192 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



are concerned. Seriola, Oligoplites, Trachynotus, and some of the large species of Carcmx, 

 such as 0. hippos, are powerful swimmers, and are likely to make long journeys, at least 

 as far as from the West Indies to the Bermudas, where many of the species occur casually. 

 Others, like Selene, drift far and wide with the currents, and are found in mid ocean, 

 apparently under much the same conditions as in Xomens. Nomeus is, however, character- 

 istically a mid-ocean lish, and is not known to breed near the shores, but there is good 

 reason to believe that Selene does. 



Seriola Dumcrilii, Risso, is said by Canestrini to occur everywhere in the Mediter- 

 ranean, but to dwell at great depth (a grande profondita), so that its capture is uncommon. 

 The young of Seriola are pelagic surface forms. 



Garanx amblyrhynchus, C. & V. has been found several times under circumstances which 

 would seem to indicate that it came from very great depths, but it so closely resembles in 

 structure the other members of the genus that it is hard to believe that there is not some 

 error of observation. It was brought up by the Blake at station 324 (Lat. 33° 27", Ion. 

 75o 53' 30"), in G47 fathoms. 



Porthmeus amia(Lichia am ia, Auctorum, in its adult form — Porthmeus argenteus, in young 

 state) is while young a pelagic form, and has been found off the west coast of Africa. The 

 young of Chorinemus and of Oligoplites are, according to Liitkeu, also pelagic (Spolia At- 

 lautica, p. 192 (600)). Two species belonging to this family have been taken in the deep- 

 sea nets, but it seems hard to believe that they were caught at the bottom. 



Family SCOMBRID^E. 



GU ScombrM, Rafixesque, Indiee d'lttioliogia Siciliana, 1810, 



Scomhrini, Bonaparte, Cat. Metodico, 73 (Sub. fam. 228). 



Scombroidei, Blekker, Tentameii, 1859, xxn, (Familia 95). 



Scombridas, Gill, Proc. Acad. Nat. Sci. Phila., 18o2, 124 ; Arr. Fam. Fishes, 1872, 8 (No. 78).— (Gcnther, Cat. 



Fish. Brit. Mus., n, 349-373. — Trichiuridw, in part, and Scombrida; in part). — Jordan and Gilbert, 



Bull, xvi, U. S. Nat. Mus., 1883, 422. 



Physoclystous Aeanthopterygians, with body elongate, fusiform; the scales minute or 

 wanting (generally cycloid, but about the thorax larger ones, sometimes ctenoid, are 

 developed, forming the so-called corselet of the tunnies). Lateral line distinct, frequently 

 sinuous. Head subconic, poiuted anteriorly. Mouth rather large, with lateral cleft; upper 

 jaw not protractile; maxillary without supplemental bone; sharp teeth on the jaws and 

 generally on the vomer, sometimes on palatines, rreoperculum entire; operculum well 

 developed, unarmed; in the extremely young the preoperculum is usually armed witli 

 several radiating spines, subsequently absorbed and lost. Gill-openings large, confluent 

 below. Gill-rakers usually long. Pseudobranchire present, large. A slit behind the fourth 

 gill. Brauchiostegals generally 7. Dorsal fins 2, the first composed of rather slender, 

 spinous rays, depressible in a groove, the second with branched rays, the posterior ones 

 usually detached and separate, forming series of Unlets. The first dorsal is always either 

 elongate or widely separate from soft dorsal. Anal similar to second dorsal. Caudal 

 peduncle very slender, usually keeled, the caudal deeply forked, adapted for rapid propul- 

 sion. Ventrals moderate, thoracic. Vertebra numerous (more than 25). Pyloric caeca 

 well developed, numerous. Stomach sac-shaped. Air bladder frequently absent. 



KEY TO THE GENERA. 



I. Body fusiform, moderately elongate Scombrin.e, Gill 



A. Spinous dorsal short (of less than 12 spines), with wide space separating it from second dorsal; pec- 

 torals high up ; caudal not carinated. 



1. Vomer and palatines with teeth ; corselet obsolete Scomber 



2. Vomer and palatines toothless ; corselet well developed Auxis 



B. Spinous dorsal long (of more than twelve spiues), contiguous to the second; pectorals low; caudal 

 with keels ; pyloric ca'ca very numerous Orycnin.e, Gill 



1. Corselet imperfect or obsolete- ; teeth of jaws strong. 



a. 11 to 18 rays in spinous dorsal Scomberomorus 



6. 25 rays in spinous dorsal; jaws beak-like Acanthooybium 



