CARCHAROIDEI. 11 



gill openings five; caudal axis little raised; no nictitating membrane 

 spiracles present; nasoral grooves present or absent 



Catuloidei (page 12) 

 two dorsals, without spine; an anal; caudal axis slightly raised 

 gill openings five; a nictitating membrane 

 spiracles present 



nasoral grooves absent (except on Scylliogaleus) 



Carcharhinoidei (page 12) 

 two dorsals, with fixed spine; an anal; no nictitating membrane 

 gill openings five; teeth raptorial and molarial 



spiracles present ; nasoral grooves present . Centracoidei (page 13) 

 two dorsals, with or without a fixed spine; no anal fin 

 gill openings five to six; no nictitating membrane 



spiracles present; teeth raptorial to sectorial; no nasoral grooves 



Squaloidei (page 13) 

 Body and head depressed; mouth anterior; teeth raptorial 

 two dorsals, on the tail, without a fixed spine; no anal 



gill openings five; pectorals produced, but free from the head 



Rhinoidei (page 13) 



Synopsis of Families. 



Hexanchoidei. 



One small spineless dorsal fin; an anal fin; caudal long, axis low; 6 to 7 gill 

 openings 

 six gill openings, anterior covers crossing the throat 

 teeth with three long sharp cusps; mouth anterior 



Chlamydoselachidae (page 13) 

 six to seven gill openings, covers not crossing the throat 



teeth compressed, blade-like, notched on the edges; mouth inferior 



Hexeptranchidae (page 15) 



Carcharoidei. 



Two spineless dorsals; a large anal; five gill openings ; no nictitating membrane 

 snout pointed, short to very long; caudal large, axis low; spiracles present 

 teeth with a long slender cusp and a two-rooted base 



Carcharidae (page 23) 



