132 THE VERTEBRATE SKELETON. 



(generally called basi-pterygium) and its radialia. The males 

 in Elasmobranchii and Holocephali have the distal end of the 

 metapterygium prolonged into a clasper. 



In Ganoids and in Teleosteans the loss of the pelvic girdle 

 causes the pelvic fin to be still further removed from the 

 primitive state. There is always a large basi-pterygium which 

 lies imbedded in the muscles and meets its fellow at its proximal 

 end. In Cartilaginous Ganoids it has a secondary segmenta- 

 tion. Its relation to its fellow is subject to much variation 

 in Teleosteans, sometimes as in the Perch the two are in 

 contact throughout, sometimes as in the Salmon they meet 

 distally as well as proximally, but are elsewhere separated by 

 a space, sometimes as in the Pike and Bony Ganoids they 

 diverge widely. The radialia are articulated to the basi- 

 pterygium. In Cartilaginous Ganoids and Polypterus they 

 are well developed, in other Ganoids and in Teleosteans they 

 are in the main replaced by dermal fin-rays. 



In some Teleosteans such as the Cod the pelvic fins have 

 migrated from their usual position and come to be attached 

 to the throat in front of the pectoral fins. Fish with this 

 arrangement are grouped together as jugulares. 



