JAPANESE ASTEROIDEA. 237 



is therefore strongly arched, this arch giving the roimded margin. Each 

 plate is covered with spinelets, stouter than those on snperomarginals, some- 

 what sqiiamiform on exposed sm-face, and very slender in the fasciolar 

 gi'ooves. These fasciolar grooves are deep, and about twice as wide at hose of 

 ray (taking transverse axis as length of plate) as the adjacent specialised ridge 

 of the plate. The latter is a thin, almost laminar ridge, very much thinner 

 than in pacißcm, where the specialised ridge is as wide or wider than the 

 gi'ooves. Fai-ther along ray in arcHciis the ridges become thicker, nearly or 

 quite as wide as grooves and the inferomarginals are more massive. A 

 longitudinal shallow fmTOW separates the two series of plates. 



" Adambulacral plates with a ciu'ved fmTow series of three or four rather 

 long, slender, bhmt, terete s^^inelets. Lateralmost spinelets sHghtly the 

 shortest. On actinal sm'face of plate the spinelets decrease gi'adually in size 

 outward, there being two or tlu-ee longitudinal series of tlu'ee or fom- spine- 

 lets, occasionally more. Sometimes a very few odd spinelets stand out of line. 

 Tlie first plate is wider than the rest, with more numerous spinelets. 



" Mouth plates naiTow, the combined pair forming a salient angle into 

 actinostome. FmTow margin long, with about ten spinules like those of 

 adambulacral plates, decreasing in size outward, and continued along adam- 

 bulacral margin in several smaller spinelets ; innermost two spinules forming 

 * teeth ' at angle. An irregular series of spinelets smaller than fmTow 

 spinules stand along edge of median sutm'e ; and at outer end of plate are 

 a few Intel-mediate spinelets between the tAvo series, which throughout the 

 length of plate stand rather close together. 



"Actinal inteiTadial areas fairly large, the plates being arranged in 

 series between inferomarginals and adambulacrals. A single series of plates 

 extends about half length of ray (from inteiTadial angle) ; a second series, 

 one-fomih ; a third series, one-eighth or less. Between fii-st superomarginal 

 and first adambulacral are about six plates in an inten-adial direction. 



" Madrei)oric body nearer margin than centre of disk ; smTounded by 

 six or seven large paxillœ wliich overhang the edges ; ridges coai-se, transverse 

 rather than centrifugal. 



" Variations. — There are thi-ee specimens from station 3602 which ai'e 



