EOSIEEN LIBTCA. 217 



M. 8152. Upper portion o£ middle region of skull, showing the nasals and tlieir relations to the 

 premaxillse and frontals (text-fig. 64). The anterior ends o£ the frontals are thrust 

 between the nasals, and probably completely separated them, but this cannot be 

 definitely ascertained on account of the breaking away of the bone at this point. The 

 posterior portion of this specimen also shows the anterior upper portion of the brain- 

 case, of which a natural cast is preserved. The width of the skull-roof between 

 temporal fossse 3"9 cm. ; width of nasal opening 3"2 cm. 



Presented hy W. E. de Winton, Esq., 1903. 



C. 10040. Mandible incomplete posteriorly. All the teeth wanting and represented only by the 

 empty alveoli. Figured in Geol. Mag. [4] vol. ix. (1902) p. 294, fig. 3 ; also on 

 PI. XX. figs. 2, 2 a. This specimen shows the presence of possibly functional incisor 

 and canine alveoli in the downwardly turned symphysial region ; this latter is enormously 

 thickened ventrally. There is some evidence that the replacement of the molars from 

 behind had already begun, at least in the mandible. The dimensions (in centimetres) of 

 this specimen so far as preserved are : — 



Totallength 20-5 



Depth of ramus beneath posterior molars 4* 6 



Width of symphysis 6"4 



Length of symphysis 6-3 



M. 8926. Imperfect mandible, wanting the vertical portions of the rami and symphysis. The greatly 

 worn posterior molars are present, the other teeth are represented by the alveoli only. 

 The length of this specimen is 20 cm., the length of the symphysis 5 + cm. 



C. 10048. Numerous ribs and vertebrae. This specimen shows that in Eosiren the ribs had attained 

 the great thickness and generally massive structure characteristic of some of the later 

 Sirenians. In the case of one rib the length is about 24 cm., the greatest diameter 

 5"4 cm. 



C. 10191. Complete left scapula, showing the peculiar backward curvature and prolongation of the 

 upper end. Figured on PI. XX. fig. 3. The dimensions (in centimetres) of this 

 specimen are : — 



Extreme length 20-8 



Width of upper prolongation 6-2 



Greatest width of blade 8'5 



Width of neck 4-2 



„ at coracoid process 5-4 



Antero-posterior diameter of glenoid cavity 4 



Lateral diameter of glenoid cavity 2'5 



M. 9232. Plaster cast of the above specimen. Alade in the British Museum. 



M. 9238. Left humerus, wanting the proximal epiphyses. Described above ; figured on PI. XX. 

 fig. 7. The dimensions (in cpntimetres) of this specimen are : — 



Length (so far as preserved) 13-2 



Width of proximal end 4-7 



„ middle of shaft 1-8 



„ distal end 4-8 



„ distal articular surface 2-9 



2f 



