STARFISHES OF THE PHILIPPINE SEAS. 309 



Madreporic body small, situated one-third of r from center, and 

 surrounded by 3 large plates. 



Gonads in a single cluster on either side of the membranous inter- 

 brachial septum. 



Type.— C^t. No. 30554, U.S.N.M. 



Type-locality. — Station 5166, 4.6 miles southeast of Observation 

 Island, Tawi Tawi Group, Sulu Archipelago, 97 fathoms, coral 

 sand, bottom temperature 69.4° F. ; 1 specimen. 



D'lstrlhution. — Known only from the type-locality. 



Reinarks. — The generic position of this species is very puzzling. 

 The dorsal skeleton and the very tumid roughened superomarginals 

 would ally it to Astroceramus. But the actinal intermediate plates 

 are like those of Iconaster and LithosoTna^ being without central 

 granules. The adambulacral armature is similar to that of Icon- 

 aster^ while suggesting AstroceraTnus in the slightly more differ- 

 entiated inner subambulacral series and in the presence of a con- 

 spicuous transversely oriented pedicellaria. To put these facts in a 

 different way, /. pe7'ierctus differs from Iconaster in having the 

 dorsal radial plates entirely surrounded by granules, and in having 

 the tumid superomarginals roughened by uneven elevations (which, 

 unlike those of Astroceramus., do not bear scattered granules). It 

 differs from Astroceramus in lacking any trace of marginal and 

 enlarged central actinal intermediate granules, in having the adam- 

 bulacral armature graded from the short furrow spines to the outer 

 granules, and in the absence of a conspicuously enlarged subambu- 

 lacral spine on the outer part of the ray. 



The types of Iconaster and Astroceramus are so distinct that I see 

 no utility in merging the 2 genera. For the present, at least, I think 

 it is better to regard the arrangement of the peripheral granules of 

 the radial plates as of less than generic importance, and to rest the 

 distinction between the 2 groups upon the difference in the adam- 

 bulacral and actinal intermediate armature, as w^ell as upon the 

 absence, in Iconaster., of granules on the marginal plates. 



Despite the small size of /. perierctus., the gonads are well de- 

 veloped. 



In the transactions of the Linnaean Society of London for 

 1909-1910 (vol. 13, Zoology, p. 22), Bell diagnoses Iconaster gardi- 

 neri from Saya de Malha Bank, western Indian Ocean, 125 fathoms. 

 I have examined the type at the British Museum. It is a typical 

 Nymphaster related, perhaps, to N. dyscritus Fisher. 



Genus ASTROCERAMUS Fisher. 



Astroceramus Fisher, 1906, p. 1056. Type, A. callimorphus Fisher. 



Diagnosis. — Related to Iconaster Sladen, but differs in having the 

 marginal plates beset with rather coarse, deciduous granules; in hav- 



13434— Bull. 100—19 21 



