146 Memoir Sears Foundation for Marine Research 



Family CETORHINIDAE 



Characters. Essentially those of Isurldae (p. 109), except that each gill arch bears 

 a great number of long, horny bristle-like rakers directed forward, analogous to those of 

 many bony fishes; the gill openings are very much larger; the teeth are minute, very nu- 

 merous, and conical with one cusp; the dorso-rostral cartilages are very slender, and the 

 ventro-rostral cartilage broad and blade-like^ (in the Isuridae all three of the rostral 

 cartilages are rod-like, and about equally stout) . 



Remarks. The Cetorhinidae have usually been placed among the Isuridae, of which 

 they appear to be an offshoot. However, the presence of horny rakers on their gill arches, 

 a character which makes them unique among modern sharks, suggests to us that they be 

 classed as a distinct family. 



Genera. Only one genus, Cetorhinus Blainville, 1 8 1 6. 



Genus Cetorhinus Blainville, 1 8 1 6'' 

 Basking Sharks 



Cetorhinus Blainville, Bull. Soc. philom. Paris, 1816: 121 ; type species, Squalus gunnerianus Blainville, 1810, 

 equals Squalui maximus, Gunnerus, 1765.' 



Generic Synonyms: 



Squalus (in part) Gunnerus, K. norske Vidensk.-Selsk. Skr. Trondh., 1765: 33; and subsequent authors; not 



iSyWtt/ Linnaeus, 1758. 

 Selache Cuvier, Regne Anim., 2, 1817: 129; type species, Selache maxima Cuvier, equals Squalus maximus 



Gunnerus, 1765. 

 Selanche Jaroki, Zoologi, 4, 1822: 452 (not seen); type species, S. maximus Jaroki, equals Squalus maximus 



Gunnerus, 1765. 

 Selachus Minding, Lehrb. Naturg., 1832: 52 (not seen); type species, Selachus maximus Minding, equals 



Squalus maximus Gunnerus, 1 765. 

 Polyfrosofus Couch, Brit. Fishes, i, 1867: 68; type species, P. m.acer Couch; type locality English Channel. 

 Cethorhinus Escribano, An. Soc. esp. Hist, nat., p, 1909: 340; type species, C. maximus Escribano, equals 



Squalus maximus Gunnerus, 1 765. 



Doubtful Synonyms: 



Halsydrus Fleming, Scots. Mag. Edinb. Misc., 1809: 6; type species, H. fontoffidani Fleming; type locality, 



Orkney Islands.* 

 Tetraoras Rafinesque, Carratt. Gen. Nuov. Sicil., 1810: 46; type species, T. angiona Rafinesque. 



1. The dorso-rostral cartilages have been pictured either as uniting some distance posterior to the point of union 

 between the resultant bar and ventral cartilage (Senna, Arch. ital. Anat. Embriol., 22, 1925: pi. 9, fig. 1, 2), or 

 as connected with each other by a pair of transverse bars which unite in the median line and extend thence forward 

 as a single member to the point of union with the ventral cartilage (Pavesi, Ann. Mus. Stor. nat. Genoa, 6, 1874: 

 pi. 2, fig. I, 2). 



2. For reasons why Cetorhinus is retained for this genus rather than Halsydrus Fleming, 1809, see footnote 4, 

 p. 146. 



3. Type designated by Jordan (Genera Fish., i, 1917: 95) as C. gunneri Blainville, 1816, which was a substitution 

 for Squalus gunnerianus Blainville, 1810. 



4. Whitley (Mem. Qd. Mus., 10, 1934: 196), followed by Fowler (Bull. U.S. nat. Mus., 100 [t^], 1940: 112), has 

 replaced the generic name Cetorhinus with Halsydrus on the ground that the carcass of the Orkney animal, for 

 which the latter was proposed, was actually that of a very large Basking Shark, as is certainly suggested by pub- 



