Vertebrate Remains 
98 Dr. C. W. Andrews 
beneath the cheek-teeth. It is, however, seen from the present 
specimen (Fig. 1) that the condition of things was even more 
remarkable than was supposed, and that the hook-like process was 
merely the thickened antero-inferior border (/.b.) of a large bullate 
expansion (/foss.) of very thin (1-2mm.) bone projecting outwards 
and forming a large prominence on the postero-inferior portion of the 
mandibular ramus. Superiorly this is continuous with the outer face 
of the narrow thickened alveolar part of the ramus; it is convex 
externally and concave internally. Posteriorly it is strengthened on 
the inner side by a rounded vertical buttress (p.d.) of bone situated 
about the level of the talon of m. 3. What the function of this 
inflated expansion of the lower portion of the mandible may have been 
it is difficult to conjecture. It may possibly have lodged a very large 
salivary gland or some kind of buccal sac, perhaps connected with the 
vocal organs. Another peculiarity of this specimen is that behind the 
Fie. 1.—Geniohyus mirus. Right ramus of mandible from the inner side. The 
portion of the figure behind the black line is drawn from the new specimen ; 
the anterior portion and the ventral border is from the type-specimen. 
for. line showing the position of the foramen perforating the base of the 
ascending ramus; joss. the inner concave surface of the bullate expansion ; 
i. 1; base of first incisor; 7.b. ventral thickened border of mandible; /.r. 
broken anterior end of the right ramus of the mandible; m. 1-3, molars ; 
y.6. posterior buttress; ym. 1-4, premolars; sym. symphysial portion of 
mandible. nat. size. 
last molar there is a foramen that perforates the base of the ascending 
process and opens on the inner side of the jaw; so far as I am aware, 
this only occurs in the Hyracoidea, and its presence here suggests the 
possibility that. Gencohyus may have some relationship with that group, 
though from the cheek-teeth alone it would certainly be regarded as 
not remotely related to the Suide. The teeth are well preserved, and 
agree precisely in structure with those of the type-specimen, though 
slightly more worn. The talon of m. 3 is complete. It is large and 
composed of a large main cusp, on the antero-internal side of which is 
a small accessory tubercle. The valley between the talon and the 
body of the tooth is partly filled by an accessory tubercle of the 
postero-external main V. 
