2564 Bulletin ^y, United States National Miise^un. 



first dorsal low, without differentiated spine-. Scales cycloid, unarmed; 

 lateral line strongly arched over the pectoral. Deep seas. This genus 

 differs from Macroiirus and its allies in the structure of both the first 

 and last gill arches. It is perhaps the most primitive of the family and 

 as such is nearest allied to the Gadidce. {fiaBvz, deep; Gadus, codfish.) 



a. Pectoral and ventral fins moderate, not much, if any, longer than head. 



h. Jaws without teeth ; pectoral fin broad, of 25 rays; depth Sj in length. 



ARCUATDS, 2938. 

 66. Jaws with small teeth; pectoral tin narrow; depth 6 to 6i in length. 



c. Eye moderate, 5 in head ; jiectoral rays 14, the fin J as long as head. 



FAVOSUS, 2939. 

 cc. Eye very large, 2| in head ; pectoral as long as head without snout. 



MACKOPS, 2940. 

 aa. Pectoral and ventral fins much produced, much longer than head, each reaching 

 about halfway to tip of caudal ; depth 7J in length ; pectoral rays 13. 



LONGIFILIS, 2941. 



2938. BATHYGADUS ARCUATUS, Goode & Bean. 



Head 5 in total length; depth 5|; eye 4 J in head; snout 4^. D. II, 9 or 

 10-135; A. 120; P. 25; Y. 8; scales 8-140-13 or 14 (counting backward 

 from vent to lateral line), 22 counting forward. Body shaped much as in 

 Chalinura Simula, hnt the nape still more convex; back gibbons, tlie dor- 

 sal outline rising rapidly from interorbital region to origin of first dorsal, 

 whence it descends gradually to end of tail. Scales moderate, cycloid, 

 subovate, without armature, those of abdominal region and those above 

 pectorals the largest ; lateral line strongly arched over the pectorals, length 

 of the arched portion contained about 3J times in straight portion, great- 

 est height of arch about i its chord ; scales covering all parts of head 

 except jaws and chin. Interorbital area flat, its width 6 in head; post- 

 orbital portion of head about 2A^ times diameter of eye; operculum termi- 

 nating in a fiat obtuse spine, its length, including the flap, about equal to 

 diameter of eye; preoperculum entire, with a prominent ridge in advance 

 of its posteiior edge; snout very broad, obtuse, the intermaxillaries 

 extending beyond it, its width at nostrils eciual to about twice length of 

 eye ; posterior extremities of intermaxillary processes elevated, producing 

 a decided hump upon top of snout; ridge formed by prefrontal and sul)- 

 orbital bones terminating very slightly behind posterior margin of orbit, 

 and not connected with angle of preoperculum. Nostrils immediately in 

 front of lower part of eye, not tubular, the anterior one very small, pore- 

 like, only about :} as large as posterior one ; distance of anterior nostril 

 from tip of snout about f length of eye. Length of barbel 6| in length of 

 body, and equal to length of bead without snout, more than 3 times as 

 long as eye. No true teeth, the intermaxillaries and mandible being broad 

 plates, covered with minute asperities; a naked space at the symphysis of 

 intermaxillaries ; distance of first dorsal from snout nearly 3^ times length 

 of its base, the first spine minute, the second (in the type) somewhat 

 mutilated, its length nearly 3 in length of head, not stouter than the 

 branched rays, and entirely smooth ; second dorsal fin separated from first 

 by a very short interspace, equal to about i, of length of eye, its rays long, 

 subeiiual, the first slightly the longest, its length equal to that of base of 



