SCOTT : LITOPTERNA OF THE SANTA CRUZ BEDS. 4 1 



terotherium. The molars are broad and heavy, with thick, massive cusps : 

 in m-, and especially in m-, the internal cusps are less distinctly separated 

 than in Proterothermm and in m- these cusps are connected by a low ridge 

 of enamel. The third molar differs from that of the last named genus in 

 having the hinder half of the crown less reduced and, in several of the 

 species, a distinct, though very minute hypocone is present : m- closely 

 resembles p-. 



Lower Jaw. The incisors do not differ in any noteworthy manner from 

 those of Proterothermm, except that they tend to be more procumbent. 

 The canine is small and, in most instances, is placed in contact with the 

 lateral incisor, but is sometimes separated from it by a very short space. 

 The first premolar is usually larger than in Proterothermm and p2 resem- 

 bles that of the latter in form, but has less prominent internal ridges ; py 

 is almost molariform, but the anterior crescent has a shallower valley and 

 is less complete than the posterior, and the antero-internal cusp is a partly 

 separated pill.ar. In p^, which is quite molariform, the antero-internal 

 pillar is much reduced or absent, but the postero-internal one is well- 

 developed, though varying in degree of separateness. 



In the typical species oi Licaphrmm, such as L.floweri, the lower molars 

 differ from those of Proterothermm in their breadth and massiveness and 

 in the shallowness of their valleys, especially in the anterior crescents, but 

 in L. proximum, the proportions are much more nearly as in the latter 

 genus. A constant difference, however, is to be noted in the much larger 

 size of the postero-internal pillar, which is always very conspicuous, and 

 the talon of va^ is less distinctly separated from the posterior crescent. 



Comparatively little is known of the skeleton. I have seen no complete 

 example of the skull (Pis. VI, fig. i; VII, fig. i), but, so far as it is pre- 

 served in the available specimens, it has great resemblance to that of Pro- 

 terothermm, but is heavier and more massive and the bones composing it 

 are much thicker. The occiput is broader than in Diadiaphorus, nar- 

 rowing less dorsally. The face is short and very deep dorso-ventrally, 

 though this proportion varies much in the different species. The orbit 

 has a somewhat lower position than in the last named genus, and in front 

 of the orbit the dorsal part of the maxillary has a curiously inflated appear- 

 ance, doubtless owing to an enlargement of the antrum. This swollen 

 appearance is most conspicuous in old animals. The lachrymal foramen 

 is placed a little in front of the oribital rim, as in Diadiaphorus ; the infra- 



