582 MR. W. PERCY SLADEN ON 
consequence of the size and arrangement of the ventral plates, the ventral 
paxille are more widely spaced than the dorsal ones, and are disposed in 
regular lines which run from the adambulacral plate to the margin, the lines 
or columns being marked off by straight furrows or wrinkles in the membrane. 
As the paxille are equidistantly spaced in each of these transverse rows, 
equally regular and uniform longitudinal lines are also traceable along the ray. 
In the arm-angle nine to ten paxillz stand in each transverse series, the same 
number being maintained until about the outer fifth of the furrow. 
The adambulacral plates are broader than long, and appear to stand on 
the furrow margin as the terminal plates of the transverse series of ventral 
plates ; about 75 adambulacral plates may be counted along the furrow. The 
ambulacral spines are delicate and taper, irregular in number and disposition, 
forming a compact group, transversely elongate in form, in relation to the 
direction of the ray, which occupies the whole surface of the plate, and re- 
sembles a compressed and enlarged paxilla. There are 15 to 20 spinelets in each 
group. Two of the spinelets (sometimes three) larger than the rest, slightly 
flattened and tapering to a point, stand at the margin of the furrow, their rela- 
tive individual position being generally slightly oblique. The succeeding spine- 
lets are less robust, and pass in gradation to the group of outermost spinelets, 
which are about equal in size to those of the ventral paxille. The five or six 
innermost adambulacral plates have much larger spinelets than the others. 
The united mouth-plates form a sharp angle inwardly, and a large elongately 
ovoid, sub-tubercular swelling is developed on their superficies,—the whole 
surface being covered with spinelets arranged in somewhat similar series to the 
ambulacral spinelets, standing perpendicular, seven to eight along each side of 
the mouth-angle. The aboral portion of each plate is occupied by a compressed 
paxilliform group, similar to those on the adambulacral plates. The madre. 
poriform body is obscure and concealed by paxille. 
The ambulacral sucket-feet are arranged in pairs ; they are robust and large, 
with a well-developed fleshy disk, devoid of spicules. 
No traces of any form of pedicellarize are present. 
Remarks.—This magnificent starfish is entirely distinct from any of its 
northern congeners ; and its structure is very remarkable, especially on account 
of presenting an association of characters which belong to several independent 
groups of Asteroids. 
The arrangement and appearance of the paxille, and the numerous papule 
interspersed, recall in a striking manner the habit of Solaster. On dissection, 
however, it is found that this appearance is deceptive and not real; and that 
the true structural resemblance lies in a very different and unexpected direction. 
In Solaster endeca (Linn.), the form which at first sight is most nearly suggested 
