70 FISHES. 



scapular arch suspended from the skull or vertebral column ; 

 it is merely sunk, and fixed in. the substance of the muscles. 

 Behind, at the point of its greatest curvature, three carpal 

 cartilages are joined to the coracoid, which Gegenbaur has 

 distinguished as propterygium, mesopterygiutn, and metaptery- 

 gium, the former occupying the front, the latter the hind 

 margin of the fin. Several more or less regular transverse 

 series of styliform cartilages follow. They represent the 

 phalanges, to which the horny filaments which are imbedded 

 in the skin of the fin are attached. 



In the Eays, with the exception of Torpedo, the scapular 

 arch is intimately connected with the confluent anterior por- 

 tion of the vertebral column. The anterior and posterior 

 carpal cartilages are followed by a series of similar pieces, 

 which extend like an arch forwards to the rostral portion of 

 the skull, and backwards to the pubic region. Extremely 

 numerous phalangeal elements, longest in the middle, are sup- 

 ported by the carpals, and form the skeleton of the lateral 

 expansion of the so-called disk of the Eay's body, which thus, 

 in fact, is nothing but the enormously enlarged pectoral 

 fin. 



The pubic is represented by a single median transverse 

 cartilage, with which a tarsal cartilage articulates. The latter 

 supports the fin-rays. To the end of this cartilage is also 

 attached, in the male Chondropterygians, a peculiar accessory 

 generative organ or clasper. 



The Holocephali differ from the other Chondropterygians 

 in several important points of the structure of their skeleton, 

 and approach unmistakably certain Ganoids. That their 

 spinal column is persistently notochordal has been mentioned 

 already. Their palatal apparatus, with the suspensorium, 

 coalesces with the skull, the mandible articulating with a 

 short apophysis of the cranial cartilage. The mandible is 

 simple, without anterior symphysis. The spine with which 



