36 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 
Okder E— RAU3. 
[The Rails.) 
Gill-openings inferior, slit-like, live in number; spiracles present; no 
anal bn; dorsal tins, if present, inserted on the tail; body tyi^ically 
disk-like, broad and liat, the margin of tbe disk being formed by the 
expanded peetorals. Tail comparatively slender, the caudal bn small. 
With the exception of the Raiida’, most or all of the rays are ovo-vivi- 
parons. (Suborder Batoidci Giinther, viii, 434-498.) (Latin, raia or 
raja, a ray.) 
* Tail comparatively tliick, visually with rayed dorsal and cauvlal tins ; no serr.ated 
caudal spine nor se])arate cephalic lins. [Pachyura.) 
(t. Snout saw-like, much produced, iirmed with stron>>' lateral teeth ..P1USTID,E, 17. 
ao,. Snout not saw-like. 
b. Disk passing gradually into the long stout tail ; pectorals not extending to 
the snout RhinobatiD/E, 18. 
bh. Disk .abrujdly contracted at base of the tail. 
c. Electric organs present; disk perfectly smooth Torpedinid.e, 19. 
cc. Electric organs absent; disk and tail more or less prickly Raiiiee, 20. 
Tail very slender, whip-like, its lins, if any, small and near its base. [Mastkmra.) 
(1. Pectoral lins uninterrupted, coiilluent around the snout; teeth small. 
TuYGONIDAi, 21. 
(Id. Pectoral fins interrupted, the appendages on the snout (“cephalic lins”) 
separate from the pectorals. 
e. Teeth large, Hat, tessellated MvEiOBATiDAi, 22. 
ce. Teeth very small, Hat or tubercular Cepiialoptekiiee, 23. 
SuPEK-FAMILY PRI8TOIDEA. 
[The Prisfoid Rays.) 
Family XVII.— PRISTID.E. 
( The Bate -fishes.) 
Body elongate, depressed ; ivectoral bus moderate, tlie front margin 
quite free, not extending to the head ; snout produced into a very long, 
thin, bat blade, which is armed with a series of strong tooth-lilce iiro- 
(;esses along eaeh edge; teeth in jaws minute, obtuse; gill-oitenings 
moderate, inferior; .spiracles wide, behind the eye; no.striJs inferior; 
no tentacles ; no nictitating membrane ; dorsal bus large, without spine, 
the first nearly opposite the ventrals. Caudal well developed, bent 
upwards; a fold along each side of tail. A single genus, with bve or 
more species, inhabiting warm seas, .sometimes ascending the rivers. A 
family of sharks, Pristiophoridee, .similarly armed with a “ saw,” occurs 
in the l^aeibc Ocean. [Prisfkke Giinther, viii, 430-439.) 
