REPORT ON THE ASTEROIDEA. 649 



■with delicate membrane bearing a number of small pedicellarise ; the position of the 

 aboral spine is rather high in the furrow, over which it is directed at an angle of about 

 45°, and at a right angle to the margin. The two actinal spines arc very unequal in 

 size, the smaller one, situated close to the aboral end of the plate and a little on the 

 furrow side of the median longitudinal line, is about twice the length of the small inner 

 spine or even rather more, but very much more robust, especially at the base, which is 

 thick, and the shaft tapers to a pointed extremity ; it is articulated on a small tubercle 

 and is covered with delicate membrane bearing small pedicellarije. The adoral com- 

 panion, which may be considered the true actinal spine, is large and robust, about 4 mm. 

 in length, and is articulated on a tubercular eminence, midway between the extremities 

 of the plate and a little on the outer side of its median longitudinal line. The shaft is 

 thick, cylindrical, and in the eight or ten innermost spines flaring at the extremity, and 

 with its surface marked with comparatively coarse striations, which have often a slightly 

 twisted appearance, and is covered with delicate membrane crowded with pedicellarise. 

 The lateral spine is long, robust, and tapering, similar in character to the large actinal 

 spine. It is articulated on a prominent tubercle-like rudimentary infero-marginal plate 

 ankylosed on the lateral side of the adambulacral plate, and is covered with delicate 

 membrane with crowded pedicellarijE. The lateral spines are quite remarkable for their 

 robustness in relation to the small size of the disk. 



The actinostome is wide, 7*5 mm. in diameter, that of the disk being 12 mm. The 

 mouth-plates are small but powerful, and are remarkable for the number and size of 

 the mouth-spines they bear. On the margin of each plate are three small cylindrical 

 spinelets, two of them in front but away from the median suture, well spaced, radiating 

 apart, and directed horizontally over the buccal membrane, whdst the third is further 

 back and directed across the entrance of the furrow. Behind these are three long 

 robust spines, placed close to the margin, which should in reality be counted as secon- 

 dary spines,, although when seen from above they have the appearance of being the 

 marginal mouth-spines, and quite mask the small spines just mentioned. The inner- 

 most are the longest and reach to the centre of the actinostome, the pair being directed 

 horizontally over the buccal membrane, parallel to one another. The other two spines 

 are smaller and the outermost is the least, and they radiate outward from the foremost 

 slightly and in increasing degree. The shafts of these large secondary mouth-spines are 

 cylindrical, robust, tapering, coarsely striated, covered with delicate membrane crowded 

 with pedicellarise, which, though small, are larger than any of those before mentioned. 

 The armature of the first pair of adambulacral plates succeeding the mouth-plates is so 

 placed as to appear to belong to the mouth-plate armature ; it consists of two small 

 spines one behind the other placed quite in the furrow, then a larger actinal spine which 

 appears to belong to the series of the large secondary mouth-spines, and still more inward 

 on the plate a much larger and more robust actinal spine, this with its companion on the 



(ZOOL. CHALL. ESP. rART LI. 1888.) 82 



