EOSIEEN LIBTCA. 215 



condyle (i.e.) is greatly developed and is directed backwards; its lower end is about on 

 a level with the lowest point of the trochlea, a condition not seen in other Sirenia. 



The proximal end of a large humerus perhaps belongs to this species. In this 

 specimen the head is strongly convex in all directions and somewhat oval in outline ; 

 its edge forms a projecting rim. The tuberosities are worn, but it can be seen that 

 the outer was the largest, and that there was a small bicipital groove. 



In many respects the humerus of Eosiren resembles that of Moeritherium, the chief 

 points of similarity being the form of the distal trochlea and of the inner condyle, and 

 the arrangement of the deltoid crest ; on the other hand, in Moeritherium the humerus 

 is relatively longer and more slender, and the supinator crest is strongly developed. 



Hind Limb. — A right os innominatum (text-fig. 68, B) was found associated with the 

 anterior portion of a skull and the vertebrae described above. This specimen is of 

 great interest, as showing in some respects a degree of reduction intermediate between 

 that seen in the pelvis of Eotherium (text-fig. 68, C) lately described by Abel * and that 

 found in Halitherinm schinzi (text-fig. 68, A), though approaching much more nearly the 

 form of the latter. The bone, as a whole, is considerably abraded, so that many details 

 of structure have been obliterated. The ilium (il.) is roughly trihedral in section for 

 some distance in front of the acetabulum, and further forwards still it expands some- 

 what, becoming a little flattened from within outwards. The outer convex face is 

 traversed by a slightly marked ridge running from the anterior point to the anterior 

 angle of the rim of the acetabulum. The inner face of the anterior end is somewhat 

 flattened and probably was in contact with the end of the sacral rib. Immediately in 

 front of and above the acetabulum there is a roughened prominence, apparently the 

 point of origin of the rectus femoris muscle. No trace of an ilio-pectineal tubercle 

 is preserved. The ischium {is.) is a broad bar of bone, expanding a little towards 

 its somewhat thickened distal end, which is sharply truncated by a surface looking 

 inwards and backwards ; its upper and lower borders are both concave, the latter most 

 deeply so ; the outer face is divided by a slight ridge running from the posterior angle 

 of the acetabulum to the ischial tuberosity into a narrower dorsal portion and a much 

 wider ventral region. The pubis {pu.) is represented by a large triangular process, the 

 anterior border of which rises just opposite the lower angle of the acetabulum. The 

 posterior border forms a continuous curve with the lower edge of the ischium. There 

 is no descending process of the pubis or ascending process of the ischium, so that 

 there is no complete obturator foramen, the whole of the lower and posterior borders 

 found in the ordinary mammalian pelvis and still persisting in Eotherium (Abel, op. cit. 

 p. 191) being wanting. At the same time the remnants of the pubis and ischiu©! 

 so far as they go approach rather more nearly the normal form than is the case in 

 the later Halitherium (see also supra, p. 119). The oval acetabulum is well developed, 

 with a prominent border ; the acetabular notch {a.n.) is situated as in Eotherium. 



* Abe], op. cit. pp. 187-195, pi. vii. fig. 1. 



