24 FISHES OF THE VICINITY OF NEW YORK 



(I) Teeth narrow, sharp, white, with 



small cusps at their bases. Two 



back fins of about equal size. 



Carcharndce 



(II) Teeth not as above. Second back fin 



usually small. Galeidce 



b. Peduncle with keel on its side. Tail fin 



less unsymmetrical, more or less lunate. 



(I) Teeth large. Lamnidce 



(II) Teeth small, gill slits very wide, 



crossing practically the entire 



breadth of the neck. Cetorhinidce 



2. Body moderately flattened. Head circular, some- 



what constricted at the neck. Mouth almost 

 terminal. Squatinidce 



3. Body notably flattened, no demarcation between it 



and the pectoral fins with which it is confluent at 

 the sides to form a disk; neck region not con- 

 stricted. 



A. Disk squarish with one corner at the snout. Tail 



elongate, moderately stout. Spines and 

 prickles scattered on body and tail. Rajidce 



B. Disk rounded, without spines or prickles. Tail 



fin squarish, rather broad. Narcobatidce 



C. Disk more or less rounded at the sides, sometimes 



with a few spines. Tail long or short, usually 

 lash-like, usually with a single large serrate 

 spine at its base. Head not elevated. 



Dasyatidce 



D. Disk pointed at the sides. The head elevated 



and squarish. Tail lash-like and moderately 

 long. Myliobatidce 



III. Front of head elongate beak-like, sometimes only one of 

 the jaws elongate. 



1. Both jaws elongate, bearing strong teeth. 



A. Scales large, plate-like, regular (fresh water). 



Lepisosteidce 



