246 BULLETIN 10 0, UNITED STATES NATIONAL MUSEUM 



Genus ETMOPTERUS Rafinesque 



Etmopterus Rafinesque, Caratleri aiiiinali piante Sicilia, p. 14, 1810. (Type, 



Squalus aculeatus Rafinesque, monotypic.) 

 Spinax Cuvier, R^gne animal, vol. 2, p. 129, 1817. (Type, Squalus spinax Lin- 

 naeus, tautotypic.) 

 Acanthidivm. Lowe, Proc. Zool. Soe. London, 1839, p. 91. (Type, Acanthidium 

 pusiUum Lowe, designated by Goode and Bean, Oceanic Ichthyology, p. 10, 

 1895. Precludes Acanthidium Montrouzier, 1S5S, in Rhynchota.) 

 Acanthidim Soixas, Zool. Record, vol, 43, 1906, p. 58, 1907. (Type, Acanthidium 

 pusillum Lowe.) 

 Body partly cylindrical or fusiform, longer than tail. Snout pro- 

 duced, blunt, wide. Eyes large, lateral, shielded by pigment in up- 

 per front of orbit, without nictitating membranes. Mouth trans- 

 verse, moderately arched, long deep groove at each mouth angle. 

 Teeth dissimilar in 2 jaws; upper erect, tricuspid, bladelike; lower 

 very oblique, inner margin forming cutting edge. Nostrils well ad- 

 vanced, on lateral edge of snout. Gill openings narrow. Spiracle 

 large, above and behind eye, superior. Scales small, with wide 

 quadrangular or radiate bases and with or without an erect cusp. 

 Often with luminous organs, very minute and numerous as lines and 

 patches covering nearly entire ventral body surface. Dorsals with 

 spines doubly grooved laterally, second longer than first, behind ven- 

 trals. No anal. Caudal short, without pit in front, with shallow 

 notch between subterminal and subcaudal portions. 



Bathypelagic. Like Isistius some of the species of interest as 

 luminous. 



ANALYSIS OF SPECIES 



a}. AcANTHmruM. Second dorsal origin behind ventral base ; first dorsal origin 

 midway between orbit and second dorsal origin. 

 6\ Ventrals inserted nearer pectoral origin than sxibcaudal origin. 

 c\ Caudal long as head to last gill opening ; second dorsal inserted opposite 



hind basal ventral edge lucifer 



cl Caudal long as head to first gill opening; second dorsal inserted nearly 



or entirely behind ventral brachyurus 



5'. Ventrals inserted midway between pectoral and subcaudal origins or little 

 nearer latter; second dorsal Inserted close behind hind basal ventral edge. 



pusillus 

 a'. Etmoptebus. Second dorsal origin over or little before ventral base ; ventral 

 origin slightly nearer subcaudal than pectoral origin. 



d\ First dorsal origin much nearer second dorsal origin than spiracle. 



villosus 

 d^. First dorsal origin much nearer spiracle than second dorsal origin. 



spinax 

 Subgenus Acanthidium Lowe 



ETMOPTERUS LUCIFER Jordan and Snyder 



Etmopterus lucifer Jordan and Snyder, Proc. U. S. Nat. Mus., vol. 25, p. 79, 1902 

 (type locality: Misaki) ; Annot. Zool. Japon., vol. 3, p. 129, 1901 (KuroSiwo, 

 off Misaki; no description ) .—Jordan and Fowleb, Proc. U. S. Nat. Mus., 



