EDENTATA OF THE SANTA CRUZ BEDS. 21 



foramen rotundum and behind this, on the same horizontal line, is the 

 foramen ovale. A large, irregular opening in front of the tympanic ring 

 probably includes both the eustachian canal and the foramen lacerum 

 medium, while the posterior lacerated foramen is a narrow, slit-like open- 

 ing behind the petrous portion of the periotic. The glenoid foramen, which 

 is present in Tatu, appears to be wanting, but the stylo-mastoid foramen 

 is large and distinct. The condylar foramen has nearly the same position 

 as in the existing genus, but is larger and more conspicuous. 



The mandible is extremely peculiar and although it may be not inade- 

 quately described as that of Tatu in a very exaggerated form, it suggests, 

 at first sight, a likeness to the jaw of an anteater. The horizontal ramus 

 is very long, slender and laterally compressed ; its posterior portion has 

 a slightly thickened alveolar border to carry the minute teeth, but, for 

 much the greater portion of its length, it is a narrow, edentulous ridge ; 

 the anterior portion tapers forward more gradually than in Tatu and ends 

 in a blunter point and the inner surface of the jaw is quite concave. The 

 symphysis is merely a very short contact between the rami at the fore- 

 most end of the jaw. The ascending ramus is very low, but very broad 

 antero-posteriorly, and the condyle is placed far behind the teeth, though 

 relatively not so far as in Tatu, and is much lower in position than that 

 of the latter; the masseteric fossa is obscurely marked, but large and 

 becoming quite deep beneath the condyle. The anterior border of the 

 ascending ramus is a long, gentle and slightly concave slope, though the 

 coronoid proper is a very low, relatively broad, and recurved hook, 

 entirely different from the high, slender and pointed coronoid of the 

 existing genus. The sigmoid notch is very wide and shallow, in marked 

 contrast to the much narrower and deeper notch of Tatu. The condyle 

 is especially peculiar; it is sessile, longitudinal and scroll-shaped, being 

 strongly curved toward the inner side of the jaw, and convex in both 

 directions ; it is altogether different from the condyle of the modern genus. 

 The notch between the condyle and angle is much broader and deeper 

 than in the latter, in which the angle is greatly reduced, while in the 

 fossil it is a broad, very thin plate and forms a blunt hook, which projects 

 well behind . the condyle. There are two mental foramina, one which 

 opens below the anterior teeth and is large and conspicuous, the other, 

 much smaller, is considerably in advance of this. The inferior dental 

 foramen, which is also large, is placed high up on the inner side of the 



