ASTEROIDEA DREDGED DURING CRUISE OF H.M.S. "TRITON." 157 



The spinous dorsal area is punctured with numerous small but conspicuous 

 pores, which are irregularly distributed at small but unequal distances apart 

 over the whole area, excepting the extremities of the rays and a narrow band 

 along the median interradial line ; towards the margin the apertures are 

 smaller, wider apart, and less frequent. Through these apertures the papulae 

 are protruded, and under magnification a small but definite circlet of the dorsal 

 membrane surrounding the puncture of the papula, and unencroached upon by 

 spinelets, may be seen. No grouping of the dorsal spinelets occurs, which in 

 any way indicates the outlines. of the underlying plates of the abactinal floor ; 

 and the only break in this perfectly uniform covering consists of a number of 

 most minute channel-lines, which run irregularly here and there amongst the 

 spinelets, the only one of these maintained with any regularity being a long 

 straight channel, similar in breadth to all the others, extending along the 

 median interradial line. The anal aperture is subcentral and distinct, and is 

 surrounded by slightly larger spinelets. The madreporiform body is very 

 small, round, and with numerous striae. It is situated rather nearer to the 

 margin than midway to the centre of the disk, and the surrounding portion of 

 the test is slightly prominent. 



Actinal interradial areas extensive, and with their outer margin conspicu- 

 ously festooned by the infero-marginal plates. Infero-marginal plates eight to 

 nine in number from the interbrachial line to the tip of the ray ; the contour of 

 their outer margin is rounded, and bears a group of eight to twelve spinelets, 

 rather larger and more robust than those of the dorsal area above described. 

 The plates are entirely covered with spinelets — the part which falls in the 

 side of the ray with spinelets similar to those on the dorsal area, and the 

 ventral portion with spines similar to those on the ventral area. When 

 the starfish is viewed in profile, the marginal plates are seen to be clearly 

 marked out by vertical furrows as well as by their prominent tumidity ; 

 but the junction of the infero-marginal with the supero-marginal plates, or 

 indeed the presence of these latter at all, is indiscernible to superficial obser- 

 vation. Seen on the actinal side, the marginal plates are clearly defined by 

 well-marked channels or furrows, and these run in oblique lines from the 

 margin up to the adambulacral plates. The furrows are almost regularly 

 parallel, hence the areas or columns they define are of nearly uniform 

 breadth throughout. Consequent on their diagonal direction, a triangular 

 space occurs in the median interbrachial line in the inner portion of the area, 

 which is not conformable to the arrangement above described, the channels 

 which traverse it converging towards the apex of the triangular space, a short 

 distance removed from the margin of the disk. The whole ventral area is 

 covered with small, almost spicular, spinelets, which are short, sharply pointed, 

 and with their bases buried in membrane. The spinelets are all nearly uniform 



