SUBORDER C 



PROBOSCIDEA 



255 



posterior cusp. Molars with two pairs of cusps each and a talonid. The anterior 

 portion of the lower premolars and molars is higher than the posterior. Skull low, 

 almost flat, with long, slender cranium and massive, projecting zygomatic arch. 



The Moeritheriidae appear first in the Upper Eocene of Egypt and become 

 extinct in the Oligocene. They indicate in skull ^structure and in the 

 number and form of the teeth 

 a transitional stage between the 

 Sirenia and Proboscidea, and show 

 most distinctly that both groups 

 are descended from a common 

 ancestor. 



Moeritherium Andrews (Fig. 

 337). Lower incisors chisel- 

 shaped, anteriorly directed, upper 

 incisors and canine almost verti- 

 cally placed. Second incisor in 

 both jaws enlarged, the upper 

 being developed as a massive, 

 curved tusk. The remaining 

 incisors and canines are relatively 

 small, The incisors and canines 

 are covered with enamel on all 

 sides. Upper premolars with two 

 outer and one inner cusp. Up- 

 per premolars triangular. Molars 

 in both jaws with two outer and 

 inner cusps each, the cusps being 

 joined to form transverse ridges. 

 The lower molars with strong, and 

 upper molars with small talonid. 

 Lower premolars with unpaired 

 anterior cusps, anterior mostly higher than the posterior. Nasal openings 

 far forward, indicating a short proboscis, cranial roof almost perfectly 

 horizontal, orbits far forward. Nasal bones short. Frontals and parietals 

 long, cranium slender and low, with saggittal crest. Occiput vertical. 

 Zygomatic arch massive anteriorly and posteriorly, much projecting and 

 ending posteriorly near the occiput. The limb bones are slender. The 

 femur has a third trochanter and the astragalus a relatively long neck. The 

 sacrum becomes reduced gradually posteriorly, which would indicate the 

 presence of a long tail. The ilium is distinguished by its great length and 

 slenderness. It strongly resembles that of Creodonts. The species of this 

 genus attained approximately the size of a tapir. Upper Eocene. M. lyonsi 

 Andr. Oligocene. M. andrewsi Schlosser. 



Moeritherium, lyonsi Andrews. Upper Eocene, Fayum, 

 Egypt. A, Upper cheek teeth, 1/2. B, Lower cheek teeth, 

 1/3- C, Skull and ]ower jaw restored, 1/9- (After Andrews.) 



Family 2. Barytheriidae Andrews. 



1.0.3.3. 



' ' ' ' • Lower incisors large, anteriorly directed and separated from the 



second premolar by a long diastema. P^ triangular, P^ and P^ tvith a thick 



