them so closely together as a natural order. How heterogeneous Bryozoa,
Brachiopods, and Tunicata are among themselves, as far as their form is concerned,
everybody knows who has paid the least attention to these animals.
- Unless, then, form be too vague an element to characterize any kind of natural
groups in the animal kingdom, it must constitute a prominent feature of families.
I have already remarked, that orders and families are the groups upon which
zodlogists are least agreed, and to the study and characterizing of which they have
paid least attention. Does this not arise simply from the fact, that, on the one
hand, the difference between ordinal and class characters has not been understood,
and only assumed to be a difference of degree; and, on the other hand, that the
importance of the form, as the prominent character of families, has been entirely
overlooked? For, though so few natural families of animals are well characterized,
or characterized at all, we cannot open a modern treatise upon any class of
animals without finding the genera more or less naturally grouped together, under
the heading of a generic name with a termination in zde or me indicating family
and sub-family distinctions ; and most of these groups, however unequal in absolute
value, are really natural groups, though far from designating always natural families,
being as often orders or sub-orders, as families or sub-families. Yet they indicate
the facility there is, almost without study, to point out the intermediate natural
groups between the classes and the genera. ‘This arises, in my opinion, from the
fact, that family resemblance in the animal kingdom is most strikingly expressed
in the general form, and that form is an element which falls most easily under
our perception, even when the observation is made superficially. But, at the same
time, form is most difficult to describe accurately, and hence the imperfection of
most of our family characteristics, and the constant substitution for such characters
of features which are not essential to the family. To prove the correctness of
this view, I would only appeal to the experience of every naturalist. When we
see new animals, does not the first glance, that is, the first impression made upon
us by their form, give us at once a very correct idea of their nearest relation-
ship? We perceive, before examining any structural character, whether a Beetle
is a Carabicine, a Longicorn, an Elaterid, a Curculionid, a Chrysomeline ; whether
‘a Moth is a Noctuelite, a Geometrid, a Pyralid, etc.; whether a bird is a Dove,
a Swallow, a Humming-bird, a Woodpecker, a Snipe, a Heron, ete, ete. But before
we can ascertain its genus, we have to study the structure of some characteristic
160 ESSAY ON CLASSIFICATION. Parr I.
parts; before we can combine families into natural groups, we have to make a
thorough investigation of their whole structure, and compare it with that of other
families. So form is characteristic of families; and I can add, from a careful investi-
gation of the subject for several years past, during which I have reviewed the whole
animal kingdom with reference to this and other topics connected with classifica-
tion, that form is the essential characteristic of families’ I do not mean the mere
outline, but form as determined by structure; that is to say, that families cannot
be well defined, nor circumscribed within their natural limits, without a thorough
investigation of all those features of the internal structure which combine to deter-
mine the ‘form. : : |
The characteristic of the North American Chelonians which follows, may serve
as an example how this subject is to be treated. I will only add here, that how-
ever easy it is at first, from the general impression made upon us by the form
of animals, to obtain a glimpse of what may fairly be called families, few inves-
tigations require more patient comparisons than those by which we ascertain
the natural range of modifications of any typical form, and the structural features
upon which it is based. Comparative anatomy has so completely discarded every
thing that relates to Morphology; the investigations of anatomists lean so uniformly
towards a general appreciation of the connections and homologies of the organic
systems which go to build up the body of animals, that for the purpose of under-
standing the value of forms and their true foundation, they hardly ever afford any
information, unless it be here and there a consideration respecting teleological rela-
tions.
Taking for granted, that orders are natural groups characterized by the com-
plication of their structure, and that the different orders of a class express the
different degrees of that complication; taking now further for granted, that families
are natural groups characterized by their form as determined by structural pecu-
liarities, it follows that orders are the superior kind of division, as we have seen
that the several natural divisions which are generally considered as orders, contain
each several natural groups, characterized by different forms, that is to say, con-
stituting as many distinct families.
After this discussion it is hardly necessary to add, that families cannot by any
means be considered as modifications of the orders to which they belong, if orders
are to be characterized by the degrees of complication of their structure, and families
* These investigations, which have led to most Dr. A. A. Gould, and which I would not allow to
interesting results, have delayed thus far the publi- appear before I could revise the whole animal king-
cation of the systematic part of the Principles of | dom in this new light, in order to introduce as much
Zoology, undertaken in common with my friend, precision as possible in its classification.
Cuap. IL. GENERA. , | 161
by their forms. I would also further remark, that there is one question relating
to the form of animals, which I have not touched here, and which it is still more
important to consider in the study of plants, namely, the mode of association of
individuals into larger or smaller communities, as we observe them, particularly
among Polyps and Acalephs. These aggregations have not, as far as their form
is concerned, the same importance as the form of the individual animals of which
they are composed, and therefore seldom afford trustworthy family characters. But
this point may be more appropriately considered in connection with the special
illustration of our Hydroids, to which my next volume is to be devoted.
I have stated above, that botanists have defined the natural families of plants
with greater precision than zodlogists those of animals; I have further’ remarked
also, that most of them make no distinction between orders and families. This
may be the result of the peculiar character of the vegetable kingdom, which is
not built upon such entirely different plans of structure as are animals of different
branches. On the contrary, it is possible to trace among plants a certain gradation
between their higher and lower types more distinctly than among animals, even
though they do not, any more than animals, constitute a simple series. It seems
to me, nevertheless, that if Cryptogams, Gymnosperms, Monocotyledons, and Dico-
tyledons can be considered as branches of the vegetable kingdom, analogous to
Radiata, Mollusks, Articulata, and Vertebrata among animals, such divisions as Fungi,
Algee, Lichens, Mosses, Hepatic, and Ferns in the widest sense, may be taken as
classes. Diatomacex, Conferve, and Fuci may then be considered as orders; Mosses
and Hepatice as orders; Equisetacee, Ferns proper, Hydropterids, and Lycopodiacese
as orders also; as they exhibit different degrees of complication of structure, while
their natural subdivisions, which are more closely allied m form or habitus, may
be considered as families; natural families among plants having generally as distinct
a port, as families among animals have a distinct form. We need only remember
‘the Palms, the Conifers, the Umbelliferse, the Composite, the Leguminose, the Lab-
iatee, etc. as satisfactory examples of this kind.
SOTO a vs
GENERA.
Linnzus already knew very well that genera exist in nature, though what he
calls genera constitute frequently groups to which we give at present other names,
as we consider many of them as families; but it stands proved by his writings
21
162 ESSAY ON CLASSIFICATION. | Pane”-f,
that he had fully satisfied himself of the real existence of such groups, for he
says distinctly in his Philosophia Botanica, sect. 169, “Scias characterem non con-
stituere genus, sed genus characterem. Characterem fluere e genere, non genus
e charactere. Characterem non esse, ut genus fiat, sed ut genus noscatur.”
It is surprising that notwithstanding such clear statements, which might have
kept naturalists awake respecting the natural foundation of genera, such loose ideas
have become prevalent upon this subject, that at present the number of inves-
tigators who exhibit much confidence in the real existence of their own generic
distinctions is very limited. And as to what genera really are, the want of pre-
cision of ideas appears still greater. Those who have considered the subject at
all seem to have come to .the conclusion that genera are nothing but groups
including a certain number of species agreeing in some more general features
than those which distinguish species; thus recognizing no difference between generic
and specific characters as such, as a single species may constitute a genus, when-
ever its characters: do not agree with the characters of other species, and many
species may constitute a genus, because their specific characters agree to a certain
extent among themselves! Far from admitting such doctrines, I hope to be able
to show that, however much or however little species may differ among themselves
as species, yet they may constitute a natural genus, provided their respective generic
characters are identical.
I have stated before, that in order to ascertain upon what the different groups
adopted in our systems are founded, I consulted the works of such writers as are
celebrated in the annals of science for having characterized with particular felicity
any one kind of these groups, and I have mentioned Latreille as prominent among
zodlogists for the precision with which he has defined the genera of Crustacea
and Insects, upon which he has written the most extensive work extant” An
anecdote which I have often.heard repeated by entomologists who knew Latreille
well, is very characteristic as to the meaning he connected with the idea of genera.
At the time he was preparing the work just. mentioned, he lost no opportunity
of obtaining specimens, the better to ascertain from nature the generic peculiarities
_of these animals, and he used to apply to the entomologists for contributions to his
collection. It was not show specimens he cared to obtain, any would do, for he
used to say he wanted them only “to examine their parts.” Have we not here
a hint, from a master, to teach us what genera are and how they should be
characterized? Is it not the special structure of some part or other, which charac-
1 Spring, Ueber die naturhistorischen Begriffe 2 LaTREILLE, Genera Crustaceorum und Insect-
von Gattung, Art und Abart, Leipzig, 1838, 1 vol. orum, Paris et Argent. 1806-1809, 4 vols. 8vo.
8vo.
Cuap. II. SPECIES. | 163
terizes genera? Is it not the finish of the organization of the body, as worked
out in the ultimate details of structure, which distinguishes one genus from another?
Latreille, in expressing the want he felt with reference to the study of genera,
has given us the key-note of their harmonious relations to one another. Genera
are most closely allied groups of animals, differing neither in form, nor in com-
plication of structure, but simply in the ultimate structural peculiarities of some
of their parts; and this is, I believe, the best definition which can be given of
genera. They are not characterized by modifications of the features of the fami-
lies, for we have seen that the prominent trait of family difference is to be found
in a typical form; and genera of the same family may not differ at all in form. Nor
are genera merely a more comprehensive mould than the species, embracing a wide
range of characteristics; for species in a natural genus” should not present any
structural differences, but only such as express the most special relations of their
representatives to the surrounding world and to each other. Genera, in one word,
are natural groups of a peculiar kind, and their special distinction rests upon the
ultimate details of their structure.
SECTION VI.
SPECIES.
It is generally believed that nothing is easier than to determine species, and
that of all the degrees of relationship which animals exhibit, that which consti-
tutes specific identity is the most clearly defined. An unfailing criterion of specific
identity is even supposed to exist in the sexual connection which so naturally
brings together the individuals of the same species in the function of reproduc-
tion. But I hold that this is a complete fallacy, or at least a petitio principii, not
admissible in a philosophical discussion of what truly constitutes the characteristics’
of species. I am even satisfied that some of the most perplexing problems involved
in the consideration of the natural limits of species would have been solved long
ago, had it not been so generally urged that the ability and natural disposition
of individuals to connect themselves in fertile sexual intercourse was of itself
sufficient evidence of their specific identity. Without alluding to the fact that every
new case of hybridity’ is an ever-returning protest against such an assertion, and
1 Wiecman, Gekronte Preisschrift iiber die Bas- ron, (S. G.,) Essay on Hybridity, Amer. Jour.,
tarderzeugung im Pflanzenreich, Braunschweig, 1828, 1847. — Additional Observations on Hybridity in
8vo.— Brawn, (A.,) Ueber die Erscheinung der Ver- Animals and on some collateral subjects, Charleston
jiingung in der Natur, Freiburg, 1849, 4to.—Mor- — Med. Journ., 1850.
pcsnanenennerenny
164 ESSAY ON CLASSIFICATION. ofp ae
without entering here into a discussion respecting the possibility or practicability
of setting aside this difficulty by introducing the consideration of the limited fer-
tility of the progeny of individuals of different species, I will only remark,
that as long as it is not proved that all the varieties of dogs, and of any others
of our domesticated animals, and of our cultivated plants, are respectively derived
from one unmixed species, and as long as doubts can be entertained respecting
the common origin of all races of men from one common stock, it is not logical
to admit that sexual connection resulting even in fertile offspring is a trustworthy
evidence of specific identity.
To justify this assertion, I would only ask, where is the unprejudiced naturalist
who in our days would dare to maintain: Ist, that it is proved that all the
domesticated varieties of sheep, of goats, of bulls, of Hamas, of horses, of dogs,
of fowls, etc., are respectively derived from one common stock; 2d, that the
supposition that these varieties have originated from the complete amalgamation of
several primitively distinct species is out of the question; and 3d, that varieties
imported from distant countries and not before brought together, such as the
Shanghae fowl, for instance, do not completely mingle? Where is the physiologist
who can conscientiously affirm that the limits of the fertility between distinct
species are ascertained with sufficient accuracy to make it a test of specific identity ?
And who can say that the distinctive characters of fertile hybrids and of unmixed
breeds are sufficiently obvious to enable anybody to poimt ‘out the primitive feat-
ures of all our domesticated animals, or of all our cultivated plants? As long
as this cannot be done, as long as the common origin of all races of men, and
of the different animals and plants mentioned above, is not proved, while their
fertility with one another is a fact which has been daily demonstrated for thou-
sands of years, as long as large numbers of animals are hermaphrodites, never
requiring a connection with other individuals to multiply their species, as long as
there are others which multiply in various ways without sexual intercourse, it is
not justifiable to assume that those animals and plants are unmixed species, and
that sexual fecundity is the criterion of specific identity. Moreover, this test can
hardly ever have any practical value in most cases of the highest scientific inter-
est. It is never resorted to, and, as far as 1 know, has never been applied with
satisfactory results to settle any doubtful case. It has never assisted any anxious
and conscientious naturalist in investigating the degree of relationship between
closely allied animals or plants living in distant regions or in disconnected geo-
graphical areas. It will never contribute to the solution of any of those difficult
cases of seeming difference or identity between extinct animals and plants found
in different geological formations. In all critical cases, requirmg the most minute
accuracy and precision, it is discarded as unsafe, and of necessity questionable.
Accurate science must do without it, and the sooner it is altogether discarded, the
5 a at in a —_ win a ase ee ee
Cuap. II. SPECIES. 165
better. But, like many relics of past time, it is dragged in as a sort of theo-
retical bugbear, and exhibited only now and then to make a false show in discus-
? sions upon the question of the unity of origm of mankind. — , il ||
rt There is another fallacy connected with the prevailing ideas about species to it
which I would also allude: the fancy that species do not exist in the same way | | il
in nature as genera, families, orders, classes, and types. It is actually maintained \ Si
by some that species are founded in nature in a manner different from these groups; |
that their existence is, as it were, more real, whilst that of the other groups is |
considered as ideal, even when it is admitted that these groups have themselves a
natural foundation. |
Let us consider this point more closely, as it involves the whole question of
individuality. I wish, however, not to be understood as undervaluing the impor-
tance of sexual relations as indicative of the close ties which unite, or may unite, | Hy
the individuals of the same species. I know as well as any one to what extent | | |
they manifest themselves in nature, but I mean to insist upon the undeniable fact al
that these relations are not so exclusive as those naturalists would represent them,
who urge them as an unfailing criterion of specific identity. I would remind those
who constantly forget it, that there are animals which, though specifically distinct
kh do unite sexually, which do produce offspring, mostly sterile, it is true, in some
species, but fertile to a limited extent in others, and in others even fertile to an
extent which it has not yet been possible to determine. Sexual connection is the
result, or rather one of the most striking expressions of the close relationship
established in the beginning between individuals of the same species, and by no
means the cause of their identity in successive generations. When first created,
animals of the same species paired because they were made one for the other ;
they did not take one another in order to build up their species, which had full
existence before the first individual produced by sexual connection was born.
This view of the subject acquires greater importance in proportion as it becomes
more apparent that species did not originate in single pairs, but were created in
large numbers, in those numeric proportions which constitute the natural harmonies
between organized beings. It alone explains the possibility of the procreation
of Hybrids, as: founded upon the natural relationship of individuals of closely
allied species, which may become fertile with one another, the more readily as they
differ less, structurally.
To assume that sexual relations determine the species it should further be shown
that absolute promiscuousness of sexes among individuals of the same species is the
prevailing characteristic of the animal kingdom, while the fact is, that a large num-
ber even of animals, not to speak of Man, select their mate for life and rarely
have any intercourse with others. It is a fact known to every farmer, that differ-
\
166 ESSAY ON CLASSIFICATION. Part I.
ent breeds of the same species are less inclined to mingle than individuals of the
same breed. For my own part, I cannot conceive how moral philosophers, who
urge the unity of origin of Man as one of the fundamental principles of their
religion, can at the same time justify the necessity which it involves of a sexual
intercourse between the nearest blood relations of that assumed first and unique
human family, when such a connection is revolting even to the savage. Then again,
there are innumerable species in which vast numbers of individuals are never
developed sexually, others in which sexual individuals appear only now and then
at remote intervals, while many intermediate generations are produced without any
sexual connection, and others still which multiply more extensively by budding
than by sexual generation. 1 need not again allude here to the phenomena of
alternate generation, now so well known among <Acalephs and Worms, nor to
the polymorphism of many other types. Not to acknowledge the significance of
such facts, would amount to the absurd pretension, that distinctions and definitions,
introduced in our science durmg its infancy, are to be taken as standards for
our appreciation of the phenomena in nature, instead of framing and remodelling
our standards, according to the laws of nature, as our knowledge extends. It is,
for instance, a specific character of the Horse and the Ass to be able to con-
nect sexually with each other, and thus to produce an offspring different from that
which they bring forth among themselves. It is characteristic of the Mare, as
the representative of its species, to bring forth a Mule with the Jackass, and of
the Stallion to procreate Hinnies with the Sheass. It is equally characteristic of
them to produce still other kinds of halfbreeds with the Zebra, the Daw, etc. And
yet in. face of all these facts, which render sexual reproduction, or at least pro-
miscuous intercourse among the representatives of the same species, so questionable
a criterion of specific identity, there are still naturalists who would represent it as
an unfailing test, only that they may sustain one single position, that all men are
derived from one single pair. 3 |
These facts, with other facts which go to show more extensively every day the
ereat probability of the independent origin of individuals of the same species in
disconnected geographical areas, force us to remove from the philosophic definition
of species the idea of a community of origin, and consequently, also, the idea of
_ & necessary genealogical connection. The evidence that all animals have originated
\
\. naturalists. Now if this is the case, sexual derivation does not constitute a neces-
in large numbers is growing so strong, that the idea that every species existed in
the beginning in single pairs, may be said to be given up almost entirely by
‘sary specific character, even though sexual connection be the natural process of
their reproduction and multiplication. If we are led to admit as the beginning of
each species, the simultaneous origin of a large number of individuals, if the same
Cuap. II. SPECIES. | 167
species may originate at the same time in different localities, these first repre-
sentatives of each species, at least, were not connected by sexual derivation; and as
this applies equally to any first pair, this fancied test criterion of specific identity
must at all events be given up, and with it goes also the pretended real exist-
ence of the species, in contradistinction from the mode of existence of genera,
families, orders, classes, and types; for what really exists are individuals, not species.
We may at the utmost consider individuals: as representatives of species, but no one
individual nor any number of individuals represent its species only, without repre-
senting also at the same time, as we have seen above (Sect. I. to V.), its genus, its
family, its order, its class, its type.
Before attempting to prove the whole of this proposition, I will first con-
sider the characters of the individual animals. Their existence is scarcely limited
as to time and space withm definite and appreciable limits. No one nor all of
them represent fully, at any particular time, their species; they are always only the
temporary representatives of the species, inasmuch as each species exists longer in
nature than any of its individuals. All the individuals of any or of all species
now existing are only the successors of other individuals which have gone before,
and the predecessors of the next generations; they do not constitute the species,
they represent it. The species is an ideal entity, as much as the genus, the family,
the order, the class, or the type; it continues to exist, while its representatives
die, generation after generation. But these representatives do not simply repre-
s specific m the individual, they exhibit and reproduce in the same
sent what 1
manner, generation after generation, all that is generic in them, all that charac-
terizes the family, the order, the class, the branch, with the same fulness, the
same constancy, t
manner as any other groups, they are quite as ideal in their mode of existence_/
as genera, families, etc, or quite as real. But individuals truly exist in a differ-
ent way; no one of them exhibits at one time all the characteristics of the species,
even though it be hermaphrodite, neither do any two represent it, even though i
the species be not polymorphous, for individuals have a growth, a youth, a mature
age, an old age, and are bound to some limited home during their lifetime.
It is true species are also limited in their existence; but for our purpose, we can
consider these limits as boundless, inasmuch as we have no means of fixing their
duration, either for the past geological ages, or for the present period, whilst
the short cycles of the life of individuals are easily measurable quantities. Now
as truly as individuals, while they exist, represent their species for the time being,
and do not constitute them, so truly do these same mdividuals represent at the
same time their genus, their family, their order, their class, and their type, the
characters of which they bear as indelibly as those of the species. ?
the same precision. Species then exist im nature in the same
|
168 ; ESSAY ON CLASSIFICATION. Part. 1.
As representatives of Species, individual animals bear the closest relations to one
another; they exhibit definite relations also to the surrounding elements, and their
existence is limited within a definite period. 7
As representatives of Genera, these same individuals have a definite and_ specific
ultimate structure, identical with that of the representatives of other species.
As representatives of Families, these same individuals have a definite figure exhibit-
ing, with similar forms of other genera, or for themselves, if the family contains
but one genus, a distinct specific pattern.
As representatives of Orders, these same individuals stand in a definite rank when
compared to the representatives of other families.
As representatives of Classes, these same individuals exhibit the plan of structure
of their respective type in a special manner, carried out with special means and
in special ways.
As representatives of Branches, these same individuals are all organized upon a dis-
tinct plan, differmg from the plan of other types.
Individuals then are the bearers, for the time being, not only of sa tal char-
acteristics, but of all the natural features in which animal life is displayed in all
its diversity.
Viewing individuals in this light, they resume all their dignity; they are no
longer absorbed in the species to be for ever its representatives, without ever being
any thing for themselves. On the contrary, it becomes plain, from this point of view,
that the individual is the worthy bearer, for the time being, of all the riches of
nature’s wealth of life. This view further teaches us how we may investigate, not
only the species in the individual, but the genus also, the family, the order, the
class, the type, as indeed naturalists have at all times proved in practice, whilst
denying the possibility of it im theory.
Having ‘thus cleared the field of what does not belong therein, it now remains
for me to show what in reality constitutes species, and how they may be dis-
tinguished with precision within their natural limits.
If we would not exclude from the characteristics of species any Scions which is
essential to it, nor force into it any one which is not so, we must first acknowledge
that it is one of the characters of species to belong to a given period in the
history of our globe, and to hold definite relations to the physical conditions then
prevailing, and to animals and plants then existing. These relations are manifold,
and are exhibited: Ist, in the geographical range natural to any species, as well
as in its capability of being acclimated in countries where it is not primitively
found; 2d, in the connection in which they stand to the elements around them,
when they inhabit either the water, or the land, deep seas, brooks, rivers and —
lakes, shoals, flat, sandy, muddy, or rocky coasts, limestone banks, coral reefs, swamps,
Re
Cuap. II. SPECIES. 169
meadows, fields, dry lands, salt deserts, sandy deserts, moist land, forests, shady groves,
sunny hills, low regions, plains, prairies, high tablelands, mountain peaks, or the
frozen barrens of the Arctics, ete. ; 3d, in their dependence upon this or that kind
of food for their sustenance; 4th, in the duration of their life; 5th, in the mode
of their association with one another, whether living in flocks, small companies, or
isolated; 6th, in the period of their reproduction; 7th, in the changes they undergo
during their growth, and the periodicity of these changes in their metamorphosis;
8th, in their association with other beings, which is more or less close, as it
may only lead to a constant association in some, whilst in others it amounts
to parasitism; 9th, specific characteristics are further exhibited in the size animals
attain, in the proportions of their parts to one another, in their ornamentation, _
etc, and all the variations to which they are liable. 2
As soon as all the facts bearing upon these different points have been fully
ascertained, there can remain no doubt respecting the natural limitation of species ;
and it is only the insatiable desire of describing new species from insufficient data
which has led to the introduction in our systems of so many doubtful species,
which add nothing to our real knowledge, and only go to swell the nomenclature
of animals and plants already so intricate. |
Assuming then, that species cannot always be identified at first sight, that it
may require a long time and patient investigations to ascertain their natural limits;
assuming further, that the features alluded to above are among the most promi-
nent characteristics of species, we may say, that species are based upon well
determined relations of individuals to the world around them, to their kindred, and
upon the proportions and relations of their parts to one another, as well as upon their
ornamentation. Well digested descriptions of species ought, therefore, to be com-
parative; they ought to assume the character of biographies, and attempt to trace
the origin and follow the development of a species during its whole existence.
