ARCTIC SEA TO THE WEST OF GREENLAND. 33 



3-5-laminate and correspondingly denticulate at the apex. The membrane of the 

 interspaces is punctured for papulae, of which, in young stages of growth, seldom more 

 than one is present in each ; but in specimens of larger size one to four or more may 

 be found. The ventro-lateral plates form two or three series, and their spinelet-groups 

 are arranged at right angles, or sometimes slightly diagonally, to the median line of 

 the ray. The foot-papillae are somewhat larger and stouter than the rest of the spinu- 

 lation ; those which form the immediate margin of the ambulacral furrow consist of 

 one or two still stouter spinelets, which at an early age are generally arranged in single 

 file upon the adambulacral plate, and are followed by 2-4 pairs of spinelets merging 

 gradually into the size of those of the ventro-lateral series. At a more advanced stage 

 of growth the innermost foot-papillae have not unfrequently become arranged as a pair of 

 spinelets, very obliquely placed upon the plate, and followed by one or two of similar 

 size and character, these in turn being succeeded by the series of intermediate spinelets 

 forming the transition into the ventro-lateral spinulation. Occasionally the innermost 

 spinelets form an oblique comb-like arrangement on the plate. Each adambulacral 

 plate also bears another spiuelet, very small in size, situated high up in the furrow, 

 and generally invisible to superficial examination. The anal orifice is central and 

 conspicuous. The madreporiform body is large and irregular in form, and situated 

 midway between the margin and the centre ; in young stages it is covered with spinelets, 

 but in older specimens these very frequently disappear, leaving visible the more or less 

 irregular arrangement of curved and dichotomosing striae that intersect the organ. 



Size. The largest Greenland specimen is cited by Lutken as 140 millims., whilst 

 Sars mentions one 165 millims. in diameter from Esmark in Christiania Fjord. The 

 usual size is from 50 to 75 millims. 



Colour. The Greenland specimens are described as brick-red when alive (Lutken). 

 Those on our own coasts are generally dark red or deep purple above and straw-coloured 

 beneath, whilst occasionally bright vermilion is met with (Forbes). A bright saffron- 

 yellow variety occurs at Bergen (D. & K.) and Shetlands (Norman), which is a thick- 

 armed deep-water form ; and it is also on record that the same form was taken off 

 Fife by Henry Goodsir. In the Asiatic specimens brought home by Von Middendorffs 

 Expedition, bluish or purple tints seem to have prevailed on the dorsal side, the 

 underside varying from vermilion to flesh-colour (Brandt, Midd. Seise, p. 34). 



Habitat. From the shore to 175 fathoms depth a specimen being taken at this 

 last-named depth off Hare Island, Waigat Strait, during the ' Valorous ' Expedition. 



Premature Form. In young examples the length of the ray is much less in pro- 

 portion to the disk than in the adult Starfish. The arms are also relatively wider at 

 the base, and taper more rapidly to the extremity. The spinulation of the dorsal sur- 

 face is very delicate, in fact almost microscopic, and the ossicles bear fewer spinelets, 

 which are associated in more compact groups. The ventro-lateral series are more 

 distinctly defined from the rest of the spinulation than at a greater age, two to four 

 lateral rows, in addition to the foot-papillae series, being clearly discernible. Seldom 

 more than a single papula is present in the interspaces of the dorsal network, and the 

 madreporiform body is more prominently covered with long spines. 



F 



