20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 



This species occurs at stations 3, 13, 15, 38, and 59. 



Behavior. — This species lives in protected niches. It inhabits holes 

 or shallow recesses in rock, clings to the bases of sponges or coral 

 heads, works its way under detached slabs of rock, or gets under 

 clumps of shell and broken coral that are bound together by growths 

 of algae and sponge. It has been found in the same environments, 

 living closely associated with E. viridis, although the depth range of 

 that species is greater. 



The species was seen in great numbers living in holes in rock at 

 station 60 and along the shore of Molasses Key, but did not appear 

 to be trapped in the holes. Some regular echinoids are reported to 

 enter small holes in rock as juveniles, and to enlarge the holes as 

 they grow, finally becoming too large to pass through the entrance. 

 E. lucunter inhabited holes and niches with openings large enough to 

 permit exit ; possibly they leave their protected habitats at night, and 

 travel over the substrate as does Diadema antillarum. 



ECHINOMETRA VIRIDIS Agassiz 

 Plate 10, figure 6 



This species is very similar to E. lucunter but differs in having a 

 smaller test, purple, gray, or blue tips on its spines, and fewer spines 

 in the apical system. Both species occur together at some localities. 



Occurrence. — Echinometra viridis was found in shallow water 

 associated with E. lucunter, and also as deep as 40 feet on the main 

 reef. In the shallow areas it was on rock or in sandy areas in clumps 

 of shell and coral debris held together by growth of algae and sponge. 

 One specimen was found in deeper water on rock at the edge of the 

 reef. Its range extends from the shoreline (observed at Molasses 

 Key, not in the area of this study) to the outer edge of the main reef ; 

 from intertidal to 40 feet and possibly deeper. 



This species was found at stations 3 and 37. 



Behavior. — Specimens living in the shoreline intertidal zone on 

 Molasses Key were in holes in the rock. These holes appeared to be 

 large enough to permit the urchin to enter and leave. Specimens liv- 

 ing on sandy bottom in the area of study, just off Rodriguez Key, 

 clustered together with individuals of E. lucunter among clumps of 

 coral and shell debris bound together by living sponge. In these two 

 shallow water habitats the two species of Echinometra lived together, 

 with no apparent differences in habitat or behavior. Further research 

 into this matter is intended, to examine the basis upon which they 



