584 Verrill, Notes on Eadiata. 



Evechinus chloroticus VerrUi. 



Echinus chloroticus Val., Voy. Venus, Zooph., PI. 7, figs. 2-2d, 1846. 

 Heliocidaris chlorotica Destnl. ; Ag. and Des., Ann. des Sci. nat, vi, p. 374, 1846. 

 Psammechinus chloroticus A. Ag., Bulletin, M. C. Z., i, p. 23. 1863. 

 Boletia viridis Verrill, these Trans., p. 304, 1867. 



The specimen erroneously described by me (page 304) as from 

 Peru, proves to be identical with the New Zealand species, and was 

 undoubtedly collected there by Mr. H. Edwards, and accidentally 

 misplaced while packing the Peruvian collection. As I am unable to 

 refer it to either of the four genera in which it has already been 

 placed, it seems necessary to establish a new genus to include it, 

 together with a smaller xindetermined species in our collection. 



The arrangement of the pores and the few distant plates of the actinal 

 membrane are sufficient to separate it from Psammechinus. Boletia 

 differs in having a thin test, deeper actinal ciits, and in being desti- 

 tute of tubercles in the middle of the interambulacral areas above, 

 etc. Heliocidaris has a very diffei'ent arrangement of pores, and the 

 zones are expanded beneath. 



Tripnenstes depressus a. Ag. 



Verrill, these Trans., p. 375; Amer. Jour. Sci., xlix, p. 99, 1870. 



Of this large species there are 24 specimens from La Paz, with their 

 spines partially preserved. They are quite variable in form, but often 

 more elevated than ordinary specimens of T. ventricosus. Some are 

 conical, others broadly rounded above. The largest spines on the 

 upper surface of the largest specimen are '45 of an inch long, -04 in 

 diameter, and rapidly taper to the acute point ; those of the lower sur 

 face are often '60 of an inch long, "04 in diameter, tapering but little^ 

 the end blunt. 



Several specimens give the following proportions : 



Diameter, (inches) 5'80 5-40 5-35 5-25 5-15 5-10 4-90 4-75 4-60 

 Height, 3-00 3-40 2-90 3-25 2-60 2-85 2-65 2-85 2-80 



One specimen has much larger ovarial plates than the others, and 

 consequently a larger abactinal area. These plates are also more 

 pointed, giving to the abactinal area a more stellate form. 



ToxOCidaris Mexicana A. Agassiz, (p. 307), (non Helioddcvris Mexicana Ag.) 



This is a large species, belonging to a group distinct from the tyjii- 

 cal species of Toxopneustes [T. tuber culatus)^ of which Mr. Agassiz 

 has recently brought authentic specimens from Europe. The original 

 Heliocidaris Mexicana Ag., according to Mr. A. Agassiz, is a variety 



