. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. PACHYDERMATA. 867 transitional species, extinct, such as the Macrauchenia, the adult Rhinoceros no traces of canine teeth are visible, but Professor Owen succeeded in de- tecting their existence in a rudimentary condi- tion in the mature fetus of the Rhinoceros Indicus, although both the teeth and their sockets disappear at a very early age. The vast hiatus which in the series of existing Mammals divides the Rhinoceros from the Tapir, and this from the Elephant, was once filled up by interesting which have long become Pu
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. PACHYDERMATA. 867 transitional species, extinct, such as the Macrauchenia, the adult Rhinoceros no traces of canine teeth are visible, but Professor Owen succeeded in de- tecting their existence in a rudimentary condi- tion in the mature fetus of the Rhinoceros Indicus, although both the teeth and their sockets disappear at a very early age. The vast hiatus which in the series of existing Mammals divides the Rhinoceros from the Tapir, and this from the Elephant, was once filled up by interesting which have long become Pulieotherium and the Lophiodon, Coryp/iodon, and others requiring no particular notice in this place. But that most extraordinary of extinct Pachyderms, the Dinotherium, must not be so lightly passed over, inasmuch as its dentition appears to have been quite unique in character, as may be seen on reference to fig. 478, which represents the lower jaw of this gigantic quadruped. From this it will be seen that the molar and premolar teeth resemble in some respects those of the Mastodon; but the great peculiarity of the Dinotherium exists in its tusks projecting from the lower jaw. These tusks are two in number, implanted in the prolonged and deflected sym- physis of the lower jaw, in close contiguity with each other, and having their exserted crown directed downwards and bent backwards, while their deeply implanted base is excavated by a wide and deep conical pulp cavity, like the tusks of the Mastodon and Elephant. No such tusks nor germs of such have yet been discovered in the upper jaw, so that it is highly probable that this gigantic Pachyderm was of aquatic habits, like the Hippopotamus, and that its tusks served to detach and tear up by the roots the aquatic plants upon which it fed, as well as for weapons of defence or combat. No family of Mammalian Quadrupeds has suffered more from the destructive operations of time than that of the Proboscidian Pachy- dermata. Two species
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