EXPLANATION OF PLATES 



Plate 1. ASTROPYGA MAGNIFICA IN ITS HABITAT 



1-5. Astropyga magnified Clark at station 36 (depth 85 feet) on flat sand 

 terrace. 



1. Oblique view of specimen with spines grouped in defensive posture; 

 inflated anal sac visible. 



2. Nearly vertical view from above, dorsal spines bundled for defense, 

 anal sac visible, iridescent spots along ambulacra apparent. 



3. Two specimens showing bundled spines, anal sacs, and iridescent spots ; 

 glove at top gives scale. 



4. Small fish (Apogon) which characteristically swims among spines of 

 this species. 



5. Same individuals as figure 3, seen from side with black glove in back- 

 ground, showing bundled upper spines, inflated anal sac, iridescent spots, 

 color-banding of spines. 



Plate 2. HABITATS OF EUCIDARIS TRIBULOIDES, DIADEMA 

 ANTILLARUM, AND ARBACIA PUNCTULATA 



1-3. Encidaris tribuloides (Lamarck). 



1. Station 36 (depth 85 feet) in niche between boulders. 



2. Station 28 (depth 22 feet) in dense turtle grass. 



3. Station 22 (depth 30 feet) on sand in sparse turtle grass. 

 4-7. Diadema antillarum Phillipi. 



4. Station 28 (depth 22 feet) flock of medium size specimens on fine 

 sand in sparse turtle grass. One in bottom center of photograph shows 

 inflated anal sac; small striped fish swim among spines in upper right. 



5. Station 22 (depth 30 feet) solitary juvenile with banded spines on sand 

 in moderately dense turtle grass. 



6. Station 25 (depth 110 feet) large specimen in niche in living coral 

 bank. 



7. Station 60 (depth 20 feet) medium size specimens in niches among 

 living coral on reef. 



8-9. Arbacia punctulata (Lamarck). 



8. Station 28 (depth 22 feet) clinging to base of isolated sponge on sand 

 in sparse turtle grass. White specks are small mysid shrimps which inhabit 

 area protected by spines of this species and D. antillarum. 



9. Station 28 (depth 22 feet) two specimens clinging to base of small 

 clump of corals and sponges, on sand in sparse grass. 



Plate 3. HABITATS OF LYTECHINUS VARIEGATUS, 

 TRIPNEUSTES VENTRICOSUS, AND MEOMA VENTRICOSA 



1. Lytechinus variegatus (Lamarck) station 28 (depth 22 feet), specimen in 

 turtle grass completely camouflaged by shells and blades of grass held onto 

 test by tube feet. 



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