REPOKT ON THE ASTEROIDEA. 449 



longer than the diameter of the disk, robust, broad at the base, and tapering to the 

 extremity, slightly convex actinally. Interbrachial arcs acute. 



Abactinal area with plates forming a reticulated network with wide meshes. The 

 plates bear at widely spaced intervals tubercular eminences, on which are borne paxilliform 

 tufts of four or five spinelets, which are robust at the base, tapering to a point, about 

 3 mm. in length, and usually all drawn together at the tip like a paint-brush when 

 moistened and drawn to a point. No order of arrangement is discernible in the dis- 

 position of the paxillae. Large isolated papulae are present in the meshes, five, six, or 

 even more, in those which are largest. These are remarkable from the fact that the 

 margin of the orifice is beset with a ring of round, granule-like, fleshy papillae, groups of 

 which also occur on the intervening membrane, giving it a more or less verrucose appear- 

 ance. The papulae also appear to be delicately verrucose. 



The marginal plates (? supero-marginal) form a regular and well-defined longitudinal 

 line, and each bears a tuft of five or six spinelets rather longer and more robust than 

 those on the abactinal paxillse and appressed to the ray, the direction being nearly hori- 

 zontal and outward. This series of plates is separated by a rather wide and well-defined 

 space, occupied by smooth membrane, from another perfectly regular longitudinal series 

 of plates situated midway between the supero-marginal plates and the adambulacral plates, 

 and consequently midway on the actinal surface of the ray. These are either infero-marginal 

 plates or actinal intermediate plates, but I am unable to say definitely which series they 

 represent without mutilating the single example ; I am inclined to rank them as inter- 

 mediate plates. The plates in question are armed with a flat comb of four or five spinelets, 

 similar to those on the marginal plates above described, more or less appressed to the ray, 

 their direction being usually oblique and outward at an angle of about 45° to the line of 

 the furrow. 



The adambulacral plates are large and broader than long. Their armature consists of 

 two series of spinelets. (1.) An inner or furrow series of seven or eight delicate, rather 

 elongate, tapering spinelets, the outermost of the series rather smaller than the others, and 

 all united for about half their length by a membranous web, forming a rather elongate, 

 semicircular scoop or fan, the membrane extending uninterruptedly upon and covering the 

 plate. (2.) Far back on the actinal surface of the plate is an oblique flat comb of four 

 elongate, pointed spinelets, much larger and more robust than the furrow series, and 

 similar to the spinelets on the actinal intermediate plates above described. They are 

 appressed to the ray, their base line is oblique in position on the plate, and their direction 

 is outward and at an angle of about 45° to the line of the furrow. The series of these 

 actinal spines forms a regular longitudinal line along the ray. There are thus three regular, 

 distinctly spaced, longitudinal lines of combs of spines visible on the actinal surface of 

 the starfish. 



The mouth-plates are very large, and have an elongate median eminence along the line 



(ZOOL. CHALL. EXP. — PART L. — 1888.) 57 



