SKELETON OF TELEOSTEI. 83 



and interhaemals simple. Only the abdominal vertebrae have 

 parapophyses, with which the ribs are articulated. 



The configuration of the skull, and the development and 

 arrangement of its component parts, approaches so much the 

 Teleosteous type that, perhaps, there are greater differences in 

 skulls of truly Teleosteous fishes than between the skulls of 

 Amia and many Physostomi. Externally the cranium is 

 entirely ossified ; and the remains of the cartilaginous primor- 

 dial cranium (which, however, has no vacuity in its roof) can 

 only be seen in a section, and are of much less extent than 

 in many Physostomous fishes. The immovable intermaxillary, 

 the double vomer, the plurality of ossifications representing 

 the articulary, the double artieulary cavity of the mandible 

 for junction with the quadrate and symplectic bones, remind 

 us still of similar conditions in the skull of Lepidosteus, but 

 the mobility and formation of the maxillary, the arrange- 

 ment of the giLl-covers, the development of the opercles, 

 the suspensorium, the palate, the insertion of a number of 

 branchiostegals on the long middle hyoid piece, the composi- 

 tion of the branchial framework (with upper and lower 

 pharyngeals), are as in the Teleosteous type. A gular plate 

 replaces the urohyal. 



The scapular arch is composed entirely of the membrane- 

 bones found in the Teleostei, and the two sides are loosely 

 united by ligament. The base to which the limb is attached 

 is cartilaginous ; short semi-ossified rods are arranged along 

 its hinder margin and bear the pectoral rays. 



The skeleton of the hind-Umb agrees entirely with that 



of Z&pidosteus. 



[T. W. Bridge, The Cranial Osteology of Amia caliia ; in Journ. Anat. 

 and Physiol, vol. xi. ] 



In the Teleosteous fishes the spinous column consists of 

 completely ossified amphicoelous vertebrae ; its termination 

 is homocercal — that is, the caudal fin appears to be more or 