Moreover, all the changes which species may undergo in course of time, especially
under the fostering care of man, in the state of domesticity and cultivation, belong
to the history of the species; even the anomalies and diseases to which they are
subject, belong to their cycle, as well as their natural variations. Among some
species, variation of color is frequent, others never change, some change periodi- —
cally, others accidentally; some throw off certain ornamental appendages at regular
times, the Deers their horns, some Birds the ornamental plumage they wear in
the breeding season, etc. All this should be ascertained for each, and no species
can be considered as well defined and satisfactorily characterized, the whole history
of which is not completed to the extent alluded to above. The practice prevailing
since Linnzeus of limiting the characteristics of species to mere diagnoses, has led
to the present confusion of our nomenclature, and made it. often impossible to
170 ESSAY ON CLASSIFICATION. Part I.
ascertain what were the species the authors of such condensed descriptions had
before them. But for the tradition which has transmitted, generation after. gener-
ation, the knowledge of these species among the cultivators of science in Europe,
this confusion would be still greater; but for the preservation of most original
collections it would be inextricable. In countries, which, like America, do not enjoy
these advantages, it is often hopeless to attempt critical investigations upon doubtful
cases of this kind. One of our ablest and most critical investigators, the lamented
Dr. Harris, has very forcibly set forth the difficulties under which American
naturalists labor in this respect, in the Preface to his Report upon the Insects
Injurious to Vegetation.
SHOLLON VET.
OTHER NATURAL DIVISIONS AMONG ANIMALS.
Thus far I have considered only those kinds of divisions which are introduced
in almost all our modern classifications, and attempted to show that these groups
are founded in nature and ought not to be considered as artificial devices, invented
by man to facilitate his studies. Upon the closest scrutiny of the subject, I find
that these divisions cover all the categories of relationship which exist among
animals, as far as their structure is concerned.
Branches or types are characterized by the plan of their structure,
Classes, by the manner in which that plan is executed, as far as ways and means
are concerned, .
Orders, by the degrees of complication of that structure,
Families, by their form, as far as determined by structure,
Genera, by the details of the execution in special parts, and
Species, by the relations of individuals to one another and to the world in
which they live, as well as by the proportions of their parts, their ornamenta-
tion, etc.
And yet there are other natural divisions which must be acknowledged in a
natural zodlogical system; but these are not to be traced so uniformly in all
classes as the former,—they are in reality only limitations of the other kinds of
divisions. | 5 es
A class in which one. system of organs may present a peculiar development,
while all the other systems coincide, may be subdivided into sub-classes; for instance,
the Marsupialia when contrasted with the Placental Mammalia. The characters
R\((
seats
OTHER NATURAL DIVISIONS.
Cap. II.
upon which such a subdivision is founded, are of the kind upon which the class
itself is based, but do not extend to the whole class. An order may embrace
natural groups, of a higher value than families, founded upon ordinal characters,
which may yet not determine absolute superiority or inferiority, and therefore not
constitute for themselves distinct orders; as the characters upon which they are
founded, though of the kind which determimes orders, may be so blended as to
determine superiority in one respect, while with reference to some other features
they may indicate inferiority. Such groups are called sub-orders. The order of
Testudinata, which I shall consider more in detail in the second part of this volume,
may best illustrate this point, as it contains two natural sub-orders. <A natural
family may exhibit such modifications of its characteristic form, that upon these
modifications subdivisions may be distinguished, which have been called sub-families
by some authors, tribes or legions by others. In a natural genus, a number of
species may agree more closely than others in the particulars which constitute
the genus and lead to the distinction of sub-genera. The individuals of a species,
occupying distinct fields of its natural geographical area, may differ somewhat from ,
one another, and constitute varieties, ete.
These distinctions have long ago been introduced into our systems, and every
practical naturalist, who has made a special study of any class of the animal king-
dom, must have been impressed with the propriety of acknowledging a large number
of ' subdivisions, to express all the various degrees of affinity of the different members
eke any higher natural group. Now, while I maintain that the branches, the classes,
the orders, the families, the genera, and the species are groups established in nature
respectively upon different categories, and while I feel prepared to trace the natural
limits of these groups by the characteristic features upon which they are founded,
I must confess at the same time that I have not yet been able to discover the |.
principle which obtains in the limitation of their respective subdivisions. All l/
can say is, that all the different categories considered above, upon which branches,
classes, orders, families, genera, and species are founded, have their degrees, and upon
these degrees sub-classes, sub-orders, sub-families, and sub-genera have been established.
For the present, these subdivisions must be left to arbitrary estimations, and we
shall have to deal with them as well as we can, as long as the principles which
regulate these degrees in the different kinds of groups are not ascertained. [_
hope, nevertheless, that such arbitrary estimations are for ever removed from our
science, as far as the categories themselves are concerned.
Thus far, inequality of weight seems to be the standard of the internal valua-
tion of each kind of group; and this inequality extends to all groups, for even
within the branches there are classes more closely related among themselves |
than others: Polypi and Acalephs, for instance, stand nearer to one another than
|
}
|
/
|
ESSAY ON CLASSIFICATION. Part I.
to Echinoderms; Crustacea and Insects are more closely allied to one another than
to Worms, etc. Upon such degrees of relationship between the classes, within
their respective branches, the so-called sub-types have been founded, and these differ-
ences have occasionally been exaggerated so far as to give rise to the establishment
of distinct branches. Upon similar relations between the branches, sub-kingdoms
have also been distinguished, but I hardly think that such far-fetched combinations
can be considered as natural groups; they seem to me rather the expression of
a relation arising from the weight of their whole organization, as compared with
that of other groups, than the expression of a definite relationship.
SECTION VIII.
SUCCESSIVE DEVELOPMENT OF CHARACTERS.
It has been repeated, again and again, that the characters distinguishing the
different types of the animal kingdom were developed in the embryo in the suc-
cessive order of their importance: first the structural features of their respective
branches, next the characters of the class, next those of the order, next those
of the family, next those of the genus, and finally those of the species. This
assertion has met with no direct opposition; on the contrary, it seems to have been
approved almost without discussion, and to be generally taken for granted now.
The importance of the subject requires, however, a closer scrutiny; for if Embry-
ology is to lead to great improvements in Zodlogy, it is necessary, at the outset,
to determine well what kind of information we may expect it to furnish to its
sister science. Now I would ask if at this day, zodlogists know with sufficient
precision what are typical, class, ordinal, family, generic, and specific characters, to
be justified in maintaining that, in the progress of embryonic growth, the features
which become successively prominent correspond to these characters and in the
order of their subordination? I doubt it. I will say more: I am sure there is
no such understanding about it among them, for if there was, they would already
have. perceived that this assumed coincidence, between the subordination of natural
groups among full-grown animals and the successive stages of growth during their
embryonic period of life, does not exist in nature. It is true, there are certain
features in the embryonic development which may suggest the idea of a progress
from a more general typical organization to its ultimate specialization, but it nowhere
proceeds in that stereotyped order of succession, nor indeed even in a general way,
in the manner thus assumed.
Cuap. II. SUCCESSION OF CHARACTERS. , 173
Let us see whether it is not possible to introduce more precision in this matter:
Taking for granted that what I have said about the characteristics of the natural
groups in the animal kingdom is correct, that we have, Ist, four great typical
branches of the animal kingdom, characterized by different plans of structure;
2d, classes, characterized by the ways in which and the means with which these
plans of structure are executed; 3d, orders, characterized by the degrees of simplicity
or complication of that structure; 4th, families, characterized by differences of form,
or by the structural peculiarities determining form; oth, genera, characterized by
ultimate peculiarities of structure in the parts of the body; 6th, species, charac-
terized by relations and proportions of parts among themselves, and of the indi-
viduals to one another and to the surrounding mediums; we reach, finally, the
individuals, which, for the time being, represent not only the species with all
their varieties, and variations of age, sex, size, etc., but also the characteristic features
of all the higher groups. We have thus, at one end of the series, the most com-
prehensive categories of the structure of animals, while at the other end we meet
individual beings. Individuality on one side, the most extensive divisions of the
animal kingdom on the other. Now, to begin our critical examination of the
progress of life in its successive manifestations with the extremes, is it not plain,
from all we know of Embryology, that individualization is the first requirement
of all reproduction and multiplication, and that an. individual germ, (or a number
of them,) an ovarian egg, or a bud, is first formed and becomes distinct as an
individual from the body of the parent, before it assumes either the characters
of ite great type or those of its class, order, etc.? This fact is of great significance,
as showing the importance of individuality m nature. Next, it is true, we perceive
generally the outlines of the plan of structure, before it becomes apparent in
what manner that plan is to be carried out; the character of the type is marked
out, in its most general features, before that of the class can be recognized with
any degree of precision. Upon this fact, we may base one of the most important
generalizations in Embryology.
It has been maintained, in the most general terms, that the higher animals
pass during their development through all the phases characteristic of the inferior
classes. Put in this form, no statement can be further from the truth, and yet
there are decided relations within certain limits, between the embryonic stages of
growth of higher animals and the permanent characters of others of an inferior
grade. Now the fact mentioned above, enables us to mark with precision the limits
within which these relations may be traced. As eggs, in their primitive condi:
tion, animals do not differ one from the other; but as soon as the embryo has
begun to show any characteristic features, it presents such peculiarities as dis-
tinguish its type. It cannot, therefore, be said that any animal passes through
174 ESSAY ON CLASSIFICATION. Pant
phases of development, which are not included within the limits of its own type;
no Vertebrate is, or resembles, at any time an Articulate, no Articulate a Mollusk,
no Mollusk a Radiate, and vice versd. Whatever correlations between the young of
higher animals and the perfect condition of inferior ones may be traced, they are
always limited to representatives of the same great types; for instance, Mammalia
and Birds, in their earlier development, exhibit certain features of the lower classes
of Vertebrates, such as the Reptiles or Fishes; Insects recall the Worms in some
of their earlier stages of growth, etc, but even this requires qualifications to
which we shall have to refer hereafter. However, thus much is already evident, |
that no higher animal passes through phases of development recalling all the lower
types of the animal kingdom, but only such as belong to its own branch. What
has been said of the infusorial character of young embryos of Worms, Mollusks,
and Radiates, can no longer stand before a serious criticism, because, in the first
place, the animals generally called Infusoria cannot themselves be considered as a
natural class; and in the second place, those to which a reference is made in this
connection, are themselves free¢moving embryos.’
With the progress of growth and in proportion as itp type of an animal
becomes more distinctly marked, in its embryonic state, the plan of structure appears
also more distinctly in the peculiarities of that structure, that is to say, in the
ways in which and the means by which the plan, only famtly indicated at first,
is to be carried out and become prominent, and by this the class character is
pointed out. For instance, a wormlike insect larva will already show, by its trachex,
that it is to be an Insect and not to remain a Worm, as it at first appears to
be; but the complications of that special structure, upon which the orders of
the class of Insects are based, do not yet appear; this is perfected only at a late
period in the embryonic life. At this stage, we frequently notice already a remark-
able advance of the features characteristic of the families over those characteristic of
the order; for instance, young Hemiptera, young Orthoptera may safely be referred
to their respective families, from the characteristics they exhibit before they show
ihose peculiarities which characterize them as Hemiptera or as Orthoptera; young
Fishes may be known as members of their respective families before the charac-
ters of their orders are apparent, etc.
It is very obvious why this should be so. With the progress of the develop-
ment of the structure, the general form is gradually sketched out, and it has
already reached many of its most distinctive features, before all the complications
of the structure which characterize the orders have become apparent; and as form
characterizes essentially the families, we see here the reason why the family type
1 See above, Chap. I., Sect..18, p. 75
Cuap. II. SUCCESSION OF CHARACTERS. 175
may be fully stamped upon an animal before its ordinal characters are developed.
Even specific characters, as far as they depend upon the proportions of parts and
have on that ground an influence in modifyimg the form, may be recognized long
before the ordinal characters are fully developed. The Snapping-Turtle, for instance,
exhibits its small crosslike sternum, its long tail, its ferocious habits even before it
leaves the egg, before it breathes through lungs, before its derm is ossified to form
a bony shield, etc.; nay, it snaps with its gaping jaws at any thing brought
near, though it be still surrounded by its amnios and allantois, and its yolk still
exceeds in bulk its whole body. The calf assumes the form of the bull before \
it bears the characteristics of the hollow-horned Ruminants; the fawn exhibits all
the peculiarities of its species before those of its family are unfolded. |
~
~~
With reference to generic characters, it may be said that they are scarcely
ever developed in any type of the animal kingdom, before the specific features
are for the. most part fully sketched out, if not completely developed. Can there
be any doubt that the human embryo belongs to the genus Homo, even before it
has cut a tooth? Is not a kitten, or a puppy distinguishable as a cat or a dog,
before the claws and teeth tell their genus? Is this not true also of the Lamb,
the Kid, the Colt, the Rabbits, and the Mice, of most Birds, most Reptiles, most
“f Fishes, most Insects, Mollusks and Radiates? And why should this be? Simply,
because the proportions of parts, which constitute specific characters, are recog-
nizable before their ultimate structural development, which characterizes genera, is
completed.
It seems to me that these facts are likely to influence the future progress
of Zodlogy, in enabling us gradually to unravel more and more distinctly, the
features which characterize the different subordimate groups of the animal king.
dom. The views I have expressed above of the respective value and the promi-
nent characteristics of these different groups, have stood so completely the test in | !
this analysis of their successive appearance, that I consider this circumstance ag
adding to the probability of their correctness. ; : |
But this has another very important bearing, to which I have already alluded i}
|
|
in the beginning of these remarks. Before Embryology can furnish the means of
settling some of the most perplexing problems in Zodlogy, it is Indispensable to
ascertain first what are typical, classic, ordinal, family, generic, and specific charac-
fl ters; and as long as it could be supposed that these characters appear necessarily i
1 Pr, M. v. Nev-Wrep quotes as a remarkable it was still a pale, almost colorless embryo, wrapped HI
° >) Hi
fact, that the Chelonara serpentina bites as soon as it up in its foetal envelopes, with a yolk larger than |
is hatched. I have seen it snapping in the same itself hanging from its sternum, three months before
fierce manner as it does when full-grown, at a time hatching.
176 ESSAY ON CLASSIFICATION. } Part I.
durmg the embryonic growth, in the order of their subordination, there was no
possibility of deriving from embryological monographs, that information upon this
point, so much needed in Zodlogy, and so seldom alluded to by embryologists.
Again, without knowing what constitutes truly the characters of the groups named
above, there is no possibility of finding out the true characters of a genus of
which only one species is known, of a family which contains only one genus, etc.,
and for the same reason no possibility of arriving at congruent results with refer-
ence to the natural limitations of genera, families, orders, etc. without which we
cannot even begin to build up a permanent classification of the animal kingdom;
and still less, hope to establish a solid basis for a general comparison between
the animals now living and those which have peopled the surface of our globe
in past geological ages. ; 7
It is not accidentally I have been led to these investigations, but by necessity.
As often as I tried to compare higher or more limited groups of animals of the
present period with those of former ages, or early stages of growth of higher living
animals. with full-grown ones of lower types, 1 was constantly stopped in my
progress by doubts as to the equality of the standards I was applying, until I
made the standards themselves the object of direct and very extensive investiga-
tions, covering indeed a much wider ground than would appear from these remarks,
for, upon these principles, I have already remodelled, for my own convenience, nearly
the whole animal kingdom, and introduced in almost every class very unexpected
changes in the classification.
I have already expressed above’ my conviction that. the only true system is
that which exists in nature, and as, therefore, no one should have the ambition
of erecting a system of his own, I will not even .attempt now to present these
results in the shape of a diagram, but remain satisfied to express my belief, that
all we can really do is, at best, to offer imperfect translations in human language
of the profound thoughts, the innumerable relations, the unfathomable meaning of
the plan actually manifested in the natural objects themselves; and I should con-
sider it as my highest reward should I find, after a number of years, that I had
helped others on in the right path. :
1 See Chap. E., Sect. We, 09
7
Poon
CONCLUSIONS.
Cuap. II.
SBHCTION IX.
CONCLUSIONS.
The importance of such an investigation as the preceding, must be obvious to
every philosophical investigator. As soon as it is understood that all the different
groups introduced into a natural system may have a definite meaning; as soon
as it can be shown that each exhibits a definite relation among living beings,
founded in nature, and no more subject to arbitrary modifications than any other
law expressing natural phenomena; as soon as it is made plain that the natural
limits of all these groups may be ascertained by careful investigations, the interest
in the study of classification or the systematic relationship existing among all
organized beings, which has almost ceased to engage the attention of the more
careful original investigators, will be revived, and the manifold ties which link
together all animals and plants, as the living expression of a gigantic conception,
carried out in the course of time, like a soul-breathing epos, will be scrutinized
anew, determined with greater precision, and expressed with increasing clearness
and propriety. Fanciful and _ artificial classifications will gradually lose their hold
upon a better informed community; scientific men themselves will be restrained
from bringing forward immature and premature investigations; no characteristics of
new species will have a claim upon the notice of the learned, which has not been
fully investigated and compared with those most closely allied to it; no genus
will be admitted, the structural peculiarities of which are not clearly and distinctly
illustrated ; no family will be considered as well founded, which shall not exhibit
a distinct system of forms mtimately combined and determined by structural rela-
tions; no order will appear admissible, which shall not represent a well-marked
degree of structural complication; no class will deserve that name, which ghall
not appear as a distinct and independent expression of some general plan of struc-
ture, carried out in a peculiar way and with peculiar means; no type will be
recognized as one of the fundamental groups of the animal kingdom, which shall
. not exhibit a plan of its own, not convertible into another. No naturalist will
be justified in introducing any one of these groups into our systems without show-
ing: Ist, that it is a natural group; 2d, that it is a group of this or that kind,
to avoid, henceforth, calling families groups that may be genera, families groups that
may be orders, classes or types groups that may be orders or classes; 38d, that the
characters by which these groups may be recognized are in fact respectively specific,
23
Sn en A ERT A RPT A ne eee
178 ESSAY ON CLASSIFICATION. Part I.
generic, family, ordinal, classic, or typical characters, so that our works shall no
longer exhibit the annoying confusion, which is to be met almost everywhere, of
generic characters in the diagnoses of species, or of family and ordinal characters
in the characteristics of classes and types! _
It may perhaps be said, that all this will not render the study of Zodlogy
more easy. ‘I do not expect that it will; but if an attentive consideration of what
I have stated in the preceding pages respecting classification, should lead to a
more accurate investigation of all the different relations existing among animals,
and between them and the world in which they live, I shall consider myself
as having fully succeeded in the object I have had in view from the beginning,
in this inquiry. Moreover, it is high time that certain zodlogists, who would ‘call
themselves investigators, should remember, that natural objects, to be fully under-
stood, require more than a passing glance; they should imitate the example of
astronomers, who have not become tired of looking into the relations of the few
members of our solar system to determine, with increased precision, their motions,
their size, their physical constitution, and keep in mind that every organized
being, however simple in its structure, presents to our appreciation far more com-
plicated phenomena, within our reach, than all the celestial bodies put together;
they should remember, that as the great literary productions of past ages attract
ever anew the attention of scholars, who can never feel that they have exhausted
the inquiry into their depth and beauty, so the living works of God, which it is
the proper sphere of Zodlogy to study, would never cease to present new attractions
to them, should they proceed to the investigation with the right spirit. Their
studies ought, indeed, inspire every one with due reverence and admiration for such
wonderful productions.
The subject of classification in particular, which seems to embrace apparently
so limited a field in the science of animals, cannot be rightly and fully under-
stood without a comprehensive knowledge of all the topics alluded to in the
preceding pages.
1 As Ido not wish to be personal, I will refrain any characterization of genera, of families, of orders,
from quoting examples to justify this assertion. I of classes, and of types, to satisfy themselves that
would only request those who care to be accurate, to characters of the same kind are introduced almost
examine critically almost any description of species, indiscriminately to distinguish all these. groups.
ee Dae
OH A PolEaties ida Hel).
NOTICE OF THE PRINCIPAL SYSTEMS OF ZOOLOGY.
SECTION I.
GENERAL REMARKS UPON MODERN SYSTEMS.
Wirnovr attempting to give an historical account of the leading features of all
zodlogical systems, it is proper that I should here compare critically the practice
of modern naturalists with the principles discussed above. With this view, it
would hardly be necessary to go back beyond the publication of the “Animal
Kingdom,” by Cuvier, were it not that Cuvier is still represented, by many naturalists,
and especially by Ehrenberg, and some other German zoUlogists, as favoring the
division of the whole animal kingdom into two great groups, one containing the
Vertebrates, and the other all the remaining classes, under the name of Inverte-
brates, while in reality it was he, who first, dismissing his own earlier views,
introduced into the classification of the animal kingdom that fourfold division which
has been the basis of all improvements in modern Zodlogy. He first showed that
animals differ, not only by modifications of one and the same organic structure,
but are constructed upon four different plans of structure, forming natural, distinct
groups, which he called Radiata, Articulata, Mollusca, and Vertebrata.
It 38 trac, that the further subdivisions of these leading groups have under-
gone many changes since the publication of the “Reégne Animal.” Many smaller
groups, even entire classes, have been removed from one of his “embranchments”
to another; but it is equally true, that the characteristic idea which lies at the
bottom of these great divisions was first recognized by him, the greatest zodlogist
of all times.
1 Enrenserc, (€. G.,) Die Corallenthiere des rothen Meeres, Berlin, 1834, Ato., p. 30.
lt at SA III a
180 Soe ESSAY ON CLASSIFICATION. Part I.
The question which I would examine here in particular, is not whether the
circumscription of these great groups was accurately defined by Cuvier, whether
the minor groups referred to them truly belong there or elsewhere, nor how far
these divisions may be improved within their respective limits, but whether there
are four great fundamental groups in the animal kingdom, based upon -four differ-
ent plans of structure, and neither more nor less than four. This question is
very seasonable, since modern zodlogists, and especially Siebold, Leuckart, and Vogt
have proposed combinations of the classes of the animal kingdom into higher groups,
differing essentially from those of Cuvier. It is but justice to Leuckart to say
that he has exhibited, in the discussion of this subject, an acquaintance with the
whole range of Invertebrata,’ which demands a careful consideration of the changes
he proposes, as they are based upon a critical discrimination of differences of great
value, though I think he overrates their importance. The modifications intro-
duced by Vogt, on the contrary, appear to me to be based upon entirely unphysio-
logical principles, though seemingly borrewed from that all important guide, Em-
bryology.
The divisions adopted by Leuckart are: Protozoa, (though he does not enter
upon an elaborate consideration of that group,) Coelenterata, Echinodermata, Vermes,
Arthropoda, Mollusca, and Vertebrata. The classification adopted, many years before,
by Siebold, in his text-book of comparative anatomy, 1s nearly the same, except
that Mollusks follow the Worms, that Coelenterata and Echinoderms are united
into one group, and that the Bryozoa are left among the Polyps.
Here we have a real improvement upon the classification of Cuvier, imasmuch
as the Worms are removed from among the Radiates, and brought nearer the
Arthropods, an improvement however, which, so far as it is correct, has already
been anticipated by many naturalists, since Blainville and other zodlogists long
ago felt the impropriety of allowing them to remain among Radiates, and have
been induced to associate them more or less closely with Articulates. But I
believe the union of Bryozoa and Rotifera with the Worms, proposed by Leuckart,
to be a great mistake; as to the separation of Coelenterata from Echinoderms, I
consider it as an exaggeration of the difference which exists between Polyps and
Acalephs on the one hand, and Echinoderms on the other.
