238 K. MITSUKUEI : STUDIES ON 



micldorsal interradialia is like the lateral dorsal radialia. There 

 are five small teeth around the anus. 



The calcareous deposits form two layers : The inner layer 

 is very thick and crowded, consisting of thick elliptical plates 

 with smooth margin. The smallest plates have four holes, there 

 being very often a liandle-like arch between the two holes in the 

 longitudinal axis (c). In the larger plates, the four main holes 

 are often eccentrically situated, in which cases the arch is also 

 eccentric in position and lies longitudinally between the two 

 main holes in the longitudinal axis. Some plates in the layer 

 are of an elongate shape ; these show foar main holes in the 

 middle broad parts, besides having some more holes in a row in 

 the narrower prolonged parts {d, e). The supporting rods of the 

 pedicels are mostly of this form. They have a sort of tower in 

 the middle. In the outer layer the calcareous deposits are not so 

 closely packed together as in the inner layer. They are bodies 

 which may best be called reticulated ellipses (/>). They all have 

 an elliptical basal plate with four or more distinct holes ; from 

 any spot in the periphery of this basal plate, there may arise 

 several smooth, slender rods. These branch, and the branches 

 fuse whenever and wherever they come into touch. The result 

 is a basket-like table with a very complicated tower, the 

 appearance from above being simply that of a bush consisting of 

 small branches with smooth tips. All stages of development may 

 be observed. 



This species seems to be a northern one. It is known by 

 the name of " Ishiko " in Prov. Owari. 



Locality ;— Vaucouver's I. (Théel '^G) ; Piiget Sound (Clark '01) ; Pacific 

 Grove, Cal. (Clark '01) ; Pacific coast of Japan from Hokkaido to Prov. 

 Shima. 



