470 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



brane. The first is articulated to the second adambulacral. The 

 spines do not meet interradially their fellows of adjacent ray, but 

 leave a narrow wedge-shaped area. The length of this wedge (the 

 apex touching mouth plates) is about half the extent of the free 

 edge of one ray measured along edge of actinolateral membrane. 

 This actinolateral membrance is nearly flat. 



Madreporic body globular, and without a paxilla on its surface. 



Type.—C2,t. No. 28660, U.S.N.M. 



Type-locality. — Station 5623, Molucca Passage between Gillolo and 

 Makyan Islands (lat. 0° 16' 30'' N.; long. 127° 30' E.), 272 fathoms, 

 fine sand, mud ; 25 specimens. 



Distribution. — Sulu Archipelago, and Molucca Passage, 258 to 272 

 fathoms, mud and fine sand. 



Specimens examined. — Eight, 4 from type-locality and 4 from the 

 following stations : 



Station 5549, vicinity of Jolo Island, Sulu Archipelago, 263 

 fathoms, sand, globigerina, foraminifera, bottom temperature, 52.3° 

 F. ; 1 specimen. 



Station 5550, same locality, 258 fathoms, fine sand, shells, 52.3° F. ; 

 2 specimens. 



Station 5622, Molucca Passage, near Makyan Island (lat. 0° 19' 

 20" N.; long. 127° 28' 30" E.), 275 fathoms, gray mud; 1 specimen. 



Remarks. — This genus constitutes a very distinct, new type, which 

 differs from Eymenaster in much the same way that Diplopter aster 

 differs from Pteraster. The most easily recognized characters of 

 Eymenasterides are the alternating prominent and nonprominent 

 adambulacral plates, correlated with the quadriserial arrangement 

 of the tube feet. 



Family ZOROASTERIDAE Sladen, 1889. 



KET TO THE KNOWN GENERA OF ZOROASTERIDAE. 



a^ Dorsal surface not devoid of spines and not covered with a smooth tough 

 membrane in sharp contrast to the spiniferous or squamiferous actino- 

 lateral regions. 

 6* Superambulacral plates absent; no conspicuous buttress connecting upper 

 enlarged end of first 2 pairs of ambulacral plates with the body wall 

 at interradial angle. 

 & All the adambulacral plates carinate on the furrow face. Prognaster* 



Perrier. 

 c' Adambulacral plates alternately carinate and noncarinate on the furrow 

 face. 



^Prognaster Perrier, Comptes rendus, vol. 112, May 5, 1891, p. 1226. Type, P. gri- 

 tnaldii, monotyplc. Also 1894, p. 120, where it is stated that the genus Is new and where 

 only one species, P. longicauda, is mentioned. In 1896 in R6sultats des campagnes scien- 

 tlfiques du Prince de Monaco, fasc. 11, p. 22, Prognaster is redescribed, with P. grimaldii. 

 P. longicandua is probably not congeneric with grimaldii. The internal structure of both 

 is unknown. 



