PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 381 



arches, almost obsolete on the the third and fourth. (In Lepidopus 

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



Type, Lepidopus elongatiis Clarke, 



Benthode-smus may he distinguished from Lepidopus, the most closely 

 related genus, by the following- salient characters : 



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

 eJongatus at the A'eut is one-fourth the length of the head, in L.epi- 

 dopus caudatus, nearly half the length of the head. 



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

 head. 



3. In tlie 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. 



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

 G. lu the extension of the opercula beyond the origin of the pectorals, 

 and in the rottnded upper outline of the pectorals. 



7. In the mnch 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. 2911G), 896 millimeters (35i 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 interorbital area. 



Length of head contained 7^ 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 tlie head. Length of snout contained 2J times in length of 

 head. Ui)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 heiglit of body. Mandibular 

 ti}) nearly one-third as long as the diameter of (he eye. Eye slightly 

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

 the snoiut. 



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

 9 of moderate size j 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 gill rakers, the longest of which mcas- 



