

RHINOCEROS LEPTORHINUS. 393 



X. — Description of Lower Jaw of Ehinoceros Leptorhinus figured 



BY CORTESI. 1 



London, October 13, 1862. 



The description which follows is believed by me to be of the 

 missing lower jaw of Rhinoceros figured by Cortesi, and which Ca- 

 pellini tells me was discovered, since my visit, in a box at Parma, by 

 Strobelli. 



Among the marbles and polished stones of the Italian Court in the 

 London Exhibition of 1862 are two rami of the lower jaw, evidently 

 right and left of the same individual, of a fossil Rhinoceros, believed to 

 have been sent by Professor Scacchi of Naples. The left side is entire 

 from the ascending ramus to the symphysial margin, the condyle alone 

 being wanting. On the right side the anterior part of the ramus, as far 

 as the third premolar, has been crushed by a recent injury. The jaw is 

 evidently that of an adult animal, with six molars in situ, all of them 

 fully in wear, but the abrasion of the crown of the last true molar is 

 not very far advanced. There are six molar teeth out, but no appear- 

 ance of the socket of the pre-antepenultimate or first premolar. The 

 symphysial beak is perfect on both sides, with a very short diasteme, 

 which shows a doubtful trace of a socket for an incisor. 



Dimensions : — 



Length of the line of six molars, 9*25 in. Joint length of three true molars, 

 5-1 in. Ditto of three premolars, 3-9 in. Length of crown of last molar, 1'7 in. 

 Greatest width of ditto, 11 in. Length of penultimate, summit of crown, 17 in. 

 Greatest width of ditto, 1-2 in. Length of antepenultimate, 1'6 in. Length of 

 last premolar, 1-4 in. Ditto of penultimate ditto, 1-3 in. Ditto of antepenulti- 

 mate ditto, T05 in. Ditto from anterior edge of antepenultimate premolar to 

 incisive border, 17 in. Ditto of diastemal ridge, 0'65 in. Height of ramus under 

 penultimate premolar, 2-4 in. Ditto at middle of last true molar, 2-9 in. Greatest 

 thickness of ramus (aboiit), 2-1 in. 



The first premolar is not very far advanced in wear, the anterior 

 part of its crown being still intact ; the penultimate is further ad- 

 vanced, having both barrels worn so as to have confluent discs. The 

 last premolar is nearly in the same state of wear, but less advanced. 

 The first true molar is worn very low into a uniform sinuous depressed 

 disc. The second is less worn, showing a horse-shoe pattern to the 

 front division, confluent with a simple cornu to the hind division. The 

 last molar has the anterior and posterior discs quite distinct and at dif- 

 ferent levels, the anterior one showing a disc of a form between a sagit- 

 tate and horse-shoe pattern ; the hinder disc forms a narrow band, but 

 slightly curved into a kind of clavate form and at a much lower level 

 than the anterior. Regarded from the outer side, the anterior barrel of 

 the last true molar and of the penultimate shows distinctly the oblique 

 crenate bourrelet indicated by De Christol in his R. megarhinus. On 

 the right side the same bourrelet is shown on the premolars still more 

 distinctly. The enamel surface is comparatively smooth, as in R. me- 

 garhinus, and perfectly free from the reticular inequalities so boldly 

 shown in R. tichorhinus. On the inner side it is perfectly smooth and 

 shows occasionally the parallel lines characteristic of R. megarhinus 



1 This is evidontly a different lower jaw from that already described. — [Ed.] 



