270 DISCOVERY REPORTS 



An examination of the skeleton of the larger specimen (R 40 mm.) reveals that it 

 differs from that of Patiria miniata only in the presence, on the primary plates, of 

 hyaline convexities. These are the surface ends of what appear to be hyaline cylmders 

 descending into the matrix of the plate. The primary plates overlap by the lobes or 

 corners and the papular areas are occupied by small secondary plates as in P. miniata. 



NOTE ON PARASTERINA FISHER 



It is curious that Patiria bellula again becomes known by the combination which 

 Sladen originally used. Sladen's Patiria was not Gray's. It was a group, originating 

 with Perrier (1875, p. 323), which omitted Gray's type, and comprised 2 species, P. 

 oceUifera Gray and P. crassa Gray. This genus, not the original Patiria, was named 

 Parasterina by me (1908, p. 90), with P. crassa Gray the type. Justification for the genus 

 lay in Perrier's statement that, in crassa, the dorsal ossicles are rounded, nearly circular, 

 and are not imbricated as ordinarily the case in Asterina, but touch one another. This 

 statement is repeated in Sladen's key to the genera of Asterinidae (1889, p. 276). 



Through the kindness of Dr H. L. Clark I have received a specimen of Parasterina 

 crassa, from near Fremantle, Western Australia.^ 



This specimen has R 45 mm., r 10 mm., brii-i2mm., and the abactinal aspect 

 resembles superficially that of Nardoa variolata, as the convex primary plates are spaced 

 and the spinelets extremely fine, close-set, and visible only under strong magnification. 

 The species is quite unlike a true Patiria but resembles Nepanthia. In fact, the actinal 

 surface does not differ from that of Nepanthia (e.g. A", belcheri) in any important parti- 

 cular. The actinal plates are covered with co-ordinated groups of very numerous 

 spinelets. There are 15-18 similar subambulacral spinelets, and 8 or 9 furrow spinelets. 

 The inner longiseries of actinal plates extends to 3 or 4 inferomarginals short of the end 

 of ray ; the next two series nearly as far ; the fourth series about three-fifths length of 

 ray measured on side ; while a fifth and sixth series constitute a small additional chevron 

 in the interbrachial angle. 



The two series of marginal plates are quite regular, and correspond, plate to plate; 

 they are obviously larger than the adjacent abactinals and actinals, which are small. 



There are two differentiated areas on the abactinal surface. ( i ) A lateral triangular 

 area reaching, at interradius, one-half of r toward centre of disk and distally nearly half 

 length of ray ; from this point it extends usually as a double series of plates nearly to tip 

 of ray. The plates of this area, in regular longiseries, strongly imbricate, and the upper 

 margin is excavated to accommodate a papula. Around this papular opening are 2-4 

 small superficial plates. Nearly all the plates carry a spiniform pedicellaria. (2) The 

 other area, that of the convex primary plates, comprises the central part of disk and rays. 

 It broadens distally to include most of the sides of ray also. The roundish and irregular, 

 convex, almost tubercular primary plates for a short distance at base of ray imbricate 

 irregularly but over rest of area are joined by smaller and lower secondary plates. These 



1 Clark, H. L., Echinoderms from Australia, Mem. Mus. Comp. ZooL, lv, 1938, pp. 179-181. 