The fundamental groups adopted by Vogt,’ are: Protozoa, Radiata, Vermes, Mol-
lusca, Cephalopoda, Articulata, and Vertebrata, an arrangement which is based solely
upon the relations of the embryo to the yolk, or the absence of eggs. But, as
* LevcKart, (R.,) Ueber die Morphologie und die 2-Voat, (CarL,) Zoologische Briefe. Naturge-
Verwandtshaftsverhiltnisse der wirbellosen Thiere, schichte der lebenden und untergegangenen Thiere.
Braunschweig, 1848, 1 vol., 8vo. | Frankfurt a. M., 1851; vol. 1, p. 70.
4
Cuap. III. MODERN SYSTEMS. 181
I have already stated, this is an entirely unphysiological principle, inasmuch as it
assumes’ a contrast between the yolk and the embryo, within limits which do not
exist in nature. ‘The Mammalia, for instance, which are placed, like all other Verte-
brata, in the category of the animals in which there is an opposition between the
embryo and the yolk, are as much formed of the whole yolk as the Echinoderms
or Mollusks. The yolk undergoes a complete segmentation in Mammalia, as well as
in Radiates or Worms, and most Mollusks; and the embryo when it makes its
appearance no more stands out from the yolk, than the little Starfish stands
out from its yolk. These simple facts, known since Sars and Bischoff published
their first observations, twenty years ago, is in itself sufficient to show that the
whole principle of classification of Vogt is radically wrong.
Respecting the assertion, that neither Infusoria nor Rhizopoda produce any eggs,
I shall have more to say presently. As to the arrangement of the leading groups,
Vertebrata, Articulata, Cephalopoda, Mollusca, Vermes, Radiata, and Protozoa in
Vogt’s system, it must be apparent to every zodlogist conversant with the natural
affinities of animals, that a classification which interposes the whole series of Mollusks
between the types of Articulata and Worms, cannot be correct. A. classification
based, like this, solely upon the changes which the yolk undergoes, is not likely
to be the natural expression of the manifold relations existing between all animals.
Indeed, no system can be true to nature, which is based upon the consideration
of a single part, or a single organ.
After these general remarks, I have only to show more in detail, why I believe
that there are only four great fundamental groups in the animal kingdom, neither
more nor less.
With reference to Protozoa, first, it must be acknowledged that, notwithstanding
the extensive investigation of modern writers upon Infusoria and Rhizopoda, the
true nature of these beings is still very little known. The Rhizopoda have been
wandering from one end of the series of Invertebrata to the other, without finding
a place generally acknowledged as expressing their true affinities. The attempt
to separate them from all the classes with which they have been so long associated,
and to place them with the Infusoria in one distinct branch, appears to me as
mistaken as any of the former arrangements, for I do not even consider that their
animal nature is yet proved beyond a doubt, though I have myself once sug-
gested the possibility of a definite relation between them and the lowest Gaste-
ropods. Since it has been satisfactorily ascertained that the Corallines are genuine
Algz, which contain more or less lime in their structure, and since there is hardly
any group among the lower animals and lower plants, which does not contain
simple locomotive individuals, as well as compound communities, either free or adher-
ing to the soil, [ do not see that the facts known at present preclude the possibility
182 ESSAY ON CLASSIFICATION. Part I.
of an association of the Rhizopods with the Algx.! This would almost seem natural,
when we consider that the vesicles of many Fuci contain a viscid, filamentous
substance, so similar to that protruded from the body of the Rhizopods, that the
most careful microscopic examination does not disclose the slightest difference in its
structure from that which mainly forms the body of Rhizopods. The discovery
by Schultze? of what he considers as the germinal granules of these beings, by no
means settles this question, though we have similar ovoid masses in Algx, and
though, among the latter, locomotive forms are also very numerous.
With reference to the Infusoria, I have long since expressed my conviction that
they are an unnatural combination of the most heterogeneous beings. A large
number of them, the Desmidiee and Volvocine, are locomotive Algz. Indeed,
recent investigations seem to have established beyond all question, the fact, that
all the Infusoria Anentera of Ehrenberg are Algz. The Enterodela, however, are
true animals, but belong to two very distinct types, for the Vorticellide differ
entirely from all others. Indeed, they are, in my opinion, the only independent
animals of that group, and so far from having any natural affinity with the other
Enterodela, I do not doubt that their true place is by the side of Bryozoa,
among Mollusks, as I shall attempt to show presently. Isolated observations which
I have been able to make upon Paramecium, Opalina, and the like, seem to me
sufficient to justify the assumption that they disclose the true nature of the
bulk of this group. I have seen, for instance, a Planaria lay eggs out of which
Paramecium were born, which underwent all the changes these animals are known to
undergo up to the time of their contraction into a chrysalis state; while the Opalina
is hatched from Distoma eggs. I shall publish the details of these observations
on another occasion. But if it can be shown that two such types as Paramecium
and Opalina are the progeny of Worms, it seems to me to follow, that all the
Enterodela, with the exception of the Vorticellide, must be considered as the
embryonic condition of that host of Worms, both parasitic and free, the meta-
morphosis of which is still unstudied. In this connection, I might further remark,
that the time is not long past when Cercaria was also considered as belonging
to the class of Infusoria, though at present no one doubts that it belongs to
the cycle of Distoma; and the only link in the metamorphosis of that genus which
was not known is now supplied, since, as I have stated above, the embryo which
is hatched from the egg laid by the perfect Distoma is found to be Opalina.
All this leads to the conclusion, that a division of the animal kingdom to be
called Protozoa, differing from all other animals in producing no eggs, does not
exist in nature, and that the beings which have been referred to it have now
1 Comp. Chap. I., Sect. 18, p. 75. 2 Scnuttzz, (M. S.,) Polythalamien, q. a.; p. 24.
183
Cuap. III. MODERN SYSTEMS.
to be divided, and scattered, partly among plants, in the class of Algs, and partly
among animals, in the classes of Acephala, (Vorticelle,) of Worms, (Paramecium and
Opalina,) and of Crustacea (Rotifera); Vorticelle being genuine Bryozoa and there-
fore Acephalous Mollusks, while the beautiful investigations of Dana and Leydig
have proved the Rotifera to be genuine Crustacea, and not Worms.
_ The great type of Radiata, taking its leading features only, was first recognized
by Cuvier, though he associated with it many animals which do not properly
belong to it. This arose partly from the imperfect knowledge of those animals
at the time, but partly also from the fact that he allowed himself, in this instance,
to deviate from his own principle of classification, according to which types are
founded upon special plans of structure. With reference to Radiata, he departed,
indeed, from this view, so far as to admit, besides the consideration of their peculiar
plan, the element of simplicity of their structure as an essential feature in the
typical character of these animals, in consequence of which he introduced five classes
among Radiata: the Echinoderms, Intestinal Worms, Acalephs, Polypi, and Infusoria.
In opposition to this unnatural association, I need not repeat here, what I have
already stated of the Infusoria, when considering the case of Protozoa; neither is it
necessary to urge again the propriety of removing the Worms from among Radiata,
and connecting them with Articulata. There would thus remain only three classes
among Radiates, — Polypi, Acalephs, and Echinoderms, — which, in my opinion, con-
stitute really three natural classes in this great division, inasmuch as: they exhibit
the three different ways in which the characteristic plan of the type, radiation,
is carried out, in distinct structures.
Since it can be shown that Echinoderms are, in a general way, homologous
in their structure with Acalephs and Polypi, it must be admitted that these classes
belong to one and the same great type, and that they are the only representa-
tives of the branch of Radiata, assuming of course that Bryozoa, Coralline, Sponges,
and all other foreign admixtures have been removed from among Polyps. Now,
it. is this Cuvierian type of Radiata, thus freed of all its heterogeneous elements,
which Leuckart undertakes to divide into two branches, each of which he considers
coequal with Worms, Articulates, Mollusks, and Vertebrates. He was undoubtedly
led to this exaggeration of the difference existing between Echinoderms on one
side and Acalephs and Polypi on the other, by the apparently greater resemblance
of Medusz and Polypi,! and perhaps still more by the fact, that so many genuine
Acalephs, such as the Hydroids, including Tubularia, Sertularia, Campanularia, etc,
are still comprised by most zodlogists in the class of Polypi.
1 We see here clearly how the consideration of overridden the primary feature of branches, their
anatomical differences which characterize classes has plan, to exalt a class to the rank of a branch.
184 ESSAY ON CLASSIFICATION. Part I.
But since the admirable investigations of J. Miiller have made us familiar with
the extraordinary metamorphosis of Echinoderms, and since the Ctenophere and
the Siphonophoree have also been more carefully studied by Grube, Leuckart,
Koélliker, Vogt, Gegenbaur, and myself, the distance which seemed to separate Echino-
derms from Acalephs disappears entirely, for it is mo exaggeration to say, that
were the Pluteus-like forms of Echinoderms not known to be an early stage in
the transformation of Kchinoderms, they would find as natural a place among
Ctenophore, as the larve of Insects among Worms. I therefore maintain, that
Polypi, Acalephs, and Echinoderms constitute one indivisible primary group of the
animal kingdom. The Polypoid character of young Meduse proves this as plainly
as the Medusoid character of young Echinoderms.
Further, nothing can be more unnatural than the transfer of Ctenophore to
the type of Mollusks which Vogt has proposed, for Ctenophore exhibit the closest
homology with the other Meduse, as I have shown in my paper on the Beroid
Meduse of Massachusetts. The Ctenophoroid character of young Echinoderms
establishes a second connection between Ctenophore and the other Radiata, of as
great importance as the first. We have thus an anatomical link to connect the
Ctenophoree with the genuine Meduse, = an embryological link to connect them
with the Echinoderms.
The classification of Radiata may, therefore, stand thus: —
Ist Class: Polypi; including two orders, the Aetinoids and the Halcyc-
noids, as limited by Dana. |
2d Class: Acalephae; with the following orders: Hydroids, (including Sipho-
nophore,) Discophore, and Ctenophore.
3d Class: Echinoderms; with Crinoids, Asteroids, Eehinoids, and Holothu-
rioids, as orders.
The natural limits of the branch of Mollusks are easily determined. Since the
Cirripeds have been removed to the branch of Articulata, naturalists have generally
agreed to consider, with Cuvier, the Cephalopods, Pteropods, Gasteropods, and
Acephala as forming the bulk of this type, and the discrepancies between modern
investigators have mainly resulted from the views they have taken respecting the
Bryozoa, which some consider still as Polyps, while others would unite them with
the Worms, though their affinity with the Mollusks seems to me to have been
clearly demonstrated by the investigations of Milne-Edwards. Vogt is the only
naturalist who considers the Cephalopoda “as built upon a plan entirely peculiar ;1
though he does not show in what this peculiarity of plan consists, but only mentions
the well-known anatomical differences which distinguish them from the other classes
1 Voat, (C.,) Zoologische Briefe, q. a.; vol. 1, p. 361.
re
Cnap. IIL. MODERN SYSTEMS. 185
of the branch of Mollusks. These differences, however, constitute only ‘class charac-
ters and exhibit in no way a different plan. It is, indeed, by no means difficult
to homologize all the systems of organs of the Cephalopods with those of the
other Mollusks, and with this evidence, the proof is also furnished that the Cepha-
lopods constitute only a class among the Mollusks.
As to the differences in the development of the Cephalopods and the other
Mollusks, the type of Vertebrata teaches us that partial and total segmentation
of the yolk are not inconsistent with unity of type, as the eggs of Mammalia and
Cyclostomata undergo a total segmentation, while the process of segmentation is
more or less limited in the other classes. In Birds, Reptiles, and Selachians, the
segmentation is only superficial ; in Batrachians, and most Fishes, it is much deeper;
and yet no one would venture to separate the Vertebrata into several distinct
branches on that account. With reference to Bryozoa, there can be no doubt,
that their association with Polypi or with Worms is contrary to their natural
affinities. The plan of their structure is in no way radiate; it is, on the con-
trary, distinctly and essentially bilateral ; and as soon as their close affinities with
the Brachiopods, alluded to above,’ are fully understood, no doubt will remain of
their true relation to Mollusks. As it is not withm the limits of my plan to
illustrate here the characters of all the classes of the animal kingdom, I will only
state further, that the branch of Mollusks appears to me to contain only three
classes, as follows :— .
Ist Class: Acephala; with four orders, Bryozoa, including the Vorticellx, Bra-
chiopods, Tunicata, and Lamellibranchiata. |
2d Class: Gasteropoda; with three orders, Pteropoda, Heteropoda, and Gas-
teropoda proper.
3d Class: Cephalopoda; with two orders, Tetrabranchiata and Dibranchiata.
The most objectionable modification introduced m the general classification of
the animal kingdom, since the appearance of Cuvier’s Régne Animal, seems to
me to be the establishment of a distinct branch, now very generally admitted
under the name of. Vermes, including the Annulata, the Helminths, the Rotifera,
and as Leuckardt would have it, the Bryozoa also. It was certainly an improve-
ment upon Cuvier’s system, to remove the Helminths from the type of Radiates,
but it was at the same time as truly a retrograde step to separate the Annelides
from the branch of Articulata. The most minute comparison does not lead to the
discovery of a distinct plan of structure, uniting all these animals into one natural
primary group. What holds them together and keeps them at a distance? from
other groups is not a common plan of structure, but a greater simplicity in their -
* Chap. IL, Sect. 7, p. Lee Fae Wp)
1 Chap. I., Sect. 18, p. 72.
24
186 ESSAY ON CLASSIFICATION. Part I.
organization." In bringing these animals together, naturalists make again the same
mistake which Cuvier committed, when he associated the Helminths with the
Radiates, only in another way and upon a greater scale? The Bryozoa are as it
were depauperated Mollusks, as Aphanes and Alchemilla are depauperated Rosacee.
Rotifera are in the same sense the lowest Crustacea; while Helminths and Annelides
constitute together the lowest class of Articulata. This class is connected by the
closest homology with the larval states of Insects; the plan of their structure is
identical, and there exists between them only such structural differences as con-
stitute classes. Moreover, the Helminths are linked to the Annelides in the same
manner as the apodal larve of Insects are to the most highly organized cater-
pillars. It may truly be said that the class of Worms represents, in perfect animals,
the embryonic states of the higher Articulata. The two other classes of this
branch are the Crustacea and the Insects, respecting the limits of which, as much
has already been said above,* as is necessary to state here.
The classification’ of the branch of Articulata may, therefore, stand thus:—
Ist Class: Worms; with three orders, Trematods, (including Cestods, Planariz,
and Leeches,) Nematoids, (including Acanthocephala and Gordiacei,) and Annelides.
2d Class: Crustacea; with four orders, Rotifera, Entomostraca, (including
Cirripeds,) Tetradecapods, and Decapods.
3d Class: Insects; with three orders, Myriapods, Arachnids, and Insects
proper.
There is not a dissenting voice among anatomists respecting the natural limits
of the Vertebrata, as a branch of the animal kingdom. Their character, however,
does not so much consist in the structure of their backbone or the presence of
a dorsal cord, as in the general plan of that structure, which exhibits a cavity
above and a cavity below a solid axis. These two cavities are circumscribed by
complicated arches, arising from the axis, which are made up of different systems
of organs, the skeleton, the muscles, vessels, and nerves, and include, the upper
one the centres of the nervous system, the lower one the different systems of
organs by which assimilation and reproduction are carried on.
The number and limits of the classes of this branch are not yet satisfactorily
ascertained. At least, naturalists do not all agree about them. For my part, I
believe that the Marsupialia cannot be separated from the Placental Mammalia,
as a distinct class, since we observe, within the limits of another type of Verte-
brata, the Selachians, which cannot be subdivided into classes, similar differences in
the mode of development to those which exist between the Marsupials and the other
1 See above, Chap. I., Sect. 18, p. 74-78. # Compare Chapetl, Sock 9, pe 125!
Y Pp Pp
7 Compare Chap. II, Sect. 1, p. 142. 4 Compare Chap. I., Sect. 18, p. 78-80.
r¢
Cuap. III. EARLY ATTEMPTS. . 187
Mammalia. But I hold, at the same time, with other naturalists, that the Batrachia
must be separated, as a class, from the true Reptiles, as the characters which distin-
guish them are of the kind upon which classes are founded. I am also satisfied
that the differences which exist between the Selachians, (the Skates, Sharks, and
Chimerx,) are of the same kind. as those which distinguish the Amphibians from-
the Reptiles proper, and justify, therefore, their separation, as a class, from. the
Fishes proper. I consider also the Cyclostomes as a distinct class, for similar
reasons; but I am still doubtful whether the Ganoids should be separated also from
the ordinary Fishes. This, however, cannot be decided until their embryological
development has been thoroughly investigated, though I have already collected data
which favor this view of the case. Should this expectation be realized, the branch
of Vertebrata would contain the following classes :—
Ist Class: Myzontes; with two orders, Myxinoids and Cyclostomes.
2d Class: Fishes proper; with two orders, Ctenoids and Cycloids,
3d Class: Ganoids; with three orders, Coelacanths, Acipenseroids, and Sauroids ;
and doubtful, the Siluroids, Plectognaths, and Lophobranches.
Ath Class: Selachians; with three orders, Chimerx, Galeodes, and Batides.
Sth Class: Amphibians; with three orders, Cecilie, Ichthyodi, and Anura.
6th Class: Reptiles; with four orders, Serpentes, Saurii, Rhizodontes, and
Testudinata.
7th Class: Birds; with four orders, Natatores, Grallz, Rasores, and Insessores,
(including Scansores and Accipitres.)
8th Class: Mammalia; with three orders, Marsupialia, Herbivora, and Car-
nivora.
I shall avail myself of an early opportunity to investigate more fully how
far these groups of Vertebrata exhibit such characters as distinguish classes, and I
submit. my present impressions upon this subject, rather as suggestions for further
researches, than as matured results.
SHOTION:. £1.
EARLY ATTEMPTS TO CLASSIFY ANIMALS.
So few American naturalists have paid special attention to the classification
of the animal kingdom in general, that I deem it necessary to allude to the
different principles which, at different times, have guided zodlogists in their attempts
to group animals according to their natural affinities, This will appear the more
188 ESSAY ON CLASSIFICATION. Parr I.
acceptable, I hope, since few of our libraries contain even the leading works of
our science, and many zealous students are thus prevented from attempting to study
what has thus far been done.
Science has begun, in the introduction of names, to designate natural groups
of different value with the same vagueness which still prevails im ordinary lan-
guage in the use of class, order, genus, family, species; taking them either as
synonyms or substituting one for the other at random. lLimneus was the first
to urge upon naturalists precision in the use of four kinds of groups in natural
history, which he calls classes, orders, genera, and species.
Aristotle, and the ancient philosophers generally, distinguished only two kinds
of groups among animals, yéo¢ and «dos, (genus and species.) But the term genus
had a most unequal meaning, applying at times indiscriminately to any extensive
group of species, and designating even what we now call classes as well as any
other minor group. In the sense of class, it is taken in the following case:
Aéyo 88 yévoc, lov ognda, xat (Oo, (Arist. Hist. Anim., Lib. I, Chap. I,) while eidos is
generally used for species, as the following sentence shows: «ai éorw edn mleiw iydier
zat ogvidor, though it has occasionally also a wider meaning. ‘The sixth chapter of
the same book, is the most important in the whole work of Aristotle upon this
subject, as it shows to how many different kinds of groups the term ys is applied.
Here, he distinguishes between yéy péyore and yy peyeha and yevos shortly. Iéy 8:
utnota tov Coov, sig & Suugeiver tédla Cou, cad soriv: & pev oovidor, &» SF iyOvor, GLO dz xjrove.
Ado 88 yévog iati tO THY doTeAKodEQUOY” Tov d& owtav Coowv ovu got tH yin pEydha* ov yao
mspueyes molad edn év eidoc,.... 1a 3 eye per, ad? cvodvrpe. ‘This is further insisted upon anew:
zou 58 yévovg tay tetounddar Cooov nat Cowtoxwr edn per sic modda, cvroveua de Here eidog has
evidently a wider meaning than our term species, and the accurate Scaliger translates
it by genus medium, in contradistinction to ys, which he renders by genus summum.
Eidos, however, is generally used in the same sense as now, and Aristotle already
considers fecundity as a specific character, when he says, of the Hemionos, that
it is called so from its likeness to the Ass, and not because it is of the same
species, for he adds, they copulate and propagate among themselves: of xadovora
juiovor Se ouoryra, ovt ovoa amhag to adrd eidog> nat yaQ oxevortos not yervovtee && addydov. In
another passage it applies, however, to a group exactly identical with our modern
genus Equus: éei éorw & w yévog nol ett tog *ovor yaitnr, opovoeoig xcadovugvog, olov ina xct
Or nat dget nat yovm nor treo nat coig iv Sugig xahovpévoug udvors.
Aristotle cannot be said to have proposed any regular classification. He speaks
constantly of more or less extensive groups, under a common appellation, evidently
considering them as natural divisions; but he nowhere expresses a conviction that
these groups may be arranged methodically so as to exhibit the natural affinities
of animals. Yet he frequently introduces his remarks respecting different animals
aK
Cuap. III. PERIOD OF LINNAUS. 189
in such an order and in such connections as clearly to indicate that he knew their
relations. When speaking of Fishes, for instance, he never includes the Selachians.
After Aristotle, the systematic classification of animals makes no progress for
two thousand years, until Linneus introduces new distinctions and assigns a more
precise meaning to the terms class, (genus summum,) order, (genus intermedium,) genus,
(genus proximum,) and species, the two first of which are introduced by him for the
first time as distinct groups, under these names, in the system of Zodlogy.
SECTION III.
PERIOD OF LINNAUS.
When looking over the “Systema Naturs” of Linneeus, taking as the standard
of our appreciation even the twelfth edition, which is the last he edited himself,
it is hardly possible, in our day, to realize how great was the influence of that
work upon the progress of Zodlogy.’ And yet it acted like magic upon the age,
and stimulated to exertions far surpassing any thing that had been done in pre-
ceding centuries. Such a result must be ascribed partly to the circumstance that
he was the first man who ever conceived distinctly the idea of expressing in a
definite form, what he considered to be a system of nature, and partly also to
the great comprehensiveness, simplicity, and clearness of his method. Discarding
in his system every thing that could not easily be ascertained, he for the first time
divided the animal kingdom into distinct classes, characterized by definite features;
he also for the first time introduced orders into the system of Zodlogy besides
genera and species, which had been vaguely distinguished before? And though
he did not even attempt to define the characteristics of these different kinds of
groups, it is plain, from his numerous writings, that he considered them all as
subdivisions of a successively more limited value, embracing a larger or smaller
number of animals, agreeing in more or less comprehensive attributes. He expresses
1 To appreciate correctly the successive improve- reprints of the second; the seventh, eighth, and ninth
ments of the classification of Linnzus, we need only are reprints of the sixth; the eleventh is a reprint of
compare the first edition of the “Systema Nature,” the tenth; and the thirteenth, published after his
published in 1735, with the second, published in 1740, death, by Gmelin, is a mere Sompilation, deserving
the sixth published in 1748, the tenth published in little confidence.
1758, and the twelfth published in 1766, as they are * See above, Sect. 2, p. 188. The yen weywove.
the only editions he revised himself. The third is of Aristotle correspond, however, to the classes of
only a reprint of the first, the fourth and fifth are Linneus; the yey ueyade to his orders.
190 ESSAY ON CLASSIFICATION. Part I.
his views of these relations between classes, orders, genera, species, and varieties,
by comparisons, in the following manner:—?
Classis. Ordo. Genus. - Species. Varietas.
Genus summum. Genus intermedium. Genus proximum. Species. Individuum.
Provincie. Territoria. Pareecie. Pagi. Domicilium.
Legiones. Cohortes. Manipuli. Contubernia. Miles.
His arrangement of the animal kingdom is presented in the following diagram,
compiled from the twelfth edition, published in 1766.
CLASSIFICATION OF LINNZAUS.
- Mammalia. Ord. Primates, Bruta, Ferx, Glires, Pecora, Bellu, Cete.
. Aves. Ord. Accipitres, Pice, Anseres, Gralle, Galline, Passeres.
. Amphibia. Ord. Reptiles, Serpentes, Nantes.
- Pisces.. Ord. Apodes, Jugulares, Thoracici, Abdominales.
