On Two New Species of Asthenosoma 

 from the Sea of Sagami. 

 By S. Yoshiwara. 



Zoological Institute, Science College, Imp. Univ., Tokyo. 

 With PL n. 



The Echinoid collection of the Science College Museum contains, 

 amongst others, five interesting specimens referable to the genus As- 

 thenosoma, of which I propose to make two new species as described 

 below. 



Asthenosoma longispinum, nov. sp. 

 . (Figs. 1-7.) 



Four specimens of this species have been obtained from a depth of 

 313-376 fathoms in Sagami Sea. 



Test flexible, disc-shaped, flat actinally, depressed abactinally, 

 somewhat polygonal in ambital outline. Dimensions of the largest 

 specimens : 135 mm. in diameter and 18 mm. in height. Color of 

 covering membrane dark red as preserved in alcohol. 



Plates numerous. In a specimen of 110 mm. in diameter, there 

 are in a vertical row : actinally, about 17 interambulacral and about 23 

 ambulacral plates ; abactinally, about 30 interambulacral and more than 

 30 ambulacral plates. Plates overlapping as in other species of the 

 genus. Between every two interambulacrals in vertical succession, there 

 exists actinally a considerable membranous area in the middle, but 

 abactinally this membrane is reduced to a minimum, and the plates 

 overlap one another even in the middle of transverse sutures, although 



