DISCUSSION OF SPECIES AND THEIR DISTRIBUTION. 1 2."> 



length <»nly 7 millimeters. Also ihe relative position of the luminous organs, which are 

 congregated in groups, is subject to unimportanl variations. 

 Two forms arc recognized by Giinther: 



(1) in the first and more common (Fig. I>) the eye is comparatively larger and its 

 diameter more than the depth of the triangular space, which is formed by the margins of 

 the preoperculum, of the jaws, and of the orbil : the upper part of the mouth is also con- 

 spicuously above the level of the lower margin of the orbit. 



(2) In tli c second form (Fig. D') the diameter of the eye is not longer than the < 1 «'i >t li of 

 the triangular spare described, and the upper pari of the clef! of the month is on a level 

 with the lower margin of the orbit. 



Both tonus occur in the Indo-Pacitic as well as Atlantic, and seem sometimes to have 

 been obtained on the same occasion; and as, moreover, intermediate forms occur which 

 migirl be assigned to either of the two forms, it is evident that the differences mentioned 

 are not of specific value. 



Very young specimens, of 15 millimeters in length, were found by Giinther already to 



possess all the characteristics of the adult. 



Specimens of this species were taken by the Blake, from Station xxxv, off Santa Cruz, 

 at a depth of 508 fathoms; from Station cccxxiu, in 33° 19' N. hit., 70 1l" 30" W. Ion., at 

 a depth of -T.7 fathoms: and from Station CCOXVT, in 32<: 7' > T . hit., 78 .".7' 30" \Y. Ion., at a 

 depth of 229 fathoms. Also by the Albatross from the follow bag localities: Cat. No. 32668, 

 !'. S. N. M., from station 2003, in 37° 10' 30" ST. hit., 74° 20' 36" W. Ion., at a depth of 641 

 fathoms; ,at. No. 33471, U. S. N. M., from station :.'070, in 41° 13' N. hit., 66° 00' 50" W. 

 Ion., at a depth of 906 fathoms; cat. No. 33563, U. S. N. M., from statical 2101, in 3«J° 18' 

 30" X. hit., 68 24' W. Ion., at a depth of 1686 fathoms; also specimens from station 2111 

 in 35° 00' 50" X. hit., 71 57' 40 \\ . Ion., at a depth of 938 fathoms: station 2118 in 13° 32' 

 40" K lat., 62° 54' W. Ion., at a debth of 690 fathoms; station 3553 in39 c 48' X. hit., 7<P36' 

 W. Ion., at a depth of 551 fathoms: and station L'.V.l in 39° 48' 3(1" N. hit., 70° 40' 30" \V. 

 Ion., at a depth of 44.". fathoms. A single specimen (Cat. No. 26235, U. S. N. M.) was taken 

 by the schooner Guy Cunningham off the Grand Bank at a depth of 150 fathoms. 



Dr. Giinther, after studyingthe specimens obtained during the voyage of the Challenger, 

 reached the conclusion that its frequent capture at all depths from surface downward is 

 only a proof of its abundance in all tropical seas, and of the slowness of its movements, 

 which prevent it from getting out of the way of the dredge or net. He infers that, like 

 Argyropeleeus, it is a pelagic fish, which probably lives in shoals, as sometimes more than 

 one example were obtained in the same haul, and that possibly it may descend to or beyond 

 the 100 fathom line during the daytime. More information is needed upon all these 

 points. 



ARGYROPELECUS, Cocco. 



Arijyrnpi In-us, Cocco, Gioni.Sci. si.il.. 1829, fasc. 77, 146; CuviER and VALENCIENNES, Hist. Nat. l'oiss., 



xxn, 392. — Gcxther, Cat. Fish. Brit. Mils., v, 389; Challenger Report, xxn, 1(37. 

 Pleurothyris, Lowe, Fish. Madeira, 64. 



Trunk much elevated and compressed, passing abruptly into the tail, which is narrow; 

 body covered with a silvery pigment, without regular scales: series of luminous (phosphor- 

 escent) spots run along the lower side of the head. body, and tail. Head large, compressed, 

 and elevated, with the bones thin, but ossified. Cleft of the mouth wide, with the lower 

 jaw prominent. The margin of the upper jaw is formed by the intermaxillary and max- 

 illary, both of these bones having a sharp edge, which is beset with a single series of 

 minute teeth: lower jaw and palatine bones with a series of small, curved teeth. Eyes 

 rather large, and, although lateral, directed upward and very close together. Pectorals 

 well developed, ventrals very small. The humeral arch and the pubic bones arc prolonged 

 into Hat, pointed processes, which project in the median line of the belly: a series of imbri- 

 cate scutes runs from the humeral to the pubic bone, forming a sort of serrature along the 

 belly. The dorsal fin is short and occupies about the middle of the length of the fish; it 

 is preceded by the first commencement of the formation of a spinous dorsal, several neural 



