NO. 6 ECHINOID DISTRIBUTION AND HABITS — KIER, GRANT 35 



wherever it occurs, it was found only at a few localities. The range 

 of depth of E. michelini in this area is between 10 and 20 feet. 



This species was found at stations 23, 30, 45, 55, and 58. 



Behavior. — Encope michelini is the most active of the clypeasteroids 

 in this area. When actively burrowing it moves anteriorly through 

 the upper surface of the sand at the rate slightly less than an inch per 

 minute, a speed about twice that of Leodia sexiesperforata. It buries 

 itself in about four minutes which is about half the time required by 

 L. sexiesperforata and about a fourth of the time required by 

 Clyp easier subdepressus. The outlines of most specimens are plainly 

 visible as they move through the sand, and the trails that they leave 

 have two low parallel lateral ridges produced by the posterolateral 

 notches, and occasionally a median one produced by the posterior 

 lunule (pi. 5, fig. 7). 



The distribution of spines in this species is similar to that described 

 for L. sexiesperforata by Goodbody (1960). The dorsal surface has 

 only club-shaped and miliary spines ; all ambulatory spines are around 

 the periphery of the test and in radiating concentrations in the inter- 

 ambulacral areas of the oral surface, and one transverse concentration 

 just posterior to the posterior lunule. Therefore, the manner of burial 

 and of turning over is similar in the two species. E. michelini buries 

 itself by passing sand grains onto the dorsal surface in two coalescing 

 sheets from the anterior and the anterolateral edge6. These grains are 

 moved progressively toward the posterior end by nonambulatory 

 spines, and the test is effectively covered by sand before it has moved 

 anteriorly more than three-fourths of its own length (pi. 7, figs. 6-8). 

 Similarly, when this species is turned onto its dorsal surface, it rights 

 itself by the same activity of ambulatory spines that normally pro- 

 duces forward motion. Inasmuch as these spines are concentrated on 

 the periphery and on the oral surface of the test, the result is to bury 

 the anterior portion of the test progressively deeper, pulling the test 

 into an increasingly upright position (pi. 7, figs. 1-5) until it turns 

 over. Then as it continues this motion of spines, gravity brings an 

 increasing number of the ambulatory spines into contact with the sand, 

 and the animal moves anteriorly through the sand into the normal 

 position. 



Feeding habits of this species were not observed, but the distribu- 

 tion of spines, podia, lunules (and notches), and food tracts is so 

 similar to that of Leodia sexiesperforata that it undoubtedly feeds in 

 the same manner. 



