JAPANESE ASTEEOIDEA. 33 



the outer side of this a second, but smaller and more delicate, spinelet is- 

 present, and frequently also a small miliaiy spinelet on the adorai side of 

 the large spinelet. The j)i"esence, however, of the second spine and of the 

 miliaiy is by no means constant. They are often (perhaps usuall}) absent 

 in small examples and on the inner and outer parts of the ray even of large 

 specimens. The larger actinal spine measures about 1.7 mm. in length on 

 the fifth or sixth plate from the mouth-angle, the marginal or furrow series 

 being normally less than lialf tliis length. 



" The mouth-plates are large, and convex actiually, and the imited pair 

 form a broad projection towards the actinostome, the free margin being 

 more than a semicircle, and bulging laterally. The armatm'e consists of a 

 marginal series of five, or sometimes six, short, slightly tapering mouth-spines 

 on each plate, the innermost being twice as large as the others. On the 

 actinal sm'face of the plate are tln-ee subequal tapering spinelets, forming a 

 line parallel to the imperfectly closed median suture ; sometimes a fourth is 

 present on the outer side of the series, and sometimes its place is occupied by a 

 miliary thornlet only ; but often it is wanting altogether. No other spines are 

 present, and the surface of the plates is covered with thin membrane. 



" The actinal interradial areas are ver}- small indeed, not more tlian 

 three or four intermediate plates being present in young examples, and in 

 larger ones not more than eight to ten. These form only a single series 

 between the marginal plates and the adambulacral and mouth-plates ; their 

 sm^face is covered with membrane and the larger plates bear two or three 

 small thomlets. There is usually one small pedicellarian apparatus in each 

 area, wliich does not stand in the median interradial line, but is usually 

 sej)arated therefrom by one plate. It is of the ' spiracle '-like or double- 

 comb form, previously described. Harely two are present. There are no 

 pedicellarian apparatus between the infero-marginal plates. 



" The anal apertm-e is subcentral and distinct, and usuall}' there are 

 two or thi-ee spinelets in its neighbom-hood larger than those borne on the 

 spicules generall3^ 



" The madi-eporiform body is comparatively large and oval, placed about 

 midway between the centime of the disk and the margin, and its siu:face is 



