WEST INDIAN STARFISHES 155 



Other specimens, almost identical in other respects, lack the 

 pedicellai-iae, or have very few. 



The most distinct or most divergent species in our fauna, is 

 A. americanus, a form exceedingly abundant off the middle At- 

 lantic coast of the United States, in 40 to 150 fathoms. 



This not only has abundant pedicellari^, but it is peculiar in 

 many other ways. The dorsal paxillae have unusually long slen- 

 der spinules; the marginal plates are spinulose, instead of being 

 granulose, as in most species and the adambulacral spines are all 

 slender, a feature not found in most species. The superomar- 

 ginal plates are concave transversely in the middle and thick- 

 ened near the margins, a peculiarity not found in any other 

 species known to me. 



In the West Indian fauna there are now recognized eleven 

 species, besides two or three named subspecific or varietal forms 

 and two or three doubtful or insufficiently described species. 



The character of the superomarginal spines, although a con- 

 spicuous feature is too variable to be of primar>^ importance in 

 grouping the species. Moreover, if classified by this as a prim- 

 ary feature, closely related or even varietal forms may be widely 

 separated, and very diverse, species brought together. The fol- 

 lowing lists may, however, be of some use in the approximate 

 location of adult specimens. 



A. Species having two rows of spines on the superomarginal 

 plates at least proximally: A. duplicatus; A. antUlensis; A. 

 hraziliensis. 



B. Species having one row of superomarginal spines or tu- 

 bercles; rows often incomplete: A. arficiilatus; A. alligator; 

 A. nuttingii. 



C. Species having no superomarginal spines or tubercles: 

 A. comptus Ver., nov. ; A. americanus Yer. ; A. americanus siib- 

 graciUs Ver., nov; A. richardii Perrier; A. cingulatus Sladen; 

 A. articulaius duhiiis (Gray) ; A. nitidus Ver., nov.; A. nitidus 

 forcipatus Yer., nov. ; A. ciliaius Grube. 



Analytical Tahle of West Indian Species of Astropecten. 



A. Adambulacral plates have one or two notably enlarged 

 spines in the second row. Few or no pedicellariae. 



B. Superomarginal plates have, in the adult, one or two 

 rows of spines. 



