FISHES OF THE PHILIPPINE ISLANDS AND ADJACENT SEAS 15 



anal. Caudal tip usually notched, fin short, mostly bent up. Anal 

 small. 



Small sharks of warm or tropical Pacific waters, of interest chiefly 

 from their abundance as fossils of Mesozoic time. The few recent 

 forms belong to the genus Heterodontus. Their food is apparently 

 mollusks, the shells of which are crushed by means of the molar or 

 pavementlike teeth. They are oviparous and the large egg cases of 

 unusual spiral form with two long tendrils. Owing to the large 

 blunt head the common name of Bullhead Sharks has been applied, 

 though as the oldest Imown species is from Australia that of Port 

 Jackson Shark has gained most usage. 



Genus HETERODONTUS Blainville 



Heterodmitus Blainville, Bull. Soc. Philom. Paris, vol. 8, p. 121, 1816. (Type 



Squalus philippi Schneider, monotypic.) {Heterodon Latreille in reptiles 



not involved.) 

 Cestradon Schaeffeb, Epistola . . . studii ichthyologici, etc., p. 20, 1760. — 



Oken, Isis, 1817, p. 1183. (On Cuvier, Regne animal, vol. 2, p. 129, 1817. 



Type, Squalus philippi Schneider, monotypic.) 

 Centracion Gray, Zool. Misc., p. 5, 1831. (Type, Centracion sebra Gray, mono- 

 typic.) (Evidently variant spelling of Cestracion.) 

 Oyroplenrodus Gill, Proc. Acad. Nat. Soc. Philadelphia, 1862, p. 331. (Type, 



Cestracion francisci Girard, monotypic.) 

 Tropidodus Gill, Proc. Acad. Nat. Sci. Philadelphia, 1862, p. 489. (Type, 



Cestracion pantherimis Gill, monotypic.) 

 Drepanephorus Egeeton, Mem. Geol. Surv. Great Britain, 1872, dec. XIII, no. 9. 



(Type, Acrodns rugosus Agassiz.) (Fossil.) 

 Molochophrys Whitley, Australian Zool., vol. 6, p. 310, 1931. (Type, Cestracion 



galeatus Gihither, orthotypic.) 

 Wuia Fowler, Proc. Acad. Nat. Sci. Philadelphia, vol. 85, p. 233, 1934. (Type, 



Centracion zebra Gray, orthotypic.) 



Body robust, heavy forward. Head oblong, broad. Snout blunt. 

 Eye high, ridges above mostly prominent, without nictitating mem- 

 branes. Mouth small, with thick labial folds on both jaws. Front 

 teeth pointed, with 3 to 5 cusps in young; hind molars twice broad 

 as long, in oblique series and in one series enlarged. No narial cirri. 

 Crown of head narrowed between prominent supraorbital ridges. 

 Gill openings narrow. Spiracle near lower eye edge. Scales small, 

 sometimes cruciform. Caudal short, subcaudal well developed. 

 Pectorals large. 



Besides the species noticed below the others are all from the East- 

 ern Pacific. They are Heterodontus frmicisci (Girard), Heterodon- 

 tus quoyi (Freminville), and Heterodontus peruarius (Evermann 

 and Radcliffe) and form the subgenus Gyropleurodus with spotted 

 coloration. 



