372 BULLETlISr 100, UNITED STATES NATIONAL MUSEUM. 



first appears there is no granule. With the exception of the hist 3 

 the inferomarginals are not at all tumid. 



Actinal intermediate plates squarish, slightl}'' tumid. The series 

 adjacent to adambulacrals extends to within about 3 inferomarginals 

 of end of ra}^; a second row extends to the beginning of the sixth 

 inf eromarginal ; a third row to the beginning of the fourth infero- 

 marginal, while the beginning of a fourth row is present in the inter- 

 brachial arc. The plates are not uniform in size but tend to become 

 larger and convex opposite the transverse sutures of the inf eromar- 

 ginal series. Granulation uniform with that of abactinal surface, 

 largest on the sutures and decreasing in size toward middle of plate. 

 It is very close and covers the aclambulacral plates also, rising on the 

 outer side of the aclambulacral spines nearly to their tip. 



Adambulacral plates slightly wider than long, about 15 corre- 

 sponding to the first 10 actinal intermediate plates of the inner series. 

 Adambulacral spinelets truncate, slightly flattened, in a single series 

 on the edge of the furrow. Each plate has 3, or near the end of ray, 

 2 spines, but there is no break in the series. Ambulacral furrow 

 closed. 



Madreporic body small, elliptical, resembling in miniature half 

 a peach stone. 



Color in alcohol, light brownish, the granules encircling the bare 

 areas and the center of small abactinal plates whitish, elsewhere dull 

 orange, especially on disk; actinally the orange hue is duller. The 

 naked areas are light yellowish brown, sometimes with a dark center. 



Type.— Cdit. No. 32636, U.S.N.M. 



Type-locality. — Station 5640, Buton Strait, Celebes (1 mile west 

 of Labuan Blanda Island), 24 fathoms, sand, broken shells; 1 speci- 

 men. 



Distribution. — Known only from type-locality. 



Remarks. — Although this species resembles F. offreti (Ceylon and 

 Andaman Islands) in the prominent superomarginal and abactinal 

 plates, the resemblance is general only. A very important difference 

 is the absence in glyptodisca of a series of small actinal intermediate 

 plates subequal to the adambulacrals, which in ojfreti reach the 

 extremity of the ray, and are only about Jialf as large as the second 

 series. In glyptodisca all the prominent abactinal plates and all the 

 marginals of both series are naked centrally, and the small abactinal 

 plates are much less tumid. The granules of the central part of the 

 covered plates are larger, in o^freti^ than those near the margin, while 

 in glyptodisca the reverse is the case. A comparison of figures will 

 show that the superomarginals of glyptodisca are much larger in 

 proportion to the width of ray, and the abactinal area much narrower 

 than in offreti. Finally, ajfreti has 2 adambulacral spines while 

 glyptodisca has 3. 



