72 NATURAL HISTORY BULLETIN 



scalloped margin to the rays. Each bears two rows of spinules; 

 a short row of about three on the upper surface, which are acute 

 and divergent ; and a marginal row, usually of four slender half- 

 webbed spines, the middle ones largest, so that the outline of 

 the group is curved. On the under side they are naked, trans- 

 versely oblong, and the surface is covered with microscopic, 

 raised dots. 



The interactinal plates form three regular chevrons, with a 

 few additional small plates in the interradial angle. (In smaller 

 examples there are but two chevrons) . In the first series there 

 may be twelve or more plates, all paired. In the second and 

 third chevrons there is an impaired interradial plate. All these 

 plates have two or three small acute spinules, near the aboral 

 edge, standing side by side, and subappressed. The plates are 

 somewhat imbricated, more or less ovate, or subangular with 

 rounded lateral edges, variable in size. The surface is covered 

 with raised microscopic dots and covered only with a thin dermis 

 that does not conceal them. 



The adambulacral plates are small ; each has a regular furrow 

 comb of three slender webbed spines, directed horizontally. On 

 the actinal face, and separated from the inner ones by a naked 

 groove, are two or three, usually two, larger divergent spines, 

 standing transversely to the groove. 



The adoral and epioral spines are similar to the ordinary adam- 

 bulacrals, but rather larger and longer; the perorals are some- 

 what stouter and blunt. 



This was dredged by the Albatross, off West Florida, at sta- 

 tions 2334 (No. 10,190, Nat. Mus., type) 67 fathoms; 2324, No. 

 10,129, 23 fathoms; 2333, No. 10,179, 169 fathoms; 2323, No. 

 18,484, in 163 fathoms. Also Bahamas, station 2649, No. 18,474, 

 in 36 fathoms. 



Young. The smallest specimen seen (No. 18,474) has the radii 

 4min 6.5°™. Marginal plates seven in each row. 



The dorsal plates are arranged nearly as in the type, but the 

 specimen is preserved in better shape and all parts are neatly 

 regular. 



The plates are not only much smaller, hut lie flatter and their 

 outlines are less distinct because the dermis is a little thicker, 

 most of the plates bear one small sharp spinule, situated on the 



