30 THE VOYAGE OF H.M.S. CHALLENGER. 



Young Phase. — In the small example above referred to (from Station 9 of the 

 "Triton" dredgings, 608 fathoms), the spinulation of the abactinal surface is decidedly 

 papilliform and well-developed. On the adambulacral plates there are already two large 

 spines on the actinal surface, together with traces of a small companion in the same series. 

 There are five or six spinelets in the furrow series. The pedicellaria is large and already 

 characteristic. On the mouth-plates there is a marginal series of eight spines on each, the 

 innermost being much larger and stouter than the others. The paxillse of the abactinal 

 surface are comparatively large and compact, composed of low robust papilliform spinelets, 

 of which in the largest paxillse there are from nine to twelve. The central one, when 

 present, is equal to the others, and not large and prominent, as in the adult. The anal 

 aperture is large and distinct, and decidedly excentral in position. 



Localities. — " Porcupine " Expedition : 



Station 54. In the Faeroe Channel. Lat. 59° 56' 0" N., long. 6° 27' 0" W. Depth 

 363 fathoms. Bottom temperature 0°'3 C. ; surface temperature ll° - 4 C. 



Off Valentia, 100-150 fathoms. 



" Knight Errant " Expedition : 



Station 8. In the Faeroe Channel. August 17, 1880. Lat. 60° 3' 0" N., long. 

 5° 51' 0" W. Depth 540 fathoms. Ooze. Bottom temperature 29 0, 2 Fahr. ; surface 

 temperature 56°*5 Fahr. 



" Triton " Expedition : 



Station 9. In the Faeroe Channel. August 23, 1882. Lat. 60° 5' 0" N., long. 

 6° 21' 0" W. Depth 608 fathoms. Bottom temperature 30° "0 Fahr. 



2. Pontaster planeta, n. sp. (PI. X. figs. 1 and 2 ; PI. XIII. figs. 1 and 2). 



Rays five. R=37 mm., r=6'5 mm. R > 5'5r. Breadth of the ray near the base, 6 mm. 



Rays elongate, narrow, tapering continuously up to the extremity. Interbrachial arcs 

 well rounded. Abactinal surface subplane, slightly convex along the median radial line. 

 Actinal surface of disk convex, prominent at the mouth-angles, sloping thence to the 

 margin, and slightly along the rays to the extremity. 



The paxillse of the abactinal surface are small, numerous, and tolerably well spaced. 

 Midway along the ray the crown is composed of four to six short papilliform spinelets, the 

 larger ones with a central elongate and tapering spinelet, which appears to increase in 

 proportional length towards the extremity of the ray. Within the area of the disk larger 

 paxillaj are more frequently interspersed amongst the small ones, some of them with eight 

 or nine spinelets surrounding the larger central one. The spinelets throughout are small 

 and delicate. No pedicellariae are present on the abactinal surface. 



The supero-marginal plates, thirty to thirty-two in number from the median inter- 

 radial line to the extremity, form a narrow and inconspicuous border when viewed from 



