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XXIV. On the Development and Homologies of the Molar Teeth of the Wart-Hogs 
(Phacochcerus), with Illustrations of a System of Notation for the Teeth in the 
Class Mammalia. By Professor Owen, F.R.S. 8^c. 
Received November 12, 1849, — Read February 7, 1850. 
In a paper by Everard Home, Esq., read before the Royal Society, May 30, 1799, 
some observations were communicated upon the form, structure and succession of 
the teeth of the Wart-Hogs of Africa, now included in the genus of the Hog-family 
called Phacochoerus, but noticed in that paper as a single species under the name of 
Sus JEthiopicus. The observations are illustrated by two plates. The first (tab. xviii.) 
gives “a side view of the skull of the Sus jF,thiopicus (half the natural size), to show 
the situation and appearance of the large grinder, and the remains of the alveoli be- 
longing to the fangs of the preceding one*.” The second (tab. xix.) gives a “ side view 
of the skull of the young Sus jFthiopicus, to show the mode in which the grinders 
come forward as the large one increases in size-l-.” This plate includes also a side 
view and a transverse section of the crown of the large full-grown grinding tooth. 
The conclusions drawn from the facts given are, that the Sus Hlthiopicus resembles 
the Elephant “ in the whole number of grinding teeth belonging to each side of the 
jaw being confined in a case of bone, so as to form one large grinding surface, and 
the teeth being pushed forward from behind, instead of a second set being formed 
immediately under the fangs of the first, as in other animals ; which are peculiarities 
not met with in any teeth hitherto described, except those of the Elephant^,” The grind- 
ing teeth of the Sus H^thiopicus are described to be four in number on each side of 
the jaw”§ ; the fourth or last large tooth is considered to be a second set of teeth, 
which, as it advances forwards, pushes the other teeth before it ; the most anterior 
of these, as soon as its body is worn away, has its fangs removed by absorption and 
drops out : the same thing takes place with the second and third ; and, in this way, 
room is made for the large one to supply the place of all the others Ij.” The mode in 
which they succeed one another is stated to be illustrated by the side view of the jaw 
given in tab. xix., in which the fangs of the different teeth are exposed. 
I have shown in my ‘Odontography’ that the facts detailed in Home’s paper were 
insufficient to enable him to explain all the necessary circumstances respecting the 
curious mode of dentition of the Wart-Hogs ; that other stages of dentition, unknown 
to that author, had demonstrated a second set of teeth formed under the fangs of some 
* Philosophical Transactions, 1799, p. 256. t Ibid. p. 257. + Ibid. p. 247. 
§ Ibid. p. 250. II Ibid. p. 250. % Voi. i. p. 554. 
MDCCCL. 3 Q 