- Insecta. Ord. Coleoptera, Hemiptera, Lepidoptera, Neuroptera, Hymenoptera, Diptera,
Aptera.
- Vermes. Ord. Intestina, Mollusca, Testacea, Lithophyta, Zoophyta.
In the earlier editions, up to the tenth, the class of Mammalia was called
Quadrupedia, and did not contain the Cetaceans, which were still included among
the Fishes. There seems never to have existed any discrepancy among naturalists
respecting the natural limits of the class of: Birds, since it was first characterized
by Linnzus, in a manner which excluded the Bats and referred them to the class
of Mammalia. In the early editions of the “Systema Nature,” the class of Reptiles
embraces the same animals as in the systems of the most recent investigators ;
but since the tenth edition, it has been encumbered with the addition of the
cartilaginous and semicartilaginous Fishes, a retrograde movement suggested by some
inaccurate observations of Dr. Garden. The class of Fishes is very well limited
in the early editions of the Systema, with the exception of the admission of the
Cetaceans, (Plagiuri,) which were correctly referred to the class of Mammalia, in
the tenth edition. In the later editions, however, the Cyclostoms, Plagiostoms,
Chimerx, Sturgeons, Lophioids, Discoboli, Gymnodonts, Scleroderms, and Lopho-
branches are excluded from it and referred to the class of Reptiles. The class
of Insects” as limited by Linneus, embraces not only what are now considered as
? See Systema Nature, 12th edit., p. 18. He seems also to’ have understood correctly the
? Aristotle divides this group more correctly than natural limits of the classes of Mammalia and Rep-
Linneus, as he admits already two classes, (yd tiles, for he distinguishes the Viviparous and Ovipa-
wéyota) among them, the Malacostraca, (Crustacea,) rous Quadrupeds, and nowhere confounds Fishes with
and the Entoma, (Insects.) Hist. Anim., Chap. VI. Reptiles. Ibid.
See lien aac oe ee ES
Cuap. III. PERIOD OF LINNAUS. 191
Insects proper, but also the Myriapods, the Arachnids, and the Crustacea; it }|
corresponds more accurately to the division of Arthropoda of modern systematists. \ |
The class of Worms, the most heterogeneous of all, includes besides all Radiata | i ||
f or Zoophytes and the Mollusks of modern writers, also the Worms, intestinal and
free, the Cirripeds, and one Fish, (Myxine.) It was left for Cuvier! to introduce
order in this chaos. :
Such is, with its excellences and short-comings, the classification which has given Vil
the most unexpected and unprecedented impulse to the study of Zodlogy. It is 1]
useful to remember how lately even so imperfect a performance could have so |
great an influence upon the progress of science, in order to understand why it is : | 1
still possible that so much remains to be done in systematic Zodlogy. Nothing, | |
indeed, can be more instructive to the student of Natural History, than a careful | iil
and minute comparison of the different editions of the “Systema Nature” of |
Linneus, and of the works of Cuvier and other prominent zodlogists, in order to
detect the methods by which real progress is made in our science.
Since the publication of the “Systema Nature” up to the time when Cuvier
published the results of his anatomical investigations, all the attempts at new classi- | i
fications were, after all, only modifications of the principles introduced by Linnzeus
4 in the systematic arrangement of animals. Even his opponents labored under the
influence of his master spirit, and a critical comparison of the various systems
which were proposed for the arrangement of single classes or of the whole animal
kingdom shows that they were framed according to the same principles, namely, Hy
under the impression that animals were to be arranged together into classes, orders, |
genera, and species, according to thew more or less close external resemblance.
No sooner, however, had Cuvier presented to the scientific world his extensive
researches into the internal structure of the whole animal kingdom, than naturalists
vied with one another in their attempts to remodel the whole classification of
animals, establishing new classes, new orders, new genera, describing new species,
and introducing all manner of intermediate divisions and subdivisions under the
name of families, tribes, sections, etc. Foremost in these attempts was Cuvier
himself, and next to him Lamarck. It has, however, often happened that the
divisions introduced by the latter under new names, were only translations into
a more systematic form of the results Cuvier had himself obtained from his dis-
A sections and pointed out in his “ Legons sur Yanatomie comparée,” as natural divisions,
but without giving them distinct names. Cuvier himself beautifully expresses the
1 It would be injustice to Aristotle not to mention Speaking, for instance, of the great genera or classes,
that he understood already the relations of the animals he separates correctly the Cephalopods from the
united in one class by Linnzus, under the name of other Mollusks, under the name of Malakia. Wist.
Worms, better than the great Swedish naturalist. Anim., Lib. I., Chap. VI.
Bi. lc ne:
192 ESSAY ON CLASSIFICATION. Parr IL.
influence which his anatomical investigations had upon Zovdlogy, and how the
improvements in classification have contributed to advance comparative anatomy,
when he says, in the preface to the “Régne Animal,” page vi.: “Je dus donc, et
cette obligation me prit un temps considérable, je dus faire marcher de front
Panatomie et la zoologie, les dissections et le classement; chercher dans mes pre-
miéres remarques sur lorganisation, des distributions meilleures; m’en servir pour
arriver & des remarques nouvelles; employer encore ces remarques 4 perfectionner
les distributions; faire sortir enfin de cette fécondation mutuelle des deux sciences
Pune par l'autre, un systéme zoologique propre & servir d’introducteur et de guide
dans le champ de l’anatomie, et un corps de doctrine anatomique propre A servir
de développement et d’explication au systéme zoologique.”
Without entering into a detailed account of all that was done in this period
towards improving the system of Zodlogy, it may suffice to say, that before the
first decade of this century had passed, more than twice as many classes as Linneeus
adopted had been characterized in this manner. These classes are: the Mollusks,
Cirripeds, Crustacea, Arachnids, Annelids, Entozoa, (Intestinal Worms,) Zoophytes,
Radiata, Polyps, and Infusoria. Cuvier’ admitted at first only eight classes, Duméril ?
nine, Lamarck? eleven and afterwards fourteen. The Cephalopoda, Gasteropoda, and
Acephala, first so named by Cuvier, are in the beginning considered by him as
orders only in the class of Mollusks; the Echinoderms also, though for the first
time circumscribed by him within their natural limits, constitute only an order of
the class of Zoophytes, not to speak of the lowest animals, which, from want of
knowledge of their internal structure, still remain in great confusion. In this rapid
sketch of the farther subdivisions which the classes Insecta and Worms of Linnzus
have undergone under the influence of Cuvier, I have not, of course, alluded to
the important contributions made to our knowledge of isolated classes, by special
writers, but limited my remarks to the works of those naturalists who have con-
sidered the subject upon the most extensive scale.
Thus far, no attempt had been made to combine the classes among themselves
into more comprehensive divisions, under a higher point of view, beyond that of
dividing the whole animal kingdom into Vertebrata and Invertebrata, a division
which corresponds to that of Aristotle, into oa fame and toa évamea. All efforts
were rather directed towards establishing a natural series, from the lowest Infusoria
up to Man; which, with many, soon became a favorite tendency, and ended by
being presented as a scientific doctrine by Blainville.
* Cuvier, (G.,) Tableau élémentaire de Histoire ® Lamarck, (J. B. pe,) Systeme des Animaux
naturelle des Animaux, Paris, 1798, 1 vol. 8vo. sans Vertebres ou Tableau général, etc., Paris, 1801,
* Dumenrtr, (A. M. C.,) Zoologie analytique, etc., 1 vol. 8vo.— Histoire naturelle des Animaux sans
Paris, 1806, 1 vol. 8vo. Vertebres, etc., Paris, 1815-1822, 7 vols. 8vo.
Se a a aaa actin
Cuap. III. PERIOD. OF CUVIER. 195
SECTION IV.
PERIOD OF CUVIER, AND ANATOMICAL SYSTEMS. ? Pi
The most important period in -the history of Zoblogy begins, however, with the
year 1812, when Cuvier laid before the Academy of Sciences in Paris the results
of his investigations upon the more intimate relations of certain classes of the
animal kingdom to one another,’ which had satisfied him that all animals are con- I |
structed upon four different plans, or, as it were, cast in four different moulds.
A more suggestive view of the subject never was presented before to the appre- |
ciation of investigators; and, though it has by no means as yet produced all the |
results which certainly are to flow from its further consideration, it has already led | x
to the most unquestionable improvements which classification in general has made
since the days of Aristotle, and, if I am not greatly mistaken, it is only in as
far as that fundamental principle has been adhered to that the changes proposed
in our systems, by later writers, have proved a real progress, and not as many retro-
grade steps.
This great principle, introduced into our science by Cuvier, is expressed by him
in these memorable words: “Si Yon considére le régne animal d’aprés les prin-
cipes que nous venons de poser, en se débarrassant des préjugés établis sur les
divisions anciennement admises, en n’ayant égard qu’a Yorganisation et 4 la nature
‘ ae
des animaux, et non pas 4 leur grandeur, a leur utilité, au plus ou moins de
autres circonstances accessoires, on
connaissance que nous en avons, ni a toutes les
trouvera qu’il existe quatre formes principales, quatre plans généraux, si l’on peut —
s’ exprimer ainsi, d’aprés lesquels tous les animaux semblent avoir été modelés et |
dont les divisions ultérieures, de quelque titre que les naturalistes les aient déco-
rées, ne sont que des modifications assez légéres fondées sur le développement ou
l’addition de quelques parties, qui ne changent rien 4 l’essence du plan.”
It is therefore incredible to me how, in presence of such explicit expressions,
Cuvier can be represented, as he is still occasionally, as favoring a division of |
the animal kingdom into Vertebrata and Invertebrata.* Cuvier, moreover, was the
first to recognize practically the inequality of all the divisions he adopts in his
system; and this constitutes further a great and important step, even though he
may not have found the correct measure for all his groups. For we must remem-
ber that at the time he wrote, naturalists were bent upon establishing one con- |
1 Ann. du Muséum d’Histoire Naturelle, vol. xix., * EHRENBERG, (C. G.,) Die Corallenthiere des
Paris, 1812. rothen Meeres, Berlin, 1834, 4to., p- 80, note.
25
a H
|
i
194 ESSAY ON CLASSIFICATION. : Part I.
tinual uniform series to embrace all animals, between the links of which it was
supposed there were no unequal intervals. The watchword of their school was:
Natura non fact saltum. They called their system da chaine des étres.
The views of Cuvier led him to the following arrangement of the animal
kingdom : —
CLASSIFICATION OF CUVIER.
First Branch. ANnimMALIA VERTEBRATA.
Cu.1. Mammalia. Orders: Bimana, Quadrumana, Carnivora, Marsupialia, Rodentia, Eden-
tata, Pachydermata, Ruminantia, Cetacea.
Ci.2. Birds. Ord. Accipitres, Passeres, Scansores, Gallinz, Gralle, Palmipedes.
Cu. 3. Reptilia. Ord. Chelonia, Sauria, Ophidia, Batrachia.
Cu. 4. Fishes. 1st Series: Fishes proper. Ord. Acanthopterygii;— Abdominales, Sub-
brachii, Apodes;— Lophobranchii, Plectognathi; 2d Series: Chondropterygii.
Ord. Sturiones, Selachii, Cyclostomi.?
Second Branch. Animati1a Mo.iusca.
Cu. 1. Cephalopoda. No subdivisions into orders or families.
Ci. 2. Pteropoda. No subdivisions into orders or families.
CL. 3. Gasteropoda. Ord. Pulmonata, Nudibranchia, Inferobranchia, Tectibranchia, Hetero-
poda, Pectinibranchia, Tubulibranchia, Scutibranchia, Cyclobranchia.
Ci. 4. Acephala. Ord. Testacea, Tunicata.
Cu. 5. Brachiopoda. No subdivisions into orders or families.
Ci. 6. Cirrhopoda. No subdivisions into orders or families.
Third Branch. AnimaLiA ARTICULATA.
Ci. 1. Annelides. Ord. Tubicole, Dorsibranchie, Abranchie. :
Ci. 2. Crustacea. Ist Section: Malacostraca. Ord. Decapoda, Stomapoda, Amphipoda,
Lamodipoda, Isopoda. - 2d Section: Entomostraca. Ord. Branchiopoda, Poecilopoda,
Trilobite.
Ci. 38. Arachnides. Ord. Pulmonarie, Trachearie.
Ci. 4. Insects. Ord. Myriapoda, Thysanura, Parasita, Suctoria, Coleoptera, Orthoptera,
Hemiptera, Neuroptera, Hymenoptera, Lepidoptera, Rhipiptera, Diptera.
Fourth Branch. AnNimaLiA RapIATA.
Cu. 1. Echinoderms. Ord. Pedicellata, Apoda.
Cu. 2. Intestinal Worms. Ord. Nematoidea, (incl. Epizoa and Entozoa,) Parenchymatosa.
Cui. 3. Acalephae. Ord. Simplices, Hydrostatic.
Cr. 4. Polypi. (Including Anthozoa, Hydroids, Bryozoa, Coralline, and Spongie.) Ord.
Carnosi, Gelatinosi, Polypiarii.
Cu. 5. Infusoria. Ord. Rotifera and Homogenea, (including Polygastrica and some Algz.)
1 Le Régne animal distribué d’aprés son organisation, Paris, gone, compare his Tableau élémentaire, q. a., p. 192, his paper,
1829, 2de édit. 5 vols. 8vyo. The classes of Crustacea, Arach- q. a., p. 193, and the first edition of the Regne animal, published
nids, and Insects have been elaborated by Latreille. For the in 1817, in 4 vols. 8vo.
successive modifications the classification of Cuvier has under- * Comp. Regn. Anim., 2de édit., 2d vol., p. 128 and 383.
ah
ing one from the other, and of such genera he speaks as “ grands genres;
Cuap. III. PERIOD OF CUVIER.
When we consider the zodlogical systems of the past century, that of Lin-
nus, for instance, and compare them with more recent ones, that of Cuvier, for
example, we cannot overlook the fact, that even when discoveries have added little
to our knowledge, the subject is treated in a different manner; not merely in
consequence of the more extensive information respecting the internal structure of
animals, but also respecting the gradation of the higher groups.
Linneus had no divisions of a higher:order than classes. Cuvier introduced,
for the first time, four great divisions, which he called “embranchemens” or branches,
under which he arranged his classes, of which he admitted three times as many as
Linnzeus had done.
Again, Linneus divides his classes into orders; next, he introduces genera, and
finally, species; and this he does systematically in the same gradation through all
classes, so that each of his six classes is subdivided into orders, and these into
genera with their species. Of families, as now understood, Linneus knows nothing.
The classification of Cuvier presents no such regularity im its framework. In
some classes he proceeds, immediately after presenting their characteristics, to the
enumeration of the genera they contain, without grouping them either into orders
or families. In other classes, he admits orders under the head of the class, and
then proceeds to the characteristics of the genera, while in others still, he admits
under the class not only orders and families, placing always the family in a sub-
ordinate position to the order, but also a number of secondary divisions which
he calls sections, divisions, tribes, etc., before he reaches the genera and _ species,
With reference to the genera again, we find marked discrepancies in different
classes. Sometimes a genus is to him an extensive group of species, widely differ-
” others
are limited in their extent, and contain homogeneous species without farther sub-
divisions, while still others are subdivided into what he calls sub-genera, and _ this
is usually the case with his “great genera.”
The gradation of divisions with Cuvier varies then with his classes, some classes
containing only genera and species, and neither orders nor families nor any other
subdivision. Others contain orders, families, and genera, and besides these, a variety |
of subdivisions: of the most diversified extent and significance. This remarkable |
inequality between all the divisions of Cuvier is, no doubt, partly owing to the
state of Zodlogy and of zodlogical museums at the time he wrote, and to his
determination to admit into his work only such representatives of the animal
kingdom ‘as he could to a greater or less extent examine anatomically for him-
self; but it is also partly to be ascribed to his conviction, often expressed, that
there is no such uniformity or regular serial gradation among animals as many |
naturalists attempted to introduce into their classifications,
195°
ESSAY ON CLASSIFICATION.
CLASSIFICATION OF LAMARCK.
Histoire naturelle des Animaux sans vertebres, etc., Paris, 1815-1822, 7 vols. 8vo. — A second edition with notes has been pub-
lished by Messrs. DesHayes and Milne-Edwards, Paris, 1835-1843, 10 vols. 8vo.— For the successive modifications this classi-
fication has undergone, see also: Systeme des animaux sans vertebres, etc., Paris, 1801, 8vo. — Philosophie zoologique, etc., Paris,
1809, 2 vols. 8vo. — Extrait du Cours de Zoologie du Muséum d’Histoire naturelle, etc., Paris, 1812, 8vo.
INVERTEBRATA.
I. Apatuetic ANIMALS.
Cu. 1. Infusoria. Ord. Nuda, Appendiculata.
Ci. 2. Polypi. Ord. Ciliati (Rotifera), Denudati (Hydroids),
stiles Do not feel, and move
Vaginati (Anthozoa and Bryozoa), and Natantes (Crinoids, ;
ly by thei ited irri-
and some Halcyonoids.) Re eee
Cu. 38. Radiaria. Ord. Mollia (Acalephe), Echinoderms, (includ-
ing Holothurize and Actiniz.)
Cu. 4. Tunicata. Ord. Bothryllaria (Compound Ascidians),
Ascidia, (Simple Ascidians.)
Ci. 5. Vermes. Ord. Molles and Rigiduli (Intestinal Worms and
Gordius), Hispiduli (Nais), Epizoarize (Epizoa, Lerneans.) ;
tability. No brain, nor
elongated medullary mass ;
no senses; forms varied ;
rarely articulations.
II. Sensitive ANIMALS.
Ci. 6. Insects. (Hexapods.) Ord. Aptera, Diptera, Hemiptera, hse: ER es
their sensations only per-
Lepidoptera, Hymenoptera, Nevroptera, Orthoptera, Cole-
Bes HAPS ares ais fhe ets ceptions of objects, a sort
optera. ; . ;
of simple ideas, which the
.7. Arachnids. Ord. Antennato-tracheales (Thysanura and - ner : y
are unable to combine to
Myriapoda), Exantennato-tracheales and Exantennato-bran- :
‘ees ween obtain complex ones. No
asa gieds 7 ; vertebral column; a brain
.8. Crustacea. Ord. Heterobranchia (Branchipoda, Isopoda,
: and mostly an elongated
Amphipoda, Stomapoda) and Homobranchia (Decapoda.)
.9. Annelids. Ord. Apoda, Antennata, Sedentaria.
.10. Cirripeds. Ord. Sessilia and Pedunculata.
.11. Conchifera. Ord. Dimyaria, Monomyaria.
Cy. 12. Mollusks. Ord. Pteropoda, Gasteropoda, Trachelipoda,
medullary mass; some dis-
tinct senses; muscles at-
tached under the skin;
form symmetrical, the parts
being in pairs.
Cephalopoda, Heteropoda. J
VERTEBRATA. :
TI. Inrevyicenr ANIMALS. Feel; acquire preservable ideas; perform with them oper-
CL. 1 3. Fishes. ations by which they obtain others; are intelligent in different
Ci. 14. Reptiles. |
Cu. 15. Birds. distinct senses; the muscles attached to the internal skeleton ; .
Cu. 16. Mammalia. | form symmetrical, the parts being in pairs.
degrees. A vertebral column; a brain and a spinal marrow ;
It is not easy to appreciate correctly the system of Lamarck, as it combines
abstract conceptions with structural considerations, and an artificial endeavor to
arrange all animals in continuous series. The primary subdivision of the animal
kingdom into Invertebrata and Vertebrata?! corresponds, as I have stated above, to
* See, above, Chap. 2, Sect. 1, p. 138.
: — Hanan raineteoniatetnsai oe atte aha ONAGARA e<iEiiNennetNe ee
eS MTA ESE a ees iat ete ae Se a Senineetanadiairaiaemaiianmenseneriette caeammenmenetiediemeeaste
Ss!
Cuap. III. PERIOD OF CUVIER. . 197
that of Anaima and Enaima of Aristotle. The three leading groups designated | |
under the name of Apathetic, Sensitive, and Intelligent animals, are an imitation
of the four branches of Cuvier; but, far from resting upon such a definite idea
“ as the divisions of Cuvier, which involve a special plan of structure, they ‘are
founded upon the assumption that the psychical faculties of animals present a serial
gradation, which, when applied as a principle of classification, is certainly not admis- © | | |
sible. To say that neither Infusoria, nor Polypi, nor Radiata, nor Tunicata, nor 2 i
Worms feel, is certainly a very erroneous assertion. ‘They manifest sensations quite J |
as distinctly as many of the animals included in the second type which are called
Sensitive. And as to the other assertion, that they move only by their excited Al
irritability, we need only watch the Starfishes to be satisfied that their motions Hl
are determined by internal impulses and not by external excitation. Modern inves- Hl
tigations have shown that most of them have a nervous system, and many even
organs of senses.
The Sensitive animals are distinguished from the third type, the Intelligent
animals, by the character of their sensations. It is stated, in respect to the Sensi-
tive animals, that they obtain from their sensations only perceptions of objects, a
sort of simple ideas which they are unable to combine so as to derive from
ef them complex ones, while the Intelligent animals are said to obtain ideas which
: they may preserve, and to perform with them operations by which they arrive
at new ideas. ‘They are said to be Intelligent. Even now, fifty years after
Lamarck made those assertions, I doubt whether it 1s possible to distinguish in | | |
that way between the sensations of the Fishes, for imstance, and those of the
Cephalopods. It is true, the structure of the animals called Sensitive and Intelli-
gent by Lamarck differs greatly, but a large number of his Sensitive animals are
constructed upon the same plan as many of those he includes among the Apathetic;
they embrace, moreover, two different plans of structure, and animal psychology
is certainly not so far advanced as to afford the least foundation for the distinc-
tions here introduced. ;
~ Even from his own point of view, his arrangement of the classes is less perfect
than he might have made it, as the Annelids stand nearer to the Worms than
the Insects, and are very inferior to them. Having failed to perceive the value
- of the idea of plan, and having substituted for it that of a more or less com-
¢ plicated structure, Lamarck unites among his Apathetic animals, Radiates (the Polypi
and Radiaria) with Mollusks, (the Tunicata,) and with Articulates (the Worms.) :
Among the Sensitive animals, he unites Articulates (the Insects, Arachnids, Crus- !
tacea, Annelids, and Cirripeds) with Mollusks (the Conchifera, and the Mollusks
proper.) Among the Intelligent animals, he includes the ancient four classes of | |
Vertebrates, the Fishes, Reptiles, Birds, and Mammalia.
ESSAY ON CLASSIFICATION.
CLASSIFICATION OF DE BLAINVILLE.!
1. Sub-Kingdom. Artiomorpha or Artiozoaria. Form bilateral.
First Type: Osrzozoarta. (Vertebrata.)
Sub-Type: Vivipara. hae
Ci. 1. Pilifera, or Mammifera, 1st. Monadelphya. 2d. Didelphya.
Sub-Type: Ovipara.
Cu. 2. Pennifera, or Aves.
Ci. 38. Squamifera, or Reptilia.
Cu. 4. Nudipellifera, or Amphibia.
Cu. 5. Pinnifera, or Pisces.
Anosteozoaria.
Second Type: Entomozoarta. (Articulata.)
Cui. 6. Hexapoda. (Insecta proprie sic dicta.)
.7. Octopoda. (Arachnida.)
.8. Decapoda. (Crustacea, Decapoda, and Limulus.)
.9 Heteropoda. (Squilla, Entomostraca, and Epizoa.)
-10. Tetradecapoda. (Amphipoda and Isopoda.)
-11. Myriapoda.
.12. Chetopoda. (Annelides.)
.13. Apoda. (Hirudo, Cestoidea, Ascaris.)
Third Type: MaLenrozoarra.
Cit. 14. Nematopoda. (Cirripedia.)
Ci.15. Polyplaxiphora. (Chiton.)
Fourth Type: Mazracozoarta. (Mollusca.)
Cr. 16. Cephalophora. Dioica, (Cephalopoda and Gasteropoda, p. p.) Herma-
phrodita and Monoica (Gasteropoda reliqua.)
