348 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.48. 



XENERETMUS LEIOPS, new species. 

 Plate 17, fig. 10. 



Type-specimen — Cat. No. 75813, U.S.N.M., 176 mm. long, from 

 station 4410, off Catalina Island, southern California, depth 178 to 

 195 fathoms. 



Very close to X. latifrons, differing in the coloration, the more 

 slender form with longer caudal peduncle, the much longer lower lobe 

 of the pectoral fin, the reduction of the plates on the breast and 

 behind the vent, and the absence of the series of spinelets on the eye- 

 ball, characteristic of all other known species of the genus. 



Dorsal, VI, 7; anal, 7; pectoral, 14; lateral line, 43. 



Head short and broad, the greatest depth eight-tenths the great- 

 est width. Snout short, broadly triangular on its dorsal aspect, 

 marked by a transverse depression behind the nasal spines. A shal- 

 low transverse depression behind the eyes and a deeper one behind 

 the occiput. Width and depth of the body about equal under the 

 middle of the spinous dorsal. 



Ridges and spines similar to those in X. latifrons, but not so strong. 

 Interorbital space shallowly concave, narrow, without secondary 

 ridges. No preocular spines; a pair of slender postoculars; 2 pairs 

 of occipitals; a pair on the shoulder; nasal spines strong. The 

 plate at tip of snout freely movable, bearing a single strong erect 

 spine, somewhat curved backwards; lateral angles of the plate 

 bound down by the integument, not terminating in free spines. A 

 single slender spine near posterior end of subocular ridge, and one 

 behind it at angle of preopercle. Opercular ridge weak, the stria- 

 tions which diverge from the ridge above and below and cover the 

 opercle in latifrons nearly or quite obsolete in this species. Margin 

 of preopercle entire. Cheek below the subocular ridge unarmed, 

 without plates or prickles. Eye very large, 2.75 in head, the surface 

 wholly smooth, without trace of the strong spinelets present on 

 latifrons and other species. 



Mouth horizontal, broadly U-shaped, the maxillary extending 

 slightly beyond the front of the eye. Teeth in broad villiform 

 bands on the jaws; vomer with a subcircular patch, truncate pos- 

 teriorly; palatines with well-developed lenticular patches, as broad 

 as the mandibular band. A single long white maxillary barbel 

 (forked at tip on one side, in the cotype) and one or two pairs of 

 short mandibular barbels arising from the margins of the anterior 

 pores. Gill membranes with a wide free margin posteriorly. 



Plates and spines essentially as in latifrons, but the spines more 

 slender; in the ventral series, only a few of the anterior plates bear 

 spines, and in the dorsal series the plates are smooth opposite the 

 posterior portion of the soft dorsal; with these exceptions, all the 



