JAPANESE ASTEROIDEA. 317 



of the adambulacral plates are cliaracteristic, as well as the presence of 

 numerous pedicellarise." 



This species is referred to Mediaster by Vereill ['99, p. 183] : 



" Mediaster japmiicus (Sladen). 



[Eeference to Sladen '89, p. 272 etc.] 



" This species has a rather large, sessile, bivalve pedicellarife with 

 broad valves, on the adambulacral plates ; others of smaller size occur on 

 many of the actinal plates. Some of the pedicellariae have three valves. 



" South of Yeddo, Japan, with the last " [ilf. arcuatus\ 



Fisher gives a very detailed accoimt of the variation of this species under 

 the name of Ceramaster japonicus [vide supra) [ :11, p. 206, with four figures] : 



" Diagnosis. — One of the largest if not the largest species in this or 

 any closely allied genus. K = 102 mm. ; r=65mm. ; R = 1.56 r (varying to 

 E, = 1.36 r). General shape pentagonal or arcuate pentagonal, depressed, the 

 edges of body more or less thickened ; abactinal surface swollen on the 

 radial areas ; actinal surface nearly j)lane. Abactinal surface covered with 

 fairly regular, spaced hexagonal to quadrate tabula croA\Tied with a convex 

 group of numerous polygonal granules, the marginal series regular, some- 

 times compressed, and when dried showing a pit in the top. On the inter- 

 radial areas tabula are quadrate and smaller. Many of the tabula with a 

 bivalved pedicellaria, having thin, lamelliform jaws which are wider than 

 high. These vary in size, equalling one-third or one-fom*th the width of the 

 tabulum. Marginal plates variable, covered with small flat crowded granules, 

 forming an evenly rounded, or a decidedly tumid margin to ray ; a bare 

 space sometimes present on plates of both series, each superomarginal, with 

 one to foiu' smaU bivalved pedicellarise, whose tliin jaws equal two to four 

 granules in width. These are situated usually on the abactinal sm'face of 

 the superomarginals near the margins ; inferomarginals with usually only one 

 pedicellaria or none. Actinal intermediate areas very extensive, the jilates 

 decreasing in size toward margin ; and covered with crowded low flat poly- 

 gonal grantiles, of which the marginal are shghtly the largest ; individual 

 plates pei-fectly flat and variously fom--sided ; actinal intermediate pedicellarise 

 in variable numbers. Adambulacral plates usually slightly wider tlian long, 



