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 17 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 fourtli 

 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 ei^ht 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 aboiit 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 papulae 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- 



