Jordan and Evermann. Fishes of North America. 607 



subopercle enlarged and partly usurping the usual position of the pre- 

 opercle, in company with the suborbital chain, which is extended back- 

 ward to the opercular margin. Bones of head unarmed. Gills 4, a slit 

 behind the fourth. Pseudobranchia) none ; gill rakers short ; gill mem- 

 branes separate from the isthmus. Branchiostegals numerous (about 14). 

 Dorsal fin short, rather high, inserted behind ventrals and before vent; 

 no adipose fin ; no caudal fin ; anal fin extremely long, extending from 

 vent to tip .of tail (its rays about 200 in number) ; ventrals mod- 

 erate, not very far back ; pectorals rather long, narrow, inserted 

 bigh. No axillary scales. Shoulder girdle weak, its uppermost bone 

 (supraclavicle or post-temporal) touching the cranium at the nuchal 

 region, but not connected with it laterally. Air bladder large, simple. 

 Stomach co3cal ; pyloric coeca in moderate number ; intestines short. 

 Ovaries not closed. Vertebrae very many, 60 -f x. Three genera, with 

 about 10 known species. Fishes of the deep sea. (Halosauridce, Giinther, 

 Cat. vn, 482, 1868.) 



a. Ventrala normal; no second dorsal fin. 



b. Vertex covered with scales; scales of lateral line scarcely enlarged; snout obtusely 



rounded; anal high. HALOSAURUS, 292. 



bb. Vertex scaleless; scales of lateral line enlarged, provided with photophores; snout 



pointed; anal moderate. ALDROVANDIA, 293. 



292. HALOSAURUS, Johnson. 



Halosaurus, JOHNSON, Proc. Zool. Soc. London, 1863, 406, (otrem). 



Ventrals normal; no second dorsal fin; anal high. Snoub obtusely 

 rounded. Head without angular ridges. Vertex covered with scales. 

 Scales of lateral line scarcely enlarged. Characters otherwise included 

 above, (u^c, sea; aavpos, lizard.) 



a. Preoral portion of snout equal to half its length. Height of body nearly equal to half 



length of head and ^ of total; diameter of eye f postorbital portion of headandmuch 



greater than width of interorbital epace; about 60 scales in lateral line in front of 



vent. OWENI, 905. 



aa. Preoral portion of snout less than half its length; height of body about % length of head 



and ^5 of total; diameter of eye half length of postorbital portion of head (which is 



equal to that of snout), and much greater than width of interorbital space; about 67 



scales in lateral line in front of vent. GUNTHERI, 906. 



905. HALOSAURUS OWENI, Johnson. 



Head 7i. B. 14; D. 11; A. 191; P. 11; V. 10; scales about 14-170-6. 

 Height 14^ in total length ; eye 2 in snout, 5 in head, reaching to profile; 

 snout produced, its preoral portion being nearly \ its length. Eye rather 

 large, postocular portion of head, and much more than width of inter- 

 orbital space ; maxillary reaching vertical from front of eye. Length 

 of head more than its distance from ventral fin, the base of which is 

 entirely in front of and somewhat remote from base of dorsal ; pectoral 

 fin with narrow base, very long, extending nearly to root of ventral. 

 Scales of lateral line scarcely larger than the others, without phospho- 

 rescent organs being visible in the only specimen known ; anterior por- 

 tion of dorsal fin covered with small scales ; anal fin scaleless. Brownish 



