52 



the penultimate one arc more or less broken away. The basal half of the crown of the 

 long and large terminal premolar (/; 4) shows its two roots one before the other. If the 

 succeeding teeth have their root divided, the fangs must stand on the same transverse line, 

 one on the inner side of the other. The fore part of the base of the coronoid projects, 

 ridge-like, curving forward to subside upon the outer surface of the ramus, as in the type- 

 jaw (tig. 15 a). The base of the ascending branch extends straight backward to a like 

 degree, and there is a similar slight indent at or above the angle («), dividing this from 

 the ridge (b), which would end in the condyle. 

 The size is the same in both specimens 



The apparent slenderness and separation of the crowns of the molars (in the figure) is 

 due so much to the degree of exposure of the specimen that I do not feel the ground safe 

 for proposing specific distinction. 



[n PI. Ill, fig. 2, nat. size (2 a, magn. 3 diam.), are shown the outer side of a portion 

 of the left mandibular ramus of Stylodon pusillus, with the seven molars and part 

 of the last premolar. This specimen gives another example of the mandibular molar 

 characters of the present genus and species. I figure it because it shows better than 

 in any of the foregoing specimens the angle at which the fore part of the coronoid 

 process arises in this species. The last two molars progressively diminish in size; the 

 crowns of the fourth and fifth are the highest. 



The Becklesian collection, containing the counterpart slab with the impression of the 

 above fossil, indicates its fragmentary state when imbedded in the fresh-water marl, 

 and confirms the idea which was derived from inspection of the type-fossil. 1 



Another variety of Stylodon pusillus is exemplified in the portion of the left man- 

 dibular ramus, showing the outer side, with the last premolar and six following molar 

 teeth in situ, forming the subject of PI. Ill, fig. 3, and fig. 3 a. 



The second and sixth molars have longer crowns, for example, than in fig. 2. The 

 generic and specific characters of the type-jaw (PI. II, fig. 15) are, however, instructively 

 repeated in the extent of the dentition here displayed. 



There is a small outlet of the dental canal below the interval between the penulti- 

 mate and last premolars and another foramen in advance. 



Species 2. — Stylodon robustus, Owen. Plate III, figs. 1, 1 a. 



The present example (PL III, fig. 1, nat. size ; 1 a, magn. 3 diam.) shows a Stylodon 

 with a deeper and more robust character of jaw than the preceding specimens. It 

 consists of a left mandibular ramus, mutilated at both ends, with ten of the molary 

 series in situ, one only wanting the crown ; the outer side is exposed. The foremost 



'Geol. Mag.,' loc. cit., p. 199. 



