THE FISHES OF NEW JERSEY. 51 



margin. Ova few and large, impregnated and sometimes devel- 

 oped internally. Embryo with deciduous external gills. Tail 

 heterocercal. Ventral fins abdominal. Male with large intro- 

 mittent organs or claspers attached to ventral fins. Skin naked 

 or covered with minute rough scales, sometimes with spines. 



Key to the orders and families. 



a. AsTEROSPONDYivi. Anal fin present. 

 h. No nictitating membrane to eye. 



c. Upper caudal lobe moderate, though much longer than lower. 



CARCHARIID^ 



cc. Upper caudal lobe long as rest of body. alopiid.^. 



ccc. Caudal lunate, lower lobe not much shorter than upper; side of 

 tail with a keel. 



d. Gill-openings rather large; teeth large. i^amnid^ 



dd. Gill-openings very large, nearly meeting above and below; 

 teeth small. cetorhinid^ 



hh. Eye with nictitating membrane. 



e. Head normal. galeid^ 



ee. Head kidney or hammer-shaped, much wider than long. 



CESTRACIONTID^ 



aa. Tectospondyli. No anal fin. 



f. (Cyclospondyli.) Gill-openings lateral; each dorsal with a spine. 



SQUALID^ 



ff. (Batoidei.) Gill-openings ventral. 



g. Tail with 2 dorsals ; no serrated caudal spines. 



h. Snout saw-like; body shark-like. pristid^ 



hh. Snout not saw-like; disk ending abruptly at base of tail. 



RAJID^ 



gg. Tail slender, with one or no dorsal, and usually with one or more 

 serrated spines. 



i Pectorals uninterruptedly confluent with snout ; teeth small. 



DASYBATID^ 



a. Pectorals divided, leaving detached cephalic fins on snout. 



y. Teeth large, flat and tessellated. myliobatid^ 



jj. Teeth small, flat or tubercular ; . size enormous, largest 



of rays. mobulid^ 



Family CARCHARIID^. 



The Sand Sharks. 



Body rather elongated. Snout sharp. Mouth wide, crescent- 

 shaped. Teeth large, long, narrow, subulate, most with i or 



