The Embryology of Heterodontus japonicus 663 



mediate between the Notidanidae and Chlamydoselachidae on the one hand, and the 

 remaining Selachii on the other. In Heterodontus francisci as figured by Daniel (1915) 

 the vertebral column is better developed, and the notochord is more constricted than 

 in Heptanchus and Chlamydoselachus. Presumably these structures are much alike in 

 all species of Heterodontus. 



THE SPECIES OF HETERODONTUS 



In Volume VIII of his "Catalogue of the Fishes in the British Museum", under the 

 heading Cestraciontidae, Giinther (1870) lists and briefly describes four species of Ces- 

 tracion (Heterodontus): phillipi, quoyi, francisci, and galeatus. Another species known at 

 that time, Heterodontus (Cestracion) zebra Gray, was lumped (by Giinther) with phillipi. 

 Thus it appears that, of the species now recognized, all but one (Japonicus) were known at 

 this early date (1870), though zebra was not uniformly recognizied as a distinct species. 

 As we shall see later, even japonicus was then represented in museum collections, and 

 drawings of this species had been published before it was identified as a species distinct 

 from phillipi. 



Garman (1913, pp. 180-181) gives a key to the species of Heterodontus, which he 

 calls Centracion, based mainly on the position and shape of the anal fin, the position of 

 the first dorsal with respect to the pectorals, and the color pattern of the entire body. 

 This is followed by a synonymy and a comprehensive list of the distinctive external 

 characters for each species. Carman's classification agrees, in the main, with that of 

 Maclay and Macleay (1879, 1884 and 1886) but differs from that of Regan (1908). 



CARMAN'S KEY TO THE SPECIES OF CEJiTRACIOK (HETERODONTUS) 



Base of anal about two' thirds of its length distant from the caudal. 



Origin of first dorsal above the hind portion of the pectoral base, hind margin concave. 



Bands transverse and broad to absent galeatus [page 686] 



Base of anal nearly one length distant from the caudal. 



Origin of the first dorsal above the forward part of pectoral base, hind margin concave. 



Spots black, small, scattered francisci [page 681] 



Base of anal two-thirds of its length distant from the caudal. 



Origin of first dorsal behind the end of the pectoral base, hind margin convex. 



Spots black, moderate, more or less grouped in twos and fours quoyi [page 676] 



Base of anal fin two or more times its length from that of the caudal. 



Origin of first dorsal above the middle of the base of the pectoral, hind margin deeply 

 concave. 



Bands transverse, narrow zebra [page 675] 



Base of anal little less than twice its length from that of the caudal. 



Origin of first dorsal above mid'pectoral base; fin somewhat concave on hind margin. 



Bands both transverse and longitudinal phillipi [page 664] 



Base of anal about one and one-fourth times its length from that of the caudal. 



Origin of first dorsal above the end of the pectoral base, hind margin concave ([some- 

 times] convex in second dorsal). 



Bands transverse, broad japonicus [page 688] 



