54 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



of WasLiiigtou in G85 to 877 fathoms. All of these spedes were apparently black in life. 

 In all of them the eye is large and is believed to be intended for the utilization of phosjihor- 

 esceut light produced by other animals of the deep sea. These fishes are not predaceous. 

 Their bones are very thin, the fin rays feeble, and the scales easily deciduous. Dr. Giiuther 

 considers Bathylayus nearly allied to Microstoma. 



Mr. Murray has made a very important observation on the circumstances attending the 

 capture of this fish, which has direct bearing on the question as to the bathybial range of 

 many of the fishes cai)tured by the deep-sea trawl. At this station the trawl was over the 

 side seven hours, but it never seemed to touch the bottom. Yet it contained, besides the 

 specimen of Bathylagiis, several large Medusa?, several bright scarlet shrimps, and other 

 animals. " It is impossible to say how near the trawl may have been to the bottom, l)ut 

 Mr. Murray considers it quite certain that most, if not all, of the animals above mentioned 

 \\ere captured in the intermediate water, between a depth of 100 fathoms from the surface 

 and a short distance from the bottom." 



"Notwithstanding this circumstance," says Giinther, " the thinness of the bones, the 

 fragility of the fin rays, the delicacy of the skin and scales, and the enormously large eyes, 

 seem to be sufficient evidence that these fishes are actually inhabitants of very great depths, 

 although there may be reasonable doubts as regards the exact depth at which Bathylagns 

 atlanlu'UH was obtained. These fishes must therefore be entirely dependent for vision on 

 the phosphorescent light which is produced by other abyssal creatures. Not being fish of 

 prey themselves, or only to a slight degree, they would be attracted by the light issuing 

 from the Pediculates and Stomiatids of the deep, and thus fall an easy prey to these fishes." 



BATHYLAGUS, Gunther. 



Bathylagus, GItntiter, Ann. and Mag. Nat. Hist., 1878, 5th series, n, 248; ("hallenger Report, xxii, 219. 



Body oblong, compressed, covered with thin deciduous scales of moderate size. No 

 phosphorescent organs. Head short, rather compressed, with thin membranaceous bones. 

 Mouth very narrow, transverse, anterior; the margin of the upper jaw is formed by the 

 intermaxillary and maxillary, which is short dilated. Teeth on the intermaxillary rudi- 

 mentary; those of the lower jaw extremely small, implanted on the edge of the bone, form- 

 ing a minute serrature; a series of minute teeth across the vomer and along the palatine. 

 Eye very large. Pectoral and ventral fins developed; the latter seven rayed and inserted 

 opposite to the dorsal, at a considerable distance from the pectoral. Dorsal fin in the mid- 

 dle of the length of the body; adispose fin small, not very far from the caudal. Anal fin of 

 moderate length or many-rayed. (Jill opening narrowed, commencing opposite to the root 

 of the pectoral, and extending across the isthmus, the gill membranes being united and not 

 attached to the isthmus. Gill rakers lanceolate, rather long; gills small; pseudobrauchiaj 

 well developed. 



KEY TO THE SPECIES OF BATHYLAGUS. 



I. Anal fin short, with 13 to 19 rays, D. 9. 



A. Dorsal equidistant from snout and caudal, 13 anal rays BATnYi,Af;u8 atlaxtici's 



B. Dorsal nearer to snout than caudal. 



1. Length of head one-fourth of total, V. 7 ; A. 16 Hath ylaiu'.s euryops 



2. Length of head two-ninths of fntal, V. 9; A. 19 Bathylacus Benemcii 



II. Anal lin moderate, 22 or more rays, 1 ». 10. 



A. Length of head two-ninths of total, body slender, A. 22; V. 8 Bathy-lagus antarcticl'S 



BATHYLAGUS ATLANTICUS, Gunther. 



Baihylagm atlantieus, GCnther, Ann. and Mag. Nat. Hist., 1878, ii, 248; Challenger Report, xxil, 1887, 219. 



The height of the body is a little less than the length of the head, which is one-fourth 

 of the total (without caudal); the eye one half of the length of the head. The width of the 

 iuterorbital space is only two-thirds of that of the eye. Snout very short, with steep ante- 



