80 



ANATOMY OF VEHTEBEATES. 



condyles, processes extend backward from each side of the occi- 

 pital foramen and clasp, as it were, the bodies of three or four 

 anterior vertebras of the trunk. The pterygoidean arches extend 

 outward, in Carcharias, from the base of the cranium, but, as in 

 embryo osseous fishes, are confluent therewith at both ends. The 

 maxillary arch, suspended near its closed anterior extremity to 



64 



28 



Skate (_Eaia bat is) 



the vomerine part of the base of the skull, is thence extended 

 backward to the articulation of the lower jaw. A simple carti- 

 laginous pedicle forms the upper part (pleurapophysis) of the 

 mandibular arch, which is completed below by the lower jaw. A 

 few cartilaginous rays diverge outward and backward from the 

 pedicle, and support a small opercular flap or fin. The hyoid 



