206 DEVELOPMENT OF AN AUSTRALIAN SEA-URCHIN. 



being there still distinctly recognisable, But I feel quite con- 

 vinced that this will not be a unique case. I think I may pre- 

 dict rather safely that a quite similar shortened development 

 will prove to obtain in two other of the common Echinoids of 

 Port Jackson, namely in Phyllacanthus pa7'vispi7ius and Holop- 

 neustes purpui'ascens. In both of these, the eggs are large and 

 intransparent, and float at the surface. {I succeeded in finding 

 a few ripe eggs in a specimen of Phyllacanthus, and got them 

 fertilised; but, unfortunately, none of the embryos obtained 

 survived the Gastrula-stage). It is remarkable to find such a 

 large percentage of the littoral Echinoids of the New South 

 Wales coast having such an aberrant type of development, and 

 one can scarcely help thinking that the natural conditions there 

 may account for that. But which are the real factors to which 

 such influence on the development is due, nobody, of course, can 

 say, at present at least. 



I may still mention that Holoprieustes pU7'purascens shows a 

 very marked diff'erence in the coloration of the gonads of the 

 two sexes; the male genital organs are bright pink, the female 

 ironads dark olive-coloured. The black intestine also affords a 

 very conspicuous contrast in colour to the generally pink test 

 and spines. Judging from the different size and colour of the 

 eggs in the same gonad, this species would appear to breed twice 

 in the season. 



On board s.s. "Sonoma," 



The Pacific, 2°S., 172"W., March 20, 1915. 



Postscript: added June pJi, i(^i<5— Lyman Clark assigns the 

 name Heliocidar is to the group of species to which I have applied 

 the name Toxocidaris. As I cannot, of course, go deeper into 

 these matters of nomenclature here [Honolulu], I shall, at present, 

 at least, keep the name Toxocidaris, leaving the possible change 

 till later, when I have had the opportunity of carefully cousitler- 

 inii" Clark's reasons for this use of the name Ileliocidaris . 



