RETORT ON TTTE ASTEROIDEA. 545 



the series next to the adarnbulacral plates, which is the longest, only extends about 

 half way along the ray. All these plates intervening between the series that I have 

 called the supero-marginal series and the adarnbulacral plates are remarkable for the 

 manner in which the plates of the several series form vertical or transverse series ; these 

 pass from the adarnbulacral plates to the supero-marginal plates, and continuations of 

 the same lines are also seen to extend for a short distance above the supero-marginal 

 series, the abactinal plates there having a tendency to fall into the same arrangement. 

 All the plates above mentioned are thickly beset with compact groups of spinelets similar 

 to those on the abactinal plates, and large papula; occur in the interspaces. 



The armature of the adarnbulacral plates consists of a transverse series of about three 

 comparatively large, robust, slightly tapering spinelets, followed by one or two pairs of 

 much smaller spinelets at the outer end of the plate. Occasionally there may be four or 

 five spinelets in the transverse series, and occasionally one or more may be out of the 

 line, thus appearing to form an oblique pair with its neighbour in the series. There is a 

 single isolated small spinelet at the apex of the plate placed very high up in the furrow. 



The madreporiform body is large, circular, and slightly raised. It is situated at the 

 summit of one of the interradial sulci. Its surface is marked with rather coarse striations 

 which radiate from the centre to the periphery, and the dissepiments are studded with 

 comparatively large, low, rounded granules. 



Colour in alcohol, a sbghtly brownish ashy grey. 



Localities. — Station 315. Port William, Falkland Islands. January 26, 1870. Lat. 

 51° 40' 0" S. ; long, 57° 50' 0" W. Depth 12 fathoms. Sand, gravel. Surface tem- 

 perature 50 o, Fahr. 



Station 311. Off the entrance to Smyth Channel. January 11, 1876. Lat. 52° 45' 

 30" S., long. 73° 46' 0" W. Depth 245 fathoms. Blue mud. Bottom temperature 46°0 

 Fahr. ; surface temperature 50° "0 Fahr. 



Remarks. — In the character of its spinulation this species resembles to a certain extent 

 Cribrella ornata, but differs greatly from it in the widely open network formed by the 

 abactinal plates. The general habit of the two forms is altogether different ; and the 

 definite transverse or vertical series of plates on the lateral and actinal regions of the ray, 

 and the character of the adarnbulacral armature of Cribrella obesa, furnish strikingly 

 conspicuous characters by which the species may be distinguished. 



The examples from the Strait of Magellan are somewhat less robust in the ray than 

 the type form. 



5. Cribrella prsestans, n. sp. (PI. XCVI. fig. 7 ; PI. XCVIII. figs. 7 and 8). 



Rays five. R= 88 to 90 mm ; r = 14 mm. R > 6 r. Breadth of a ray at the base, 

 about 18 mm. Breadth about midway between the disk and the extremity, 10 mm. 



Rays elongate, cylindrical, but subdepressed near the base and over the disk, which is 



(ZOOL. CHALL. EXP. — PART LI. 1888.) 69 