Cu.17. Acephalophora. Palliobranchia (Brachiopoda), Lamellibranchia (Acephala),
Heterobranchia (Ascidiz.) ;
2. Sub-Kingdom. Actinomorpha or Actinozoaria. Form radiate.
Ci. 18. Annelidaria, or Gastrophysaria (Sipunculus, etc.)
Ci. 19. Ceratodermaria. (Kchinodermata.)
Cr. 20. Arachnodermaria. (Acalephe.)
Cu. 21. Zoantharia. (Actiniz.)
Ci. 22. Polypiaria. (Polypi tentaculis simplicibus), (Anthozoa and Bryozoa.)
Cu. 23. Zoophytaria. (Polypi tentaculis compositis), (Halcyonoidea.)
3. Sub-Kingdom. Heteromorpha or Heterozoaria. Form irregular.
Cr. 24. Spongiaria. (Spongie.)
Cu. 25. Monadaria. (Infusoria.)
Ci. 26. Dendrolitharia. (Coralline.)
The classification of de Blainville resembles those of Lamarck and Cuvier much
more than a diagram of the three would lead us to suppose. The first of these
systems is founded upon the idea that the animal kingdom forms one gradated
1 De VOrganisation des Animaux, Paris, 1822, 1 vol. 8vo.
— — nn ene eet ea ne enemas tt le eR ENENNAatt EitDem ZARB aM I ne mee a Aa 5 - .
sn amr aN RN NE OIE LET OE LG EAT cS CS at. alin OD i ay engsat Seal = . em = — — — mn
~ onan aia ascot ms nena teers aineediaemaendl = a a chats eset . = —— oe Peewee ao = SP ee P 2 a eon am,
PERIOD OF CUVIER.
Cuap. III. 199
series; only that de Blainville inverts the order of Lamarck, beginning with the — | |
highest animals and ending with the lowest. With that idea is blended, to some
extent, the view of Cuvier, that animals are framed upon different plans of structure ; |
f but so imperfectly has this view taken hold of de Blainville, that instead of — | | |
recognizing at the outset these great plans, he allows the external form to be i
the leading idea upon which his primary divisions are founded, and thus he divides i
the animal kingdom into three sub-kingdoms: the first, mcluding his Artiozoaria, | |
|
|
with a bilateral form; the second, his Actinozoaria, with a radiated form, and the
third, his Heterozoaria, with an irregular form (the Sponges, Infusoria, and Corallines.)
The plan of structure is only introduced as a secondary consideration, upon which he
establishes four types among the Artiozoaria: Ist. The Osteozoaria, corresponding to I
Cuvier’s Vertebrata; 2d. The Entomozoaria, corresponding to Cuvier’s Articulata ; —
3d. The Malentozoaria, which are a very artificial group, suggested only by the
necessity of establishing a transition between the Articulata and Mollusca; 4th.
The Malacozoaria, corresponding to Cuvier’s Mollusca. The second sub-kingdom,
Actinozoaria, corresponds to Cuvier’s Radiata, while the third sub-kingdom, Hetero-
goaria, contains organized beings which for the most part do not belong to the
animal kingdom. Such at least are his Spongiaria and Dendrolitharia, whilst his
ef Monodaria answer to the old class of Infusoria, about which enough has already
been said above. It is evident, that what is correct in this general arrangement
is borrowed from Cuvier; but it is only justice to de Blainville to say, that in the
limitation and arrangement of the classes, he has introduced some valuable improve-
ments. Among Vertebrata, for instance, he has, for the first time, distinguished
the class of Amphibia from the true Reptiles. He was also the first to remove
the Intestinal Worms from among the Radiata to the Articulata; but the establish-
ment of a distinct type for the Cirripedia and Chitons was a very mistaken con- |
ception. Notwithstanding some structural peculiarities, the Chitons are built essen- ne
tially upon the same plan as the Mollusks of the class Gasteropoda, and the | 14
investigations, made not long after the publication of de Blainville’s system, have left 13
no doubt that Cirripedia are genuine Crustacea. The supposed transition between iE
Articulata and Mollusks, which de Blainville attempted to establish with his type of
Malentozoaria, certainly does not exist in nature.
If we apply to the classes of de Blainville the test introduced in the preceding
: chapter, it will be obvious that his Decapoda, Heteropoda, and Tetradecapoda par-
take more of the character of orders than of that of classes, whilst among Mol-
lusks, his class Cephalophora certainly includes two classes, as he has. himself acknowl-
edged in his later works. Among Radiata his classes Zoantharia, Polypiaria, and
Zoophytaria partake again of the character of orders and not of those of classes.
One great objection to the system of de Blainville is, the useless introduction of so
————
- 200 ESSAY ON CLASSIFICATION. Parr I.
many new names for groups Sdutols had already been correctly limited and well
named by his predecessors. He had, no doubt, a desirable object im view in doing
this, — he wished to remove some incorrect names; but he extended his reform
too far when he undertook to change those also which did not suit his system.
CLASSIFICATION OF EHRENBERG.
The characteristics of the following twenty-eight classes of animals, with a twenty-ninth for Man alone,
are given more fully in the Transactions of the Academy of Berlin for 1836, in the paper q. a., p. 138.
lst Cycle: Nations. Mankind, constituting one distinct class, is characterized by the equable development of
all systems of organs, in contradistinction of the
2d Cycle: Animas, which are considered as characterized by the prominence of single systems. These are
divided into:
A. Myeloneura.
I. Nurrrentira. Warm-blooded Vertebrata, taking II. OrrHanozoa. Cold-blooded Vertebrata, taking
care of their young. no care of their young.
Cit.1. Mammalia. Cl. 3. Amphibia.
Ci. 2. Birds. ; Cl. 4. Pisces.
B. Ganglioneura.
A, Sphygmozoa, Cordata. B. Asphycta, Vasculosa.
Circulation marked by a heart or pulsating vessels. Vessels without pulsation.
III. Artrcurata. Real articulation, marked by V. Tusurata. No real articulation. Intestine, a
rows of ganglia and their ramifications. simple sac or tube.
Ci. 5. Insecta. . -17. Bryozoa.
Ci. 6. Arachnoidea. . 18. Dimorphea. (Hydroids.)
Ci. 7. Crustacea (including Entomostraca, -19. Turbellaria. (Rhabdocela: De-
Cirripedia, and Lernza.) rostoma, Turbella, Vortex.)
Ci. 8 Annulata. (The genuine Annelids -20. Nematoidea. (Entozoa, with sim-
dectuaih io? Naty) ple intestine ; also Gordius and Anguillula.)
(Naidina.) .21. Rotatoria.
- 22. Echinoidea. (Echinus, Holothuria,
Sipunculus.)
Ci. 9. Somatotoma.
Mouuvusca. No articulation. Ganglia dis-
persed.
4,10) Cephalopoda. - Racemirera. Intestine divided, or forked, ra-
Beli, Picsonada. 7 diating, dendritic, or racemose.
Cree Gar aro pols. CL. 23. Asteroidea.
Ci 15: Aes phata: Ci. 24. Acalephae.
Cu. 14. Brachiopoda. Cr. 25. Anthozoa.
Ci. 15. Tunicata. (Ascidie simplices.) Cu. 26. Trematodea. (Entozoa with rami-
Cr. 16. Aggregata. (Ascidia composite.) fied intestine, also Cercaria.)
Ci. 27. Complanata. (Dendrocela: Pla-
naria, etc.)
Ci. 28. Polygastrica.
— se een ee em enenen
eee antec ann aetna ined et AO EE weet — “ - ‘ i
2 ee Ae a INL EL it AR ce ET et a SD a iy aR RO ETON a ORR Ai — eNO OUR Sai i OR Og le Lait ene
®
Cuap. ‘IIL. ANATOMICAL SYSTEMS. 901 Vi
The system of Zodlogy, published by Ehrenberg in 1836, presents many new | |
views in almost all its peculiarities. The most striking of its features is the prin- i
ciple laid down, that the type of development of animals is one and the same
A from Man to the Monad, implying a complete negation of the principle advocated
by Cuvier, that the four primary divisions of the animal kingdom are characterized
by different plans of structure. It is very natural that Ehrenberg, after having
illustrated so fully and so beautifully as he did, the natural history of so many 3 |
organized beings, which up to the publication of his investigations were generally
considered as entirely homogeneous, after having shown how highly organized and
complicated the internal structure of many of them is, after having proved the
fallacy of the prevailing opinions respecting their origm, should have been led to
the conviction that there is, after all, no essential difference between these animals,
which were then regarded as the lowest, and those which were placed at the
head of the animal creation. The investigator, who had just revealed to the
astonished scientific world the complicated systems of organs which can be traced
in the body of microscopically small Rotifera, must have been led irresistibly to the |
conclusion that all animals are equally perfect, and have assumed, as a natural con-
sequence of the evidence he had obtained, that they stand on the same level with one
ef another, as far as the complication of their structure is concerned. Yet the diagram
of his own system shows, that he himself could not resist the internal evidence of
their unequal structural endowment. Like all other naturalists, he places Mankind
at one end of the animal kingdom, and such types as have always been considered
as low, at the other end.
Man constitutes, in his opinion, an independent cycle, that of nations, in contra-
distinction to the cycle of animals, which he divides into Mygnonzura, those with ner-
vous marrow (the Vertebrata,) and Ganationzura, those with ganglia (the Invertebrata.)
The Vertebrata he subdivides into udrientia, those which take care of their young,
and Orphanozoa, those which take no care of their young, though this is not strictly. |
true, as there are many Fishes and Reptiles which provide as carefully for their 17
young as some of the Birds and Mammalia, though they do it in another way.
The Invertebrata are subdivided into Sphygmozoa, those which have a heart or
pulsating vessels, and Asphycta, those in which the vessels do not pulsate. These
two sections are further subdivided: the first, into Articulata with real articulations
} and rows of ganglia, and Mollusks without articulation and with dispersed ganglia ; : |
the second, into Tubulata with a simple intestine, and Racemifera with a branching
intestine. These characters, which Ehrenberg assigns to his leading divisions, imply
necessarily the admission of a gradation among animals. He thus negatives, in
the form in which he expresses the results of his, mvestigations, the very principle
he intends to illustrate by his diagram. The peculiar view of Ehrenberg, that |
26
rr ar a
202 ESSAY ON CLASSIFICATION. Part I.
all animals are equal in the perfection of their organization, might be justified, if
it was qualified so as to imply a relative perfection, adapted in ‘all to the end
of their special mode of existence. As no one observer has contributed more
extensively than Ehrenberg to make known the complicated structure of a_ host
of living beings, which before him were almost universally believed to consist of
a simple mass of homogeneous jelly, such a view would naturally be expected
of him. But this qualified perfection is not what he means. He does not wish
to convey the idea that all animals are equally perfect in their way, for he states
distinctly that “Infusoria have the same sum of systems of organs as Man,” and
the whole of his system is intended to impress emphatically this view. The separa-
tion of Man from the animals, not merely as a class but as a still higher division,
is especially maintained upon that ground.
The principle of classification adopted by Ehrenberg is purely anatomical; the idea
of type is entirely set aside, as is shown by the respective position of his classes.
The Myeloneura, it is true, correspond to the branch of Vertebrata, and the
Sphygmozoa to the Articulata and Mollusca; but they are not brought together
on the ground of the typical plan of their structure, but because the first have
a spinal marrow and the other a heart or pulsating vessels with or without articula-
tions of the body.» In the division of Tubulata, it is still more evident how the
plan of their structure is disregarded, as that section embraces Radiata, (the
Echinoidea and the Dimorpheza,) Mollusca, (the Bryozoa,) and Articulata, (the
Turbellaria, the Nematoidea, and the Rotatoria,) which are thus combined simply
on the ground that they have vessels which do not pulsate, and that their intestine
is a ‘simple sac or tube. The Racemifera contain also animals constructed upon
different plans, united on account of the peculiar structure of the intestine, which
is either forked or radiating, dendritic or racemose.
The limitation of many of the classes proposed by Ehrenberg is quite objec-
tionable, when tested by the principles discussed above. A large proportion of them
are, indeed, founded upon ordinal characters only, and not upon class characters.
This is particularly evident with the Rotatoria, the Somatotoma, the Turbellaria, the
Nematoidea, the Trematodea, and the Complanata, all of which belong to the branch
of Articulata. The Tunicata, the Aggregata, the Brachiopoda, and the Bryozoa are
also only orders of the class Acephala. Before Echinoderms had been so exten-
sively studied as of late, the separation of the Echinoidea from Asteroidea might
have seemed justifiable; at the present day, it is totally inadmissible. Even
Leuckart, who considers the Echinoderms as a distinct branch of the animal king-
dom, insists upon the necessity of uniting them as a natural group. As to the
Dimorphea, they constitute a natural order of the class Acalephe, which is generally
known by the name of Hydroids. 3
—— — -—. an A eet am RN itn nadNN ee ne mate aetna -
va aa EY EE A ON AS ENLIST cE NEE cE am Sf ES A EER COLO LER CORE ~—s rR Z : - -
ANATOMICAL SYSTEMS.
Cup? “TIT.
CLASSIFICATION OF BURMEISTER.
The following diagram is compiled from the author’s Geschichte der Schépfung rates 1843, 1 vol. 8vo
> 4 9 ° e
‘4 Type I. IrreGuiar ANIMALS.
1st Subtype. Cu. 1. Infusoria.
Type II. Reeurar ANIMALS.
2d Subtype. Cr. 2. Polypina. Ord. Bryozoa, Anthozoa.
3d Subtype. Cx. 8. Radiata. Ord. Acalephw, Echinodermata, Scytodermata.
Type II. Symmerrricat ANIMALS.
4th Subtype. Cr. 4. Mollusca. Ord. Perigymna (Tunicata); Cormopoda (Acephala); Brachio-
poda, Cephalophora (Pteropoda and Gasteropoda) ; Cephalopoda.
5th Subtype. Arthrozoa.
Cu. 5. Vermes. Ord. Helminthes, Trematodes, and Annulati.
Cu. 6. Crustacea. 1° Ostracoderma. Ord. Prothesmia (Cirripedia, Siphono-
stoma, and Rotatoria); Aspidostraca (Entomostraca : Lophyropoda, Phyllopoda,
Pecilopoda, Trilobite.) 2°. Malacostraca. Ord. Thoracostraca (Podoph-
thalma); and Arthrostraca, (Edriophthalma.)
Cu. 7. Arachnoda. Ord. Myriapoda, Arachnide.
Cu. 8. Insecta. Ord. Rhynchota, Synistata, Antliata, Piezata, Glossata, Wiriksrata.
~
6th Subtype. Osteozoa. (Vertebrata.)
CE. 9. Pisees.
" Cr. 10. A m'p hibia.
Ci. ii: Aves:
Ci. 12. Mammalia.
The general arrangement of the classification of Burmeister recalls that of
de Blainville; only that the order is inverted. His three types correspond to the
three subkingdoms of de Blainville: the Irregular Animals to the Heterozoaria, the
Regular Animals to the Actinozoaria, and the Symmetrical Animals to the Artiozo-
aria; while his subtypes of the Symmetrical Animals correspond to the types de
Blainville admits among his Artiozoaria, with this important improvement, however,
that the Malentozoaria are suppressed. Burmeister reduces, unhappily, the whole
branch of Mollusks to one single class) The Arthrozoa, on the contrary, in the
investigation of which Burmeister has rendered eminent service to science, are pre-
sented in their true light. In his special works,’ his classification of the Articulata
is presented with more details. I have no doubt that the correct views he entertains
7 respecting the standing of the Worms in the branch of Articulata are owing to his inP
extensive acquaintance with the Crustacea and Insects, and their metamorphoses. |
1 These works are: Beitriige zur Naturgeschichte 1836. — Die Organisation der Trilobiten, aus ihren | ;
der Rankenfiisser, (Cirripedia,) Berlin, 1834, 1 vol. lebenden Verwandten entwickelt, Berlin, 1843, 1 vol. | |
4to.- Handbuch der Entomologie, Berlin, 1832-47, 4to.; Engl. by the Ray Society, London, 1847, | |
5. vols.. 8vo.; Engl. by W. E. Shuckard, London, 1 vol. fol.
ESSAY ON CLASSIFICATION.
CLASSIFICATION OF OWEN.
The following diagram is compiled from R. Owen’s Lectures on the Comparative Anatomy and
Physiology of the Invertebrate Animals, 2d edit., London, 1855, 1 vol. 8vo.
Province. VERTEBRATA. Myelencephala. (Owen.)
Mammalia. .
A The classes Mammalia, Aves, and Reptilia are not yet included in the second volume
Ves.
: of the “Lectures,” the only one relating to Vertebrata thus far published.
Reptilia.
Pisces. Ord. Dermopteri, Malacopteri, Pharyngognathi, Anacanthini, Acanthopteri, Plectognathi,
Lophobranchii, Ganoidei, Protopteri, Holocephali, Plagiostomi.
Province. ArticuLaTa. Homogangliata. (Owen.) j
Cu. Arachnida. Ord. Dermophysa, Trachearia, Pulmotrachearia, and Pulmonaria.
Cyr. Insecta. Subclass: Myriapoda. Ord. Chilognatha and Chilopoda. Subclass: Hexapoda.
Ord. Aptera, Diptera, Lepidoptera, Hymenoptera, Homoptera, Strepsiptera, Nevroptera, Orthop-
_tera, and Coleoptera.
Crustacea. Subclass: Entomostraca. Ord. Trilobites, Xiphosura, Phyllopoda, Cladocera,
Ostracopoda, Copepoda. Subclass: Malacostraca. 1°. Edriophthalma. Ord. Lemodipoda,
Isopoda, Amphipoda. 2°. Podophthalma. Ord. Stomapoda, Decapoda.
Epizoa. Ord. Cephaluna,. Brachiuna, and Onchuna.
Annellata. Ord. Suctoria, Terricola, Errantia, Tubicola.
Cirripedia. Ord. Thoracica, Abdominalia, and Apoda.
Province. Moriusca. Heterogangliata. (Owen.)
Ct. Cephalopoda. Ord. Tetrabranchiata and Dibranchiata.
Cr. Gasteropoda. A. Monecia: Ord. Apneusta (K6ll.), Nudibranchiata, Inferobranchiata,
Tectibranchiata, Pulmonata. B. Diccia. Ord. Nucleobranchiata, Tubulibranchiata, Cyclo-
branchiata, Scutibranchiata, and Pectinibranchiata.
Pteropoda. Ord. Thecosomata and Gymnosomata.
Lamellibranchiata. Ord. Monomyaria and Dimyaria.
Brachiopoda. Only subdivided into families.
Tunicata. Ord. Saccobranchiata and Tniobranchiata.
Subprovince. Rapraria.}
Echinodermata. Ord. Crinoidea, Asteroidea, Echinoidea, Holothurioidea, and Sipunculoidea.
Bryozoa. Only subdivided into families.
Anthozoa. Only subdivided into families.
Acalephae. Ord. Pulmograda, Ciliograda, and Physograda.
Hydrozoa. Only subdivided into families.
Subprovince. Enrozoa.
Cr. Celelmintha. Ord. Gordiacea, Nematoidea, and Onchophora.
Ci. Sterelmintha. Ord. Tenioidea, Trematoda, Acanthocephala. — Turbellaria.
Subprovince. Inrusortia.
Ci. Rotifera. Only subdivided into families.
Cyt. Polygastria. Ord. Astoma, Stomatoda, — Rhizopoda.
1 In the first edition of the work quoted above, published
contradistinction of the subkingdoms, Mollusca, Articulata,
in 1843, the three subprovinces, Radiaria, Entozoa, and Infu-
and Vertebrata, and that subkingdom is subdivided into two
soria are considered as one subkingdom called Radiata, in groups, Nematoneura and Acrita.
em +s
—— cite an a ne te nA ie lin a nS OS — eats : sats
EE RUE NS Tt RS Te ee th a RE A TR ODOT LORE EEO COC wae OU git et is nial aati egy eantis mates
Y
ANATOMICAL SYSTEMS.
—Cnap. III. 205
The classification with which Owen! introduces his “Lectures on Comparative ;
Anatomy” is very instructive, as showing, more distinctly than other modern systems, |
the unfortunate ascendency which the consideration of the complication of structure
“4 has gained of late over the idea of plan. His provinces, it is true, correspond
in the main to the branches of Cuvier, with this marked difference, however, that
he does not recognize a distinct province of Radiata coequal with those of Mollusca,
Articulata, and Vertebrata, but only admits Radiaria as a subprovince on a level
with Entozoa and Infusoria. Here, the idea of simplicity of structure evidently |
prevails over that of plan, as the subprovinces Radiaria, Entozoa, and Infusoria
embrace, besides true Radiata, the lowest types of two other branches, Mollusks |
. and Articulates. On the other hand, his three subprovinces correspond to the
first three types of von Siebold; the Infusoria* of Owen embracing the same ~
animals as the Protozoa of Siebold, his Entozoa* the same as the Vermes, and his
Radiaria the same as the Zoophyta, with the single exception that Owen refers
the Annellata to the province of Articulata, whilst Siebold includes them among
his Vermes.. Beyond this the types of Mollusca and Articulata (Arthropoda) of
the two distinguished anatomists entirely agree. The position assigned by Owen
to the provinces Articulata and Mollusca, not one above the other, but side by
ce side with one another, is no doubt meant to express his conviction, that the com-
plication of structure of these two types does not justify the idea that either
of them stands higher or lower than the other; and this is perfectly correct.
Several groups, established by previous writers as families or orders, are here es |
admitted as classes. His class Epizoa, which is not to be confounded with that
established by Nitzsch under the same name, corresponds exactly to the family |
called Lernizs by Cuvier. His class Hyprozoa answers to the order Hyprowa of |
Johnston, and is identical with the class called DimorpH#a by Ehrenberg. His
class Ca@LetminrHa corresponds to the order of Inrestinavx Cavrrarres established
+ I have given precedence to the classification
of Owen over those of von Siebold and Stannius,
Milne-Edwards, Leuckart, ete., because the first edi-
tion of the “Lectures on Comparative Anatomy”
was published in 1843 ; but in estimating its features,
as expressed in the preceding diagram, it should be
borne in mind that, in the first edition, the classes
alone are considered, and that the orders and families
were only added to the second edition in 1855. I
mention this simply to prevent the possibility of
being understood as ascribing to Owen all those sub-
divisions of the classes, which he admits, and which
do not appear in the systems considered before his.
2 The Rhizopoda are considered as g group
coequal to Rotifera and Polygastria, on p. 16 of
‘the “Lectures,” but on p. 59, they stand as a sub-
order of Polygastria.
an inde-
pendent group, on p. 16, and referred as a suborder
to the Trematoda, on p. 118.
® The Turbellaria are represented ag
* From want of room, I have been compelled,
in reproducing the classification of Owen in the
preceding diagram, to place his provinces Articulata
and Mollusca one below the other upon my page;
according to his views, they should stand on a level,
side by side with one another.
206 ESSAY ON CLASSIFICATION. Part I
by Cuvier, with the addition of Gordius; while his class Sreretamra has the
same circumscription as the order Inrystmvaux Parencuymateux of Cuvier. Generally
speaking, it. should not be understood that the secondary divisions mentioned by the
different authors, whose systems I have analyzed here, were established by them.
They are frequently borrowed from the results obtained by special investigators of
isolated classes. . But it would lead me too far, to enter here into a discussion
of all these details. |
This growing resemblance of the modern systems of Zodlogy is a very favorable
sign of our times. It would, indeed, be a great mistake to assume, that it is solely
owing to the influence of different authors upon one another; it is, on the con-
trary, to a very great extent, the result of our better acquaintance with Nature.
When investigators, at all conversant with the present state of our science, must
possess nearly the same amount of knowledge, it is selfevident that their views
can no longer differ so widely as they did when each was familiar only with
a part of the subject. A deeper insight into the animal kingdom must, in the
end, lead to the conviction that it is not the task of zodlogists to introduce order
among animals, but that their highest aim should be simply to read the. natural
affinities which exist among them, so that the more nearly our knowledge embraces
the whole field of investigation, the more closely will our opinions coincide.
