16 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



The family, as thus defined, embraces Scyllium, Pristiurus, Stegostoma, Parascyllium, 

 Chiloscyllium, and related genera. They are inhabitants entirely of the sens of the Old 

 World and Australia, none being found in American waters. They are among the lew- 

 sharks which lay eggs iuvestedin parchment-like eases, like those of the rays. 



KEY TO THE ATLANTIC GENERA OF SCYLLIOKHINID.E. 



(Adapted from Giiuther. 



I. Nasal and buccal cavities separate. 



A. Caudal fin with upper edges entire. 



1. First dorsal short, elevated ; anal origin in advance of second dorsal SCYLLIORHINUS 



2. First dorsal long, very low; anal origin behind that of second dorsal PsEUDOTRIACIS 



15. Caudal tin with upper edges serrated PRISTIURUS 



II. Nasal and buccal cavities confluent. 



C. Second dorsal fin nearly opposite anal GlNGLYMOSTOMA 



Other genera, Stegostoma, Parascyllium, Chiloscyllium, and Crossorhinus are peculiar to 

 oriental faunas. Ginglymostoma is a shallow-water form, inhabiting warm waters. Few 

 species of Scyllium have been found at considerable depths. 



This family is nearly cosmopolitan, bat has no representatives in either the western 

 Atlantic or in the eastern Pacific, except a single Scyllium on the coast of Chile. 



SCYLLIORHINUS, Blainville. 



Scylliorhinus, Blainville (Jordan and Gilbert, Bull, xvi, U. S. Nat. Mux. 18*;s, S69). 



Scyllium, Cuvier, Regne Animal, 18211. u. 386. — Muller and Henle, S. B. Plag., 3.— Gunther, Cat. Fish. 

 Brit. Mas., VIII, 400.— Day, Fish. (it. Britain and Ireland, it, 309.— Gill, Ann. Lye. Nat. Hist., in. 107. 



Spiracles behind the eyes. Nasal cavities distinct from that of the mouth. Teeth 

 small, in many rows, usually with a central and one or two lateral cusps. Origin of anal 

 fin in advance of that of the second dorsal; upper edge of caudal not serrated. (Day.\ 



SCYLLIORHINUS RETIFER, (Garman). (Figures 14, 15.) 



Scyllium retiferum, Carman, Bull. Mus. Comp. Zool., 1881, vm, No. 11, 233. — Goode ami Bean, Bull. Mus. 



Comp. Zool., vol. x, No. 5, 2L'ti. 

 Scylliorhinus retifer, Jordan, Cat. Fish. N. A., 1885, 5. 



Body moderate, portion behind the vent longer; head depressed, width nearly equal to 



its length in front of the spiracles. Distance across the head at anterior angles of eyes, from 

 angle of eye to end of snout, between angles of mouth, between outer angles of nostrils, or 

 between angle of nostril and that of month, about equal. Shape of body similar to thai of 

 S. canicula. Snout moderate, length from mouth less than the distance between the outer 

 margins of the nostrils. Nasal valves separated by an interspace of less than their width, 

 not reaching the mouth, somewhat folded, without a free cirrus. Mouth medium; the height 

 of the irregular arch formed by its outline is little more than half its width. Labial fold 

 on lower jaw extending nearly one-fourth of the distance to the symphysis; fold on upper 

 jaw rudimentary. Teeth small, alike on upper and lower jaws, bearing a sharp central 

 cusp, on each side of which are two smaller ones, several series in function at the same 

 time. No nictitating membrane. Spiracles small. Gill openings small, fourth and tilth 

 over the base of the pectoral. Pectorals moderate, broad, short, anterior margins curved, 

 extremities rounded. Veutrals rather small, united for a short distance behind the claspers, 

 outer extremity broadly rounded, posterior angle acute. First dorsal much larger than tin- 

 second, about twice the length of its base in advance of the latter, extending forward above 

 the free portions of the veutrals, insertion very near the middle of the total length. Second 

 dorsal smaller than the anal, which extends below the anterior half of its entire length, not 

 reaching the caudal. Caudal not large, a shallow notch between its upper and lower 

 lobes, upper slightly indented on its hinder margin. Scales of shagreen small, unequal: on 

 those of the back there are three or five carina;, the median of which is prolonged into an 

 acute point. 



