PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 381 



arches, almost obsolete on the the third and fonrth. (In Lepidopvs 

 caudatus all the arches are supplied with several series of •rakers.) 



Type, Lepidopus elongatus Clarke. 



Benthodesmus may be distinguished from Lepidojms, the most closely 

 related genus, by the following salient characters : 



1. The slenderer, lower form of the body, the height of which in B. 

 elongatus at the A^ent is one-fourth the length of the head, in Lepi- 

 dopns cm(datus, nearly half the length of the head. 



2. In the location of the vent, which is considerably nearer to the 

 head. 



3. In the straighter course of the lateral line, and the greater size of 

 the furrow in which it is situated. 



4. In the depressed form of the head, its flat profile, the insignificance 

 of the frontal ridges, and the absence of the occipital crest. 



5. In the horizontal instead of oblique position of the nostrils. 



6. In the extension of the opercula beyond the origin of the pectorals, 

 and in the rounded upper outline of the pectorals. 



7. In the much greater number of dorsal rays. 



8. In the more advanced position of the rudimentary ventrals, which 

 are situated in Benthodesmus under the base of the pectorals, in Lepidopus 

 under their tips. 



9. In the presence of a single small postanal scute, in place of the 

 two larger ones in Lepidopus. ■ 



10. In the characteristic arrangement of the gill-rakers. 



Benthodesmus elongatus (Clarke) Goode and Bean. 



Extreme length of type (No. 2011()), 896 millimeters (35^^ inches). 



Body attenuate, its height at the vent contained four times in length 

 of head, its width being about one-third of its height at the point men- 

 tioned. Length of caudal peduncle half of greatest height of body. 

 Least height of tail one-third width of iuterorbital area. 



Length of head contained 7J times in length of body, its greatest 

 width one-sixth of its length; its greatest height nearly one-fourth of 

 its length ; width of interorbital area (on the bone) one-fourth of the 

 height of the head. Length of snout contained 2i times in length of 

 head. Uj)per jaw not reaching to vertical from anterior margin of eye, 

 and equal in length to the postorbital portion of head. Lower jaw in 

 length equal to about twice the greatest height of body. Mandibular 

 tip nearly one-tbird as long as the diameter of the eye. Eye slightly 

 postmedian in location, the orbital diameter equal to half the length of 

 the snout. 



Besides the three long teeth, there are on each intermaxillary 8 or 

 9 of moderate size 5 on one side many small intermediate teeth are pres- 

 ent. The number of teeth in the lower jaw varies from 13 on the one 

 side to 21 on the other. 



The first branchial arch has 13 giU -rakers, the longest of which meas- 



