4 13 
Animals without vertebra? never respire* by 
cellular lungs ;, and in no instance have they 
voice : their jaws have various directions, and 
often their mouths are merely suckers ; they 
have neither kidneys nor urine ; if they have 
articulated members they are always at least 
six in number. The invertebral animals 
maybe divided into five classes; the mol- 
lusca, Crustacea, insects, worms, and polypi 
or zoophytes. 
First order of invertebral animals, forming 
the fifth general class — Mollusc a. 
The body of the mollusca is soft, fleshy, 
and destitute of articulated members: some- 
times they have hard parts situated internally. 
They respire by branchiae. Their brain is a 
distinct mass, from which proceed the nerves 
and a medulla oblongata. They have gang- 
lions. Their external senses vary with re- 
spect to number. In some the eyes and ears 
are perceptible, while in others we are not 
capable of detecting any other senses than 
those of taste and touqh. Many of the mol- 
lusca can masticate, while others can merely 
swallow, This class of animals has a volumi- 
nous liver, which secretes a large quantity of 
bile. Their generative organs are exceedingly 
various. 
Sixth class — Crustacea. 
In the Crustacea the body is covered with 
scales: .these animals have often a consider- 
able number of articulated members ; their 
nervous system is composed of a long knotted 
cord, from the ganglions of which all the 
nerves are distributed. The Crustacea have 
hard moveable eyes ; their ears are very im- 
perfect in their organization : the sense of 
touch is furnished by antenna? and feelers, as 
in insects : they have a heart with arterial 
and venous vessels, and they respire by 
branchiae : their jaws are transverse, strong, 
and numerous ; teeth are found in the sto- 
mach ; a number of intestinula emea afford a 
brown fluid, which appears to supply the 
office of bile. The male of the Crustacea 
lias two penes, the female two ovaria. 
Seventh class — Insecta. 
Insects have antennae and articulated 
members, like the Crustacea. Some of these 
animals have wings, in which case they have 
existed in different forms, and in certain 
stages of their existence have been entirely 
motionless. Insects have a nervous system, 
like that of the Crustacea ; they have, how- 
ever, neither heart nor vessels, and respire 
only by trachea?. Not only the liver, but all 
the secretory glands, are in insects replaced 
by. long vessels, which float in the abdomen. 
As the animal passes through its different 
states, of existence, the form of the intestinal 
canal varies considerably in the same in- 
dividual. i 
Eighth class — Vermes. 
These animals, which greatly resemble the 
insect tribe, might be joined with insects, 
but they do not undergo a metamorphosis. 
Some of them have a distinct vascularity, 
and they may be regarded as forming an in- 
termediate class between the mollusca, Crus- 
tacea, and insects ; such are the terrestrial 
worms, and leeches. 
A inlh class — Zoophyta. 
The parts of the body in this class of equi- 
vocal animals are formed like the radii of a 
7 
COMPARATIVE ANATOMY. 
circle, in the centre of which the mouth is 
1 1 iced. The anatomist has not hitherto 
been able to trace in the zoophytes, heart, 
blood-vessels, brain, or nerves. 
The following table will present at one 
view, without the necessity of detail, the 
various subdivisions of the classes of animals 
above described. To render this descrip- 
tion more intelligible, the Linmran classifi- 
cation and generic names of animals have 
been connected with the anatomical divisions 
and nomenclature, 
M AMMALIA. 
A. With nails. 
a. Having each kind of teeth. 
I. Thumbs only separate on the superior ex- 
tremities. — Germs homo; of the primates 
of Linnaeus. — Bimana. 
II. Thumbs separate on all four feet. — Gene- 
ra simia, lemur ; primates Linnai. — Qua- 
drumana. 
III. On the fore feet, no thumbs separate. 
1. Hands elongated; membranes from the 
neck to the anus. — Gen. vespertilio, ga- 
leopithecus ; primates Lin. — Chirop- 
tera. 
2. The whole of the soles of tire feet rest- 
ing on the ground.— -G. erinaceus, sorex, 
talpa, ursus; ferm Lin. — Plantigrada. 
3. Feet resting only on the toes. — G. 
mustela, viverra, f el is, canis ; ferae Lin. 
— Carnivora. 
4. Thumbs separate on the hind feet. — 
Genus didelphis; ferae Lin. — Pedirnu- 
na. 
b. Without some kinds of teeth. 
IV. Without canine teeth. — G. kangarus, 
hystrix, lepus, cavia, castor, sejurus, chei- 
oromys, mus; glires Lin. — Rodentia. 
V. With no incisive or canine teeth. — Gen. 
myrmeeophaga, orycteropus, dasypus ; 
bruta Lin. — Edentula. 
