REPORT ON TIIE ASTEROIDEA. 71 



paxillae in an entire specimen ; and the appearance of the abactinal surface, either to the 

 naked eye, or even under a low power of magnification, is that of a fine granulation. 

 The pseudo-paxillae upon the disk are larger than those along the rays, in that they are 

 composed of more spinelets, but this is only noticeable under magnification, for the 

 character is the same throughout both on disk and rays. A number of small pedicellaria), 

 formed of three or four slightly enlarged and modified spinelets, occur at intervals amongst 

 the paxillae, both upon the disk and along the sides of the abactinal surface of the rays. 



The supero-marginal plates, forty-six or forty-seven in number from the median inter- 

 radial line to the extremity, are confined almost entirely to the lateral wall of the ray, and 

 although there is a slight sharp bevel towards the abactinal surface, little more than their 

 thickness is visible when viewed from above. They constitute a very narrow but remarkably 

 well-defined border to the rays and disk. When seen from the sides the plates are perfectly 

 rectangular, the length being slightly greater than the height, excepting the seven or eight 

 innermost plates on each side of the median interradial line in which the height is at 

 first slightly greater than, and then equal to, the length. Each plate bears on its upper 

 margin, immediately on the angle uniting the abactinal and lateral planes, a shorn 

 robust, conical, sharply pointed spine, not placed exactly midway between the adoral and 

 aboral extremities of the plate, but rather nearer the latter. It is directed parallel to the 

 vertical plane through the axis of the ray, and points towards the extremity at an angle of 

 about 45° to the horizontal. The longest of these spines measures about 2 - 5 mm., and 

 they decrease in length slightly as they proceed along the ray. The surface of the plate 

 is covered with small, hemispherical, widely spaced granules, which become crowded along 

 the vertical margins, and two or three embracing the base of the conical spine are often 

 more or less spiniform. 



The infero-marginal plates are exactly correspondent to the superior series ; their 

 length and height in the lateral wall being the same as in the superior series on the inner 

 portion of the ray, whilst the height diminishes proportionally rather more along the ray 

 than in the superior series. Their breadth on the actinal surface is at first much greater, 

 and afterwards only slightly less, than the length. The lateral and actinal planes form a 

 right angle, the union being sharp and scarcely rounded. Each plate bears a single, short, 

 conical spinelet, similar in size and character to the supero-marginal spine. It is placed 

 on the angle at the junction of the lateral and actinal planes, and is directed horizontally 

 and at a slight angle towards the outer extremity. On isolated and rarely occurring plates 

 two spines may be present, one rather smaller than the other. The surface of the plate is 

 covered with small, widely spaced hemispherical granules, with a tendency to become 

 papilliform on the actinal surface. They are crowded along the adoral and aboral margins, 

 and several at the base of the lateral spine are usually definitely spiniform. 



The adambulacral plates are long and narrow, subequal to the infero-marginal plates, 

 to which they appear to correspond throughout, with very few exceptions. The margin 



