CROMEKIA. 



95 



absent. The alisphenoid is largely developed. In the occipital arch all elements are 

 present, and both supra- and basioccipital take part in the formation of the foramen 

 magnum. One small membrane-bone in this region is difficult to homologise ; it may 

 be regarded as the parietal or as the squamosal ; for several reasons the former seems 



Fig. 15. 



,..sp 



Side view of skull, upper view of cranium, aud external view of pectoral girdle. X 25. 



an. Angular. 





P- 



Parietal. 



ar. Articular. 





pe. 



Parethmoid. 



as. Alisphenoid. 





P i. 



Palatine. 



bo. Basioccipital. 





pm. 



Prsemaxilla. 



c. Coracoid. 





pop. 



Pra3operculum. 



61. Clavicle. 





ps. 



Parasphenoid. 



d. Dentary. 





pt. 



Pterygoid. 



eo. Epiotic. 





pto. 



Pterotic. 



exo. Exoccipital. 





pit. 



Post-temporal. 



/. Frontal. 





2- 



Quadrate. 



hym. Hyomandibular. 





sc- 



Scapula. 



top, Interoperculum. 





scl. 



Supraclavicle. 



m. Maxilla. 





so. 



Suborbitals. 



iwpt. Metapterygoid. 





soc. 



SupraoccipitaL 



n. Fused mesethmoid, 



nasal, and suborbital. 



sop. 



Suboperculum. 



op. Operculum. 





sp. 



Sphenotic. 



osp. Orbitosphenoid. 





V. 



Vomer. 



to be the more correct view. The supraoccipital is so large that one naturally expects 

 to find the parietals widely separated. The pterotic is large. 



The anterior region of the cranium shows signs of reduction, and is characterised by 

 the presence of a peculiar bone (n), which seems to be formed by the fusion of a 

 minute mesethmoid with the two nasals and with the solitary suborbitals of either side. 



