KEPOKT ON THE ASTEROIDEA. 29 



Station 90. 1 In the Faeroe Channel. Lat. 59° 41' 0" N., long. 7° 34' 0" W. Depth 

 458 fathoms. Bottom temperature 7° '3 C. ; surface temperature 11 0, 7 C. 



Station 65. In the Faeroe Channel. Lat. 61° 10' 0" N., long. 2° 21' 0" W. Depth 

 345 fathoms. Bottom temperature 1 0, 1 C. ; surface temperature 11°*1 C. 



la. Pontaster tenuispinus, var. platynota, nov. (PL VI. fig. 7 ; PI. VII. figs. 3 and 4). 



There appear to be at least two ■well-marked forms of Pontaster tenuispinus, one of 

 which may be looked upon as typical and the other as representing a variety, which for 

 convenience of reference may appropriately be spoken of as Pontaster tenuispinus, var. 

 platynota. 



The variety is characterised by its large disk, by the rapid attenuation of the rays at a 

 short distance above their base, by the numerous large spines on the actinal surface of the 

 adambulacral plates, and indeed by the well-developed spinulation of the actinal surface 

 generally. Several well-developed spinelets are frequently present on the supero-marginal 

 plates, and the number of spinelets composing the paxillse on the disk is greater. It is 

 further to be noted that the two-jawed pedicellarise on the adambulacral plates are usually 

 specially developed and large, the jaws being widely dilated and spatuliform, or of a 

 pronounced spoon-bill shape. The habit of the variety is much larger than that of any 

 examples which I have seen of the type-form. 



Remarkably fine specimens have been procured from the cold water area in the Faeroe 

 Channel in depths of 363 to 608 fathoms, and well-marked examples of the variety were 

 likewise obtained off Valentia in 100 to 150 fathoms. 



These latter show at the same time a facies of their own, the result of the association 

 of several trivial but well-marked differences, which, although scarcely definable separately, 

 are sufficient to produce a characteristic aspect whereby the specimens from this locality 

 may be distinguished from any others with which I have compared them. At one time 1 

 was under the impression that the large-disked forms were only an older or more luxuriant 

 stage of growth of the examples which I have called the type-form, and I recorded these 

 specimens in my Reports upon the Asteroidea of the "Knight Errant" 2 and "Triton" 

 cruises under the simple name of Archaster tenuispinus ; but after a careful study of the 

 series which I have had the opportunity of examining, it seems undeniable that this 

 explanation is not sufficient to account for the differences, because the smallest specimen 

 in my possession — which measures R=ll mm., r=3 mm. — already presents characters 

 which show that it belongs unquestionably to the variety. This circumstance has 

 strengthened my decision in recognising the form as a well-marked and nameworthy 

 variety. 



1 This occurrence is recorded in Sir Wyville Thomson's Depths of the Sea ; but I have not seen a 

 specimen. 



2 Proc. Roy. Soc. Edin., 1881-82, vol. xi. p. 699. 3 Trans. Roy. Soe. Edin., 1883, voL xxxii. p. 154. 



