CETORHINUS MAXIMUS. 39 



little, if any, larger than second dorsal. Ventrals below the middle of the space 

 between the dorsals. The width of the gill openings of the specimen described 

 equals the length of the snout; the hindmost opening is in front of the pectoral. 

 The teeth are larger than in a specimen of /. punctatus of the same length. 



Back dark bluish or blackish brown, the dark color being distinctly limited 

 on the level of the caudal carinae from the white of the lower surfaces. 



Idzu Sea, Japan. Alan Owston. 



ISURUS GUNTHERI. 



Lamna giintheri Mueray, 1884, Ann. mag. nat. hist., ser. 5, 13, p. 349; Day, 1888, Ind. fishes, Suppl., 

 p. 810. 



Snout much produced, triangular. Nostrils nearer to the eye than to the 

 end of the snout. Teeth " §§ on either side " (Day), with smooth sharp edges, 

 without basal cusps. Anterior teeth of the lower jaw largest; third tooth at 

 each side of the symphysis on the upper jaws smaller than the rest. First 

 dorsal nearer to the pectorals than to the ventrals, a little farther behind the 

 base of the former than in I. spallanzanii, that is, about its own length behind 

 the bases of the pectorals. Anal about its own length behind the second dorsal. 



This species differs in the large numbers of rows of teeth from the other 

 known Isuri. 



Type, from Kurrachee, India, 86 inches in total length, caudal 18, and 

 pectorals 16 inches. 



Cetorhinus. 



Celorhinus Blatnv., 1816, Bull. Soc. philom., p. 121. 

 Selache Cuv., 1817, Reg. anim., 2, p. 129. 

 Polyprosopus Couch, 1867, Brit, fishes, 1, p. 67. 



Body elongate, subfusiform. Snout produced, subcorneal. Nostrils near 

 the mouth. No nictitating folds. Mouth large. Teeth conical, small, numer- 

 ous. Spiracles small, behind the eye. Gill openings five, very wide, hindmost 

 in front of the pectorals. Gills with strainers. Pectorals and first dorsal large, 

 latter above the space between pectorals and ventrals; second dorsal and anal 

 small. Tail with a keel at each side and with caudal pits. Caudal large, 

 vertebral axis raised, subcaudal lobe much produced. One living species known. 



Fossil forms have been described from the Chalk and later. 



Cetorhinus maximus. 



Squalus maximus Gunner, 1765, Trondj. sels. selskr., 3, p. 33, tab. 2; Linn6, 1766, Syst., 1, p. 400; 

 Gunner, 1770, Norsk, vid. selsk. skr., 4, p. 14, tab. 3; Bonnaterre, 1788, Ichth., p. 10; Schn., 

 1801, Bloch Ichth., p. 134; Blainville, 1810, Jour, de phys., p. 1 extra; Mitch., 1815, N. Y- lit. 

 & philos. trans., 1, p. 486; Fleming, 1828, Brit, anim., p. 164. 



