CIDAIITD^. 3 



In specimens of P. 3IiUcn oi very different size, Fig. 11, the ratio be- 

 tween the actinal system and the diameter of the test does not differ. 

 It is reduced to a trifle less than half in D. panameiim, Fig. 12, In 

 P. Cohosi, Fig. lo, the actinal system is not more than one third the 

 diameter of the test. 



18 mm. 28 mm. 



Fig. 11. PoKOciDARis Millebi. 



@ 



10 mm. 



18 mm. 26 mm. 30 mm. 



Fl6. 12. DOROCIDAEIS PANAMENSIS. 



®(o)(0 



18 mm. 21 mm. 



Fl«. l.S. POKOCIDARIS COBOSI. 



35 mm. 



According to Lov^n^ the anal system in 

 the young stages of Goniocidaris is covered 

 with a single plate (the dorso-central disk). In 

 a young Dorocidaris (PI. 13, fig. 5) of 2.8 mm., 

 dredged by Pourtales off Key West in 138 

 fathoms the anal system was covered with five 

 anal' plates, Fig. 14. This is contrary to what Fig. 14. dorocidaris papillata. 

 is known of the young of Echinidae proper, in which the anal system is 



1 Echinologica, Pis. I. fig. 2; II. figs. 5, 7. 



