Boone, Echinodermata, Cruises of "Ara" and "Alva" 167 



in the West Indies down to Santa Lucia, the usual bath>Tiietric 

 occurrence being from 100 to 200 fathoms, with an occasional 

 shallow water depth, such as Dr. H. L. Clark's record of it in 32 

 meters (1908), also some records of C. abyssicola from depths 

 greatly exceeding 200 fathoms, in the "Blake" and "Albatross" 

 dredgings, where the present species was confused with Cidaris 

 cidaris (Linne) and Stylocidaris affinis (Philippi) under Doroci- 

 daris papillata. The "Alva" stations, off Sand Key Light, Florida, 

 in 100 to 65 fathoms, add another record within the southern 

 geographic range of C. abyssicola. 



Material examined: Three specimens dredged in 100 fath- 

 oms, by the yacht "Alva," nine miles off Sand Key Light, Florida, 

 bearing 311° true, March 18, 1936 ; 14 specimens, of various sizes, 

 also dredged off Sand Key Light, bearing 315°, in 65 fathoms, 

 November 25, 1935. 35 commensal barnacles, Verruca alba Pils- 

 bry. 



Colour : The "Alva" specimens were of a light straw-colour, 

 or deep ivory, tinged with light olivaceous green, the primary 

 spines being a deep yellowish cream with fugitive rosy tints. The 

 denuded test is pearly white. 



Technical description : Test firm, pearly white, circular in 

 outline (three young specimens approach pentagonal), much 

 wider than high, turban-shape, sides decidedly arched, the actinal 

 and abactinal regions similarly flattened, but with the upper show- 

 ing a moderate convexity. 



The peristome is normally flattish, of variable pentagonal out- 

 line, larger in ratio to the horizontal diameter of young specimens, 

 relatively small in large specimens, being one-third to three-fifths 

 of the width. There are twelve to fourteen ambulacral plates per 

 series in an average large specimen. The ambulacra are slightly 

 undulating, about 0.25 to 0.20 of the width of the interambulacra. 

 The series of marginal tubercles is regular, evenly spaced, sepa- 

 rated, inconspicuous. There is an inner regular vertical series of 

 secondary tubercles, composed of one smaller secondary tubercle 

 situated adradial to the marginal tubercle and a little below the 

 center on each plate. On the lower margin of each plate one, two 

 or three miliary granules are present, these forming a more 

 numerous series on the larger specimens. There is no distinct 

 smooth or sunken median space. The pores are in pairs, well 

 spaced, smallish, subequal or sometimes with the outer one the 



