REPORT ON THE ASTEROIDEA. 33 
The spinelets on the supero-marginal plates are extremely small. The large actinal 
spinelet on the adambulacral plates is robust and accompanied by a well-developed 
companion, and sometimes a smaller third spinelet is also present. At least two to four 
intermediate or ventral plates are present in the actinal interradial areas. The miliary 
spinulation on these and on the marginal plates is very small, widely spaced, and papilli- 
form, giving little more than a subgranular appearance under a low magnification. The 
knob at the distal extremity of the tube-feet is very large. 
Locality.— Station 311. Off western coast of South America, near the entrance to 
the Straits of Magellan, opposite Port Churruca. January 11,1876. Lat. 52° 45’ 30’S., 
long. 73° 460” W. Depth 245 fathoms. Blue mud. Bottom temperature 46°:0 Fahr.; 
surface temperature 50°°0 Fahr. 
Remarks.—This species is remarkable for its close resemblance to the northern Pon- 
taster tenuispinus. It is, however, distinguished by its smaller disk, by its delicate 
spinulation, as well as by the character of its paxillee, and of the adambulacral armature. 
The general habit is also much smaller. 
3. Pontaster hebstus, n. sp. (Pl. VIII. figs. 1 and 2; Pl. XII. figs. 1 and 2). 
Rays five. R=103mm.;7r=16mm. R<6'5r. Breadth of the ray near the base, 
15 mm. In another example, R= 100 mm.; 7=15 mm. Breadth of the ray near 
the base, 13°2 mm. 
Rays elongate, comparatively robust and broad, but tapering continuously from the 
base to the extremity, the outer part being very attenuate. The expansion at the extreme 
base is very slight, which causes the disk to appear small, and the interbrachial arcs to 
be rather acutely rounded. Abactinal surface subplane and level over the disk, but some- 
times arched along the ray. Actinal surface of disk slightly convex, sloping from the 
mouth-angles to the margin and slightly along the ray. 
The paxillee of the abactinal surface are small, crowded upon the disk, but rather 
more widely spaced along the rays. ‘The larger ones are composed of eight to ten, and 
occasionally more, very small, short, papilliform spinelets, which form a circlet round a 
central spine; the latter is cylindrical and tapering, and though small and delicate is 
much longer than its surrounding papilliform series. Smaller paxillae, composed of five to 
seven spinelets, or even a smaller number, are interspersed amongst the larger ones upon 
the disk, and are the rule along the ray ; the central spinelet, however, of these is often 
only papilliform, and equal to the encircling series, and is often wanting. 
The supero-marginal plates, sixty in number from the median interradial line to the 
extremity, form a narrow bevelled margin to the rays and disk. The plates are very low 
and their length is slightly greater than their breadth. ach plate bears a short, conical, 
and tolerably robust spinelet, often truncate at the tip, so placed that it stands on the 
(ZOOL, CHALL, EXP.—PART LI.—1887.) 5 