As to the value of the classes adopted by Owen, I may further remark that
recent investigations, of which he might have availed himself, have shown that the
Cirripedia and his Epizoa are genuine Crustacea, and that the Entozoa can no
longer be so widely separated from the Annellata as in his system. With reference
to the other classes, I refer the reader to my criticism of older systems, and to
the first. section of this Chapter.
It is a great satisfaction for me to find that the views I have advocated in
the preceding sections, respecting the natural relations of the leading groups of
the animal kingdom, coincide so closely with the classification of that distinguished
zoblogist, Milne-Edwards, lately presented by him as the expression of his present
views of the natural affinities of animals. He is the only original investigator
who has recently given his unqualified approbation to the primary divisions first
proposed by Cuvier, admitting, of course, the rectifications among the group of
secondary rank, rendered necessary by the progress of science, to which he has
himself so largely contributed.
As to the classes adopted by Milne-Edwards, I have little to add to what I
have already stated before, with reference to other classifications. Though no
longer overruling the idea of plan, that of complication of structure has still too.
much influence with Milne-Edwards, inasmuch as it leads him to consider as classes,
groups of animals which differ only in degree, and are therefore only orders.
RSL ERRKE tad Saar eL ees EL —— 2 enema ca
w= en a Sea NSA AER NE HO serene a
ee ee Oe a i a SE ca Styne i enibangeaiateiaiilianatia tenant eatiemamanece eerenasiny sagunend acetal ue os Faint ~ hee gore =
Cuap. IIL. _ ANATOMICAL SYSTEMS. 207 |
Such are, no doubt, his classes of Molluscoids and those of Worms, besides the |
Myriapods and Arachnids. Respecting the Fishes, I refer to my remarks in the
first section (p. 187) of this Chapter.
CLASSIFICATION OF MILNE-EDWARDS. |
The following diagram is drawn from the author’s Cours élémentaire d’ Histoire naturelle, Paris, 1855
y
1 vol. 12mo., 7th edit., in which he has presented the results of his latest investigations upon the classifica-
tion of the Vertebrata and Articulata; the minor subdivisions of the Worms, Mollusks, and Zoophytes,
however, are not considered in this work.’
I. OstTEozoOARIA, or VERTEBRATA.
Subbranch. Allantoidians. Subbranchh Anallantoidians.
Cyr. Mammalia. 1°. Monodelphya. a. Propria. Ord. Bimana, Cr. Batrachians. Ord. Anura,
Quadrumana, Cheiroptera, Insectivora, Rodentia, Edentata, Carni- Urodela, Perennibranchia, Czciliz.
vora, Amphibia, Pachydermata, Ruminantia. 6. Pisciformia. Ord. Ci. Fishes. 1°. Ossei. Ord. Acan-
Cetacea. 2°. Didelphya. Ord. Marsupialia, Monotremata. thopterygii, Abdominales, Subbrachii, |
Cu. Birds. Ord. Rapaces, Passeres, Scansores, Galline, Apodes, Lophobranchii, and Plectog- .
Gralle, and Palmipedes. ; nathi. 2°. Chondropterygii. Ord. Stu- TE
Ci. Reptiles. Ord. Chelonia, Sauria, Ophidia. riones, Selachii, and Cyclostomi. |
:
Fe II. Enromozoa, or ANNELLATA. ,
Subbranch. Arthropoda. Subbranch. Vermes.
Cu. Insecta. Ord. Coleoptera, Orthoptera, Nevroptera, Hymatioptcrss Cy. Annelids.
Lepidoptera, Hemiptera, Diptera, Rhipiptera, Anoplura, and Thysanura. — Cit. Helminths.
Cu. Myriapoda. Ord. Chilognatha and Chilopoda. CL. Turbellaria.
Cu. Arachnids. Ord. Pulmonaria and Trachearia. CL. Cestoidea.
Cr. Crustacea. 1°. Podophthalmia. Ord. Decapoda and Stomapoda. Ci. Rotatoria.
2°. Edriophthalma. Ord. Amphipoda, Lemodipoda, and Isopoda. 3°. Bran- |
chiopoda. Ord. Ostrapoda, Phyllopoda, and Trilobite. 4°. Entomostraca. Ord.
Copepoda, Cladocera, Siphonostoma, Lernzida, Cirripedia. 5°. Xiphosura.
Il. Maxracozoaria, or MOLLusca. |
Subbranch. Mollusks proper. Subbranch. Molluscoids.
Cir. Cephalopods. Gr Tuhicatas
CL. - Pteropods. Cu. Bryozoa.
Cit. Gasteropods.
Cir. Acephala.
/ IV. Zoopuyres.
Subbranch. Radiaria, or Radiata. — Subbranch. Sarcodariéa. .
Cit. Echinoderms. Cu. Infusoria.
CL. Acalephs. Cu. Spongiaria.
Cu. Corallaria, or Polypi.
1 Consult, for these, his recent papers upon Polyps, Mollusks, and Crustacea, in the Ann. des Se. Nat,
ESSAY ON CLASSIFICATION.
CLASSIFICATION OF VON SIEBOLD AND STANNIUS.
This classification is adopted in the following work: Srmsoxp, (C. Tu. v.,) and Srannivs, (H.,) Lehrbuch
der vergleichenden Anatomie, Berlin, 1845, 2 vols. 8vo. A second edition is now in press.
EVERTEBRATA.
I. Protozoa.
Cu.1. Infusoria. Ord. Astoma and Stomatoda.
Ci. 2. Rhizopoda. Ord. Monosomatia and Polysomatia.
ZOOPHYTA.
Cu. 3. Polypi. Ord. Anthozoa and Bryozoa.
Ci. 4. Acalephae. Ord. Siphonophora, Discophora, Ctenophora.
Ci. 5. Echinodermata. Ord. Crinoidea, Asteroidea, Echinoidea, Holothurioidea, and
Sipunculoidea. :
VERMES.
Cx. 6. Helminthes. Ord. Cystici, Ces- Since the publication of the work quoted above, Sie-
E bold has introduced most important improvements in the
todes, Trematodes, Acanthocephali, ee . , ‘
classification of the Worms, and greatly increased our
Gordiacei, Nematodes. knowledge of these animals.
Ci. 7. Turbellarii. Ord. Rhabdoceli, Dendrocceli.
Ci. 8. Rotatorii. Not subdivided into orders.
Cu. 9. Annulati. Ord. Apodes and Chetopodes.
Mo..usca. :
Cxu.10. Acephala. Ord. Tunicata, Brachiopoda, Lamellibranchia.
Cr. 11. Cephalophora, Meck., (Gasteropoda.) Ord. Pteropoda, Heteropoda, Gasteropoda,
Sedo Ao phalop oda. Not subdivided into orders.
ARTHROPODA. j
Ci. 18. Crustacea. Ord. Cirripedia, Siphonostoma, Lophyropoda, Phyllopoda, Peecilopoda,
| Lemodipoda, Isopoda, Amphipoda, Stomapoda, Decapoda, Myriapoda.
Ci. 14. Arachnida. Orders without names. : |
Cu. 15. Insecta. a. Ametabola. Ord. Aptera. 6 Hemimetabola; Ord. He-—
miptera, Orthoptera. _ c. Holometabola. Ord. Diptera, Lepidoptera, Hymenop-
tera, Strepsiptera, Nevroptera, and Coleoptera.
VERTEBRATA.
VI. VERTEBRATA.
Cu. 16. Pisces. Subclasses: Ist. Leptocardii. 2d. Marsipobranchii. 34.
Elasmobranchii; Ord. Holocephali, Plagiostomi. 4th. Ganoidei; Ord.
Chrondrostei, Holostei. Sth. Teleostei; Ord. Acanthopteri, Anacanthini, Pharyn-
, gognathi, Physostomi, Plectognathi, Lophobranchii. 6th. Dipnoi.
Ci.17. Reptilia. Subclasses: 1st. Dipnoa; Ord. Urodela, Batrachia, Gymnophiona.
2d. Monopnoa: a. Streptostylica; Ord. Ophidia, Sauria. 6. Monimostylica; Ord.
Chelonia, Crocodila. ) The subdivisions of the classes Pisces and Reptilia are taken from the sec-
ond edition, published in 1854-1856, in which J. Miiller’s arrangement of the
~ Aves. Fishes is adopted; that of the Reptiles is partly Stannius’s own. The
classes Aves and Mammalia, and the first volume of the second edition, are
. Mammalia. not yet out.
Cuar. IIL. ANATOMICAL SYSTEMS. . = Bee |
The most original feature of the classification of von Siebold is the adoption
of the types Protozoa and Vermes, in the sense in which they are limited here.
The type of Worms has grown out of the investigations of the helminthologists,
’ who, too exclusively engaged with the parasitic Worms, have overlooked their rela-
tions to the other Articulata. On the other hand, the isolation in which most ento-
mologists have remained from the zodlogists in general, has no doubt had its share in
preventing an earlier thorough comparison of the Worms and the larval conditions of
Insects, without which the identity of type of the Worms, Crustacea, and Insects
can hardly be correctly appreciated. Concerning the classes* adopted by von Sie- |
bold and Stannius, I have nothing to remark that has not been said already.
CLASSIFICATION OF R. LEUCKART.
The classification of Leuckart is compiled from the following work: LevoKkarr, (R.,) Ueber die Mor- -
phologie und die Verwandtschaftsverhiltnisse der wirbellosen Thiere, Braunschweig, 1848, 1 vol. 8vo.
I. Cor venterata, Lkt. |
Cu. 1. Polypi. Ord. Anthozoa and Cylicozoa (Lucernaria.)
Ci. 2. Acale phae. Ord. Discophore and Ctenophore. |
II. Ecurnopermata, Lkt. |
Cu. 3. Pelmatozoa, Lkt. Ord. Cystidea and Crinoidea. |
¢ Cu. 4. Actinozoa, Latr. Ord. Echinida and Asterida.
“fips Cu. 5. Scytodermata, Brmst. Ord. Holothurie and Sipunculida.
Ill. Vermes.
Cu. 6. Anenterati, Lkt. Ord. Cestodes and Acanthocephali. (Helminthes, Burm.)
. Apodes, Lkt. Ord. Nemertini, Turbellarii, Trematodes, and Hirudinei. (Trematodes, Burm.)
t
Cy. 8. Ciliati, Lkt. Ord. Bryozoa and Rotiferi.
9. Annelides. Ord. Nematodes, Lumbricini, and Branchiati. (Annulati, Burm., excl. Ne-
mertinis et Hirudineis.)
IV. ARTHROPODA.
Cr. 10. Crustacea. Ord. Entomostraca (Neusticopoda Car.) and Malacostraca.
Cu. 11. Insecta. Ord. Myriapoda, Arachnida, (Acera, Latr.,) and Hexapoda.
V. Mortusca, Cuv. (Palliata, Nitzsch.)
: SS. Leuckart is somewhat inclined to consider the Tunicata a
Cu. 12. | Tunicata. Ord. Ascidie (Tethyes not simply as a class, but even as another great type or branch, fy
Sav.) and Salpe (Thalides Sav.)
Cu. 18. Acephala. Ord. Lamellibranchiata (Cormopoda Nitzsch, Pelecypoda Car.) and Bra-
intermediate between Echinoderms and Worms.
chiopoda.
Ci. 14. Gasteropoda. Ord. Heterobranchia, (Pteropoda, Inferobranchia, and Tectibranchia,) .
4 . Dermatobranchia, (Gymnobranchia and Phlebenterata,) Heteropoda, Ctenobranchia, Pulmo-
nata, and Cyclobranchia.
Ci. 15. Cephalopoda.
VI. Verresrata. (Not considered.)
1 The names of the types, Protozoa and Vermes, are older ous ways for nearly half a century, while that of Worms was first
than their limitation in the classification of Siebold. That of adopted by Linnaeus, as a great division of the animal king-
Protozoa, first introduced by Goldfuss, has been used in vari- dom, but in a totally different sense.
27
210 ESSAY ON CLASSIFICATION. Part I.
IT need not repeat here what I have already stated, in the first section, respecting
the primary divisions adopted by Siebold and Leuckart. As to the classes, I may
add that his three classes of Echinoderms exhibit only ordinal characters. Besides
Birds and Cephalopods, there is not another class so well defined, and so little
susceptible of being subdivided into minor divisions presenting any thing like class
characters, as that of Echinoderms. Their systems of organs are so closely homo-
logical, (compare p. 183,) that the attempt here made by Leuckart, of subdividing
them into three classes, can readily be shown to rest only upon the admission, as
classes, of groups which exhibit only ordinal characters, namely, different degrees of
complication of structure. With reference to the classes of Worms, the same is
equally true, as shown above. The arrangement of these animals proposed by Bur-
meister is certainly more correct than those of von Siebold and of Leuckart, inas-
much as he refers already correctly the Rotifera to the class of Crustacea, and does
not, like Leuckart, associate the Bryozoa with the Worms. I agree, however, with
Leuckart respecting the propriety of removing the Nemertini and Hirudinei from
among the true Annelides. Again, Burmeister appreciates also more correctly the
position of the whole type of Worms, in referring them, with de Blainville, to the
branch of Articulata. 7
The common fault of all the anatomical classifications which have been proposed
since Cuvier consists, first, in having given up, to a greater or less extent, the funda-
mental idea of the plan of structure, so beautifully brought forward by Cuvier, and
upon which he has insisted with increased confidence and more and more distinct con-
sciousness, ever since 1812; and, second, in having allowed that of complication of
structure frequently to take the precedence over the more general features of plan,
which, to be correctly appreciated, require, it is true, a deeper insight into the struc-
ture of the whole animal kingdom than is needed merely for the investigation of
anatomical characters in single types.
Yet, if we take a retrospective glance at these systems, and especially con-
sider the most recent ones, it must be apparent to those who are conversant with
the views now obtaining in our science, that, after a test of half a century, the
idea of the existence of branches, characterized by different plans of structure, as
expressing the true relations among animals, has prevailed over the idea of a
gradated scale including all. animals in one. progressive series. When it is con-
sidered that this has taken place amidst the most conflicting views respecting classi-
fication, and even in the absence of any ruling principle, it must be acknowl-
edged that this can be only owing to the internal truth of the views. first pro-
pounded by Cuvier. We recognize in the classifications of Siebold, Leuckart, and
others the triumph of the great conception of the French naturalist, even though
their systems differ greatly from his, for the question whether there are four or
ee a ta
— Aen ated co nn tt i FRate B e
nee ae a SE AM Eanes Sn SS ea eeene ee
fn OE
Cuap. III. PHYSIOPHILOSOPHICAL SYSTEMS. 211
more great plans, limited in this or any other way, is not a question of prin-
ciple, but one involving only accuracy and penetration in the -investigation; and
I maintain that the first sketch of Cuvier, with all its imperfections of details, pre-
if sents a picture of the essential relations existing among animals truer to nature
than the seemingly more correct classifications of recent writers. |.
SECTION V.
PHYSIOPHILOSOPHICAL SYSTEMS.
About the time that Cuvier and the French naturalists were tracing the structure
of the animal kingdom, and attempting to erect a natural system of Zovlogy upon
this foundation, there arose in Germany a school of philosophy, under the lead
of Schelling, which extended its powerful influence to all the departments of physical
science. Oken, Kieser, Bojanus, Spix, Huschke, and Carus are the most eminent A
naturalists who applied the new philosophy to the study of Zodlogy. But no |
one identified his philosophical views so completely with his studies in natural
< history as Oken.
Now that the current is setting so strongly against every thing which recalls
the German physiophilosophers and their doings, and it has become fashionable
to speak ill of them, it is an imperative duty for the impartial reviewer of the
history of science to show how great and how beneficial the influence of Oken
has been upon the progress of science in general and of Zodlogy im particular. |
It is moreover easier, while borrowing his ideas, to sneer at his style and_ his | )
nomenclature, than to discover the true meaning of what is left unexplained in |
his mostly paradoxical, sententious, or aphoristical expressions; but the man who | |
has changed the whole method of illustrating comparative Osteology,—who has
carefully investigated the embryology of the higher animals, at a time when few |
physiologists were paying any attention to the subject, who has classified the three |
kingdoms of nature’ upon principles wholly his own, who has perceived thousands |
of homologies and analogies among organized beings entirely overlooked before, who Hi
has published an extensive treatise of natural history containing a condensed account
4 of all that was known at the time of its publication, who has conducted for twenty- |
five years the most extensive and most complete periodical review of the natural i
sciences ever published, in which every discovery made during a quarter of a ;
century is faithfully recorded, the man who inspired every student with an ardent
love for science, and with admiration for his teacher,—that man will never be
forgotten, nor can the services he has rendered to science be overlooked, so long ; Wy
as thinking is connected with investigation.
" si in 9 Tn 2
ESSAY ON CLASSIFICATION. |
CLASSIFICATION OF OKEN.
The following diagram of Oken’s classification is compiled from his Allgemeine Naturgeschichte fiir alle
Stiinde, Stuttgardt, 1833-1842, 14 vols. 8vo.; vol. 1, p. 5. The changes this system has undergone may
be ascertained by comparing his Lehrbuch der Naturphilosophie, Iena, 1809-1811, 3 vols. 8vo.; 2d edit.,
Tena, 1831; 3d edit., Ziirich, 1848; Engl. Ray Society, London, 1847, 1 vol. 8vo.— Lehrbuch der Natur-
geschichte, Leipzig, 1813; Weimar, 1815 and 1825, 8vo.— Handbuch der Naturgeschichte zum Gebrauch
bei Vorlesungen, Niirnberg, 1816-1820, 8vo. — Naturgeschichte fiir Schulen, Leipzig, 1820, 1 vol. 8vo.,
and various papers in the Isis.
lst Grade. Inrestinan AnrmALs; also called Body-animals and Touch-animals. Only one cavity; no head
with a brain, only the lowest sense perfect, intestines and skin organs, but no flesh, that is
no bones, muscles, or nervous marrow = Jnvertebrata. .
Characterized by the development of the vegetative systems of organs, which are those of digestion, circula-
tion, and respiration. Hence —
Cycle I. Digestive Animals. = Radiata. Essential character: no development beyond an intestine.
Ci. 1. Infusoria, (Stomach animals.) Mouth with cilia only, to vibrate.
Cu. 2. Poly pi, (Intestine animals.) Mouth with lips and tentacles, to seize.
Cx. 3. Acalephae, (Lacteal animals.) Body traversed by tubes similar to the lymphatic vessels.
Cycle HI. Circulative Animals.= Mollusks. Essential character: intestine and vessels.
Cu. 4. Acephala, (Biauriculate animals.) Membranous heart with two auricles.
Ci. 5. Gasteropoda, (Uniauriculate animals.) Membranous heart with one auricle.
Ci. 6. Cephalopoda, (Bicardial animals.) Two hearts.
Cycle III. Respirative Animals. = Articulata. Essential character: intestine, vessels, and spiracles.
Ci. 7. Worms, (Skin animals.) Respire with the skin itself, or part of it, no articulated feet.
Cx. 8. Crustacea, (Branchial animals.) Gills or air tubes arising from the horny skin.
Cx. 9. Insects, (Tracheal animals.) Trachez internally, gills externally as wings.
2d Grade. Fresu ANIMALS; also called Head-animals.—= Vertebrata. Two cavities of the body, surrounded
by fleshy walls, (bones and muscles,) inclosing nervous marrow and intestines. Head with
brain; higher senses developed. Characterized by the development of the animal systems,
namely, the skeleton, the muscles, the nerves, and the senses.
Cycle IV. Carnal Animals proper. Senses not perfected.
Cui. 10. Fishes, (Bone-animals.) Skeleton predominating, very much broken up; muscles white,
brain without gyri, tongue without bone, nose not perforated, ear concealed, eyes without
lids.
Cu. 11. Reptiles, (Muscle-animals.) Muscles red, brain without convolutions, nose perforated,
ear without external orifice, eyes immovable with imperfect lids.
Cu. 12. Birds, (Nerve-animals.) Brain with convolutions, ears open, eyes immovable, lids
imperfect. \
Cycle V. Sensual Animals. All anatomical systems, and the senses perfected.
Cit. 18. Mammalia, (Sense-animals.) Tongue and nose fleshy, ears open, mostly with a conch,
eyes movable, with two distinct lids.
= a pa ae mea TE AA TUNA ECNRNE A — as
a a a a a I BR a A A AOR OEE LET NTE tas = atari: ~~ es — rn en
Cnap. IIL. PHYSIOPHILOSOPHICAL SYSTEMS. 213
The principles laid down by Oken, of which this classification is the practical
result for Zodlogy, may be summed up in the following manner: The grades or
great. types of Animals are determined by their anatomical systems, such as the
body and head; or the intestines, and the flesh and senses. Hence two grades
in the animal kingdom. Animals are, as it were, the dismembered body of man
made alive. The classes of animals are the special representation in living forms
of the anatomical systems of the highest being in creation.
Man is considered, in this system, not only as the key of the whole animal
kingdom, but also as the standard measure of the organization of animals. There
exists ‘nothing in the animal kingdom which is not represented in higher combina-
tions in Man. The existence of several distinct plans of structure among animals is
virtually denied. They are all built after the pattern of Man; the differences
among them consist only in their exhibiting either one system only, or a larger
or smaller number of systems of organs of higher or lower physiological impor-
tance, developed either singly, or m connection with one another, in their body.
The principles of classification of both Cuvier and Ehrenberg are here entirely
negatived. The principle of Cuvier, who admits four different plans of structure
in the animal kingdom, is, indeed, incompatible with the idea that all animals
represent only the organs of Man. The principle of Ehrenberg, who considers
all animals as equally perfect, is as completely irreconcilable with the assumption
that all animals represent an unequal sum of organs; for, according to Oken, the
body of animals is, as it were, the analyzed body of Man, the organs of which
live singly, or in various combinations as independent animals. Each such com-
bination constitutes a distinct class. The principle upon which the orders are
founded has already been explained above, (Chap. IL, Sect. TIL, p. 154.)
There is something very taking in the idea that Man is the standard of appre-
ciation of all animal structure’. . But all the attempts which have thus far been
made to apply it to the animal kingdom as it exists, must be considered as com-
plete failures. In his different works, Oken has successively identified the systems
of organs of Man with different groups of animals, and different authors, who
have adopted the same principle of: classification, have identified them in still differ-
ent ways. The impracticability of such a scheme must be obvious to any one
who has satisfied himself practically of the existence of different plans of structure
in the organization of animals. Yet, the unsoundness of the general principle of
the classifications of the physiophilosophers should not render us blind to all that
is valuable in their special writings. The works of Oken in particular teem with
original suggestions respecting the natural affinities of animals; and his thorough
acquaintance with every investigation of his predecessors and contemporaries shows
him to have been one of the most learned zodlogists of this century.
ms Re
a ree
ESSAY ON CLASSIFICATION.
CLASSIFICATION OF FITZINGER.
This diagram is extracted from Fitzinger’s Systema Reptilium, Vindobone, 1843, 1 vol. 8vo.
I. Provincia. EverteBRaAta.
Animalia systematum anatomicorum vegetativorum gradum evolutionis exhibentia.
A. Gradus evolutionis systematum physiologicorum vegetativorum.
I. Cireulus. GasTrozoa.
Evolutio systematis nutritionis.
a. Evolutio przvalens b. Evolutio prevalens c. Evolutio prevalens
systematis digestionis. systematis circulationis. systematis respirationis.
Cu. 1. Infusoria. CL. 2. Zoophyta. Ci. 3. Acalephae.
If. Circulus. Puys10zoa.
Evolutio systematis generationis.
Cu. 4. Vermes. Cu. 5. Radiata. Ci. 6. Annulata.
B. Gradus evolutionis systematum physiologicorum animalium.
TIT. Circulus. DerMatozoa.
Evolutio systematis sensibilitatis.
Ci. 7. Acephala. Cu. 8. Cephalopoda. Cri. 9. Mollusca.
