40 NATURAL HISTORY BULLETIN 



E CHIN ASTER SPiNULOsus Verrill. 



EcMnaster spinulosus Verrill, Proc. Boston Soc. Nat. History, vol. xii, p. 

 386, 1869. Liitken, op. cit., p. 285 [61], 1871. Ives, op. cit., p. 326, 

 1890. 



Plate iv; figures 1, 2. 



This species is characterized by having long, slender, terete, 

 tapered rays, covered with numerous small, conical, subacute or 

 often blunt spinules, in many more or less evident rows, and 

 often standing two or three on a plate. The number in each 

 row may be forty or more. 



The number of rows, exclusive of inferomarginals, may be 

 from fifteen to twenty-one in the larger examples. A medium- 

 sized specimen (type) has the radii 12^^ and 72™™; ratio, 1:6. 

 The largest specimens have the radii about 14™™ and 80™™. 



A typical specimen of medium size from West Florida has 

 these characters ; the two rows of marginal plates can readily be 

 distinguished in this and in most other dried specimens, not only 

 by their larger size and more rounded form, but also by a finely 

 granulated and well defined patch on the convex part of each 

 plate and mostly below the single spine, but often including most 

 of the surface of the plate. Over this granular surface the in- 

 vesting dermal membrane is so thin that the granules can usually 

 be seen without preparation, and sometimes they appear as if 

 naked. They are not found on the intermarginal and peractinal 

 plates. 



The two rows of marginals are pretty regular and can be 

 traced to the tips of the arms, each, bearing one small conical 

 spine. On the distal third of the ray the two rows are contigu- 

 ous; on the proximal part they are separated by two or three 

 short, irregular rows of intermarginals, each bearing a conical 

 spine. In the interradial area additional spineless plates are 

 interpolated, broadening the area, for here the upper marginal 

 row turns upward to the dorsal side. 



Many papular pores are found between the marginals and 

 intermarginals, but none below the inferomarginals in most speci- 

 mens. 



Granulated patches also occur on the plates of the principal 

 dorsal rows. 



The interactinal or peractinal plates and spines form a 

 pretty regular row, extending nearly to the tips of the rays. 



