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REPORT ON THE ASTEROIDEA. 229 
papilliform along the transverse margins, thus emphasising the suture. No spines are 
borne on the supero-marginal plates. 
The infero-marginal plates correspond to the superior series, and their breadth is 
greater than either the height or the length; their surface is covered with granules 
apparently similar to those above described and of equal size, but which have a tendency 
to become scutiform as they approach the end of the plate adjacent to the adambulacral 
plates. Their length and posture is such that they have quite the appearance of granules, 
and their squambus character is only made out after careful examination. Lach infero- 
marginal plate bears normally a single small spinelet, which is short, tapering, slightly 
compressed, and appressed to the side of the ray. It is situated at the extreme margin of 
the ray, on the rounding which unites the actinal and lateral areas of the plate, and stands 
close to the aboral margin of the plate. On two or three of the plates in the interbrachial 
are a second and similar spine may be present, placed midway between the lateral spine 
and the inner end of the plate; and in very rare instances there may be one or even two 
small spines above the lateral spine, between it and the abactinal end of the plate, these 
spines being always at the aboral margin of the plate. 
The adambulacral plates are large, with a prominent angular margin towards the 
furrow. Their armature consists of an inner or furrow series of seven or eight short, 
delicate, cylindrical, equal spinelets, encased in membrane, but apparently without any 
saccular developments. On the actinal surface of the plate are one or two longitudinal series 
of three or four equal spines, slightly shorter than the inner series. There is frequently, 
however, irregularity in the disposition of these spinelets ; and the whole armature usually 
forms a wedge-shaped group, the arrangement of which is difficult to formulate. 
The mouth-plates are elongate and very narrow; their armature consists of a marginal 
series of sixteen to eighteen short, cylindrical, obtusely rounded or subclavate papille 
on each plate, which increase slightly in length as they approach the anterior end. The 
two innermost are longer and much more robust than the rest. On the actinal surface of 
the plate is a single uniserial row of low, broad, round-topped and slightly compressed 
papillz, about sixteen or eighteen in each series. These stand vertical, and the marginal 
series are closely appressed to their sides. 
The actinal intermediate plates, though confined to a very small area in the inter- 
radial region, extend far along the ray. Those near the adambulacral plates bear 
spinelets which are indistinguishable from the adambulacral armature, whilst those near 
the marginal plates, in the interradial area at least, become somewhat more papilliform, 
and though maintaining a strictly spinulate character, approach in a certain degree the 
squamulate form of the covering of the marginal plates. All these spinelets are covered 
with thin membrane, which has to some extent the peculiar fibrillar or matted character 
sometimes noticed in the Northern form, and many of the spinelets have the same 
agolomerated appearance suggestive of entangled foreign matter or tissue. 
