NO. 3577 ECHINOIDS — KIER 9 



85 feet deep (pi. 2: fig. 2), in which a small amount of algae was present. 

 It may be of significance that, in this deepest area studied, the echi- 

 noids were almost completely naked with only a small amount of 

 algae over their tests and no sediment. Perhaps it is because of the 

 decreased amount of light at these depths that the test is not as 

 completely covered. 



Schizaster (Paraster) floridiensis Kier and Grant 



One dead test was found at a depth of 85 feet on silt bottom devoid 

 of vegetation off Point Guignard. Although no living specimens 

 were found, the great fragility of the paper-thin test suggests that 

 it could not have been carried far from where it once lived, Pre- 

 simiably, this species lives buried as is the case with all schizasterids 

 with known living habits. 



Comparison with Echinoids of the Florida Keys 



It is of interest to compare the living habits of the Dominican 

 echinoids with individuals of the same species in the Florida Keys, 

 as recently described by Kier and Grant (1965). The echinoid 

 fauna of Dominica was much less varied Avith only 10 species found, 

 only 5 of which occurred in large numbers, whereas, in the Keys, 

 17 species were reported, most of which were common. Probably 

 this difference is caused by the small number of different environ- 

 ments in the Caribbean off Dominica. 



Meoma ventricosa was never found as deeply buried in Dominica 

 as in the Florida Keys. The Dominican specimens only partially 

 bury with approximately one-fifth of their tests below the general 

 level of the substratum, whereas in the Keys most of the individuals 

 keep their tests almost completely buried, many with an inch or so 

 of sand over the upper surface. In Dominica, M. ventricosa lives 

 very much like Clypeaster rosaceus does in the Keys, mth sand and/or 

 plant material pulled up over its test. 



Lecdia sexiesperforata lives deeper in the sand in Dominica than 

 in the Keys perhaps because it occurs in shallower water there. In 

 contrast, Clypaester subdepressus lives much deeper in Dominica, 

 where it is found three to four inches below the surface, but in the 

 Keys it normally walks along the surface with sand pulled over it 

 or is buried under only an inch of sand. Because of this, they are 

 very difficult to find in Dominica but easy in the Keys. 



Diadema antillarum, Echinometra lucunter, Echinometra viridis, 

 Tripneustes ventricosus, and Eucidaris tribuloides five in similar habi- 

 tats in Dominica and the Florida Keys. It is of interest that the two 

 color types of Echinometra lucunter found in Dominica are also present 

 in the Keys. 