IV. Circulus. ARFHROZOA.
Evolutio systematis motus.
Cui. 10. Crustacea. Ci. 11. Arachnoidea. Cr. 12. Insecta.
If. Provincia. VERTEBRATA.
Animalia systematum anatomicorum animalium gradum evolutionis exhibentia.
A. Gradus evolutionis systematum physiologicorum vegetativorum.
a. Evolutio systematis nutritionis, simulque ossium: . . Cr. 138. Pisces.
b. Evolutio systematis generationis, simulque musculorum: CL. 14. Reptilia.
B. Gradus evolutionis systematum physiologicorum animalium.
ce. Evolutio systematis sensibilitatis, simulque nervorum: Cx. 15. Aves.
d. Evolutio systematis motus, simulque sensuum:. . . Cx. 16. Mammalia.
The fundamental idea of the classification of Fitzinger is the same as that
upon which Oken has based his system. The higher divisions, called by him
provinces, grades, and cycles, as well as the classes and orders, are considered as
representing either some combination of different systems of organs, or some par-
ticular system of organs, or some special organ. His two highest groups (provinces)
are the Evertebrata and Vertebrata. The Evertebrata represent the systems of
the vegetative organs, and the Vertebrata those of the animal organs, as the Gut-
Cuap. III. PHYSIOPHILOSOPHICAL SYSTEMS. 215
animals and the Flesh-animals of Oken. Instead, however, of adopting, like Oken,
anatomical names for his divisions, Fitzinger employs those most generally in use.
His subdivisions or grades of these two primary groups are based upon a repetition
of the same differences, within their respective limits. The Invertebrata, in which
the vegetative organs prevail, are contrasted with those in which the animal organs
prevail, and the same distinction is again drawn among the Vertebrata. Each of
these embraces two circles founded upon the development of one particular system
of organs, etc. It cannot be expected that the systems founded upon such principles
should present a closer agreement with one another than those which are based
upon anatomical differences; yet I would ask, what becomes of the principle itself,
if its advocates cannot even agree upon what anatomical systems of organs their
classes are founded? According to Oken, the Mollusks (Acephala, Gasteropoda, and
Cephalopoda) represent the system of circulation, at least in the last edition of
his system he views them in that light, whilst Fitzinger considers them as repre-
senting the system of sensibility. Oken identifies the Articulata (Worms, Crustacea,
and Insects) with the system of respiration, Fitzinger with that of motion, with
the exception of the Worms, including Radiata, which he parallelizes with the
system of reproduction, etc. Such discrepancies must shake all confidence m
these systems, though they should not prevent us from noticing the happy com-
parisons and suggestions, to which the various attempts to classify the animal king-
dom in this way have led ‘their authors. it is almost superfluous to add, that,
great as the disagreement is between- the systems of different physiophilosophers,
we find quite as striking discrepancies between the different editions of the system
of the same author.
The principle of the subdivision of the classes among Invertebrata is here exemplified from the Radiata,
(Echinodermata.) Each series contains three orders.
[st Series. 2d Series. 8d_ Series.
Evolutio prevalens Evolutio prevalens Evolutio przvalens
systematis digestionis. systematis circulationis. systematis respirationis.
Asteroidea. Echinodea. Scytodermata (Holothurioids.)
1. Encrinoidea. 2. Comatulina. 1. Aprocta. 2. Echinina. 1. Synaptoidea. 2. Holothurioidea.
3. Asterina. _ 8. Spatangoidea. 3. Pentactoidea.
In Vertebrata, each class has five series and each series three orders; so in Mammalia, for example :—
1st Series. 2d Series. 38d_ Series. 4th Series. 5th Series.
Evolutio prevalens Evolutio prevalens Evolutio prevalens Evolutio prevalens Evolutio prevalens
sensus tactus. sensus gustus. sensus olfactus. sensus auditus. sensus visus.
Cetacea. Pachydermata. Edentata. Unguiculata. Primates.
1. Balanodea. 1. Phocina. 1. Monotremata. 1. Glires. 1. Chiropteri.
2. Delphinodea. 2. Obesa. 2. Lipodonta. 2. Bruta. 2. Hemipitheci.
_ 8. Sirenia. 3. Ruminantia. 3. Tardigrada. 3. Fer. 3. Anthropomorphi.
nemeconan ad inant cm lla AGT tn te
a A i ct el
at i Di lag cll
216 ESSAY ON CLASSIFICATION. Part I.
Instead of considering the orders as founded upon a repetition of the characters
of higher groups, as Oken would have it, Fitzinger adopts series, as founded upon
- that idea, and subdivides them further into orders, as above. These series, however,
have still less reference to the systems of organs, which they are said to represent,
than either the classes or the higher divisions of the animal kingdom. In these
attempts to arrange minor groups of animals into natural series, no one can fail
to perceive an effort to adapt the frames of our systems to the impression we
receive from a careful examination of the natural relations of organized beings.
Everywhere we notice such series; sometimes extending only over groups of species,
at other times embracing many genera, entire families, nay, extending frequently to
several families. Even the classes of the same branch may exhibit more or less
distinctly such a serial gradation. But I have failed, thus far, to discover the
principle to which such relations may be referred, as far as they do not rest upon
complication of structure,' or upon the degree of superiority or inferiority of the
features upon which the different kinds of groups are themselves founded. Analogy
plays also into the series, but before the categories of analogy have been as
carefully scrutinized as those of affinity, it 1s impossible to say within what limits
this takes place.
CLASSIFICATION OF McLEAY.
The great merit of the system of McLeay, and in my opinion it has no other
claim to our consideration, consists in having called prominently the attention of
naturalists to the difference between two kinds of relationship, almost universally
confounded before: affinity and analogy. Analogy is shown to consist in the repeti-
tion of similar features in groups otherwise remote, as far as their anatomical
characters are concerned, whilst affinity is based upon similarity in the structural
relations. On account of the similarity of their locomotion, Bats, for instance, may
be considered as analogous to Birds; Whales are analogous to Fishes on account
of the similarity of their form and their aquatic mode of life; whilst both Bats
and Whales are allied to one another and to other Mammalia on account of the
identity of the most characteristic features of their structure. This important dis-
tinction cannot fail to lead to interesting results. Thus far, however, it has only
produced fanciful comparisons from those who first traced it out. It is assumed,
for instance, by McLeay, that all animals of one group must be analogous to
* Compare Chap. II., Sect. 8, p. 153. those of the German physiophilosophers, but on
2 I have introduced the classification of McLeay account of its general character, and because it is
in this section, not because of any resemblance to . based upon an ideal view of the affinities of animals.
mene OO —
a LE A ig OE OLA EIR DE AAI TE
Cuap. III.
PHYSIOPHILOSOPHICAL SYSTEMS. 217
those of every other group, besides forming a circle in themselves; and in order
to carry out this idea, all animals are arranged in circular groups, in such a manner
as to bring out these analogies, whilst the most obvious affinities are set aside to
favor a preconceived view. But that I may not appear to underrate the merits
of this system, I will present it in the very words of its most zealous admirer
and selfcomplacent expounder, the learned William Swainson?
“The Hore Entomologice,* unluckily for students, can only be thoroughly
understood by the adept, since the results and observations are explained in different
parts; the style is somewhat desultory, and the groups, for the most part, are rather
indicated than defined. The whole, in short, is what it professes to be, more a
rough sketch of the leading peculiarities of the great divisions of animals, and the
manner in which they are probably connected, than an accurate determination of
the groups themselves, or a demonstration of their real affinities. More than this,
perhaps, could not have been expected, considering the then state of science, and
the herculean difficulties which the author had to surmount. The work in ques
tion has now become exceedingly scarce, and this will be an additional reason
with us for communicating occasional extracts from it to the reader. Mr. McLeay’s
theory will be best understood by consulting his diagram; for he has not, as we
have already remarked, defined any of the vertebrated groups. Condensing, how-
ever, the result of his remarks, we shall state them as resolvable into the following
propositions: 1. That the natural series of animals is continuous, forming, as it
were, a circle, so that, upon commencing at any one given point, and thence
tracing all the modifications of structure, we shall be imperceptibly led, after passing
through numerous forms, again to the point from which we started ; 2. That no
groups are natural which do not exhibit such a circular series; 3. That the
primary divisions of every large group are ten, five of which are composed of
comparatively large circles, and five of smaller: these latter being termed osculant,
and being intermediate between the former, which they serve to connect; 4. That
there is a tendency in such groups as are placed at the opposite points of a
circle of affinity ‘to meet each other;’ 65. That one of the five larger groups
into which every natural circle is divided, ‘bears a resemblance to all the rest, or,
more strictly speaking, consists of types which represent those of each of the four
other groups, together with a type peculiar to itself’? These are the chief and
leading principles which Mr. McLeay considers as belonging to the natural system.
We shall now copy his diagram, or table of the animal kingdom, and then endeavor,
with this help, to explain the system more in detail.”
1 Swainson, (W.,) A Treatise of the Geography 2 McLray, (W. S.,) Hore Entomologice, or
and Classification of Animals, London, 1835, 1 vol. Essays on the Annulose Animals, London, 1819-21,
12mo., p. 201-205. 2 vols. 8vo.
28
inane eamsemsasanvatnitan,- imndten
wetettingmatactgmnanseenreshin ia
ESSAY ON CLASSIFICATION.
MOLLUSCA.
Pteropoda.
Acephala. Reptilia.
P. Vaginati. Brachiopoda. Aves.
ACRITA. VERTEBRATA.
Di benis :
gastria. Mammalia.
P. Natantes. Amphibia.
Intestina. Pisces.
‘WOPSULY 9[qGvJes59A OY} JO soulog
poztuesio 4svorT
Fistulida. Ametabola.
Acalephide. Mandibulata.
RADIATA. ANNULOSA.
Echinide. || Crustacea.
Meduside. Haustellata.
Stelleride. Arachnide.
<
=
ce
a
|
os
oo
sae
o
“We must, in the first instance, look to the above tabular disposition of all
animals, as forming themselves collectively into one great circle, which circle touches
or blends into another, composed of plants, by means of the ‘least organized beings
of the vegetable kingdom’ Next we are to look to the larger component. parts
of this great circular assemblage. We find it, in accordance with the third proposi-
tion, to exhibit five great circles, composed of the Moxvusca, or shellfish; Acriva,
or polyps; Raprata, or star-fish; ANNULOsA, or insects; and Verreprata, or verte-
brated animals; each passing or blending into each other, by means of five other
groups of animals, much smaller, indeed, in their extent, but forming so many
connecting or osculant circles.'| The number, therefore, as many erroneously suppose,
is not five, but ten. This is quite obvious; and our opinion on this point is
confirmed by the author himself, in the following passage, when alluding to his
remarks upon the whole:—‘The foregoing observations, I am well aware, are far
from accurate, but they are sufficient to prove that there are five great circular
groups in the animal kingdom, each of which possesses a peculiar structure; and that
1 Tn the original diagram, as in that above, these but merely indicated by the names arranged like
five smaller circles are not represented graphically, rays between the five large circles.
ee ee
cc nt
ee Sse Same
~
Cuap. III. PHYSIOPHILOSOPHICAL SYSTEMS. 219
these, when connected by means of five smaller osculant groups, compose the
whole province of Zodlogy. Now these smaller osculant groups are to be viewed
as circles, for, as it is elsewhere stated, ‘every natural group is a circle, more
or less complete’ This, in fact, is the third general principle of Mr. McLeay’s
system, and he has exemplified his meaning of a natural group in the above
diagram, where all animals are arranged under five large groups or circles, and
five smaller ones. Let us take one of these groups, the Vertebrata: does that
form a circle of itself? Yes; because it is intimated that the Reptiles (Reptilia)
pass into the Birds, (Aves,) these again into the Quadrupeds, (Mammalia,) Quadrupeds
unite with the Fishes, (Piésces,) these latter with the amphibious Reptiles, and the
Frogs bring us back again to the Reptiles, the point from whence we started.
Thus, the series of the vertebrated group is marked out and shown to be circular;
therefore, it is a natural group. This is an instance where the circular series
can be traced. We now turn to one where the series is imperfect, but where
there is a decided tendency to a circle: this is the Mollusca. Upon this group
our author says, ‘I have by no means determined the circular disposition to hold
good among the Mollusca; still, as it is equally certain that this group of animals
is as yet the least known, it may be improper, at present, to conclude that it
forms any exception to the rule; it would even seem unquestionable that the
Gasteropoda of Cuvier return into themselves, so as to form a circular group; but
whether the Acephala form one or two such, is by no means accurately ascertained,
though enough is known of the Mollusca to incline us to suspect that they are
no less subjected, in general, to a circular disposition than the four other great
groups. This, therefore, our author considers as one of those groups which, without
actually forming a circle, yet evinces a disposition to do so; and it is therefore
presumed to be a natural group. But, to illustrate this principle farther, let us
return to the circle of Vertebrata. This, as we see by the diagram, contains five
minor groups, or circles, each of which is again resolvable into five others, regu-
lated precisely in the same way. The class Aves, for example, is first divided
into rapacious birds, (Raptores,) perching birds, (Jusessores,) gallinaceous birds, ( asores,)
wading birds, (Gradatores,) and swimming birds (Natatores); and the proof of this
class being a natural group is, in all these divisions blending into each other at
their confines, and forming a circle. In this manner we proceed, beginning with
the higher groups, and descending to the lower, until at length we descend to
genera, properly so called, and reach, at last, the species; every group, whether
large or small, forming a circle of its own. Thus there are circles within circles,
‘wheels within wheels,—an infinite number of complicated relations; but all
regulated by one simple and uniform principle,—that is, the circularity of every
group.”
tain. snescsachteataian. ies
a lems Si a ill
220 ESSAY ON CLASSIFICATION. — Parr I.
The writer who can see that the Quadrupeds unite with the Fishes, and the
like, and yet says that Cuvier “was totally unacquainted. with the very first princi-
ples of the natural system,” hardly deserves to be studied in our days.
The attempt at representing graphically the complicated relations which exist
among animals has, however, had one good result; it has checked, more and more,
the confidence in the uniserial arrangement of animals, and led to the construction
of many valuable maps exhibiting the multifarious relations which natural groups, —
of any rank, bear to one another.
SHeTION “we,
EMBRYOLOGICAL SYSTEMS.
Embryology, in the form it has assumed within the last fifty years, is as
completely a German science as the “Naturphilosophie.” It awoke to this new
activity contemporaneously with the development of the Philosophy of Nature. It
would hardly be possible to recognize the leading spirit in this new development,
from his published works; but the man whom Pander and K. E. von Baer
acknowledge as their master must be considered as the soul of this movement,
and this man is Ignatius Déllinger. It is with deep gratitude I remember, for
my own part, the influence that learned and benevolent man had upon my studies
and early scientific application, during the four years I spent in his house, in
Munich, from 1827 to 1831; to him I am indebted for an acquaintance with what
was then known of the development of animals, prior to the publication of the
great work of Baer; and from his lectures I first learned to appreciate the im-
portance of Embryology to Physiology and Zoédlogy. The investigations of Pander!
upon the development of the chicken in the egg, which have opened the series
of those truly original researches in Embryology of which Germany may justly
be proud, were made under the direction and with the codperation of Dillinger,
and were soon followed by the more extensive works of Rathke and Baer, whom
the civilized world acknowledges as the founders of modern Embryology.
The principles of classification propounded by K. E. von Baer seem never to
have been noticed by systematic writers, and yet they not only deserve the most
careful consideration, but it may fairly be said that no naturalist besides Cuvier
has exhibited so deep an insight into the true character of a natural system,
1 PanveER, Beitriige zur Entwickelungsgeschichte des Hiihnchens im Eie, Wiirzburg, 1817, 1 vol. fol.
Cuap.. III. EMBRYOLOGICAL SYSTEMS. 221
supported by such an extensive acquaintance with the subject, as this great embry-
ologist has in his “Scholien und Corallarien zu der Entwickelungsgeschichte des
Hiihnchens im Hie.”?
These principles are presented in the form of general pro-
portions, rather than in the shape of a diagram with definite systematic names, and
this may explain the neglect which it has experienced on the part of those who
are better satisfied with words than with thoughts. A few abstracts, however, |
may show how richly the perusal of his work is likely to reward the reader.
The results at which K. E. von Baer had arrived by his embryological inves-
tigations, respecting the fundamental relations existing among animals, differed con-
siderably from the ideas then prevailing. In order, therefore, to be correctly —
understood, he begins, with his accustomed accuracy and clearness, to present a
condensed account of those opinions with which he disagreed, in these words:—
“Few views of the relations existing in the organic world have received so
much approbation as this: that the higher animal forms, in the several stages of
the development of the individual, from the beginning of its existence to its
complete formation, correspond to the permanent forms in the animal series, and
that the development of the several animals follows the same laws as those of
the entire animal series; that consequently the more highly organized animal, in
its individual development, passes in all that is essential through the stages that
are permanent’ below it, so that the periodical differences of the individual may
be reduced to the differences of the permanent animal forms.”
Next, in order to have some standard of comparison with his embryological
results, he discusses the relative position of the different permanent types of ani-
mals, as follows :—
“Tt is especially important that we should distinguish between the degree of
perfection in the animal structure and the type of organization. The degree
of perfection of the animal structure consists in the greater or less heteroge-
neousness of the elementary parts, and the separate divisions of a complicated
apparatus, —in one word, in the greater histological and morphological differen-
tiation. The more uniform the whole mass of the body is, the lower the
degree of perfection; it is a stage higher when nerve and muscle, blood and
cellular tissue, are sharply distinguished. In proportion to the difference between
_ these parts, is the development of the animal life in its different tendencies; or,
to express it more accurately, the more the animal life is developed in its several
tendencies, the more heterogeneous are. the elementary parts which this life brings
into action, The same is true of the single parts of any apparatus. That organ-
+ Ueber Entwickelungsgeschichte der Thiere, Baer, Konigsberg, 1828, 4to.— See also Acta Nova
Beobachtung und Reflexion von Dr. Karl Ernst von Acad. Leop. Cesar, vol. 18, and Meckel’s Arch., 1826.
Ps ac
sessilis
nal ii i ca a,
Part I.
2 ESSAY ON CLASSIFICATION.
ization is higher in which the separate parts of an entire system differ more among
themselves, and each part has greater individuality, than that in which the whole
is more uniform. I call type, the relations of organic elements and organs, as far
as their position is concerned. This relation of position is the expression of cer-
tain fundamental connections in the tendency of the individual relations of. life ;
as, for instance, of the receiving and discharging poles of the body. The type
is altogether distinct from the degree of perfection, so that the same type may
include many degrees of perfection, and, vice versd, the same degree of perfec-
tion may be reached in several types. The degree of perfection, combined with
the type, first determines those great animal groups which have been called classes.
The confounding of the degree of perfection with the type of organization seems
the cause of much mistaken classification, and in the evident distinction between
these two relations we have sufficient proof that the different animal forms do
not present one uniserial development, from the Monad up to Man.”
The types he has recognized are :—
I. The Peripheric Type. The essential contrasts in this type are between the
centre and the periphery.» The organic functions of life are carried on in antag-
onistic relations from the centre to the circumference. Corresponding to this, the
whole organization radiates around a common centre. There exists besides only
the contrast between above and below, but in a weaker degree; that between
right and left, or before and behind, is not at all noticeable, and the motion is
therefore undetermined in its direction. As the whole organization radiates from
one focus, so are the centres of all the organic systems arranged, ring-like, around
it, as, for instance, the stomach, the nerves and vessels, (if these parts are devel-
oped,) and the branches extending from them into the rays. What we find in
one ray is repeated in every other, the radiation being always from the centre
outwards, and every ray bearing the same relation to it. |
Il. The Longitudinal Type, as observed in the Vibrio, the Filaria, the Gordius,
the Nais, and throughout the whole series of articulated animals. The contrast
between the receiving and the discharging organs, which are placed at the two
ends of the body, controls the whole organization. The mouth and the anus are
1 From this statement it is plain that Baer of structure as determining the relative rank of
has a very definite idea of the plan of structure, and
that he has reached it by a very different road from
that of Cuvier. It is clear, also, that he understands
“the distinction between a plan and its execution.
But his ideas respecting the different features of
structure are not quite so precise. He does not
distinguish, for instance, between the complication
the orders, and the different ways in which, and the
different means with which the plans are executed,
as characteristic of the classes.
? Without translating verbatim the descriptions
Baer gives of his types, which are greatly abridged
here, they are reproduced as nearly as possible in
his own words.
“:...
EMBRYOLOGICAL
Cuap. III. SYSTEMS. 223
always at opposite ends, and usually also the sexual organs, though their opening
is sometimes farther forward; this occurs, however, more frequently in the females,
in which these organs have a double function, than in the males. When both
sexual organs are removed from the posterior extremity, the opening in the female
usually lies farther forward than in the male. So is it in the Myriapods and
the Crabs. The Leeches and Karthworms present a rare exception. The recep-
tive pole being thus definitely fixed, the organs of senses, as instrumental to the
receptivity of the nervous system, early reach an important degree of perfection.
The intestinal canal, as well as the vascular stems and the nervous system, extend
through the whole length of the body, and all organic motion in these animals
has the same prevailing direction. Only subordinate branches of these organs
arise laterally, and chiefly wherever the general contrast, manifested in the whole
length is repeated in such a manner that, for each separate segment, the same
contrast arises anew, in connection with the essential elements of the whole organ-
ism. Hence the tendency in these animals to divide into many segments in the
direction of the longitudmal axis of the body. In the true Insects, undergoing
metamorphosis, these segments unite again into three principal regions, in the first
of which the life of the nerves prevails; in the second, motion; in the third,
digestion; though neither of the three regions is wholly deprived of any one
of these functions. Besides the opposition between before and behind, a less
marked contrast is observed in a higher stage of development between above and
below. A difference between right and left forms a rare exception, and is gen-
erally wanting. Sensibility and irritability are particularly developed in this series.
Motion is active, and directed more decidedly forward, in proportion as the lon-
gitudinal axis prevails. When the body is contracted as in spiders and crabs,
its direction is less decided. The plastic organs are little developed; glands, espe-
cially, are rare, and mostly replaced by simple tubes.
Il. The Massive Type. We may thus call the type of Mollusks, for neither
length nor surface prevails in them, but the whole body and its separate parts are
formed rather in round masses which may be either hollow or solid. As the chief
contrast of their structure is not between the opposite ends of the body, nor between
the centre and periphery, there is almost throughout this type an absence of sym-
metry. Generally the discharging pole is to the right of the receptive one.
The discharging pole, however, is either near the receptive one, or removed from
it, and approximated to the posterior extremity of the body. As the tract of
the digestive apparatus is always determined by these two poles, it is more or
less arched; in its simplest form it is only a single arch, as in Plumatella.
When that canal is long, it is curled up in a spiral in the centre, and the spiral
probably has its definite laws. For instance, the anterior part of the alimentary
canal appears to be always placed under the posterior. The principal currents
maseatasee each hai ia i AN ORT nn re a
Yih alata.
ia at, a emai et
224 ESSAY ON CLASSIFICATION. Part I.
of blood are also in arches, which do not coincide with the medial line of the
body. The nervous system consists of diffused ganglia, united by threads, the
larger ones being around the cesophagus. The nervous system and the organs
of sense appear late; the motions are slow and powerless.
IV. The Vertebrate Type. This is, as it were, composed of the preceding
types, as we distinguish an animal and a vegetative system of the body, which,
though influencing one another in their development, have singly a peculiar typical
organization. In the animal system, the articulation reminds us of the second
type, and the discharging and receiving organs are also placed at opposite ends.
There is, however, a marked difference between the Articulates and the Vertebrates,
for the animal system of the Vertebrates is not only doubled along the two sides,
but at the same time upwards and downwards, in such a way that the two lateral
walls which unite below circumscribe the vegetative system, while the two tending
upward surround a central organ of the animal life, the brain and spinal marrow,
which is wanting in Invertebrates. The solid frame represents this type most com-
pletely, as from its medial axis, the backbone, there arise upward arches which close
in an upper crest, and downward arches which unite, more or less, in a lower crest.
