Boone, Echinodermata, Cruises of "Eagle" and "Ara," 1921-28 71 



ASTEROIDEA. 

 Order: PHANERAZONIA. 

 Suborder: Paxillosa. 

 Family: PORCELLANASTERIDAE. 



Genus : CTENODISCUS Muller and Troschel. 



Ctenodiscus crispatus (Eetzius). 



Plates 27 and 28. 



Type: Original description not available for examination. 



Distribution : Apparently circumpolar in the Arctic, in Europe 

 on the Scandinavian and northern British coasts ; at Iceland ; Green- 

 land ; on the east coast of North America down to Massachusetts, and 

 on the west American coasts down to Chile ; on the Asian coast down 

 to Japan. Bathymetric occurrence: from 2 to about 10 fms., but 

 apparently the species is found in greatest abundance from about 25 

 to 300 fms. 



Material examined : Seven specimens, dredged in the middle of 

 St. George's Bay, Newfoundland, September 2, 1926. 



Color: In life this species is yellowish. 



Habits and Development: C. crispatus apparently requires about 

 three years to attain its full size. Its development is unknown, but 

 from the fact that the eggs are large with big yolks, it is believed by 

 Dr. Mortensen to probably have a direct development, without a free 

 pelagic larval stage. It lives on muddy bottoms and feeds chiefly on 

 the small creatures that live in the mud. 



Technical description: Rays five, rarely four or six; varying a 

 great deal in length. R = 28 ; r = 14 ; R = 2r. The abactinal sur- 

 face is covered with closely set paxillae, consisting of a short, tabular, 

 subcircular base, crowned with 8 to 15 short, clavate spines, arranged 

 rosette fashion ; these rosettes are closely packed over the entire abac- 

 tinal surface. The madrepore is oval, 5 mm. long diameter, crossed 

 by numerous fine, wavy ridges alternated with grooves. The marginal 

 plates and oral interradial surfaces and adambulacral plates are cov- 

 ered by a fine, soft skin. On the median dorsal margin of each 

 marginal plate there is a prominent stout, conical spine. Cribriform 

 organs are present between all of the marginal plates, but are con- 

 cealed by a web of papillae along the margin of the plates and con- 

 tinued as simple channels similarly covered by webs, over the oral 

 interradial region and between the adambulacral plates. There is 

 also a stout, conical spine at about the median point of the outer or 



