PISCES 



153 



specimens reach a giant size, being about eight feet in diameter and 

 weighing as nmch as twelve hundred pounds. The skeleton is largely 

 cartilaginous and there is a very heavy dermal cartilaginous armor. 

 The skin is smooth and scaleless. All of these characters will readily 

 be recognized as criteria of senescence. Indeed it is a question as to 



Fig. 94. — Hawaiian Head-Fish, Ranzania makua, Jenkins. (Redrawn after 

 Jordan and Evermann.) 



whether these creatures or the most degraded of the Pediculati are 

 the most senescent members of the entire class of Fishes. The Ped- 

 iculati appear to be the logical culmination of the rather broad, flat 

 type of head-fish architecture, while the Sun-Fishes have carried out 

 to the extreme the evolution of the high, compressed head-fish type. 

 Both of these tendencies appear to have been manifest in the groups 

 of Acanthopterygii from which these two sub-orders have respectively 

 been derived. 



