30 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



some of which are sometimes irregularly crowded together. Between the dorsals there are, 

 as a rule, few spines. The teeth form from forty-one to forty-four series in the upper, and 

 from forty-one to forty-three in the lower jaw. Coloration dark grayish brown above; the 

 mucous pores marked with black vermicular spots. Lower surface blackish, without spots. 

 (Garthan and Gwnther.) 



This speciesis locally not uncommon on the Norwegian coast; for instance in Throndhjem 

 Fjord, at a depth of 150 to 200 fathoms. It is one of the larger skates, the specimens in the 

 British Museum measuring from 38 to 4G inches in width. 



Order HOLOCEPHALI. 



Holocephala, ,Mi i.i.i.u, Aldiandl. Akail. Wiss. Berlin, 1834, 71. — Guntuf.r, Cat. Fish. lint. Mns.. vm. 3t«. 

 Holocephali, Gill, MS. 



Selachians distinguished by the confluence of the liyomandibular bone with the cranium, 

 the coalescence of the maxillary and palatine elements with the skull, the development of 

 a rudimentary operculum, and the existence of a single external gill opening on each side 

 behind the head. (Gill.) 



Family CHIM^ERID^E. 

 chiiniiriihr, GOnther, Cat. Fish. Brit. Mns., vm, 1870, 349. 



Body lather robust, elongate, tapering posteriorly. Head compressed. Mouth inferior. 

 Upper lip deeply notched. Nostrils confluent with the mouth, separated by a narrow 

 isthmus. Jaws with the teeth confluent into four bony laminae above and two below. No 

 spiracles. Males usually with a cartilaginous hook on the upper part of the snout, armed 

 with prickles at the tip, and turned forward. Pectoral fins free, placed low. Ventral tins 

 abdominal, many rayed, provided in the male with claspeis. Dorsal fin usually divided, 

 anteriorly with a very strong spine, which is grooved behind. Caudal fin low, fold-like. 

 Skin naked, rarely somewhat prickly. Lateral line present, usually with numerous branches 

 anteriorly. Three free gills and two half gills. 



KEY TO THE GENERA OF < 1IIM.EE1TLE. 



I. Male with cephalic appendage. 



A. Snout soft, not terminating in a cutaneous flap; tail not bent forward. 



1. Posterior appendages tripartite Cttim.fra 



2. Posterior appendages bipartite HydrolaGus 



B. Snout terminating in a cutaneous flap CallokhynchuS 



II. Male without cephalic appendage ; snout very elongate Harriotta 



CH1M/ERA, Linnaeus. 

 Chimcera, Linn.evs, Mus. Ad. Frid., i, 53; Syst. Nat., ed. x, 1758, i, 236. 



Holocephali with head somewhat compressed, snout without appendage. Eyes lateral, 

 very large. Lateral line forking anteriorly, forming several series of mucous tubes on the 

 head. Male with a club-shaped, cartilaginous hook above snout, curved forward and down- 

 ward armed with decurved spines at tip, and fitting into a depression in front of eyes. 

 Ventrals rather large, with large bifid or trifid claspers in the male. Male with also rough 

 appendages at the base of the ventrals, protruding from a sheath of skin. First dorsal 

 triangular, preceded by a strong serrated spine which is grooved behind. Second dorsal 

 and caudal low, often notched. Tail sometimes produced in a filament. Skin smooth. 



KEY TO THE SPECIES. 



I. Pectorals long, extending to tips of ventrals C. MOHTSTROSA 



II. Pectorals short, terminating far in advance of the ventrals C. affinis 



