60 ELEMENTARY BIOLOGY. [CHAP. 



upon the corresponding concave facet on the 

 front of the first vertebra. 



y. The exocdpitals ; bearing the condyle on each 

 side, and bounding the foramen magnum 

 laterally. 



8. The pro-otics; lying immediately in front of y. 

 and running outwards on each side, forming 

 the roof and front wall of the auditory capsule. 



. The sguamosal; a hammer-shaped bone, ex- 

 tending from the outer edge of 8. downwards 

 and backwards towards the articulation for the 

 lower jaw. 



. The columella auris ; seen, at this stage, as a 

 bony rod which underlies the pro-otic and 

 stands out immediately behind the head of the 

 squamosal. (It is best studied later on.) 



c. The roof of the skull. 



a. The exoccipitals, pro-otics and sguamosal. Cf. 

 supra. 



^. The fronto-parietals ; two long bones united 

 by suture in the middle line, roofing in the 

 cranium. 



y. The nasals; two triangular bones immediately 

 in front of ft. set transversely and a little ob- 

 liquely. 



8. The pre-maxillce ; two small bones in front of y., 

 meeting in the middle line and bounding the 

 front of the gape. Each sends up an ascending 

 process which is directed towards the inner end 

 of the nasal bone. 



