WEST INDIAN STARFISHES 



75 



adult might be a Poraiiia or some other related genus. I have 

 seen only one type. It differs from the other similar small or 

 young forms, in ha\dng more spines in the furrow-comb, as in 

 Poraniella. 



From P. regularis it differs especially in the form and ar- 

 rangement of the dorsal plates. In the latter they are more 

 numerous and show no tendency to form oblique rows running 

 from the radials to the marginals, nor are the radial plates pent- 

 agonal, for their exposed edges are meniscoid or pelecoid. For 

 the present, or until larger specimens can be found, I prefer to 

 place this species under Poraniella, on account of its having the 

 same arrangement of adambulacral spines and interactinal plates 

 and spinules. 



Genus M^vrgixaster Perrier. (Type. M. pectinatus). 



Marginaster Perrier, Bull. Mus. Comp. Zool., ix, p. 16, 1881; Etoiles de 

 Mer, p. 229, 1884. Sladen, Voy. Chall., xxs, p. 364, 1889. Perrier, 

 Exp. Trav. et Talism., p. 164, 1874. 



Form pentagonal or stellate with short rays. Disk and rays 

 a little convex, edges thin, bordered by a fringe of marginal 

 spinules. Dorsal plates well developed, flatish, imbricated, cov- 

 ered with a thin integument, which often partially conceals the 

 plates in alcoholic specimens; median radial row distinct. The 

 larger plates usually bear few small spinules, often only one or 

 two to a plate. Papulag few isolated between the plates. 



Upper and lower marginal plates distinct, about equal in 

 number ; the lower ones are larger and more prominent, and bear 

 a terminal row of several spinules, forming a marginal fringe. 

 Upper ones have fewer and smaller spinules, in a row in the type. 

 Papular pores do not occur between the two rows of plates, in 

 the type, but are present in some of the related species. 



Interactinal plates few, rather flatish, imbricated or tesselated, 

 arranged in short rows or chevrons, usually bearing one to three 

 small clustered spinules. One or two plates are impaired be- 

 tween the jaws and the median interradial suture. 



The adambulacral spines are small and in typical species form 

 a short, transverse, usually oblique row of two to five spines; 

 the two inner ones often stand nearly side by side. Jaw-plates 

 relatively large, convex, separated by a median groove, and bor- 



