142 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



Family SYNAPHOBRANCHID.^. 



Synaphohranchida; Johnson, Proc. Zoiil. Soc. London, 18(52, 169.— Giix, Arrangement Fam. Fishes, 1872, 20; 



Stamlard Nat. Hist., ni, 1885, 108 .— Joudan and Gilukrt, Bnll. xvi, U. S. N. M., 1882, 364.— Jordan 



and Davi.s, loc. til., 671. 

 Siiiiapliubraiichoidei, Bi.kekeu, Atlas leh. ludo-Neerlaud., iv, 1864, 13. 

 Si/naphobranchina, Gunther, Cat. Fishes B. M., 1870, \ni, 19, 22. 



Apodal fishe.-^with body slender, iingaillifonii, moderately compressed anteriorly, much 

 compressed toward end of tail, and with the anus in the anterior third of the total length. 



Scales small, linear or elongate elliptical, arranged in small groups obliquely at right 

 angles to those of the neighboring groups. Lateral line distinct, more or less high up and 

 on each side of the back in front, but gradually declining, and near the middle behind. 



Head moderate, compressed, oblong, conic laterally, with all the bones invested in the 

 skin. Eyes within the anterior half of the head, directed sideways, of moderate or large 

 size, covered by thin skin. I^ostrils lateral, the posterior considerably in advance of the 

 lower half of the eye, the anterior near the tip of the snout and subtubular. Mouth with 

 the cleft slightly oblique, extending considerably beyond the eyes. Jaws well developed; 

 maxilliues approximated close to the front of the vomer, with the clamping processes selli- 

 form and appressed closely to the sides of the vomer behind its head, with ledge like exten- 

 sions within along the anterior half, and expanding vertically backwards; mandible slender, 

 the dentary with the coronoid jirocess obsolete, the surface of the bone having a corneous 

 appearance behind, ensheathing the articular, which extends well forward in front of the 

 condyle and scarcely at all backwards. Teeth conic, in a narrow baud in the jaws and 

 vomer. Lips obsolete. Tongue little developed. Periorbital bones almost membranous. 



Opercular apparatus feebly developed; operculum lamelliform and claviform, inserted 

 very low on the hyomandibular ; suboperculum expanding downwards and with an anterior 

 process continued in front of the operculum; iuteroperculum lamelliform, intervening 

 between the suboperculum and preoperculum ; preoperculum almost reduced to a muciferous 

 canal. 



Branchial apertures inferior and confluent in a single external, longitudinal slit. Bran- 

 chiostcgal rays in moderate number (about 1.5), attached to the sides of the compressed 

 ceratohyal and epihyal, .slender, abbreviated, and moderately bowed, not being curvetl up 

 above the operculum. 



Dorsal, anal, and caudal confluent in an uninterrupted fin, with the rays readily per- 

 ceptible through the skin; dorsal variable, commencing behind or in front of the anus and 

 mostly low, anal deeper and commencing close behind the anus ; caudal prominent. 



Pectorals well developed, near the breast, with the rays distinct. 



Branchial arches nearly complete, with slender glossohyal and urohyal, and with the 

 first, second, and third basibranchials ossified, first and second hypobranchials ossified, 

 third cartilaginous, ceratobranchials and epibranchials of four jtairs, ossified; pharyngo- 

 branchials of second i)au' rod-like, of third pair developed as dentigerous epipharyngeals; 

 hyi>opharyngeals oblong, closely apposed to and superincumbent on the rudimentary fifth 

 arch. Interbranchial fissures extended. ( Gill.) 



KEY TO THE GENERA OF SYNAPHOBEANCHID^. 



I. Origin of dorsal behind vent; pectoral longer than snout; snout slender; teeth in a single patch on 



vomer SYNArnoBRAXcnrs 



II. Origin of dorsal near head; pectoral not longer than snout; snout stout; teeth in two patches on 

 vomer Histiobkanchus 



SYNAPHOBRANCHUS, Johnson. 



Synaphobranchui, Johnson, Proc. Zoiil. Soc, London, 1862, 169.— GDnther, Cat. Fish. Brit. Mus., viii, 19.— 

 Gill, Standard Niitural History, m, 108; Proc. U. S. Nat. M)is., xiu, 161. — Jordan & Davis, loc. oil. 



Origin of dorsal fin far back, remote from the head and behind the vent and origin of 

 dorsal. Anterior nasal tubes prominent. Snout slender. Pectoral longer than snout. 

 Teeth on the vomer in a single patch. 



