MAMMALIA. 
i 
152 
ever, from within the true maxillaries— or they are directed outwards, as in the Pigs and Hippopotami. The 
composite structure of the molars, from which this order takes its name, attains its most remarkable develope- 
ment in the present division, as observed in the Elephant, the Capybara, and the Phascochcere. They have rarely i 
fewer than four, and often five distinct toes on each foot ; and generally a cleft upper lip, less observable when the 
nose is prolonged into a snout, or proboscis. They separate into Proboscidia, Rodentia, Chcerodia, and Syrenia. 
The close affinity of the Prohoscidia and Rodentia was distinctly pointed out and descanted upon by Cuvier in 
his Ossements Fossiles, to which valuable work the reader is necessarily referred, from want of space to enlarge j 
upon the subject here. The tusks of the Prohoscidia are mostly peculiar to the upper jaw, where they attain i 
enormous dimensions, being small when present in the lower one. Their form is cylindrical, with conically- ’ 
pointed tips, and they are surrounded with enamel.* 
The Rodentia have approximated tusks in both jaws, with enamel only in front ; and the Hares alone among 
them possess true incisors in the upper jaw only, in front of which the tusks pass, protruding in their usual site 
throughout the group. They have neither an elongated snout nor a proboscis ; and their extremities are unguicu- 
lated. In the Hare, which has six rootless molars, the three first alone are preceded by rooted milk teeth ; and 
the anterior molar, in numerous other genera, the adults of which have four, is in like manner preceded by a 
deciduous rooted tooth, which is shed about the time the last posterior molar protrudes through the gum. 
The Chcerodia have always incisors, their tusks, of similar kind to those of the two preceding groups, being 
directed outwards, and those of the upper and lower jaws generally rubbing against each other. The Swine and 
Hippopotami are characteristic examples ; and we are disposed to refer to this division (as a distinct minor group), 
the very singular genus Hyrax, the adults of which do not possess canines. 
Lastly, the Syrenia, or Cetacea herbivora, Cuv., which have no posterior extremities, like the Isodontia, are 
likewise deprived of canines, at least the existing genera ; for the Deinotherum (assuming that this lost genus is 
correctly placed here) had enormous tusks in the lower jaw only, anomalously turned downward. Their general 
anatomy leaves no doubt of the propriety of separating them altogether from the Isodontia, or zoophagous 
Cetacea, and allies them (we consider) most nearly to the Chcerodia. 
The Ungulata, or grazing animals, divide, according to the simple or complex stomach, mXoBellua & Ruminantia. ’■ . 
The Bellua consist of the Horses, Tapirs, Rhinoceroses, and proximate fossil genera ; all of which now existing t 
have a prehensile upper lip more or less developed, the nostrils being prolonged with it into a short flexible pro- " 
boscis in the Tapirs, and there is reason to conclude in many of the extinct forms. The true and false molars \\ 
present no sensible diffterence in the adult animal ; but the dentition of the young proves that the normal comple- ' 
ment of true molars is not exceeded. 
The Ruminantia fall into Ancerata and Pecora ; the former consisting of the Camels and Llamas, which have a 
cleft and prehensile upper lip, and claw-like hoofs upon which they do not rest ; and the latter of the remainder, 
which have the upper lip entire and non-prehen sile, (the tongue becoming so in its stead,) and the ends of their 
toes encased in hoofs, upon the soles of which the weight of the body is supported. The former alone possess any 
superior incisors, though only one pair ; but all have six incisors in the lower jaw, together with inferior canines, 
which in the Pecora assume the form and direction of incisors, but the true analogy of which appears on com- 
parison of them with the lower canines of either the Bellua or Ancerata, and of the Bactrian or Two-humped 
Camel in particular, which has no interspace (as in the others) between its lower canines and incisors. 
The Aplodontia, or abnormal division of the phytophagous type, corresponding to the Edentata of Cuvier, is 
now in course of becoming unexpectedly elucidated by the extraordinarily rapid discovery of fossil genera in South 
America, which present a more complicated form of molar tooth than was previously known in this division, as 
exemplified by the newly established genera Mylodon, Glyptodon, and we venture to suggest — Toxodon, 
wherein the indentations of the enamelled sides of the teeth resemble those of many rodents. However numerous 
may be the false molars in certain genera of this division, the number of their true molars appears in no instance 
to exceed three, (at least in those which we have been able to examine, comprehending all with the unfortunate 
exception of Priodon) ; and the structural distinction between their true and false molars is sufficiently evident. 
Of the two Ovo-viviparous orders, there is only space left to remark, that whereas the Placental Carnivora and 
Herbivora are (as we have seen) modified upon two distinct types, which do not pass into each other, the Marsu- 
pial Carnivora and Herbivora pertain to the same equivalent type, and grade into each other so that an analogous 
line of rigid demarcation cannot be traced. This perhaps may be added to the various indications of their 
abnormity as a group, as compared with the preceding or Placental subclass of Mammalia. 
In conclusion, it may here be noticed, that without intending any thing of the kind while gradually ascending 
to the foregoing classification, it has so happened that species with superior intelligence in conformity with their 
cerebral developement are placed at the head of each principal group, which may or may not be fortuitous coinci- 
dence. Thus, Man ranks at the head of the most highly organized order — Typodontia, the Dolphin at the head of 
the Isodontia, and the Elephant at that of the great phytophagous division, and, consequently, of the Diplodontia; , 
while the Dog ranges first among the Secundates, and the Horse first of the Ungulata. The leading genus of the 
Aplodontia may yet remain to be discovered. The animals here mentioned (at least the terrene kinds, for of the 
Dolphin we do not possess the requisite data for forming an opinion), certainly appear to possess more eminently 
culturable intellects than any others, such as may be applied to purposes having no relation to their natural 
habits ; and Man has accordingly been enabled to gain them as assistants in his various labours and occupations.] 
* It may be that the Proboscldia supply an exception to the other- 
wise universal rule of placental Mammalia having never more than 
three pairs of true molars in either jaw ; but we suspect that such 
seeming exception would upon analysis prove to be more apparent than 
real, the last of them being probably analogous to the teeth which 
human beings sometimes develope when in vigorous senility ; theoreti- 
cally, a renewal of their predecessors. 
