344 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxiv. 
the skeleton feebly ossitied. Northern seas of both hemispheres. B_y 
means of the adhesive ventral disk these fishes are enabled to attach 
themselves very firmly to rocks or other objects. The}^ feed on Crus- 
tacea, worms, small fishes, and plants. The young of Cj/doj^terus 
bear a close resemblance to Ziparu\ an evidence of the common origin 
of the 2 groups which is borne out by the anatomy. 
Cyclopterinre : 
I. Spinous dorsal present, sometimes concealed in adult. 
a. Barbels small or none; disk anterior, below the head. 
b. Skin naked or with scattered slender spines; no lateral \hw..Leihotremns, 1. 
Liparopsina' : 
II. Spinous dorsal wholly wanting. 
a. Dorsal short, opposite anal, of 9 or 10 rays; skin wholly smooth, without 
bony tubercles Oijdopterichthys, 2. 
1. LETHOTREMUS Gilbert. 
Lethoiremus Gilbert, Rept. U. S. Fish Connu., 1893 (1896), p. 449 {muticns). 
This genus differs from Ewnicrotrem i/s in the total absence of the 
bon}^ plates and of a lateral line or pores on sides of head and body. 
The skin is smooth in the typical species. 
The ventral disk is large, placed below the gill openings and base of 
pectoral. Barbels absent in the typical species, present in the Japan- 
ese. The body is almost spherical except for the short tail. The 
spinous dorsal is well developed. Gill opening very small. The genus 
is very close to Cydopteroides from Bering Sea, difl'ering chiefly in 
the absence of prickles and perhaps in the more anterior insertion of 
the ventral disk. 
(A7^6';;, f orgetf ulness ; rp?} /,<«', aperture.) 
I. LETHOTREMUS AWJE Jordan and Snyder, new species. 
Head 2i in length; depth 2; depth of caudal peduncle 3i in head; 
length of snout 4; diameter of orbit 3i; width of interorbital space 
2|; D. VI, 8; A. 7; P. 21. 
The body is almost globular, the width about equal to the depth; 
the tail compressed posteriorly. Head large, snout short, the jaws 
about equal. Eye large, lateral, situated much nearer to snout than 
to gill opening, the preorbital area about equal to diameter of pupil; 
interorbital area broad and flat. Mouth somewhat oblique, the cleft 
extending backward to a perpendicular passing between pupil and 
anterior part of orljit; jaws with l)i-()ad bands of close-set, blunt 
teeth. Gill opening narrow, located about midway between upper 
edge of base of pectoral and insertion of dorsal, the flap triangular in 
shape. 
Skin smooth. A short barbel above eve, posterior to nostril; a long, 
slender barbel on lower jaw; a second, similar one at lower edge of 
