Fishes of the Western North Atlantic 523 



2 a. Snout short, rounded or conical (Figs. 119, 121); claspers of males bifid or 

 trifid. Chimaeridae, p. 523. 



2 b. Snout long, pointed (Fig. 124); claspers of males simple, rod-like. 



Rhinochimaeridae, p. 548. 



Family CHIMAERIDAE 



Characters. Front of head rounded or conical, soft, without extended beak or hoe- 

 shaped appendage. Lower surface of head with a conspicuous groove running around 

 from one side to the other, close in front of nostrils. Second dorsal fin much longer than 

 first, lower, and separated only a short distance from first by a low fold of skin without 

 rays. Caudal fin narrow, tapering, with or without terminal filament; without distinct 

 lower anterior lobe, its axis not bent upward (tail diphycercal). Anal fin distinct from 

 caudal in some. Gums in upper jaw smooth, without transverse ridges. Dental plates 

 more or less strongly ridged radially around their margins. Angular canal joining oral 

 canal some distance out from point of union of resulting trunk with suborbital canal 

 (Figs. I 18, 120). Claspers of males either bifid or trifid; if bifid, each branch flat and 

 somewhat spatulate, with thick skin, roughened by sharp recurved thorns; if trifid, the 

 two main branches similar, the third branch more slender and rod-like, with thin 

 smooth skin and somewhat swollen tip.^* Prepelvic tenacula of male blade-like, concave, 

 the cartilage covered over by thin skin, the inner border strongly serrate (Fig. 1 18E). 

 External openings of prepelvic pouches transverse to longitudinal axis of body or 

 oblique. Females without prepelvic pouches. Ventral surface on females posterior to 

 genital openings with a longitudinal ridge or ventral pad, its lower side with a narrow 

 groove extending from end to end; its function not known. 



Vertebral column with many calcified rings surrounding notochord. Cranial orbits 

 above level of brain case, separated one from the other only by a membranous partition. 

 Cerebral hemispheres of brain separated from optic lobes, in contact with olfactory 

 bulbs. 



Genera. The 17 or so modern representatives of the family resemble one another 

 so closely that all of them have been united in a single genus {Chimaera Linnaeus 1758) 

 by two well known ichthyologists, either without further subdivision^' or with four 

 subgenera.** However, a clear-cut generic division can be drawn between those that 

 have a separate anal fin and those that do not. Those with a separate anal fin are referred 

 here to the genus Chimaera Linnaeus 1758, typified by C. monstrosa Linnaeus of the 

 eastern North Atlantic. Those that lack a separate anal fin have been distributed vari- 

 ously by recent authors among three genera or subgenera,*" depending on (a) whether 



36. For accounts of the skeleton of the claspers, see especially Jungersen (Danish Ingolf Exped., 2 [2] No. i, 1899: 

 69, pi. I, fig. 14, pi. 6, figs. 69-71); for the soft parts, see especially Leigh-Sharpe (J. Morph., j6, 1922: 201). 



37. Garman, Mem. Harv. Mus. comp. Zool., 40 (3), 191 1. 



38. Fowler, Bull. U.S. nat. Mus., 100 (13), 1941: 488-489. 



39. Hydrolagus Gill 1862 (Proc. Acad. nat. Sci. Philad., 1862: 331); Bathyopolex Collett 1904 (Forh. VidenskSelsk. 

 Krist., 9, 1904: 5); Psychichthys Fowler 1907 (Proc. Acad. nat. Sci. Philad., 59, 1908: 419) and PAasmicAtAys Jordan 

 and Hubbs (Mem. Carnegie Mus., 10, 1925; 119). 