Corresponding to this we see four rows of nervous threads along the spinal marrow,
which itself contains four strings, and a quadripartite grey mass. The muscles
of the trunk form also four principal masses, which are particularly distinct in the
Fishes. The animal system is therefore doubly symmetrical in its arrangement. It
might easily be shown how the vegetative systems of the body correspond to the
type of Mollusks, though influenced by the animal system.
From the illustrations accompanying this discussion of the great types or branches
of the animal kingdom, and still more from the paper published by K. E. von
Baer in the Nova Acta,’ it is evident, that he perceived more. clearly and. earlier
than any other naturalist, the true relations of the lowest animals to their respective
branches. He includes neither Bryozoa nor Intestinal Worms among Radiata, as
Cuvier, and after him so many modern writers, did, but correctly refers the former
to the Mollusks and the latter to the Articulates.
Comparing these four types with the embryonic development, von Baer shows
that there is only a general similarity between the lower animals and the embryonic
stages of the higher ones, arising mainly from the absence of differentiation in the
body, and not from a typical resemblance. The embryo does not pass from one
type to the other; on the contrary, the type of each animal is defined from the
? Beitriige zur Kenntniss der niedern Thiere, animals. These “ Beitriige,” and the papers in which
Nova Acta Academie Naturz Curiosorum, vol. 13, | Cuvier characterized for the first time the four great
Part 2, 1827, containing seven papers, upon Aspido- types of the animal kingdom, are among the most
gaster, Distoma, and others, Cercaria, Nitzschia, Poly- important contributions to general Zodlogy ever
stoma, Planaria, and the general affinities of all published.
ee en
ar sateen
.
Cuar. IIL EMBRYOLOGICAL SYSTEMS. 295
beginning and controls the whole development. The embryo of the Vertebrate
is a Vertebrate from the beginning, and does not exhibit at any time a corre-
spondence with the Invertebrates. The embryos of Vertebrates do not pass in
their development through other permanent types of animals. The fundamental
type is first developed, afterwards more and more subordinate characters appear.
From a more general type, the more special is manifested, and the more two forms)
of animals differ, the earlier must their development be traced back to discern—
an agreement between them. It is barely possible that in their first beginning
all animals are alike and present only hollow spheres, but the individual develop-
ment of the higher animals certainly does not pass through the permanent forms —
of lower ones. What is common in a_ higher group of animals is always sooner |
developed in their embryos than what is special; out of that which is most general -
arises that which is less general, until that which is most special appears. Each
embryo of a given type of animals, instead of passing through other definite types,
becomes on the contrary more and more unlike them. An embryo of a higher type
is, therefore, never identical with another animal type, but only with an embryo.
Thus far do the statements of von Baer extend It is evident from this, that
he has clearly perceived the limitation of the different modes of embryonic develop-
ment within the respective branches of the animal kingdom, but it is equally
certain that his assertions are too general to furnish a key for the comparison of
the successive changes which the different types undergo within their respective
limits, and that he is still vaguely under the impression, that the development
corresponds in its individualization to the degrees of complication of structure.
* The account which Huxley gives of Baer’s
views, (see Baden Powell’s Essays, Appendix 7,
p- 495,) is incorrect. Baer did not “demonstrate
that the classification of Cuvier was, in the main,
simply the expression of the fact, that there are
certain common plans of development in the animal
kingdom,” ete., for Cuvier recognized these plans in
the structure of the animals, before Baer traced
“their development, and Baer himself protests against
an identification of his views with those of Cuvier.
(Baer’s Entwick., p. 7.) Nor has Baer demon-
strated the “doctrine of the unity of organization
of all animals,” and placed it “upon a footing as
secure as the law of gravitation,” and arrived at “the
grandest law,” that, up to a certain point, the develop-
ment “followed a plan common to all animals.” On
the contrary, Baer admits four distinct types of
animals, and four modes of development. He only
29
adds:.“It is barely possible that in their first begin-
ning all animals are alike.” Huxley must also
have overlooked Cuvier’s introduction to the “ Regne
Animal,” (2d edit. vol. 1, p. 48, quoted verbatim
above, p. 193,) when he stated that Cuvier “did not
attempt to discover upon what plans animals are con-
structed, but to ascertain in what manner the facts of
animal organizations could be thrown into the fewest
possible propositions.” On the contrary, Cuvier’s
special object, for many years, has been to point out
these plans, and to show that they are characterized
by peculiar structures, while Baer’s merit consists
in having discovered four modes of development, which
coincide with the branches of the animal kingdom,
in which Cuvier recognized four different plans of
structure. Huxley is equally mistaken when he says
that Cuvier adopted the nervous system “as the Baise
of his great divisions.”
en ne ak it lit ot ihn HB. cents: Aar ct!
926 ESSAY ON CLASSIFICATION. ey.
This could hardly be otherwise, as long as the different categories of the structure
of animals had not been clearly distinguished!
CLASSIFICATION OF K. E. VON BAER.
In conformity with his embryological investigations, K. E. von Baer proposes the following classification.
I. Peripheric Type. (Rap1ata.) Evolutio radiata. The development proceeds from a centre, producing
identical parts in a radiating order.
II. Massive Type. (Motiusca.) Evolutio contorta. The development produces identical parts curved
around a conical or other space.
III. Longitudinal Type. (Arricutata.) Evolutio gemina. The development produces identical parts
arising on both sides of an axis and closing up along a line opposite the axis.
IV. Doubly Symmetrical Type. (VreRTEBRATA.) Evolutio bigemina. The development produces identical
parts arising on both sides of an axis, growing upwards and downwards, and shutting up along
two lines, so that the inner layer of the germ is inclosed below and the upper layer above. The
embryos of these animals have a dorsal cord, dorsal plates, and ventral plates, a nervous tube
and branchial fissures.
1°. They acquire branchial fringes ;
a. But no genuine lungs are developed.
a. The skeleton is not ossified. Cartilagineous Fishes.
6. The skeleton is ossified.. Fishes proper.
b. Lungs are formed. Amphibia.
a. The branchial fringes remain. Sirens.
6. The branchial fringes disappear. Urodela and Anura.
2°. They acquire an allantois, but
a. Have no umbilical cord;
a. Nor wings and air sacs. Reptiles.
6. But wings and air sacs. Birds.
6. Have an umbilical cord. Mammalia.
a. Which disappears early ;
1°. Without connection with the mother. Monotremata.
2°, After a short connection with the mother. Marsupialia.
6. Which is longer persistent ;
1°. The yolk sac continues to grow for a long time.
The allantois grows little. Rodentia.
The allantois grows moderately. Insectivora.
The allantois grows much. Carnivora.
2°. The yolk sac increases slightly.
The allantois grows little. Umbilical cord very long. Monkeys and Man.
The allantois continues to grow for a long time. Placenta in simple masses.
Ruminants.
The allantois continues to grow for a long time. Placenta spreading. Pachyderms
and Cetacea.
1 Compare Chap. II., Sect. 1 to 9.
Cuap. III.
EMBRYOLOGICAL SYSTEMS. 227
CLASSIFICATION OF VAN BENEDEN.
Van Beneden has also proposed a classification based upon Embryology, which was first sketched in
his paper upon the Embryology of Bryozoa: Recherches sur l’anatomie, la physiologie et 1’embryogénie des
Bryozoaires, Bruxelles, 1845, 4to., and afterwards extended in his Comparative Anatomy: Anatomie comparée,
Bruxelles, (without date, but probably from the year 1855,) 1 vol.. 12mo.
I. HypocoryLepones or Hypovirrniians. (Vertebrata.) The vitellus enters the body from the ven-
Cis
CL.
C1.
BS
Cre 4
(lee
3.
tral side.
Mammalia. (Primates, Cheiroptera, Insectivora, Rodentia, Carnivora, Edentata, Pro-
boscidea, Ungulata, Sirenoidea, Cetacea.)
Birds. (Psittacee, Rapaces, Passeres, Columba, Gallinz, Struthiones, Gralle, Palmipedes.)
Reptiles. (Crocodili, Chelonii, Ophidii, Saurii, Pterodactyli, Simosauri, Plesiosauri,
Ichthyosauri.)
Batrachians. (Labyrinthodontes, Peromelia, Anura, Urodela, Lepidosirenia.)
Fishes. (Plagiostomi, Ganoidei, Teleostei, Cyclostomi, Leptocardii.)
II. Eprcorytepones or Epivireriians. (Articulata.) The vitellus enters the body from the dorsal
Cn.
side.
Insects. (Coleoptera, Nevroptera, Strepsiptera, Hymenoptera, Lepidoptera, Diptera, Orthop-
tera, Hemiptera, Thysanura, Parasita.)
Myriapodes. (Diplopoda, Chilopoda.)
Arachnides. (Scorpiones, Aranez, Acari, Tardigrada.)
Crustacea. (Decapoda, Stomapoda, Amphipoda, Isopoda, Lemodipoda, Phyllopoda, Lophy-
ropoda, Xiphosura, Siphonostoma, Myzostoma, and Cirripedia.)
III. Axiocotyirepones or ALLOVITELLIANS. (Mollusco-Radiaria.) The vitellus enters the body neither
Cr 10.
CLs
CL.
Cin
oie
CL.
11.
Le
13.
14.
15.
from the ventral nor from the dorsal side.
Mollusca. Including Cephalopoda, Gasteropoda, Pcecilopoda, and Brachiopoda. (Acephala,
Tunicata, and Bryozoa.)
Worms. (Malacopoda, Annelides, Siponculides, Nemertini, Nematodes, Acanthocephali,
Scoleides, Hirudinei.)
Echinoderms. (Holothuriw, Echinides, Stellerides, Crinoides, Trematodes, Cestodes,
Rotiferi, Planarie.)
Polyps. Including Tunicata, Bryozoa, Anthozoa, Alcyonaria, and Meduse, as orders.
(Ctenophore, Siphonophore, Discophore, Hydroids, Anthophoride.)
Rhizopods. Only the genera mentioned.
Infusoria. Only genera and families mentioned.
Van Beneden thinks the classification of Linnzeus truer to nature than either
that of Cuvier or of de Blainville, as the class of Worms of the Swedish naturalist
corresponds to his Allocotyledones, that of Insects to his Hypocotyledones, and the
four classes of Pisces, Amphibia, Aves, and Mammalia to his Hypocotyledones.
He compares his primary divisions to the Dicotyledones, Monocotyledones, and
Acotyledones of the vegetable kingdom. But he overlooks that the Cephalopods
pt a ea
ae
nn in da gd, let et: ea
a = ne ea
ESSAY ON CLASSIFICATION. } Part J.
are not Allocotyledones, and that any eroup of animals which unites Mollusks, Worms,
and Radiates in one ,great mass cannot be founded upon correct principles. As
to his classes, I can only say that if there are natural classes among animals,
there never was a combination of animals proposed since Linnzeus, less likely to
answer to a philosophical idea of what a class may be, than that which unites
Tunicata with Polyps and Acalephs. In his latest work, Van Beneden has introduced
in this classification many important improvements and additions. Among the
additions, the indication of the orders, which are introduced in brackets in the
diagram above, deserve to be particularly noticed. These changes relate chiefly
to the Mollusks and Polyps; the Tunicata and Bryozoa being removed from the |
Polyps to the Mollusks. The Acalephs and Polypi, however, are still considered
as forming together one single class.
The comparison, instituted by Van Beneden between his classification of the
animal kingdom and that of the plants most generally adopted now, leads me to
call again attention to the necessity of carefully scrutinizing anew the vegetable
kingdom, with the view of ascertainmg how far the results I have arrived at
concerning the value of the different kinds of natural groups existing among
animals," apply also to the plants. It would certainly be premature to assume,
that because the branches of the animal kingdom are founded upon different plans
of structure, the vegetable kingdom must necessarily be built also upon different
plans. There are probably not so many different modes of development among
plants as among animals; unless the reproduction by spores, by naked polyem-
bryonic seeds, by angiospermous monocotyledonous seeds, and by angiospermous
dicotylodonous seeds, connected with the structural differences exhibited by the
Acotyledones, Gymnospermes, Monocotyledones, and Dicotyledones, be considered as
amounting to an indication of different plans of structure. But even then these
differences would not be so marked as those which distinguish the four branches
of the animal kingdom. The limitation of classes and orders, which presents com-
paratively little difficulty in the animal kingdom, is least advanced among plants,
whilst botanists have thus far been much more accurate than zodlogists in charac-
terizing families. This is, no doubt, chiefly owing to the peculiarities of the two
organic kingdoms. a ta
It must be further remarked, that in the classification of Wan Beneden the
animals united under the name of Allocotyledones are built upon such entirely
different plans of structure, that their combination should of itself satisfy any
unprejudiced observer that any principle which unites them in that way cannot
be true to nature. |
1 See Chap. IL, p. 187 to 178.
Gum *iit. "~~ EMBRYOLOGICAL SYSTEMS. 229
DIAGRAM OF THE DEVELOPMENT OF ANIMALS BY KOLLIKER.
Koiimer, (A.,) in his Entwickelungsgeschichte der Cephalopoden, Zurich, 1844, 1 vol. 4to., p. 175,
has submitted the following diagram of the development of the animal kingdom.
A. The embryo arises from a primitive part. (Evolutio ex una parte.)
1°. It grows in two directions, with bilateral symmetry. (Evolutio bigemina.)
a. The dorsal plates close up. Vertebrata.
b. The dorsal plates remain open and are transformed into limbs. Articulata.
2°. It grows uniformly in every direction. (Evolutio radiata.) And
a. Incloses the embryonal vesicle entirely.
a. This takes place very early. Gasteropoda and Acephala.
6. This takes place late. (Temporary vitelline sac.) Limax.
b. Contracts above the embryonal vesicle. (Genuine vitelline sac.) Cephalopoda.
A. The whole body of the embryo arises simultaneously. (Evolutio ex omnibus partibus.)
1°. It grows in the direction of its transverse axis,
a. With its hind body. Radiata. (Echinoderms.)
b. With the fore body, and
a. The hind body does not grow. Acalephs.
B. The hind body grows longitudinally. Polypi.
2°. It grows in the direction of its longitudinal axis. Worms.
I have already shown how unnatural a zodlogical system must be which is
based upon a distinction between total or partial segmentation of the yolk. No
more can a diagram of the development of animals, which adopts this difference
as fundamental, be true to nature, even though it is based upon real facts. We
ought never to single out isolated features, by which animals may be united or sep-
arated, as most anatomists do; our aim should rather be to ascertain their general
relations, as Cuvier and K. E. von Baer have so beautifully shown. I think also,
that the homology of the limbs of Articulata and the dorsal plates of Vertebrata
is more than questionable. The distinction, introduced between Polyps and Acalephs
and these and the other Radiates, is not any better founded. It seems also quite
inappropriate to call the development of Mollusks, evolutio radiata, especially after
Baer had designated, under that same name, the mode of formation of the branch
of Radiates, for which it is far better adapted.
a Chap. TEL, tects” 2, 17s gegenseitige Verwandtschaft der Thiere zu erlangen,
2 The principles of classification advocated by die verschiedenen Organisationstypen
Baer are so clearly expressed by him, that I cannot von den verschiedenen Stufen der Aus-
resist the temptation of quoting some passages from bildung stets unterscheiden. Dass man diesen
the paper already mentioned above, p. 224, especially Unterschied gewohnlich nicht im Auge behalten hat,
now, when I feel called upon to oppose the views of scheint uns zu den sonderbarsten Zusammenstel-
one of his most distinguished colleagues. “Vor allen lungen gefiihrt zu haben.” Beitrage, etc., Acta
Dingen muss man, um eine richtige Einsicht in die Nova, vol. 13, -p. 739.
=
Se ee seagate bi acs
A i in Sa el oC A Ni
waitin inant
ore eee vere!
Contrast between the Embryo and the Yolk.
ve
Transformation of the whole Yolk into the Embryo.
No Ege.
ESSAY ON CLASSIFICATION.
CLASSIFICATION OF VOGT.
I. Verteprata. Yolk ventral.
Cu.1. Mammalia. 1°. Aplacentaria; Ord. Monotremata, Marsupialia. 2°. Placen-
taria’: “Seri, Ord. Cetacea, Pachydermata, Solidungula, Ruminantia, and Edentata ;
S. 2. Pinnipedia, Carnivora; 8.3. Insectivora, Volitantia, Glires, Quadrumana, Bimana.
- Aves. Ser. 1. Insessores; Ord. Columb, Oscines, Clamatores, Scansores, Rapta-
tores; Ser. 2. Autophagi; Ord. Natatores, Grallatores, Gallinacea, Cursores,
- Reptilia. Ord. Ophidia, Sauria, Pterodactylia, Hydrosauria, and Chelonia.
-4. Amphibia. Ord. Lepidota, Apoda, Caudata, Anura.
-9. Pisces. Ord. Leptocardia, Cyclostomata, Selachia, Ganoidea, Teleostia.
II. Arricutata. Yolk dorsal.
Ci. 6. Insecta. Subcl.1. Ametabola; Ord. Aptera. Subcl.2. Hemimetabola;
Ord. Hemiptera and Orthoptera. ‘Subcl. 8. Holometabola ; Ord. Diptera, Lep-
idoptera, Strepsiptera, Nevroptera, Coleoptera, Hymenoptera.
Ci. 7. Myriapoda. Only divided into families.
Ci. 8 Arachnida. Series 1. Pycnogonida and Tardigrada; Ord. <Acarina, Araneida.
Series 2. With three families. ;
Ci. 9. Crustacea. Subcl. 1. Entomostraca; Ord. Cirripedia, Parasita, Copepoda,
Phyllopoda, Trilobita, Ostracoda. Subel. 2. Xiph osura. Subel. 3. Podo ph-
thalma; Ord. Stomapoda, Decapoda. Subcl. 4. Edriophthalma; Ord. Le-
mipoda, Amphipoda, Isopoda.
III. Cepnaropopa. Yolk cephalic.
Ci. 10. Cephalopoda. Ord. Tetrabranchiata and Dibranchiata.
IV. Mottiusca. Irregular disposition of organs.
Cr. 11. Cephalophora. Swbel.1. Pteropoda. Subel. 2. Heteropoda. Subel.
3. Gasteropoda; Ord. Branchiata and Pulmonata. — Chitonida.
Cr. 12. Acephala. Subcl. 1. Brachiopoda; Ord. Rudista, Brachiopoda. Subel. 2.
Lamellibranchia; Ord. Pleurochoncha, Orthoconcha, Inclusa.
Cr. 13. Tunicata. Ord. Ascidiz, Biphora. )
Ci. 14. Ctenophora. Only subdivided into families.
Ci. 15. Bryozoa. Ord. Stelmatopoda, Lophopoda. j
V. VeRmeEs. Organs bilateral.
Cu. 16. Annelida. Ord. Hirudinea, Gephyrea, Scoleina, Tubicola, Errantia.
Ci.17. Rotatoria. Ord. Sessilia, Natantia.
Ci. 18. Platyelmia. 1° Ord. Cestoidea, Trematoda. 2°. Ord. Planarida, Nemertina.
Ci.19. Nematelmia. Ord. Gregarinea, Acanthocephala, Gordiacei, Nematoidei.
Molluscoidea.
VI. Rapiata. Organs radiate.
Cr. 20. Echinodermata. Ord. Crinoidea, Stellerida, Echinida, Holothurida.
Ci. 21. Siphonophora. Only subdivided into families.
Cn 2H ydromeduse. Not clearly subdivided into orders.
Ci. 23. Polypi. Ord. Hexactinia, Pentactinia, Octactinia.
VII. Protozoa.
Cu. 24. Infusoria. Ord. Astoma and Stomatoda.
Cu. 25. Rhizopoda. Ord. Monosomatia and Polythalamia.
ae
|
-
a
}
:
;
Cuap. IIL. EMBRYOLOGICAL SYSTEMS. 931
The classification of Vogt (Zoologische Briefe, q. a, p. 180) presents several
new features, one of which is particularly objectionable. I mean the separation ot
the Cephalopoda from the other Mollusks, as a distinct primary division of the
animal kingdom. Having adopted the fundamental distinction imtroduced by K@l-
liker between the animals in which the embryo is developed from the whole yolk,
and those in which it arises from a distinct part of it, Vogt was no doubt led
to this step in consequence of his interesting investigations upon Actzeon, in which
he found a relation of the embryo to the yolk differing greatly from that observed
by Kolliker in Cephalopods. But as I have already shown above, this cannot
any more justify their separation, as branches, than the total seementation of the
yolk of Mammalia could justify the separation of the latter from the other Verte-
brates. Had the distinction made by Vogt, between Cephalopods and the other
Mollusks, the value he assigns to it, Limax should also be separated from the
other Gasteropods. ‘The assertion that Protozoa produce no eggs, deserves no special
consideration after what has already been said in the preceding sections respecting
the animals themselves. As to the transfer of the Ctenophora to the type of
Mollusks, it can in no way be maintained. |
Before closing this sketch of the systems of Zodlogy, I cannot forego the
opportunity of adding one general remark. If we remember how completely inde-
pendent the investigations of K. E. von Baer were from those of Cuvier, how
different the point of view was from which they treated their subject, the one
considering chiefly the mode of development of animals, while the other looked
mainly to their structure; if we further consider how closely the general results
at which they have arrived agree throughout, it is impossible not to be deeply
impressed with confidence in the opinion they both advocate, that the animal king-
dom exhibits four primary divisions, the representatives of which are organized
upon four different plans of structure, and grow up according to four different
modes of development. This confidence is further increased when we perceive
that the new primary groups which have been proposed since are neither char-
acterized by such different plans, nor developed according to such different modes of
development, but exhibit simply minor differences. It is, mdeed, a very unfortu-
nate tendency, which prevails now almost universally among naturalists, with refer-
ence to all kinds of groups, of whatever value they may be, from the branches
down to the species, to separate at once from one another any types which exhibit
marked differences, without even inquiring first whether these differences are of
a kind that justifies such separations. In our systems, the quantitative element
of differentiation prevails too exclusively over the qualitative. If such distine-
tions are introduced under well-sounding names, they are almost certain to be
adopted; as if science gained any thimg by concealing a difficulty under a Latin
2 eee Sette cn lt na A OR aie ice
232 ESSAY ON CLASSIFICATION. Part I.
or Greek name, or was advanced by the additional burden of a new nomencla-
ture. Another objectionable practice, prevailing quite as extensively also, consists
in the change of names, or the modification of the extent and meaning of old ones,
without the addition of new information or of new views. If this practice is
not abandoned, it will necessarily end in making Natural History a mere matter
of nomenclature, instead of fostering its higher philosophical character. Nowhere
is this abuse of a useless multiplication of names so keenly felt as in the nomen-
clature of the fruits of plants, which exhibits neither insight into vegetable mor-
phology, nor even accurate observation of the material facts.
May we not return to the methods of such men as Cuvier and Baer, who
were never ashamed of expressing their doubts in difficult cases, and were always
ready to call the attention of other observers to questionable points, instead of
covering up the deficiency of their information by high-sounding words!
In this rapid review of the history of Zodlogy, I have omitted several classi-
fications, such as those of Kaup and Van der Hoeven, which might have afforded
an opportunity for other remarks, but I have already extended this digression
far enough to show how the standards I have proposed in my second chapter
may assist us in testing the value of the different kinds of groups generally
adopted in our classifications, and this was from the beginning my principal object
in this inquiry. The next step should now be to apply these standards also to
the minor divisions of the animal kingdom, down to the genera and species, and
to do this for every class singly, with special reference to the works of mono-
graphers. But this is such an herculean task, that it can only be accomplished
by the combined efforts of all naturalists, during many years to come.
Cambridge University Library,
On permanent deposit from
the Botany Sito As
e
-
ae
d
.
s
i
%
~
|
,
|
:
ij
ye
}
a. —— “ ata Ad
— Be
aoe <n a = ——— ~
eA
Vogue
nee
hatoe
i
nee
Prose eft a.
Bei
; a
is
casey
SHE
¥.
A
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11