FISHES OF THE PHILIPPINE ISLANDS AND ADJACENT SEAS 269 



erect, remainder oblique, increasingly so posteriorly, edges serrate, 

 19 to 26 fine serrae on each edge, and behind single row of function- 

 ing teeth 4 overlapping rows of inwardly depressed teeth in succes- 

 sion; inner internasal space 1% in preoral length; nostrils more or 

 less rounded, separated, without serrae or oronasal grooves. Gill 

 openings equal longitudinal diameter of eye. Spiracles large. 



Head and body covered vrith small scales, each more or less quad- 

 rate, with dorsal ridge ending in a stout spine, usually also 1 or 2 

 minute basal spines. 



First dorsal inserted midway between hind eye edge and second 

 dorsal origin, length along front edge 1% in head to first gill opening ; 

 second dorsal inserted over last fourth of ventral base, length along 

 front edge 1% in head to first gill opening; caudal from subcaudal 

 origin 3% in rest of fish, front edge of subcaudal 21/4 ii^ caudal ; least 

 depth of caudal peduncle 41/5 in head to first gill opening; pectoral 

 1%, width 21/2 in its length; ventral length li/4 in head. 



Uniform dark brown, slightly lighter below. Tips of fins slightly 

 lighter. 



Length, 770-1,100 mm. (J. L. B. Smith.) 



South Africa. Differs from Dalatias Iwha according to Smith "in 

 numerous dimensional relationships, notably in the smaller fins, the 

 caudal lobes being markedly loMer . . . the teeth of the lower jaw in 

 lichxi are oblique in juveniles but erect in adults. In my specimens 

 of hrevipinnis, of which the larger are presumably adults, all but 

 the central symphyseal erect tooth of the lower jaw are oblique, the 

 posterior teeth very markedly so." 



Genus ISISTIUS Gill 



Isistius Gnx, Proc. Acad. Nat. Sci. Philadelphia, 1864, p. 264. (Type, Scymnus 



irasiliensis Quoy and Gaimard, monotypic.) 

 Leius Kner, Denkschr. Akad. Wiss. Wieu, math.-nat. Kl., vol. 24, p. 9, 1865. 



(Type, Lews ferox Kner, monotypic.) 



Body elongate, fusiform, cavity % total length. Tail short. Head 

 .subconic. Eye large, without nictitating folds. Mouth transverse, 

 with straight deep groove, covering labial folds, at each angle, ending 

 at end of transverse fold in front of and covering distinct upper lip. 

 Upper teeth raptorial, slender, subconic ; lower sectorial, compressed, 

 with smooth-edged, triangular cusp erect. Nostrils anterior, nasal 

 valve short lobe in middle. Gill openings narrow. Spiracles trans- 

 verse. Scales minute, polygonal or quadrangular, with central de- 

 pression on crown, in pavement. Dorsals and paired fins small. 

 Caudal short. Tail without lateral folds or caudal pits. 



Pelagic in tropical and temperate seas. One species, of interest 

 as one of the first sharks noticed to be luminous. 



