248 THE VOYAGE OF H.M.S. CHALLENGER. 
Inidia debilis of Grube has only the indefinite locality of ‘ Africa.’ The single type- 
specimen is so small that it might be anything, and is quite unworthy of being maintained 
as the type of a species. I therefore consider that the name should be discarded. 
Chorological Synopsis of the Species herein described. 
Ocean. Depth in Fathoms, Nature of the Sea-bottom. 
Iuidia africana. 3 . | Atlantic. Eexttoralitedas of} i one. 
LIuidia alternata  . ‘ . | Atlantic. 7 to 88 Volcanic sand (88 fathoms). 
Inidia aspera : : . | Eastern Archipelago. 10 to 115 Green mud ; Coral mud. 
Luidia ciliaris : : . | Atlantic. TeitforalstOS awl yee | vscetee. 
Luidia clathrata . ; . | Atlantic. RUORZ OME) © Man. ee ea aman 
Luidia forficifer  . ; . | Eastern Archipelago. 6 to 28 Coral mud ; Green mud. 
Luidia limbata P ; ; i) bacifie: DatQeaDae we alia wee Aro 
Luidia longispina . : . | Eastern Archipelago. 20 Mud. 
Iuidia sarsii . ; : : Atlantic. Littoral to 374 Sand ; coarse shell-sand. 
1. Lnidia aspera, v. sp. (Pl. XLII. figs. 1 and 2; Pl. XLV. figs. 9 and 10). 
Rays eight to ten.’ R=170 mm;>r=20 mm. (R=168,7=19). R=8 57, 
Breadth of a ray at the widest part near the base, 16 to 17 mm. 
Rays elongate in relation to the size of the disk, thick, robust, of a slightly depressed 
subeylindrical form, constricted for a short distance near the base, then tapering from the 
widest part slowly and gradually up to the pointed extremity. Abactinal surface convex, 
but flattened along the median radial line and upon the disk. Actinal surface rounding 
gradually to the margin. Lateral walls rounded. 
The paxillee of the abactinal area are large, rotund in form, but with a more or less 
subquadrangular facies in the regular longitudinal series, which are six in number at each 
side of the ray. In the comparatively narrow intermediate area along the median radial 
line the paxille are slightly smaller, distinctly rotund, crowded, and irregular in disposi- 
tion. Nearly all the paxillz of the innermost three longitudinal rows (at least on the 
inner half of the ray), have a robust subconical spinelet about 1°5-2 mm. in length on the 
centre of the tabulum. ‘This is surrounded by about eight very small, cylindrical, 
obtusely-rounded, papilliform spinelets likewise placed on the tabulum, often faintly sub- 
clavate, and so short that they are little more than elongate granules. External to these 
and at the margin of the tabulum is a series of about two dozen similar but slightly more 
delicate and slightly longer spinelets. Excepting of course the central large one, the 
spinelets on the tabulum and the marginal series all appear of equal height when drawn 
together. Occasional paxille in the three rows mentioned are devoid of the central 
conical spinelet, especially on the outer part of the ray, where not more than two of the 
longitudinal series have echinulated paxille. The large paxille between the echinulate 
