415 Canon A. IM. Novnian — Notes on the 



different spicules been procured from different parts of the 

 world, it Avould 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 cpiite 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 iutermediate spaces have been filled up Avith later 

 and thinner deposit ; the crenation of the rim is not very 

 easily seen. 



Genus Myriotrociius, Stecnstrup. 



Mijriotroclms Rink'd, Steenstrup. (PI. XXVII. figs. 5-9.) 



1851. Myriofrochus llinldi, Steenstrup, Yidenskab. Middel. fra den 

 naturliist. Foreninj,'- i Kjubenhavn, p. 55, pi. iii. tigs. 5-7. 



1852. Cliinnhfa brccis, Huxley, Sutherland's ^^oyage Baffin's Bay, 

 vol. ii., Appendix, p. ccxi. 



1877. Mi/riofrochus llinldi, Theel, " Quelques Tlolothuries des Mers de 

 la Nouvelle Zemble," Nov. Acta Keg. Soc. Sc. Upsala, ser. iii. p. 3, 

 pi. i. 



1881. Myriotrociius llinldi, Duncan Sc Sladen, Memoir Ecbinodcrmata 

 of the Arctic Sea to the West of Greenland, p. 15, pi. i. tigs. -JO-24. 



1882. Myriotrociius Rinldi, Danielssen & Koren, Norwegian North- 

 Atlantic Exped., Ilolothuroidea, p. 28, pi. v. figs. 1-4, pi. xiii. tij>. 1 . 



1892. Myriotrociius Ri)ildi, Ludvig, "Die Pi,adchen der Synaptideu," 

 Zeits. f. wiss. Zool. vol. liv. p. 358, pi. xvi. tigs. 12-14. 



1000. Myriotrociius Rinldi, Ludvig, Fauna Arctica, p. 160. 



1902. Mijriotroclms Rinldi, Ostergren, " Ilolothuroidea of Northern 

 Norway," Bergeus Mus. Aarbog, no. 9, p. 14. 



Ludvig and other recent authors have united Olu/otrochus 

 vitreus, M. Sars (Fauna littor. Norveg. part 3, 1877, p. 49, 



pi. vii. fig. 1) , with Mijriotrochus : but Ostergren, in his 

 recently published paper, again separates them. He has 

 examined a large number of specimens, and his opiniou I 

 here follow, though not without much doubt. I have fre- 

 quently taken the form Oligotruclms vitreusiw AVest 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 Hcrr Ostergren, I am in no position to call in 

 question the justice of his view. While Myriotrochus ( = Oli- 

 ffotrochus) vitreus lives in deci) water on the west and south 

 coasts of Norway, Myriotrociius Rinldi (typical) has only 

 noAV, in Ostergren's paper, been added to the fauua of the 

 colder fiords of West and East Eiumark. 



