Wortman — Studies of Eocene Mammalia, etc. 193 



Aet. XXIII. — Studies of Eocene Mammalia in the Marsh 

 . Collection, Peabody Museum ; by J. L. Wortman. 



[Continued from p. 154.] 



Hind limb. — The greater part of the pelvic bones of both 

 sides are present, from which an accurate idea of this ]3ortion of 

 the osteology can be formed. In comparison with the ilium, 

 the ischium, figure 32, is elongate, being 73 per cent of the 

 length of the former bone ; in Herpestes it is 79, in Crossarchus 

 69, in the Binturong 66, and in the domestic cat 65 per cent 

 of the length of the ilium. The peduncu- 

 lar portion of the ilium exhibits about the 

 same degree of constriction as that seen in 

 the Binturong, and is somewhat greater 

 than in Herpestes. The gluteal surface is 

 little expanded, and is occupied by two 

 longitudinal grooves separated by a promi- 

 nent rounded ridge ; of these the superior 

 is the wider and deeper, the inferior being 

 long and narrow. This division of the 

 gluteal surface is a characteristic feature of 

 the pelvis of all Eocene Carnivora, and in tw o and one-fourth 

 some species it persists into the Oligocene. J™ es natural size. 

 In the living forms, it has very generally dis- 

 appeared, only a trace of it remaining in some of the less special- 

 ized types. The meaning of its universal presence in the early 

 types is to be accounted for on the supposition that the primitive 



Figure 31. — Phalanx 

 of Oodectes herpestoides 

 "Wortman: dorsal view; 



Figure 

 Wortm;in ; 



32. — Portion of left half of pelvic girdle of Oodectes herpestoides 

 side view ; three halves natural size. (Type.) 



Marsupial -like ancestors had a type of ilium similar to that of the 

 living Opossum, in which it consists of a simple elongated tri- 

 hedral bar attached to a single vertebra. Slight expansion of 

 the dorsal and ventral borders of this bar would give the con- 

 ditions seen in the Eocene types, wherein the longitudinal 

 ridge corresponds to and is the remains of the primitive bar. 



