REPORT ON THE ASTEROIDEA. 551 
Chorological Synopsis of the Species. 
Volcanic mud. 
Volcanic mud. 
Perknaster densus Southern. 127 
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Ocean. Range in Fathoms. | Nature of the Sea-bottom. 
{re 
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Perknaster fuscus  . : Southern. 25 to 75 
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es 
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1. Perknaster fuscus, n. sp. (Pl. XCVII. figs. 3 and 4). 
Rays five R=45mm.; r=14 mm. R>37. 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 ares 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 eg 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 papule 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. Indistinet 
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 body, 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. 
