2728 Bulletin ^7, United States National Museum. 



are of an extremely light and thin texture, and frequently other parts of 

 their organization, their integuments, muscles, and intestines are equally 

 loose in texture when the specimens are brought to the surface. In their 

 habits they probably do not differ in any degree from their surface repre- 

 sentative, LopJtiHS. The number of the dorsal spines is always reduced, 

 and at the end of the series of these species only 1 spine remains, with a 

 simple, very small lamella at the extremity {MeJanocctus jolmsonii, Melano- 

 Cftits murraj/i). In other forms sometimes a second cephalic spine, some- 

 times a spine on the back of the trunk, is preserved. The first cei>halic 

 spine always retains the original function of a lure for other marine crea- 

 tures, but to render it more effective a special luminous organ is some- 

 times developed in connection with the filaments with which its extremity 

 is provided {Ceratias hispinostis, Oneirodes esehrichtii). So far as it is known 

 at present these complicated tentacles attain to the highest degree of 

 development in HimantoJophus and ^Ega'onichthys. In other species very 

 peculiar dermal appendages are developed, either accompanying the spine 

 on the back or replacing it. They may be paired or form a group of 3, 

 are pear-shaped, covered with common skin, and perforated at the top, a 

 delicate tentacle sometimes issuing from the foramen." {I'ediculati, 

 genus Ceratias, Giiuther, Cat., iii, 205, 1861 ; Ceratiklw, Gill, Proc. U. S. Nat. 

 Mus. 1878, 216.) 



a. Mouth moderate. 



b. Gills iu 2i jiairs. 

 Ceratiin.e: 

 c. Cleft of mouth nearly vertical; skin prickly. 

 d. Cephalic spine .single. 



e. Dorsal spine present; lateral caruncles present; no teeth on vomer. 



Ceratias, 1063. 

 ee. Dorsal spine wanting; caruncles present. 



/. Caruncles remote from soft dorsal. Mancalias, 1064. 



ff. Caruncles close to soft dorsal. Cryptopsaras, 1065. 



Oneibodin.e : 



cc. Cleft of mouth nearly horizontal; skin smooth; 1 cephalic spine and 1 



postcephalic spine. Oneikodes, 1066. 



HiMANTOLOPHIN^E : 

 bh. Gills in \ 2J pairs; hody with scattered tubercular scutella; no second dorsal 

 spine. 

 g. Body and head compressed; mouth oblique; joint of mandible below or 

 behind eye; eye rudimentary. 

 h. Body oblong, oval; dorsal rays 9; pectoral 12. Himantolophus, 1067. 

 hh. Body short and deep; dorsal rays 4; pectoral about 17. 



COBYNOLOPHUS, 1068. 



aa. Mouth with enormous gape. 



MELANOCETIX.E : 



i. Cleft of mouth nearly vertical ; pectoral small, in advance of dorsal and of 

 gill opening; second dorsal spine wanting; gills in 2i vairs. 

 j. Gular tentacle wanting; no teeth on vomer. Liocetus, 1069. 



jj. Gular tentacle present; 1 tooth on the vomer. Linophkyne, 1070. 



CAULOPHRY'NIN^ : 

 it. Cleft of mouth nearly horizontal; pectorals below dorsal and behind gill 

 opening; gills in J 2i pairs. 

 k. Dorsal and anal greatly produced; skin naked; head and body with 

 many luminous filaments. Caulophkyne, 1071. 



