68 BULLETIN 10 0, UNITED STATES NATIONAL MUSEUM 



Oinglimo stoma Agassiz, Poiss, fossil es, vol. 3, p. 85, 1838. (Type Squalus cirratus 



Gmelin. ) 

 Plicodus WiNKLEK, Arch. ]\Ius. Teyler, vol. 3, p. 301, 1874. (Type, Plicodus 



thielensis Winkler, monotypic.) (Fossil.) 

 Acrodohatis Leidy, Jouru. Acad. Nat. Sci. Philadelphia, ser. 2, vol. 8, p. 250, 



1877. (Type, Acrodohatis serra Leidy, designated by Hay, U. S. Geol, Surv. 



Bull. 179, p. 310, 1902.) (Fossil.) 

 Acrodontohatis Leidy, Journ. Acad. Nat. Sci. Philadelphia, ser. 2, vol. 8, p. 250, 



1877. (Type, Acrodohatis serra Leidy.) (Fossil.) 

 NeVrodes Gaeman, Mem. Mus. Comp. Zool., vol. 36, p. 56, 1913. (Type, Nehrius 



concolor Riippell.) 



Body moderate, depressed and broadened forward, compressed 

 posteriorly. Head broad. Snout short, obtuse. Eyes small, with- 

 out fold. Mouth wide, little curved, inferior. Teeth small, com- 

 pressed, cusps 3 to 5 or more, often strong sharp median cusp at 

 each side of which pair of denticles, several rows in function. Nos- 

 trils near snout end; front nasal valves reach mouth, broadly sepa- 

 rated by attachment across symphysis, each with cylindrical cirrus 

 at outer edge ; hind valve fold on outer side of groove. Gill openings 

 moderate, fourth and fifth close together, widest and above pectoral. 

 Spiracle minute, at distance behind eye. Dorsals approximated, 

 rather large, first above ventrals, larger, second dorsal origin forward 

 of anal. Caudal large, subcaudal not lobed. 



Species of tropical seas, pelagic. Some reach a large size, frequent 

 shallows, often associating in small schools and found drowsing near 

 the surface. 



ANALYSIS OF SPECIES 



a\ GiNGLYMosTOMA. Tall moderately long; teeth mostly tricuspid. 



h^. Angles of fins rounded ; pectorals reach less than halfway to ventrals. 



brevicaudatus 

 6*. Angles of fins pointed; pectorals reach over halfway to ventrals. 



ferrugineus 

 o". Nebrius. Tail long ; teeth multicuspid ; angles of fins pointed. 



&. Ventral length more than half space to anal origin ; caudal length more 



than half rest of body concolor 



c^. Ventral length 2% to anal origin ; caudal length more than half rest of 

 body macrurus 



Subgenus Ginglymostoma Miiller and Henle 



NEBRIUS BREVICAUDATUS (Giinther) 



Oinglymostoma hrevicaudatum Gtjnther, Fishes of Zanzibar, p. 141, pi. 21, 1866 

 (type locality: Zanzibar) ; Cat. Fishes Brit. Mus., vol. 8, p. 408, 1870 (type; 

 Seychelles).- — Regan, Proc. Zool. Soc. London, 1908, p. 351 (type; Sey- 

 chelles). — Gaeman, Mem. Mus. Comp. Zool., vol. 36, p. 55, 1913 (Zanzibar, 

 Seychelles, Indian Ocean). 



Depth 8V5 to subcaudal origin; head 6, width ly^. Snout 21/2 in 

 head ; eye 20, 8 in snout, 13 in interorbital ; mouth wide, labial folds 

 crossing half or more of space from angles to symphysis on lower 



