Report on the Echinoderms of North-East Greenland. 265 



Stat. 63. Stormbugt, 10 — 20 m. 1 specimen (R. = 7 mm, r = 2 mm), 

 — 96. (76-^/4° N. 18° W.), 160— 178 m. 2 specimens (R. = 10, 11mm, 

 г = 2-8, 3 mm). 



According to Danielssen and Ко ren (Norske Nordhavs-Exped. 

 Asteroidea p. 36) Pedicellaster palœocrystallus Sladen is a synonym 

 only of P. typicus Sars. The examination of the specimens from 

 the Danmark Expedition, wliich certainly belong to the form 

 described by Duncan & Sladen, has, however, convinced me that 

 such is not the case. I find this form differing not inconsiderably 

 from P. typicus in several points, so that it must certainly be main- 

 tained as a distinct species. Evidentlj»^ P. palœocrystallus represents 

 the cold-water form, while P. typicus is a warm-water form (boreal), 

 in analogy with so many other Echinoderms of the Northern At- 

 lantic. 



The characters given by Duncan and Sladen for this species 

 are the following : "P, palœocrystallus is of larger size, and the length 

 of the arm-radius, in proportion of the disk (about 5:1) is less than 

 in P. typicus, in the largest examples of which it is 6V2 or 6 : 1. 

 The contour of the arms is also different in our form, being more 

 tumid on the inner third, and much more attenuated on the remain- 

 ing outward portion of the ray. The dorsal spinelets are decidedly 

 radio-laminate and somewhat expanded at the tip, instead of being 

 conical, as described in P. typicus, and the shaft of the ambulacral 

 spinelet is also denticulate or serrate. The pedicellariæ of the present 

 species are even of relatively larger size, and differ in having the 

 contour of the jaws considerably swollen out about the outer third, 

 and then tapering rapidly towards the extremity, which is somewhat 

 truncate". 



Regarding the length of the arms it seems evident from the 

 measurements given by Danielssen & Ko ren that it cannot be 

 relied upon as a specific character. In the specimens from the cold 

 region the relative arm-length is seen to be from 1 : S'^U to 1:7, in 

 those from the warm area from 1 : 2V2 to 1:5. (In the specimens 

 from the Danmark Expedition the proportion is from 1 : 3V2 to 

 1 : З^/з). The form of the arms, on the other hand, seems to be 

 a good distinguishing character. The specimens in hand agree with 

 Duncan & Sladen's description in this respect (the two specimens 

 from Stat. 96 are so badly preserved, that the shape of the arms is 

 difficult to see; in the specimen from Stat. 63 this feature is very 

 distinct), and Danielssen & Ко ren likewise remark that "in a few 

 specimens, and specially in those from the cold area, the rays were 

 rather broad, and tumid at the origin, whilst, in others, again, they 



