RODENTS FROM THE SIWALIKS. 
5—109 
pm. 4. m. 1. m. 2. m. 3. 
Fig. 4. Hystrix drahmis. Fragment of the 
right ramus of the mandible ; from the Siwaliks of 
Asnot, Punjab. Indian Museum (No. D. 96). -j- 
//. refossa, Grcrvais' from the miocene of Issoire ; referred by Bravard^ to Basyprocta) 
II. primiyenia^ (Wagner) from the Pikermi group ; and H. venusta, Leidy/ from the 
pliocene of North America. An unnamed form has also been obtained from the 
pliocene of the Val d’Arno ; and another from Sicily.^ 
Species : Hysteix sivalensis, nohis. 
History. — The occurrence of a Siwalik porcupine is mentioned in the memoir 
by Sir. W. E. Baker already quoted, and in Falconer’s notes.® A fragment of a 
mandible has been noticed by the present writer under the name of H. sivalensis I 
Mandible. — The above mentioned fragment of the mandible is represented in the 
accompanying woodcut (fig. 4), and was obtained by Mr. Theobald from the Siwaliks 
of the Punjab. It consists of the middle portion 
of the right ramus, and shows mW and ni72 in 
a middle stage of wear ; the croAvn of pm. 4 
has been broken off, and m. 3 has fallen from 
its alveolus, which is filled with matrix. The 
specimen is considerably larger than the jaw of 
H. hirsutirostris, and it is, therefore, evident 
that among the living forms it is only necessary 
to compare it with that species and II. cristata. The structure of the cheek-teeth 
is of the same complex nature as those of the living species. The broken base of 
pm. 4 shows, however, that this tooth was inserted by three distinct roots f which 
from the state of wear of m. 1 must evidently have been situated only just below the 
lower extremity of the external enamel-fold. In the existing species the roots of 
this tooth are never so distinctly developed as in the fossil, and are situated at a 
distance of more than half-an-inch below the latter fold. The alveolus of pm. 4 in a 
jaw of the existing species in the same stage of wear, exhibits a large single cavity, 
without the slightest trace of any division. Precisely similar conditions prevail in 
the true molars, the roots being distinctly visible on the outer side of mTl,® in which 
there is an interval of less than a quarter-of-an-inch between their commencement and 
the inferior extremity of the external enamel-fold, the same interval being more than 
half-an-inch in length in the smaller tooth of II. hirsutirostris. In consequence of the 
short crowns of the cheek-teeth the hinder part of the incisive alveolus is placed 
1 “ Zoologio et Falcontologie Francjaises,” 2nd ed., pp. 17, 18, pi. XLVIII., fig. 11. 
2 Vide Pomel, “ Cat. Meth. Vert. Foss.,” p. 32. 
3 Vide Gaudry, “ Animaux Fossiles et Geologie de I’Attique,” p. 122, pi. XVIII., fig. 2. 
4 “ Extinct Mammalian Fauna of Dakota and Nebraska,” ^ Journ. Ac. Nat. Sci. Thiladel' ser. 2, vol. VII., p. 343, 
pi. XXVI., fig. 23 (1869). 
5 Vide, Gaudry, op. cit. p. 126. 6 “Pal. Mem.” vol. 1, p 2-3. 7 “ Eecords,” vol. XI., p. 100, (1878). 
8 The large size of the alveolus of this tooth, and the well-worn condition of the true molars, shows that the former 
could not have been a milk -molar. 
9 The crown of mTT accidentally broke off during description, when the roots were very distinctly exhibited. 
B 
