REPOKT ON THE ASTEROIDEA. 



551 



( 'horological Synopsis of the Species. 



1. Perknaster fuscus, n. sp. (PI. XCVII. figs. 3 and 4). 



Rays five. R = 45 mm. ; r= 14 mm. R>3 r. Breadth of a ray near the base, 14 

 mm. ; breadth about midway between the disk and the extremity, 5 mm. 



Disk large and inflated. Rays short, rounded, broad at the base, then rapidly 

 decreasing in breadth and tapering slightly to the extremity, which is thick and obtuse. 

 Interbrachial arcs wide and open, rounded, or with a faint trace of angularity at the 

 summit. On the disk, in the median interradial lines, are more or less sharply defined 

 depressions or sulci extending from the margin midway to the centre. The actinal surface 

 round the mouth is slightly depressed. 



The whole abactinal and lateral surfaces extending ,up to the adambulacral plates are 

 covered with undistinguishable plates which bear small tufts or groups of short, robust, 

 equal spinelets, thickly covered with skin and not particularly compactly placed ; the 

 whole forming a papillate and more or less irregularly grouped surface. No order of 

 arrangement is discernible and there is no approach to a reticulate character. Between 

 the plates numerous papulae are interspersed. 



On the interradial areas of the actinal surface a certain amount of regularity may be 

 traced, the plates there falling into more or less distinct longitudinal and transverse 

 series ; there are not more than two or three spinelets borne on these plates, and the 

 groups consequently have a rather more distinct and isolated appearance. Indistinct 

 traces of what are perhaps the representatives of a series of infero-marginal plates may be 

 made out at the junction of the actinal interradial and lateral areas. 



The armature of the adambulacral plates consists of a transverse series of three robust 

 and very thickly skin-covered spinelets, followed on the outer part of the plate by a pair 

 of much smaller spinelets. The innermost or furrow spine is longer and larger than the 

 others, and with its membranous investment nearly as thick as the length of the plate. 

 There is no small inner spinelet within the furrow. 



The madreporiform bod)-, which is large and distinctly defined, is situated about 

 midway between the centre of the disk and the margin, or may be rather nearer the 

 former. Its surface is grooved with numerous fine and convoluted striations and has 

 a strikingly coral-like appearance. 



