126 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



spines being proloiiffecl beyond tlie muscles, forming a triangular osseous plate. Adipose 

 tin rudimentary; anal fin short; caudal forked. Gill oi)ening wide; outer branchial arch 

 extending forward to behind symphysis of lower jaw and with very long gill rakers; bran- 

 chiostegals nine; pseudobrauchite present; air bladder present. Pyloric appendages 

 four. {Giiuther.) 



AEGYEOPELECUS HEMIGYMNUS, Cocco. (Figure 147.) 



Argyropelecus hemigt/mniis, Cocco, in Glorn. Sc. Sic, 1829, Case. 77, 146. — BoNArAKTE, Fauna Italica. Pcsci. 



text. — CuviER and Valenciennes, Hist. Nat. Poiss., xxn, 398. — GiiNTiiEn, Cat. Fish. Brit. Mus., v. 



385. — Challenger Eeport, xxii, 167. — Vaillant, Exp. Sci., Travailleur et Talisman, 103. 

 Sternoptyx hemim/mniis, Valenciennes in Cuviek Kegne Animal, 111., Poiss. iil. 103, fig. 3. — (Jdode and 



Bean, Bull. Mus. Comp. Zoiil. v, 10, 220. 

 Siernoplyx mediterranea, Cocco, in Giorn. II Faro, 1838, iv, 7, fig. 2. — Bonaparte, Fauna Italica, Pesci. fasc. 



XXVII, figure. 



Height of the body equals the distance between the gill opening and the caudal 

 base; posterior angle of mandible and angle of the prfeoperculum, each with a small trian- 

 gular spine ; tail slender, without spines. Pectoral reaching nearly to insertion of the anal. 



Eadial formula: B. 9; D. 7-8; A. 11; P. 9; V. 5. 



A. hcmigymnus, is according to Giinther, common in the Mediterranean and neighbor- 

 ing jiarts of the Atlantic, and frequently caught at night in the surface net. During the 

 cruise of the rorcupine an adult example was obtained between Shetland and Faroe, at a 

 depth of 180 fathoms. Giinther concludes that this fish is of nocturnal habits, living dur- 

 ing the day at a depth below the surface which varies according to circumstances. The 

 French expedition obtained it in the Gulf of Marseilles in 1,0G0 meters; in the Gulf of 

 Gascony in 741-1,534 meters; off the Canaries in 1,200 meters; off the coast of Portugal, in 

 950-1,100 meters, and off the coast of Morocco in 1,123 meters. 



This form, though usually very rare in the Mediterranean, sometimes is found in such 

 abundance that it is evident that in certain localities and depths it must be one of the 

 commonest of forms. Giglioli obtained in September, 1878, at Messina, over seven hundred 

 in three days, brought to the siu-face by the swift current passing through the Straits. 



Two sijecimens of this species were obtained by the Blake, fi'om Station cccxv, in 32° 

 18' 40" N. lat., 78° 43' W. Ion., at a depth of 225 t<i-thoms. One specimen (No. 31709, U. S. 

 N. M.) was takenby the. Fish Hmck from station 1112, in 39° 56' N. lat., 70° 35' W. hm., at 

 a depth of 245 fathoms; and one by the Albatross from station 2117, in 15° 24' 40" N. lat., 

 63° 31' 30" W. Ion., at a depth of 683 fathoms. 



A species closely similar was taken by the Investigator in the Indian Ocean, station 118, 

 in 103 fathoms. (Alcock, Ann. and Mag. Nat. Hist., 1891, ii, 126.) It may be called A. 

 Alcocki. 



AEGYEOPELECUS OLFEESII (Cuviek), C. and V. (Figure 148.) 



Sternoptyx Olfersii, CuviER, Efegne Anim., 2d edit., ll, 316, pi. Xiil, fig. 2. — DOben and Koren, in Vet. Akad. 



Handl., 1844, 80, tab. 3, fig. C. 

 Argyropelecus Olfersii, CuviER and VALENCIENNES, xxn, 408. — LoWE, Proc. Zool Soc, 1850, 247. — GCntdek, 



Cat. Fish. Brit. Mus., v, 386. — Vaillant, Exp. Sci. Travailleur et Talisman, 104. 



Height of the body is equal to, or rather less than, distance between the shoulder and 

 the root of the caudal fin, tail at its base, below the end of the dorsal fin, as high as long. 

 Mandible with a short, flat spine at its posterior corner; angle of the preoperculum with a 

 spine directed downwards ; tail without spines. Pectoral fin extends to ventral. ( Giinther.) 



Radial formula: B. 9; U. 9; A. 11; P. 10; V. G. 



This species, like the others ju.st described, has hitherto been considered to be a pclngic, 

 surface form, and has now and then been found as far north as the coast of Norway, and was 

 taken by the Frencii expedition ofl' Portugal in 950 and 1,615 meters. The Challenger dredged 

 a si>ecimen 2^ inches long, at a depth of 1,125 fathoms, at Station I, off Capo Finisterre. 



Dr. Giinther, di.scussiug this occurrence, remarks: "The question arises whether the 

 fish was really cai)tured at this great depth, or whether it entered the dredge during its 



