Boone, Echinodermata, Cruises of "Eagle" and "Ara," 1921-28 73 



Clark, Eept. Canadian Arctic Exped. 1913-18, vol. VIII, part C, 

 Echinod., p. 7c, 1920. 

 Aster acanthion polaris Muller and Troschel, op. cit., p. 16. — Lut- 

 ken, Syst. Overs. Gronslands Echinod., p. 28, 1857. — Duncan 

 and Sladen, Mem. Echinod. Arctic Sea to the west of Greenland, 

 p. 23, pi. 2, figs. 4-8, 1881. 



Family : ASTROPECTENIDAE. 



Genus : NIDORELLIA Gray. 

 Nidorellia armata Gray. 



Plates 29 and 30. 



Type : The type was collected by H. Cuming in Punta Santa Elena, 

 Ecuador, on rocky bottom, 12 to 15 fms. depth, and is deposited in 

 the British Museum. 



Distribution: Found on the American Pacific coast from Lower 

 California southward to Zorritos, Peru; also known from the Gala- 

 pagos Islands; littoral. 



Material examined : One specimen, Webb Cove, Albemarle Island, 

 Galapagos Islands, March, 1928. 



Color: In life this starfish is bright scarlet. 



Technical description: Dr. Verrill gives an excellent description 

 of this species, based on an extensive series of specimens and discuss- 

 ing the types of variation found in different rays of the same speci- 

 men, as well as the types of variation occurring between different 

 specimens. 



The "Ara" specimen has a radius of 73.5 mm. and is regularly 

 pentagonal, with the interbrachial arc concave and the rays short, 

 broad, rounded at the tips. The abactinal surface is a little convex, 

 with a stout conical spine upon a tubercular prominence in the center 

 and surrounded by similar spines, some of which correspond to the 

 interradial zone, and some of the rays, down the center of each of 

 which extends a row of similar spines. The interradial region is set 

 with similar spines placed irregularly. The spines of the abactinal 

 surface and margin are conical, thick, smooth and naked, except at 

 the base, where they are surrounded by irregular patches composed 

 of short, polygonal paxillae. Similar paxillae also form the network 

 surrounding the large groups of pores which occupy all the intervals 

 between the plates and frequently form large, sieve-like patches. Scat- 

 tered among the pores are numerous small, short and broad, oblong 



