126 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



spines being prolonged beyond the muscles, forming a triangular osseous plate. Adipose 

 fin rudimentary; anal fin short; caudal forked. Gill opening wide; outer branchial arch 

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

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

 four. (Giinther.) 



ARGYROPELECUS HEMIGYMNUS, Cocco. (Figure 147.) 



Argyropcleeus hemigymnus, Cocco, in Giorn. Sc. Sic, 1829, fase. 77, 146. — Bonaparte, Fauna Italica. Pesci. 



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



385. — Challenger Report, xxii, 167. — Vaillant, Exp. Sci., TravaiUeur et Talisman, 103. 

 Sternoptyx hemigymnus, Valenciennes in Cuvier Regue Animal, III., Poiss. pi. 103, fig. 3. — Goode and 



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

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



xxvn, figure. 



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

 base; posterior angle of mandible and angle of the prseoperculuin, 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. hemigymnus, is according to Giinther, common in the Mediterranean and neighbor- 

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

 cruise of the Porcupine 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 1,060 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 surface by the swift current passing through the Straits. 



Two specimens of this species were obtained by the Blake, from Station cccxv, in 32° 

 18' 40" N. lat., 78° 43' W. Ion., at a depth of 225 fa-thorns. One specimen (No. 31709, U. S. 

 N. M.) was takenby the Fish Haul: from station 1112, in 39° 50' N. lat., 70° 35' W. Ion., 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, n, 120.) It may be called A. 

 AlcocM. 



ARGYROPELECUS OLFERSII (Cuvier), C. and V. (Figure 148.) 



Sternoptyx Olfersii, Ccvier, Regno Anini , 2d edit., n, 316, pi. xni, fig. 2.— Duben and Koren, in Vet. Akad. 



lLindl., 1844, 80, tab. 3, fig. '.'. 

 Argyropeleous Olfersii, Cuvier and Valenciennes, xxii, 408.— Lowe, Proc. ZooL Soc, 1850, 247. — Gunther, 



Cat. Fish. Brit. Mus., v, 386.— Vaillant, Exp. Sci TravaiUeur 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 preoperculHin with a 

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



Eadial formula: B. 9; D. 9; A. 11, P. 10; V. 6. 



This species, like the others just described, has hitherto been considered to be a pelagic, 

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

 taken by the French expedition i >ff Portugal in 950 and 1,015 meters. The Challenger dredged 

 a specimen 2J inches long, at a depth of 1,125 fathoms, at Station I, off Cape Finisterre. 



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

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



