506 



FAUNA ANTIQUA SIVALENSIS. 



Fig. 1 a.- 



The orbit is not elevated 



-Lateral view of same specimen, 

 above the plane of the frontal. 



Fig. 1 h. — Palatine view of same specimen, showing three molars and 

 one premolar. The absence of the trefoil wear of the coronals is to be 

 noted. Each pair of collines takes a crescen tic form outwards, not un- 

 like that of ruminants, and the grinding surface slopes outwards, as in 

 the description given hy Cuvier of Hippopotamus minutus} 



Fig. 1 c. — Posterior or occipital view of same specimen. 



Figs. 2, 2 a, and 2 b. — M. dissimilis (var. major'). Imperfect cranium 

 including muzzle. Lateral, upper, and palatal views. — B.M. 



Figs. 3, 3 a, and 3 h. — M. dissimilis (var. major'). Cranium ; upper, 

 palatine, and lateral views, showing three molars, four premolars, and 

 canines. The second left and first right premolars have dropped out. 

 The left canine is seen to be remarkably curved downwards, first out- 

 wards and forwards, and then sHghtly backwards. — B.M. (Eeproduced 

 in PI. XIIL figs. 1 and 2.) 



Figs. 4, 4 a, 4 h, and 4 c. — M. dissimilis (var. major). Lower jaAV, 

 right side ; outer, upper, and inner views. The alveoli of three in- 

 cisors and first three premolars are empty ; the three molars and fourth 

 premolar are present, but, excepting hindmost molar, are well worn ; 

 the canine is curved upwards and outwards and slightly backwards at 

 the tip ; it is pear-shaped on section, as in Hipp. Sivalensis. The de- 

 scending process is well seen, and is separated from the horizontal ramus 

 by a considerable indentation. The anterior extremity of the horizontal 

 ramus is much more oblique than in H. Sivalensis, and the junction of 

 the lower with the anterior margin, corresponding to the lower end of 

 the symphysis, is marked by a distinct tuberosity or projection down- 

 wards (x). One large mentary foramen is seen on outer surface below 

 the foiirth molar, and between this and the canine the bone is deeply 

 channelled ; the molar ridges are almost parallel, and there is very little 

 widening of the symphysial portion of the jaw. The great peculiarity 

 of the jaw is the general slenderness of its proportions and the ineqiiality 

 of its depth. From the descending process it first becomes deeper, and 

 then it gradually diminishes towards the symphysis. In Hij)p. Sivalensis 

 the jaw is straight, thick, and massive, as in Plate LXI. 3, 4, 5. — B.M. 

 (Reproduced in PI. XIIL figs. 3 and 4.) 



Figs. 5, 5 a, and 55. — M. dissimilis (var. minor ?). Cranium; upper, 



• ' In the true molars of the Mcryco- 

 potannis, the inner demi -cones are simply 

 convex, and the two grooves on the outer 

 arcs form a deep external depression, at 

 the bottom of which is the convex ridge. 

 The antero-posterior cleft, instead of 

 being straight, as in the Hippopotamus, 

 forms two bends convex inwards, and 

 thus the symmetrical pattern of the 

 Hippopotamic molar is converted into 

 the double-crescentic arc of the Eumi- 

 nant molar. The cement at the bottom 

 of the valleys is thinner than in the 

 Euminants ; the enamel is as rugose as 

 in the Giraffe or Sivathere ; but the 



strong ragged ridge along the inner half 

 of the base of the crown forms the chief 

 distinction between the molars of the 

 Merycopotamus and those of the Eumi- 

 nant. The teeth in the lower jaw make 

 a similar approximation to the Eumi- 

 nant type, but the anterior and posterior 

 primary divisions are separated by a 

 wider cleft ; the last molar has a third 

 hinder lobe ; the lower molars are im- 

 planted by two roots. The forms, pro- 

 portions, and relative position of the 

 canines and incisors closely accord with 

 the Hippopotamic type of these teeth.' 

 Owen's 'Odontography,' i. 566. 



