416 Notes on the Natural History of East Finmark. 
I dredged Myriotrochus Rinkit in 1890 in 2-5 fathoms in 
Klosterelv Fiord, and in 5-30 fathoms in the inner part of 
Lang Fiord. 
The two forms above referred to are the only known 
recent representatives of the genus; but M. Schlumberger — 
has described under the name Séuzria elegans (‘‘ Note sur 
les Holothuridées du Calcaire Grossier,” Bull. Soc. Géol. de 
France, sér. 3, vol. xvi. p. 440, figs. 12-14) spicules which it 
seems difficult to distinguish from those of the recent form. 
In a subsequent paper (“‘ Seconde Note sur les Holothuridées 
fossiles du Calcaire Grossier,” J. c. vol. xvii. p. 191) 
M. Schlumberger refers the species which he had previously 
described to the genus Myriotrochus, and adds a second 
fossil species, Myriotrochus operculum. 
The wheel-spicules of Myriotrochus Rinkit are very 
beautiful objects. Most of the illustrations which have 
been already given are not fully satisfactory, as not giving 
aside view; but the oblique figures of Lud.ig (figs. 12 & 13) 
are excellent. His fig. 14 seems to have been drawn from a 
specimen in which calcification has been carried further than 
in any specimen previously figured or in any that I have 
myself seen. The spokes have widened at the middle of their 
length and become united with each other, but small inter- 
vening spaces remain open near their junction with the 
central boss. 
In the early stage of a wheel from the central boss there 
are developed all round radiating bars or spokes (fig. 5). 
These spokes at their distal extremity then widen out late- 
rally, and, uniting with each other, form the tyre which 
completes the wheel; then from the upper and inuer edge 
of the tyre a series of triangular processes are projected hori- 
zontally inwards, and overhang the spokes which are attached 
to the other edge of the tyre; these triangular lobes are 
always somewhat more numerous than the spokes. The 
structure will be best understood by comparison of the figures 
here given—fig. 6 representing the upper, fig. 7 the under 
surface, and fig. 8 the wheel as seen obliquely. The spokes 
at their attachment to the central boss are bent slightly 
upwards, and then with a gentle arching curve downwards and 
ultimately upwards again they form junction with the tyre*. 
The double bend of the spokes, which is very elegant in itself, 
keeps the entire thickness of the wheel as seen from the side 
(fig. 9). Ido not find any material difference in the wheels 
of this species as found in East Finmark when compared 
* Ludvig’s fig. 18 admirably illustrates the double curve of the spokes. 
