20 SELACniI: RAUl — V. 



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

 tins arc small. Sjiiracles jiresent. The Raj'ulir produce large eggs, 

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

 viparous, bringing forth their young alive. 



Families of Raise. 



(I. Tail coiiiparatK'cly thick, with two dorsal tins; no serrated caudal spine 

 nor cephalic liiis. 

 b. Snout much produced, Hat, arniud with strong teeth on each side, set 

 at rif;ht aiij^les to it.s axis; body somewhat shark-like, the disk grad- 

 ually passing into the tail Puistiuiu.k, 13. 



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



c. Electric organs wanting; skin not perfectly smooth. . Uajiu.k, 14. 



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



pectoral tins and head; skin perfectly smooth. . T<jKrKi>iNiu.E, 14. 



art. Tail slender, with but one dorsal tin or none, and usually armed with a 



serrated spine. 



d. Pectoral tins uninterrupted, conlluent about the snout; teeth small. 



Da-syatiu.k, 15. 

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

 on the snout. 



e. Teeth very large. Hat, tessellated Aetobatid.k, 16. 



e«. Teeth very small, tlat or tubercular ; size enormous, largest of the rays. 



Mantidjv, 17. 



Family XIII. PRISTIDID^. (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, (nplarris, one who saws ; the ancient 

 name.) 



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

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

 comb-toothed.) 



Family XIV. RAJID^. (The Skates.) 



Rays with the disk broad, rhombic, more or less rough; the 

 males usually with about two rows of strong spines on each pec- 

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

 dorsal (ins above ; caudal fin small or obsolete ; no serrated spine ; 

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

 having two tubular horns at each end. (icncra 1. species 40, 

 mostly of the Northern seas. 



a. Caudal fin rudimentary; prctoriilM not <'i>iitlueut, leaving a translucent 

 area at the snout ; venlrals deeply aulchud. iCiJA, ^U« 



