FISHES REGAN. 11 



( Ihaenichthyidae. 



The " Terra Nova " collection includes examples of two species of a new genus of 

 this family, and also new species of Chionodraco and Cry odraco, genera new to the 

 British Museum collection. The synopsis of the genera given in the "Scotia" report 

 may be modified as follows: — 



I. Middle rays of pelvic fin longest ; two lateral lines. 



A. Lateral line without bony plates. 



D. ix-x, 33-40. A. 32-38. no rostral spine .... ChampsocepJialus. 



D. xn-xv, 28-31. A. 2r>-27. a rostral spine ..... Pagetopsis. 



B. Lateral line with bony plates ; a rostral spine ...... ChaenichtJiys. 



II. Two outer soft rays of pelvic fin longest. 



A. Sub- and inter- operculum not spinate ; rostral spine reduced or absent. 



Pelvic fins comparatively short, with the rays branched or bifid ; spinous dorsal large, of 

 seven or eight spines, separated by a short interspace from soft dorsal : two lateral 

 lines ........... Chaenocephalus. 



Pelvic fins long, with the rays simple : spinous dorsal reduced, of three to five spines, 

 separated by a long interspace from soft dorsal ; three lateral lines . Cryodraco. 



B. Sub- and inter- operculum bearing a pair of spines behind angle of praeopereulum ; rostral spine 



well developed ; three lateral lines. 

 Pelvics i 5 ; gill-rakers reduced to a few vestiges near the angles of the arches Cliimiodraco. 

 Pelvics i 4 ; gill-rakers developed as dentigerous knobs or patches . . Chaenodraco. 



20. Pagetopsis macropterus, Bouleng. 



Three, examples from McMurdo Sound. 100 to 200 fathoms. 



21. Cryodraco atkinsoni, Regan (PI. vn, fig. 2). 



Cryodraco atkinsoni, Regan, Ann. Mag. Nat. Hist. (8), xm, 1914, p. 13. 



Depth of body 7ty in the length, length of head 3|. Diameter of eye 5 in length 

 of head, interorbital width 4§. Snout i the length of head. .Maxillary nearly reaching 

 middle of eye. Rostral spine and symphysial tubercle of mandibles vestigial. Dorsal 

 in, 42 ; spinous dorsal above base of pectoral, its spines connected by membrane, the 

 first and second subequal, j the length of head. Anal 4G ; origin a little in advance of 

 that of dorsal, nearer to end of snout than to base of caudal. Pectoral nearly f length 

 of head, extending to seventh ray of anal : pelvics 1^ as long as head, extending to 

 middle of dorsal fin. Caudal slightly emarginate. Dark spots on head and cross-bars 

 on body ; spinous dorsal blackish ; pelvics dusky. 



A single specimen, 292 mm. in total length, from the Ross Sea, 74° 25' S., 179° 3' E., 

 158 fathoms. 



This species is named after Surg. E. L. Atkinson, r.n. ; it differs from < '. antarcticus, 

 Dollo, in the smaller eye, shorter pelvic tins, etc. C. pappenheimi, Regan, has the 

 pelvic fins still shorter, and in its large head and 5-rayed dorsal fin seems to approach 

 < ^haenocephalus. 



c 2 



