NO. 3577 ECHESrOIDS — KIER 7 



every case they were living in areas of high energy with considerable 

 wave motion. Two color types were present, the most common 

 being dark brown but some specimens were much redder. Color 

 difference is distinct, with no transition between the two types. 

 Many individuals of Diadema antillarum Philippi and a few of En^^i- 

 daris tribuloides (Lamarck) and Tripneustes ventricosus (Lamarck) 

 live with this species. 



Echinometra viridis Agassia 



Only one specimen was seen and this one was found living in a 

 niche in the coral at a depth of 50 feet. A long search was made for 

 more specimens but none was found. 



Diadema antillarum Philippi 



Plate 2 (figs. 4, 5) 

 This species is the most abundant of the echinoids living on the 

 Caribbean side of the island. It occurs most commonly on the 

 rocky-coral areas and is usually absent in the sandy bays. It was 

 found in great numbers from low tide level to 65 feet and presumably 

 Uves even deeper. Most specunens live in hollows in the coral or 

 rock, but some individuals were seen on the sandy patches within 

 the rocky-coral areas. Although no individuals were ever seen under 

 attack by fish, many disassociated spines were seen, indicating that 

 successful attacks had been made. Both small fish and shrimp 

 were frequently seen living among the spines. 



Clypeaster subdepressus (Gray) 



Although many dead tests of this species were seen, only one living 

 individual was found. The species lives buried three or four inches 

 in the sandy patches in the rocky-coral areas in association with 

 Mernia ventricosa (Lamarck). It was most common in depths of 

 10 to 25 feet. The living specimen was found in 50 feet of water 

 completely buried. Its location was indicated by the presence of 

 whiter sand (which is usually underneath) on top of the specimen. 



Figure l.—Meoma ventricosa (Lamarck) with fragments of coral and shell pulled up over 

 the test in 35-foot depth at locality 2; note coarser fragments over madreporite. Figure 

 2—Meoma ventricosa (Lamarck) in 85-foot depth at locality 4; test covered only by bits 

 of algae instead of the usual thick covering of shell fragments and pieces of coral; this is 

 the greatest depth reached during the study and perhaps the echinoid is not covered very 

 much because of the decreased amount of light at this depth. Figure 3.—Meoma 

 ventricosa (Lamarck) in 3S-foot depth at locality 6, showing lack of detrital material over 

 petals and trail made by the echinoid. Figure i.— Tripneustes ventricosus (Lamarck) 

 clinging to rock in 2 feet of water at locality 8; Diadema antillarum Philippi can be seen 

 to the right. Figure S— Diadema antillarum Philippi in 5 feet of water at locality 13. 



