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third specimen with thirteen tubercles the pentagon formed by 

 the largest five is very regular and the remaining eight all lie 

 within it. These conditions bring this species nearer to St. belcheri, 

 but there is no doubt in my mind that the latter is distinct from St. 

 equestris, as the ambulacral armature of St. helclieri is according 

 to Lütken's description [71, p. 23 & PI. V, fig. 3] very diffèrent 

 from that of the present species. The individual tubercles are 

 mostly short- cylindrical in form, but in some cases, especially 

 where they are more numerous, the larger ones are more or less 

 elongated transversely, and are sometimes clearly seen to be form- 

 ed by the coalescence of two tubercles. The tubercles are to be 

 regarded either as enlarged granules or as a fased group of them. 



The anus is very distinct and is situated in the interradius 

 next the madreporite, proceeding clockwise, close to the central 

 plate. It is surrounded by eight to ten granules larger than those 

 of the general abactinal surface. 



Madreporite. — The madreporite is quite large, though not con- 

 spicuous, owing to the fact that its surface is plane and perfectly 

 level with the surrounding plates. It is usually more or less 

 elhptical or rhomboidal in outline and either is covered with 

 shallow radiating grooves, or the grooves are confined to the 

 periphery and the more central part is covered with numerous 

 separate pores. 



Terminal plate. — The terminal plates are largo and conspicuous, 

 elliptical or squarish in form, and is covered with fine granules 

 exactly similar to those of the superomarginals. 



Locality. — All my specimens are from Usuki, Prov. Bungo. 

 Collected by Mr. T. Tekazaki ; no record of depth. Specimens in 



