ON SOME WEST INDIAN ECHINOIDS. 



ByTHEODOR MORTENSEN, 



Of the Zoological Museum, University of Copenhagen. 



INTRODUCTION. 



In mv work on the Echinoidea of the Danish /«^oZ/ expedition prehmmary diag- 

 noses are" given of several new species of echinoids. These diagnoses, though, I 

 think, in general sufficient for the recognition of the species, are of course, by no 

 means detailed, and I hope in the future to be able to publish full descriptKms of all 

 the species which I have thus established. The difficulty is that most of these are 

 not represented in the Copenhagen Museum, so that I must depend on what oppor- 

 tunities there may be for me to get material from other institutions, buch an 

 opportunity was accorded me on a visit to the U. S. National Museum m the 

 spring of 1906. I found there a good representation of two of my previously 

 indicated species, namely, CalocidaHs micans and Ara^osoma belli I was allowe^ 

 to examine this material in detail, and as I had no time to do it during my hort 

 stay in Washington, I was permitted to borrow the specimens and to have them 

 sent to Copenhagen, where I could study them exhaustively. 



To-ether with this material I also received some other specimens of \Vest 

 Indian ddarids. The study of these specimens, together with «ome collections 

 made by myself durmg a stay in the Danish West Indies in the winter 1905-6, 

 mad it dZ to me that still another species of cidarid, besides tl-e previous y 

 known occurs in the West Indian seas, probably hitherto confounded with adans 

 ddaHs (Dorocidaris m>mata), as has been the case with so many other species 

 A description of this new form is induded here. A full description is also g.v^n 

 of the much discussed, but hitherto not thoroughly described, rr<o«Jam hM^^ 

 of which species I have likewise had material sent for study. Finally a few remarks 

 are added on the spedes Cidaris ahyss%cola and C. rugosa • , ^..^ T 



The revised list of North American Atlantic and West Indian Echinoids may, I 

 hope, prove not without value. 1 



