REPORT ON THE ASTEROIDEA. 21 
(2.) On the actinal surface of the plate is one comparatively large spinelet, robust at the 
base, and tapering to a pointed extremity ; on the outer side of this a second, but smaller 
and more delicate, spinelet is present, and frequently also a small miliary spinelet on the 
adoral side of the large spinelet. The presence, however, of the second spine and of the 
miliary is by no means constant. They are often (perhaps usually) absent in small 
examples and on the inner and outer parts of the ray even of large specimens. The 
larger actinal spine measures about 1°7 mm. in length on the fifth or sixth plate from the 
mouth-angle, the marginal or furrow series being normally less than half this length. 
The mouth-plates are large, and convex actinally, and the united pair form a broad 
projection towards the actinostome, the free margin being more than a semicircle, and 
bulging laterally. The armature consists of a marginal series of five, or sometimes six, 
short, slightly tapering mouth-spines on each plate, the innermost being twice as large as 
the others. On the actinal surface of the plate are three subequal tapering spinelets, 
forming a line parallel to the imperfectly closed median suture; sometimes a fourth 
is present on the outer side of the series, and sometimes its place is occupied by a miliary 
thornlet only ; but often it is wanting altogether. No other spines are present, and the 
surface of the plates is covered with thin membrane. 
The actinal interradial areas are very small indeed, not more than three or four inter- 
mediate plates being present in young examples, and in larger ones not more than eight to 
ten. These form only a single series between the marginal plates and the adambulacral 
and mouth-plates ; their surface is covered with membrane and the larger plates bear two 
or three small thornlets. There is usually one small pedicellarian apparatus in each area, 
which does not stand in the median interradial line, but is usually separated therefrom by 
one plate. It is of the “ spiracle ”-like or double-comb form, previously described. Rarely 
two are present. There are no pedicellarian apparatus between the infero-marginal plates. 
The anal aperture is subcentral and distinct, and usually there are two or three 
spinelets in its neighbourhood larger than those borne on the spicules generally. 
The madreporiform body is comparatively large and oval, placed about midway between 
the centre of the disk and the margin, and its surface is conspicuously convex and is 
grooved with deeply cut and highly convoluted striation furrows. 
The papule are tolerably numerous, but are large and distinct and limited to a small 
area at the base of the ray, which does not extend outwardly beyond the first supero- 
marginal after the odd interradial plate, and its inward extent on the disk would be 
bounded by a circle drawn upon the disk, with its margin touching the inner edge of the 
madreporiform body, 
Colour in alcohol, a bleached ashy white. 
Individual, Variation.—In some examples a second infero-marginal spine, standing 
below the true lateral spine, is much more strongly developed than in others, and this 
in specimens of the same size and from the same locality. In others again it is repre- 
