20 selaChii: rale. — v. 



expanded pectoral fins. The tail is comparatively slender, and its 

 fins are small. Spiracles present. The Rajidce produce large eggs, 

 enclosed in leathery cases; most of the other Raice are ovovi- 

 viparous, bringing forth their young alive. 



Families of Baise. 



a. Tail comparatively thick, with two dorsal fins ; no serrated caudal spine 

 nor cephalic fina. 

 t. Snout much produced, flat, armed with strong teeth on each side, set 

 at right angles to its axis ; body somewhat shark-like, the disk grad- 

 ually passing into the tail Peistidid^, 1.3. 



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

 c. Electric organs wanting; skin not perfectly smooth. . Rajid^, 14. 

 cc. Electric organs present; a structure of honeycomb-like tubes between 

 pectoral fins and head ; skin perfectly smooth. . ToKrEDiKiD^, 14. 

 aa. Tail slender, with but one dorsal fin or none, and usually armed with a 

 serrated spine. 

 d. Pectoral fius uninterrupted, confluent about the snout; teeth small. 

 ' Dasyatid^, 15. 



dd. Pectoral fins divided, leaving detached appendages (" cephalic fins ") 

 on the snout. 



e. Teeth very large, flat, tessellated AetobatiDjE, 16. 



ee. Teeth very small, flat or tubercular ; size enormous, largest of the rays. 



Maxtid^, 17. 



Family XIII. PBISTIDID.^. (The Saw-fishes.) 



Rays with elongate body, stout, thick tail, and a long saw-like 

 snout, below which is the inferior mouth with small blunt teeth. 

 Dorsals and caudal well developed. One genus, with 5 or 6 species, 

 in warm seas. 



19. PRISTIS Latham, (wpiarqi, one who saws ; the ancient 



name.) 

 24. P. pectinatus Latham. Saw-eish. Saw with 25 to 28 

 pairs of spines. L. 10 feet. West Indies; occasional N. (Lat., 

 comb-toothed.) 



Family XIV. RAJID^. (The Skates.) 

 Kays with the disk broad, rhombic, more or less rouo-h- the 

 males usually with about two rows of strong spines on e^h pec- 

 toral ; tail rather stout, with a fold of skin on each side, and two 

 dorsal fins above ; caudal fin small or obsolete ; no serrated snine • 

 no electric organs. Egg in a large leathery case, four-angled, and 

 having two tubular horns at each end. Genera 4, species 40 

 mostly of the Northern seas. 



a. Caudal fin rudimentarj' ; pectorals not confluent, leaving a translucent 

 area at the snout; ventrals deeply notched Raja -j 



