266 ON PLATYGONUS COMPRESSUS : 



cording to Cuvier), the same foramina are on the edge of the orbit. 

 The fragment of malar and lachrymal bones is represented in a 

 side view (fig. 6), to show the flatness of the external surface, and 

 also a small foramen ; the other parts are lettered as above. 



Fig. 7 is the lower jaw. It is very deep ; the articular surface 

 is placed obliquely, and formed as in Sus and Dicotyles ; but the 

 anterior margin is less prominent from the neck of the condyle at 

 its external part ; there is also a small external fossa (a, fig. 7), 

 which does not appear in the animals just mentioned. The line 

 from the condyle to the posterior molar is three fourths of an inch 

 longer than in Dicotyles torquatus, and passes more obliquely in- 

 wards ; which corresponds with the great posterior expansion men- 

 tioned in describing the cranium. Below the molars the bone swells 

 out slightly, but not so much as in Dicotyles ; the inferior margin is 

 rounded, and but little attenuated : it is deeply concave in a longi- 

 tudinal direction ; this form is caused by the expansion of the angle 

 of the jaw. The expansion commences at a point immediately 

 below the anterior lobe of the posterior molar ; it does not extend 

 backwards to form a process or hook, as in Carnivora and Roden- 

 tia; nor does it interrupt the slight but regular concavity of the 

 posterior margin, which is thin, and destitute of any prominent 

 lines. The expanded part is very concave on the outer surface ; 

 the inferior margin is rounded, as in the figure, and projects far 

 outwards, especially anteriorly.* Towards the fractured end the 

 bone is expanded, and has a large cavity for the reception of a ca- 

 nine (fig. 8) ; but as this cavity is filled with the same hard cement 

 which envelops many of the specimens, it is impossible to judge of 



* The perspective of this part of the figure is not good ; the anterior part of the 

 expansion (towards the dotted line) should be in higher relief. 



