Natural [History of East Finmark. 415 
different spicules been procured from different parts of the 
world, it would be believed that they belonged to different 
species. The fact is that the figures of Sars do not represent 
the fully adult wheel, while that figured by Duncan and 
Sladen is quite mature. In the latter condition the calca- 
reous deposit is much more developed, the central and narrow 
portions of the spokes have the greatest thickness, and the 
rest of the spokes the next greatest thickness; while the 
spokes themselves have been widened and a considerable part 
of the intermediate spaces have been filled up with later 
and thinner deposit; the crenation of the rim is not very 
easily seen. 
Genus Myriorrocuvs, Steenstrup. 
Myriotrochus Rinkii, Steenstrup. (Pl. XX VII. figs. 5-9.) 
1851. Myriotrochus Rinkd, Steenstrup, Videnskab. Middel. fra den 
naturhist. Forening i Kj6benhavn, p. 55, pl. 111. figs. 5-7. 
1852. Chirodota brevis, Huxley, Sutherland’s Voyage Baffin’s Bay, 
vol. i1., Appendix, p. ccxi. 
Ea Myr rotrochus Rinki, Theel, “ Quelques Holothuries des Mers de 
la Nouvelle Zemble,” Noy. Acta Reg. Soc. Sc. Upsala, ser. iii. p. 3, 
1 Rai 
1881. Myriotrochus Rinkw, Duncan & Sladen, Memoir Echinodermata 
of the Arctic Sea to the West of Greenland, p. 15, pl. 1. figs. 20-24. 
1882. Myriotrochus Rink, Danielssen & Koren, Norwegian North- 
Atlantic Exped., Holothuroidea, p. 28, pl. v. figs. 1-4, pl. xiii. fig. 1. 
1892. Myriotr ochus Rinku, Ludvig, “ Die Ridchen der Synaptiden, ZA 
Zeits. f. wiss. Zool. vol. liv. p. 358, pl. xvi. figs. 12-14. 
. 1900. Myriotrochus Rinkii, Ludvig , Fauna Arctica, p- 160. 
1902. Myriotrochus Rink, Satengtet “ Holothuroidea of Northern 
Norway,” Bergens Mus. Aarbog, no. 9, p. 14. 
Ludvig and other recent authors have united Oligotrochus 
vitreus, M. Sars (Fauna littor. Norveg. part 3, 1877, p. 49, 
pl. vu. fig. 1), with Myriotrochus; but Ostergren, in his 
recently published paper, again separates them. He has 
examined a large number of specimens, and his opinion I 
here follow, though not without much doubt. I have fre- 
quently taken the form Oligotrochus vitreus in West Norway, 
but on now examining them I can find no spicules; they 
have evidently from some cause been destroyed. Not having 
it in my power therefore to carry out such an investigation as 
that made by Herr Ostergren, I am in no position to call in 
question the justice of his view. While Myriotrochus (= Oli- 
gotrochus) vitreus lives in deep water on the west and south 
coasts of Norway, Myriotrochus Rinkii (typical) has only 
now, in Ostergren’s paper, been added to the fauna of the 
colder fiords of West and East Finmark. 
