352 HAWAIIAN AND OTHER PACIFIC ECHINI. 



been taken at Cape St. Lucas, Lower California, by John Xantus, about I860, 

 but if the locality is correct, it is remarkable that the explorations of the "Alba- 

 tross" in the same region have failed to bring other specimens to light. 



STRONGYLOCENTROTUS. 



Brandt, 1835. Prodrom. desc. Anim., p. 263 (or 63). 



Type-species, Strongylocentrotus chlorocentrotus Brandt, 1. c., p. 264 (or 64) = Echinus drobachiensis O. F. 

 Muller, 1776. Prodrom. Zool. Dan., p. 235. 



So homogeneous is this genus and so completely do the forms intergrade that 

 it is almost wholly a matter of opinion as to what species are to be considered 

 valid. It seems nearly certain that the widely distributed drobachiensis is the 

 parent stock from which the others have sprung, but how many species are at 

 the present time fully differentiated from this stock is very hard to decide. Of 

 course a typical franciscanus is very easily distinguished and that is certainly 

 a distinct species, yet it appears to intergrade with purpuratus which in turn 

 connects very clearly with drobachiensis. In the European seas, granularis 

 (Lamk.) has become quite an easily recognized species particularly when its 

 characteristic features are fully developed. The Japanese and Aleutian forms 

 are not so well defined and although the attempt to distinguish, from those 

 seas, pukherrimus A. Ag., depressus A. Ag., intermedius A. Ag., pulchellus A. Ag. 

 and Cl., echinoides A. Ag. and Cl., polyacanthus A. Ag. and Cl., and nudus A. Ag., 

 typical examples of which are easily recognizable, is here made, it is probable 

 that at least two or three of them are not really specifically distinct from droba- 

 chiensis, and ought not to be honored with names. There is not the slightest 

 ground for doubting that chlorocentrotus Brandt is a synonym of drobachiensis. 

 Alaskan specimens show very great diversity in the length of the spines as well 

 as in coloration. The name carnosus A. Ag. might well be revived for the very 

 handsome form from northeastern Asia, but as the coloration is not always 

 striking and seems to intergrade with that of drobachiensis, and as any other 

 distinctive character is not apparent it is better to let the case stand as it is, 

 until some zoologist can make a special study, in the field, of the North Pacific 

 forms of Strongylocentrotus. The form which Doderlein (1906, Zool. Anz., 

 XXX, p. 517) described from Sakhalin as a variety of drobachiensis under the name 

 sachalinica, seems to be very well characterized by the remarkably small number 

 of coronal plates and although specimens have not been seen, it is here raised to 

 specific rank. His proposed species hokkaidensis is however nothing more or less 



