36 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



Okder E.-RAI^. 



{The Rays.) 



Gill-openings inferior, slit-like, live in nnmber ; spiracles present ; no 

 anal tin; dorsal fins, if present, inserted on the tail; body typically 

 disk-like, broad and flat, the margin of the disk being formed by the 

 expanded pectorals. Tail comparatively slender, the caudal tin small. 

 With the exception of the Baiida'^ most or all of the rays are ovo-vivi- 

 parous. (Suborder Batoidei Gilnther, viii, 434-498,) (Latin, raia or 

 raja, a ray.) 



* Tail comparatively thick, usually ^Yith rayed dorsal aud caudal fius ; no serrated 

 caudal spine nor separate cephalic lius. (Pachyura.) 

 a. Snout saw-like, much ])roduced, armed with strong lateral teeth ..Piustid^, 17. 

 aa. Snout not saw-like. * 



b. Disk passing gradually into the long stout tail ; pectorals not extending to 



the snout Rhixobatid.e, 18. 



bh. Disk abruptly contracted at base of the tail. 



c. Electric organs present ; disk iierfectly smooth Tokpedinide, 19. 



cc. El(M;tric organs absent ; disk and tail more or less prickly RaiidyE, 20. 



"* Tail very slender, wliix)-liko, its fins, if any, small and near its base. {Masticura.) 

 d. Pectoral Jins uninterrupted, confluent around the snout ; teeth small. 



TnvGOXiD.E, 21. 

 dd. Pectoral iins iuterruj)ted, the appendages on the snout (" cephalic lius") 

 separate from the pectorals. 



e. Teeth large, flat, tessellated Myliobatid^e, 22. 



ce. Teeth very small, flat or tubercular CEPiiALoi'TEKiDy^E, 23. 



SUPEE-FAMILY PRI8T0IDEA. 



{The BrhUyid Bays.) 



Family XVII.— PRISTID.E. 



{The tiaic-fishes.) 

 Body elongate, depressed ; pectoral tins moderate, the front margin 

 ([uite free, not extending to the head ; snout produced into a very long, 

 thin, flat blade, which is armed with a series of strt)ng tooth-like pro- 

 cesses along each edge; teeth in jaws minute, obtuse; gill-openings 

 moderate, inferior; spiracles wide, behind the eye; nostrils inferior; 

 no tentacles ; no nictitating mend)ranc ; dorsal fins large, without si)ine, 

 the first nearly opposite the ventrals. Caudal well developed, bent 

 upwards ; a fold along each side of tail. A single genus, with five or 

 more species, inhabiting warm seas, sometimes ascending the rivers. A 

 family of sharks, Pristiophorldw, sinularly armed with a " saw," occurs 

 in the Pacific Ocean. {Pristidm Gilnther, viii, 43()-4;>l).) . 



