-1908.] OF THE FAMILY ORECTOLOBID^. 353 



Rhinodon (Smith) Miill. & Henle, Plagiost. p. 77 (1841) ; 

 Giintli. Cat. Fish. viii. p. 396 (1870). 



Jlicristodus Gill, Proc. Acad. Philad. 1865, p. 177. 



Head broad, obtuse ; body elongate, subcylindrical. Mouth 

 transverse, subterminal ; teeth very small, unicuspid, pointed, 

 subconical, recurved ; lower lip not divided by a symphysial 

 groove. Nasal valves separate ; no nasal cirri. Eye small ; no 

 longitudinal fold below the eye. Spiracle very small, behind the 

 eye. Gill-openings wide ; last two above the base of pectoral. 

 First dorsal above the pel vies ; second dorsal above the anal, 

 which is free from the caudal. Caudal of modei-ate length ; axis 

 strongly directed upwards ; lower lobe considerably produced 

 anteriorly and without posterior notch. 



This genus comprises a single species, which has generally been 

 placed in more or less close proximity to Cetorhinus maximus, a 

 shark which it appears to resemble in habits and in its large 

 size, small teeth, long gill-rakers, and wide gill-openings, as well 

 as in the form of the caudal fin and the keeled tail. There can 

 be little doubt, however, that Rhinodon is allied to Ginglymostoma, 

 from which it differs in a few features of specialisation. The 

 curious dei-mal keels are like those met with in other Sharks of 

 this family, i. e. Stegostoma, Chiloscyllmin. 



1. Rhinodon typicus. 



Rhinodon tyiyicus Smith, Miill. k, Henle, Plagiost. p. 77, 

 pi. XXXV. fig. 2 (1841); Smith, 111. Zool. S. Afr. Fish. pi. xxvi. 

 (1845); Dumeril, Elasmobr. p. 428 (1865); Giinth. Cat. Fish, 

 viii. p. 396 (1870) ; Haly, Ann. Mag. jS". H. (5) xii. 1883, p. 48 ; 

 Thurston, Bull. Madras Mus. 1884, Xo. 1, pi. iii. A ; Gill, 

 Science, (2) xv. 1902, p. 824. 



Micristodus punctatus Gill, Proc. Ac. Philad. 1865, jd. 177; 

 Giinth. Cat. Fish. viii. p. 396 (1870); Jord. & Everm. Bull. U.S. 

 Nat. Mus. xlvii. 1896, p. 52. 



Rhinodon pentalineatus Kishinouye, Zool. Anz. xxiv. 1901, 

 p. 694, fig. 



Lower labial folds separated by a wide interspace. A median 

 dorsal keel and on each side 2 or 3 lateral keels, the lowest of 

 wliich is continued along the middle of the tail to the caudal fin. 

 First dorsal considerably larger than the second or than the anal, 

 its base opposite to that of the pel vies ; free edge of first dorsal 

 slightly concave, anterior angle rounded, posterior angle pointed. 

 Second dorsal and anal equal and opposite. Lower caudal lobe 

 strongly produced and acutely pointed. Pectoral much longer 

 than broad, with slightly concave free edge and acutely pointed 

 anterior angle. Head and body with round whitish spots. 



This large pelagic shark has been recorded from Floi-ida, the 

 Cape of Good Hope, the Seychelles, Ceylon, Madras, Japan, 

 California, Panama, and Peru. 



1. Large stuiFed specimen. Cej'lon. Colombo Mus. 



2. Upper jaw and snout. Sej'chelles. Prof. E. P. Wright. 



23* 



