82 FISHES. 



brancliiostegals which Zepidosteus possesses ; a long and large 

 glossohyal is intercalated between the lower ends of the 

 hyoids. There are five branchial arches, the hindmost of 

 which is modified into a lower pharyngeal ; upper pharyn- 

 geals are likewise present as in the majority of Teleosteous 

 fishes. No gular plate. 



Of the scapulary arch the two halves are separated by a 

 suture in the median line; the membrane-bones are well 

 developed, only a remnant of the primordial cartilage remain- 

 ing ; the supraclavicle is very similar to that of Teleosteous 

 fishes, less so the post-temporal. The base to which the 

 limb is attached is a single osseous plate, supporting on its 

 posterior margin semi-ossified rods in small number, which 

 bear the pectoral rays. 



The pubic consists of paired bone, the anterior ends of which 

 overlap each other, the extremity of the right pubis being 

 dorsad to that of the left. The elements representing a 

 tarsus are quite rudimentary and reduced in number (two 

 or three). 



The vertebral column of the Amioidei shows unmistak- 

 able characters of the Palaiichthyic type. The arrangement 

 of its component parts is extremely simple. The centra of 

 the amphicoelous vertebme are well ossified, but the neural 

 and hcBmal arches do not coalesce with the centra, from which 

 they are separated by a thin layer of cartilage. Singularly, 

 not every vertebra has apophyses : in the caudal portion of 

 Amia the vertebra3 are alternately provided with them and 

 lack them. The heterocercal condition of the spinous column 

 is well marked : as in the other Holostei the hindmost 

 vertebrae are turned upwards, become smaller and smaller in 

 size, and lose their neural arches, the htemals remaining 

 developed to the end. Finally, the column terminates in a 

 thin cartilaginous band, which is received between the lateral 

 halves of the fifth or sixth upper caudal ray. Interneurals 



