WEST INDIAN STARFISHES 



33 



one dorsolateral on each, side, united transversely by small ossi- 

 cles. Each principal plate bears a single small spine, marginal 

 plates and spines are similar. 



The adambulacral plates are relatively large ; each bears two 

 or three small, slender spines in a transverse row. 



The madreporic plate is small, with few gyri. Minor pedicel- 

 lariae are dermal, scattered between the dorsal spines. 



R-eeorded by Perrier from four Blake stations, among the 

 Lesser Antilles, in 127 to 250 fathoms. It was also taken by the 

 Albatross in the same region. 



Order Spinulosa Perrier. 



SteUeridce Spiniiloscp Perrier, Nouv. Arch. Mus. Hist. Xat., vi, p. 154, 1884. 

 Spinulosa Perrier, Exped. Trav. et Talism., pp. 27, 138, 1894. 

 Phan^rosonia and Cryptozonia (pars) Sladen, Toy. Chall., xxx, p. xxiii, 1889. 

 Spinulosa Fisher, op. cit., 1911b. p. 251. (Table of known families.) Ver- 

 rill, op. cit., pp. 24, 304, 1914a. 



This order, established by Perrier, includes cryptozonate (rare- 

 ly snbphanerozonate) starfishes, which usually have ,but two 

 rows of ambulacral feet (four in Diplopteraster) . The am- 

 bulacral plates are not crowded. The dorsal plates, generally 

 reticulated or imbricated, spinulose, granulose or naked, often 

 form pseudopaxillae or parapaxillae, but they rarely, if ever, 

 form true paxilla?. The dorsal plates are sometimes isolated, 

 rudimentary, or absent in deep-sea genera. The pedicellariae 

 are commonly lacking ; when present they are neither forcipulate 

 nor forficulate. They may be pincer-like, with two or more 

 simple valves, and are always dermal. 



Perhaps the structure of the pedicellariae is the most positive 

 character for separating certain genera of this group from some 

 of the aberrant Porcipulosa. 



The marginal plates are nearly always small and sometimes 

 indistinct; the lower ones are usually the larger; they never 

 form a thick rigid margin ; the margin may be acute or rounded. 

 Papulae may occur both on the dorsal and on the actinal sur- 

 faces, but they are restricted to the dorsal surface in most fam- 

 ilies. The odontophores are adambulacral and of various forms. 

 The ambulacral grooves are usually narrow. The ambulacral 

 feet always have a terminal sucker. The ambulacral ampullas 

 may be single (Echinasteridae) or double. 



