198 
TEKTIAEY YEETEBEATA OF THE EATtlM. 
that Dr. Elliot Smith is of o])iiiion that their generic separation would be justified hy 
this difference alone; (3) iho os hmominnfnm is much less reduced and has a com- 
])l(‘tely closed obturator foramen and a well-defined acetabulum with which a functional 
femur ])rohahly articulated, wliereas in Eosiren the reduction of the pelvis has proceeded 
almost as far as in lialHlierium. 'Ihese particulars are taken partly from Abel’s paper 
above' referred to, and ])artly from a skull and mandible of Eotherium recently acquired 
hy the (leological Museum, Cairo : to this specimen further reference, with figures, is 
made 1)elow. 
J^rorasfomifs*, another primitive Sirenian from the Lower Tertiary beds of Jamaica, 
differs from the present form both in the general shape of the skull, the slight deflection 
of the snout, the absence of enlarged anterior incisors, and in the form of the 
mandibular symphysis. 
Jlcdit/ieriitm {ProfotJieriurn) ve)'07ie)ise,Z]gnof, approaches this genus very nearly, but 
in it the dentition seems to have already undergone considerable reduction. 
Eosiren libyca, Andrews. 
[Plate XX. figs. 1-7 ; text-figs. 04, 05, 08 B.] 
1902. Eosiret} C. AV. Andrews, Geol. Mag. [4] vol. ix. p]). 293-4, figs. 1-3. 
1904. ,, ,, 0. Abel, Aldiandl. k.-k. geol. Eeiehsanst. vol. xix. ])t. 2, passim. 
Type Specimen. — A nearly complete skull described and figured, loc.cit. ; Geological 
Museum, Cairo. 
This is the type and only s])ecies of the genus at present known. 
Eorm. & Lon.- — Qasr-el-Sagha beds (Middle Eocene) : north of Birkct-el-Qurun. 
Slxidl (PI. XX. figs. 1, 1 a, 1 b ; text-fig. 04). — The type skull is not quite corajdete, 
the zygomatic arches and a portion of the basal region of the cranium being lost. The 
occipital surfirce is high and broadens out from above downwards. The occipital 
condoles (cond.) are larger and more prominent than in any other Sirenian skull 
with which comparison has been made, except Eotherium ; they are almost pedunculate 
and their articular surface is strongly convex from above downwards and extends 
considerably on their ventral face. In the mid-ventral line they are separated by a 
deep rounded notch ; but it cannot be determined what share, if any, the hasioccipital 
took in their formation, the sutures being obliterated. 
Above the foramen magnum the e.toccipitals[exo.) meet in a suture about 2'3 cm. in 
length, thus completely excluding the supraoccipital from the opening: their upper 
* Giuirt. Journ. Geol. Soc. vol. xi. (ISoo) ]>. .541. 
t ^igiio, “SirtMiii fossili trovati nel Vencto,” 'iroin. Tst. V(‘iu'4o d. Sci. vol. xviii. (1875) j). 415; also hy 
the same author, “ Quelipies Observations sur les iSireniens fossiles,” Bull. Soc. geol. France, [BJ vol. xv. 
(1887) p. 728. 
