DISCUSSION OF SPECIES AND THEIR DISTRIBUTION. 123 



Giinther described this genus and species from a specimen '■'>.\ inches long, obtained 

 south of the Philippine Islands, ai Challenger Station coxiy, al a depth of500fathoms. He 

 had previously obtained, in 1868, the specimen collected by Lowe at Magdalena. The 

 Albatross obtained a single specimen from station 2392, in 28° 47' 30" 28. lat., 87° 27' W. 

 Ion., at a depth of 724 fathoms. 



The capacity of this form for swallowing fishes greater in size than itself appears to be 

 as great as that of Chiasmodus, as may be understood from an inspection of figure c 1 in 

 Giinther. 



Family STERNOPTYCHID^E. 



Sternoptychidw, Gcntiiei:, Cat. Pish. Brit. Mas., v, 1864, 384, (part group Slernoply china). — Gill, Arr. Fami- 

 lies Fishes, 1872, 15 (Family No. 15:>, name only); Proo. V. s. \. M.. vn, 1884, 350 — Jordan and 

 Gilbert, Bull, xvi, U. S. Nat. Mas., 283.— Jordan, Cat. Pish. N. Am., 16. 



Malacopterygians with compressed ventradiform body, carinated contour, deeply and 

 obliquely cleft and subvertical mouths, whose upper margin is constituted by the supramax- 

 illaries as well as the intermaxillaries; branchiostegal arch near and parallel with lower 

 jaw, scapular with an inferior projection, and with one or more of the neural spines abnor- 

 mally developed, and projecting above the back in advance of the dorsal fin. (Gill.) 



KEY TO THE GENERA AND SPECIES. 



I. Body naked. 



Abdominal outline nearly continuous in a sigmoid curve, a single pmdueodspike-like neural spine in front 



of the dorsal fin, and about 5 branchiostegal rays Sternoptyciiix.e, « ; ill 



A. Teeth in the jaws in several series; dorsal fin with spinous dilatations Sternoptyx 



1. Height of body equal to length, without caudal Sternoptyx diaphana 



Abdominal outline abruptly contracted in advance of anal, several produced neural spines constituting 

 a uniform edge in advance of dorsal, and about 9 branchiostegal rays Argyropelecin.*:, Gill 



A. Teeth in the jaws in a single series, minute ARGYR0PELECU8 



1. Tail spineless. 



a. Mandible with flat spine at its lower angle. 



i. Pectoral fin extending nearly to origin of anal A. HEMIGYMNT7S 



ii. Pectoral extending to ventral A. Olfeksii 



b. Mandible without spine A. D'I'kvillii 



2. Double row of spines along side of tail A. aculeatus 



B. Teeth in jaws long and recurved STERNi iptvciiides 



II. Body covered with large, thin, deciduous scales. Anterior spinous dilatation of dorsal fin lacking. 



l'.H.YII'XIN.E 



A. Luminous organs much developed POLYIPNUS 



STERNOPTYX, Hermann. 



Sternoptyx, HERMANN, Naturforscher, xvi, 1781-2. — Cuvier and Valenciennes, Hist. Nat. Poiss., XXII, 412. — 

 Gunther, Cat. Fish. Brit. Mus., v, 386; Challenger Report, xxn. 169, pi. XLV, figs. D, D'. 



Body much elevated and compressed, passing abruptly into a short and compressed 

 tail, the angle inade by the hind margin of the trunk and the lower edge of the tail being 

 tilled up by a broad fold of the integument, of peculiar transparent appearance, resembling 

 thin cartilage. This fold bears the anal fin and is supported by interhsemal rays. The 

 greater portion of the body is scaleless and covered with a silvery pigment, A series of 

 luminous spots runs along the lower edge of the abdomen and is separated from that of the 

 other side by a cartilaginous fold occupyingthe median line of the abdomen; another series 

 runs on each side of the isthmus: a row of three above and behind the root of the ventials, 

 and another row of three above the vent. The luminous organs on the lower part of the 

 tail consist anteriorly of a row of four, of which the first is prolonged along the back as a 

 narrow band, terminating about the middle of the depth of the body in a globular black 

 spot with a white center; posteriorly in front of the caudal rays there is another row of four 

 small spots. 



