REPORT ON THE ASTEROIDEA. 65 
intermediate in length and robustness between them and the general echinulation of the 
area above mentioned. 
The actinal interradial areas are large and well developed, and extend as far as the 
ninth or tenth adambulacral plate. They comprise numerous intermediate plates arranged 
in more or less regular series between the adambulacral plates and the marginal plates ; 
the separate plates are to a certain extent indicated by pseudo-sutures and the arrange- 
ment of the numerous short, equal, papilliform spinelets which they bear. The form of 
the groups is often rectangular, the papille are extremely short, and there is no tendency 
whatever to simulate paxille, the papille appearing to spring from the membrane which 
uniformly covers the whole area, 
The anal aperture is subcentral and distinct, though there is no modification of the 
paxillze surrounding it, 
The madreporiform body is compound and of great size. It occupies a circular area 
13°5 mm. in diameter, the outer margin of which is two to three mm, distant from the 
marginal plates. The area is rather higher than the plane of the abactinal surface, and is 
rendered conspicuous by the greater size of the paxillee which cover it, the spinelets com- 
posing them being a little longer and more robust. The striated surface is entirely hidden 
from superficial view. When the spinelets are removed the furrows are seen to be remark- 
ably fine and to appear to mount the base or pedicle of the paxilla, 
The ambulacral tube-feet have a small mamelon-like conical termination. 
Colour in alcohol, a greyish or yellowish white, with a slightly brownish or warmer 
shade on the abactinal paxillar area. 
Locality.—Station 246. In the Mid-North Pacific, between Yeddo and San Francisco, 
near the meridian of 180°. July 2, 1875. Lat. 36° 10’ 0” N., long. 178° 0’ 0” E. 
Depth 2050 fathoms. Globigerina ooze. Bottom temperature 35°°1 Fahr.; surface 
temperature 73°°0 Fahr, 
Remarks.—This species is at once distinguished from all the others in the genus by its 
broad and comparatively low rays, with the angularly rounded margin and the strong inward 
bevel of the whole surface of the supero-marginal plates towards the abactinal surface. It is 
further most conspicuously marked by the presence of the single long secondary spine on 
the actinal surface of the adambulacral plates behind the furrow series throughout the ray, 
2. Dytaster exilis, n. sp. (Pl. II. figs. 3 and 4; Pl. IV. figs. 9 and 10 : the var. gracilis). 
Rays five. R=124 mm.; r=19mm. R>657r. Breadth of a ray near the base, 
14 mm. 
Rays elongate, very narrow and attenuate, tapering slowly from the base to the extre- 
mity. Lateral walls rather high and vertical. Interbrachial ares wide, open, and well- 
rounded, Disk small. Abactinal area of the disk more or less inflated, especially at the 
(ZOOL, CHALL. EXP,—PART LI.—1887.) 9 
