24 THE VOYAGE OF H.M.S. CHALLENGEE. 



Bregmaceros atlanticus. Six specimens, the largest nearly 50 mm. long, were obtained 

 by the " Blake," at depths varying from 90 to 305 fathoms. This occurrence, taken 

 together with the facts that the Challenger obtained a young S2:)ecimen in the open sea in 

 the Pacific, that Bregmaceros maeclellandii has a black-coloured pharynx, and that Breg- 

 maceros macclellandii and Bregmaceros punctatus possess deeply sculptured cranial bones 

 witli wide muciferous cavities, proves that these fishes inhabit the open sea, and descend 

 to considerable depths, although they seem not rarely to be met with close to the shore. 



I have mentioned al)ove that I agree now with Mr. Hutton in regarding the New 

 Zealand form as the type of a distinct genus ; Mr. Hutton adopted the second generic 

 name given to Bregmaceros macclellandii, Calloptilum, for the genus which he 

 established for the New Zealand fish, but according to a generally accepted rule of 

 nomenclature, this course is not admissible, and a new name has to be given to the latter. 

 It is not possible at present to determine to which of the two genera the young specimens 

 -obtained by the Challenger and " Blake " should be referred. The dorsal and anal fins 

 are but little diflerentiated in the young of all these species, and the structure and changes 

 of tlieir ventral fins are very imperfectly known. 



I proceed first to give the distinctive characteristics of the two genera : — 



Bregmaceros, Thoraps. = Ccdloptilum, JHcli. = Asthenni-iis, Tick. 



Body fusiform, compressed posteriorly, covered with cycloid scales of moderate size. 

 Two dorsal fins, the anterior reduced to a single long ray on the occiput; the second and 

 the anal more or less depressed in the middle, in adult specimens tlie middle rays 

 becoming more or less obsolete, so that the fin appears to be divided into two. Ventral 

 fins well developed, composed of five rays, the three outer of which are dilated and much 

 elongated. Minute teeth in the jaws and on the vomer. Air-bladder large. Pyloric 

 appendages few in number (two). Gill openings very wide, the gill membranes being 

 united below the throat, and not attached to the isthmus. Pseudobranchise none. 

 Branchiostegals seven. 



"O" 



Auchenoceros, Gt\\v. — Qdloiitihnn, Hutt. ncc Rich. 



Head and body compressed, elongate, covered with small, exceedingly delicate and 

 deciduous scales. Two dorsal fins, the anterior reduced to a single long ray on the neck, 

 above the pectoral ; the second more or less depressed in the middle ; one anal. A'entral 

 fins rudimentary, each composed of two slender elongate rays. Minute teeth in the jaws, 

 none on the vomer. Air-bladder small. Pyloric appendages in moderate number (eight). 

 Gill openings very wide, the gill membranes not being attached to the isthmus. Pseudo- 

 l)ranchi« none. 



