REPORT ON THE ASTEROIDEA. 231 



as to give the appearance of coarse velvet pile. The supero-marginal plates bear no 

 spinelets. 



The infero-marginal plates correspond to the superior series, each plate being equal in 

 length to its companion in the upper series. Their height, however, is slightly less, and 

 they are well curved upon the actinal surface. Their surface is covered with short close- 

 set papillae similar to those on the supero-marginal plates, which become slightly larger 

 and more spiniform at the end of the plate adjacent to the adambulacral plates. Each 

 plate bears along the upper half of the aboral margin a series of four (normally, but some- 

 times three) small tapering spinelets. The uppermost spine is the smallest, the rest sub- 

 equal or with either the lowest or the median spine slightly longest. They are closely 

 appressed to the side of the ray, and are directed at a slight angle upward : the position of 

 the series on the plate being also sometimes very slightly oblique. 



The adambulacral plates are elongate, large, with a faintly convex margin towards the 

 furrow. Their armature consists of a furrow series of six or seven rather long, delicate, 

 cylindrical spinelets, equal in length, covered with membrane, and standing parallel to 

 one another. The series or " combs " thus formed are distinctly spaced from the neighbour- 

 ing series on adjacent plates. On the actinal surface of the plate and near to the marginal 

 series is a longitudinal series of three or four spines, slightly shorter and more robust, 

 widely and irregularly spaced ; and external to these is another longitudinal series of four 

 or five similar spines, but even more irregular in disposition : indeed, so far is this carried 

 in both cases that it is often impossible to distinguish any regular serial arrangement at all. 

 Sometimes a few additional spinelets may be present, external to those above mentioned, 

 and the grouped character becomes then more marked. These spinelets on the actinal 

 surface of the adambulacral plate are covered with membrane like the marginal series, 

 and they have generally a more or less straggling and irregular appearance. 



The mouth-plates are elongate and narrow, and the united pair form a convex keel 

 actinally. Their armature consists of a marginal series of small, rather robust, and 

 abruptly tapering spinelets, shorter than the marginal series on the adambulacral plates, 

 about six or seven on the free margin of the plate, although others appear to continue the 

 series up to the outer extremity of the plate. At the innermost point of each mouth-plate 

 is one elongate, flattened and round-tipped mouth-spine, greatly exceeding any of the 

 other spines in size, and the pair of spines at each mouth-angle are parallel to one another 

 and directed towards the centre of the actinostome. At first sight these enlarged spines 

 might be considered as the innermost spines of the marginal series above described, but I 

 am doubtful whether this is really the case, as there is the singular occurrence in this form 

 of a small group of short spinelets present on each plate at a still higher level than the 

 foremost mouth-spines above mentioned, and this little insignificant group is further 

 peculiar from the fact that it is not directed towards the centre of the actinostome, but in 

 the direction of a line crossing the ambulacral furrow. If this group of small and abnor- 



