NO. 6 ECHINOID DISTRIBUTION AND HABITS — KIER, GRANT 65 



7. Encope michelini Agassiz. Station 30 (depth 15 feet). Roughly triangular 

 trail in calcareous sand, showing low parallel ridges made by posterolateral 

 notches, and median row of sand grains aligned by posterior lunule; 

 specimen at top center of photograph. 



Plate 6. OVERTURNING, HABITATS AND ASSOCIATES OF 

 CLYPEASTER SUBDEPRESSUS 



1-6. Station 22 (depth 30 feet), timed series illustrating righting of C. subde- 

 Pressus after being overturned. 



1. Time 10:30. Small and large specimens overturned, begin righting by 

 action of spines along edge near anterolateral ambulacrum. 



2. Time 10:50. Small specimen at angle near 45 degrees; larger one 

 barely raised (subsequent illustrations show only the smaller specimen; 

 at end of series 45 minutes later, larger specimen still had not attained 

 vertical position) . 



3. Time 11:04. Small specimen (at left in figure 2) nearly vertical, with 

 right side dug into sand. 



4. Time 11 :10. Small specimen vertical. 



5. Time 11:13. Small specimen rapidly lowering to normal horizontal 

 position. 



6. Time 11 :18. Specimen horizontal and buried, beginning to move 

 forward. 



7. Clypeaster subdepressus and C. rosaceus, station 30 (depth 15 feet). Both 



somewhat out of normal habitat, with tests covered. C. subdepressus here 

 moving on surface of sand, with coarse particles held over petal area (this 

 species normally burrows in topmost layer of sand). C. rosaceus covered 

 by shells and some grass (this species normally lives in grassy areas). 



8. Clypeaster subdepressus, station 22 (depth 30 feet), plowing through topmost 



layer of sand, with broad flat objects held over petals. 

 9-10. Clypeaster subdepressus and Encope michelini, station 30, depth 15 feet. 



9. Two specimens of C. subdepressus and one of E. michelini covered by 

 thin layer of sand, occupying essentially the same habitats. 



10. The same three specimens uncovered. 



Plate 7. OVERTURNING OF ENCOPE MICHELINI, AND BURIAL 

 OF E. MICHELINI AND LEODIA SEXIESPERFORATA 



1-5. Encope michelini Agassiz, station 30 (depth 15 feet). 



1. Inverted specimen digs anterior edge into sand. 



2. Side view showing specimen about 45 degrees to surface of sand. 



3. Specimen nearly vertical, without having dug deeper into sand than 

 in figure 2. 



4. Righted specimen lowers posterior edge toward sand. 



5. Nearly horizontal, specimen buries itself rapidly by passing sand 

 backward along dorsal surface, and by moving forward into sand. 



6-8. E. michelini and Leodia sexiesperforata (Leske), station 30 (depth 15 

 feet). 



6. Excavated specimen of each species begins to bury by moving forward 

 into sand, passing sand backward along dorsal surface from anterior, and 



