534 Memoir Sears Foundation for Marine Research 



Generic Characters. No separate anal fin. Dorsal spine either free along its outer 

 Vz— ^/s or joined with anterior margin of first dorsal out to its tip, its posterior face 

 smooth or with double row of recurved thorns. Second dorsal fin continuous basally 

 from end to end, its upper margin straight or more or less deeply concave. Caudal 

 filament ranging from long to so short as to be almost unrecognizable. Claspers of 

 males trifid in some, bifid in others." Other characters as in Chimaera (p. 524). 



Developmental Stages. The egg capsules of the species from which they are known 

 closely resemble those of Chimaera.^^ 



Range. The known range of the genus includes: both sides of the North Atlantic, 

 in the east from Portugal to the Faroe Channnel and Faroe Bank, in the west in the 

 Gulf of Mexico and on the continental slope off New England and Nova Scotia; the 

 Pacific Coast of North America from the northern part of Lower California to western 

 Alaska;*^ the vicinity of the Hawaiian Islands; Japan; the Philippines; southern and 

 southwestern Australia, Bass Strait and Tasmania; New Zealand; and the Natal Coast 

 of South Africa. The depth range of one or another species in different seas extends 

 from close to the surface down at least to 1,000 fathoms and perhaps deeper.'* 



Species. Three species are known in the North Atlantic: H. affinis (Brito Capello) 

 1867, with second dorsal of about even height from end to end, short caudal filament, 

 and short pectorals; H. alherti Bigelow and Schroeder 1951 with second dorsal of about 

 even height, very long caudal filament and larger pectorals; and H. mirahilis (Collett) 

 1 904, with deeply concave second dorsal, long caudal filament, and longer pectorals. 

 The first of these has a close counterpart in the Japanese H. eidolon (Jordan and Hubbs) 

 1925, the second in H. mitsukurii (Dean) 1904, also from Japan. But in each case the 

 diflferences between the Atlantic and Japanese members of each pair of species (see 

 accompanying Key) seem sufficient for specific separation. Nine other named species 

 are perhaps separable by the characters given in the following Key. But critical compari- 

 son of adequate series of specimens from diflFerent regions may result in some reduction 

 in the number of supposed species. 



Provisional Key to Species 



I a. Upper margin of second dorsal either straight, or if notched, the anterior part of 

 fin is connected basally with posterior part by an unbroken series of horny rays. 



61. Trifid in H. affinis (Brito Capello) 1868 and H. ogilbyi (Waite) 1898; bifid in H.colliei (Lay and Bennett) 1839, 

 H.mirabilis (Collett) 1904, H. mitsukurii (Dean) 1904, and H. no'vae-zealandiae (Fowler) 191 1; not known for 

 H. africanus (Gilchrist) 1922, H. eidolon (Jordan and Hubbs) 1925, H. deani (Smith and RadclifFe) 1912, H. lemures 

 (Whitley) 1939, H. purpurescens (Gilbert) 1905, H. luailei Fowler 1908, or H. alberli Bigelow and Schroeder 1951. 



62. See Dean (Chimaeroid Fishes, Publ. Carneg. Instn., 32, 1906: 40-41, figs. 24-29, pi. 2, figs. 8-1 1, pi. 3) for H. 

 colliei (Lay and Bennett) 1839, California; Whitley (Fish. Aust., i, 1940: 46, 47, fig. 32) for H. ogilbyi (Waite) 

 1898, Australia; see also Dean (J. CoU. Sci. Tokyo, ig [3], 1904: pi. i, fig. 2) and Holt and Byrne (Fish. Ireland 

 Sci. Invest. [1908], 4, 1910: 13, pi. 4, figs, i, 2) for egg capsules presumed to be those oi H. mitsukurii (Dean) 1904, 

 from Japan, and of H.mirabilis (Collett) 1904, from the northeastern Atlantic, respectively. 



63. A specimen of H. colliei has been reported recently from Ensenada, Lower California (Fitch, Calif. Fish Game, 

 35> '949- 44); formerly it was thought to reach its most southerly limit near San Diego, California. 



64. H. affinis has been caught as deep as 963 fathoms off southern New England (p. 544); H. alberti wa.s taken in 305 

 fathoms in the Gulf of Mexico; the only specimen of H. purpurescens that has been seen was taken in a trawl haul 

 where the depth was between 975 and 1,067 fathoms (Gilbert, Bull. U. S. Bur. Fish., 23 [2], 1905: 582). 