VI. Without incisive teeth. — G. bradypus ; 
bruta Lin. — Tardigrada. 
B. With hoofs. 
VII. More than two toes and two hoofs. — 
G. elephas; bruta Lin. Sus, hippopota- 
mus, hyrax, and rhinoceros ; beliuae Lin. 
— Pachodermia. 
VIII. With two toes and hoofs. — Pecora 
Lin. — Rurhinanlia. 
IX. One toe and one hoof. — G. equus ; bel- 
luai Lin. — Solipeda. 
C. With finny feet. 
X. Four feet. — G phoea ; ferae Linnaei : and 
trichecus, bruta Lin. — Amphibia. 
Aves. 
I. Feet short, toes with long claws, beak 
hooked. — Accipitres Lin. except lanius. — 
Accipitres. 
II. Four toes, three anterior and one behind; 
external toes entirely or partially joined. 
— G. laneus ; passeres Lin. except coltim- 
ba, and some of the pica?. — Passeres. 
III. T wo anterior toes and two behind. — 
Part of the G. pica: Lin. Scans ores . 
IV. Anterior toes united at their base by- a 
short membrane. — Gallinae, and some of 
the gralla*, Lin . — Gallinae. 
V. Legs long and naked. — Most of the gral- 
la? Lin. — Gralla. 
VI. Toe united by extensive membranes. — 
Anseres Lin. — Arise res. 
Reptiles. 
A. Heart with two auricles. 
I. Upper part of the body enveloped by shell, 
jaws covered with horn.— G. testudo ; rep- 
tiles pedati Lin. — Chelonii, 
II. Body covered with scales, teeth. — Rep- 
tiles pedati Lin. — -Saudi . 
B. Heart with only one ventricle. 
III. Body covered with scales, no feet, no 
branchiae at any period. — Serpentes apo- 
des Lin. — Ophidii. 
IV. Skin naked, feet, branchia? in the first pe- 
riod. — Reptiles pedati Lin. — Batrachii. 
Pisces. 
A. Skeleton cartilaginous. 
I. Branchia? fixed. Part of the amphibia 
nantia Lin. — Chondropterygii. 
II. Branchia? loose. Part of the amph. nan, 
Lin. — Branchiostegi. 
B. Skeleton bony. 
III. .No ventral fins. — Apodes Lin. — Apo~ 
des. 
IV. With ventral fins anterior to the pec- 
toral. — Jugulares Lin. — Jugular es. 
V. Ventral Tins below the pectoral. — Tho- 
racici. — Thor acid. 
VI. Ventral fins behind the pectoral. — Abdo? 
minales Lin. — Abdomiiiales. 
Mollusca. 
I. Head with tentacula supplying the place 
of feet. — Sa?pia belonging to the mollusca, 
and argonauta and nautilus to the cochlea*, 
Lin. — Cephalopoda. 
II. Head free, and which craw! on the belly. 
— Cochlea? Lin. — Gasteropoda. 
III. Without a distinct head. — Principally 
conch* Lin. — Acephala. 
Crustacea. 
I. ■ Monuculus. 
II. Cancer. 
Insecta. 
A. With jaws. 
I. No wings. — Gnathaptera. 
II. Four reticulated wings. — Neuroptera. 
III. F 'our veined wings. — Hymenoptera. 
IV. Four wings, superior hard, inferior fold- 
ed transversely. — Coleoptera. 
V. Four wings, superior hard, inferior folded ' 
longitudinally. — Orthoptera. 
B. Without jaws. 
VI. Four wings much crossed, rostrum ar- 
ticulated. — Hemiptera . 
VII. Four wings covered with scales, trunk 
spirally convoluted. — Lepidoptera. 
VIII. Two wings only. — Diptera. 
IX. No wings. — Aptera. 
Vermes. 
I. With external organs of respiration, and 
hairs on the sides of their bodies. — Some 
of the mollusca, and some of the testacea, 
Lin. 
II. Without external organs of respiration. 
1. Hairs on the sides of the body. — Nais, 
lumbricus, thallaserna. 
2. No hairs on the side of the body*. — Hi- 
rudo, fasciola, planaria, gordius. 
Animals bearing a resemblance to the 
vermes, the organization of which is not suf- 
ficiently known to determine whether they 
belong to that order, or ought to form one 
contiguous to the zoophyta. 
1st family. — Tenia, hydatigenia, ligula, 
linguatiula. 
2d' family. — Ascaris, and some other intes- 
tinal worms. 
Zoophyta. 
A- Not attached. 
I. With a calcareous or coriaceous envelope, 
and intestines floating in the interior ca- 
vity. — Echinodennia . 
