198 Mr. F. A. Bather on British Fossil Crinoids : 
irregular and numerous, as in Botryoerinus, but appear to be 
more or less alternating (zincotype, figs. 3 and 4). 
The total length of the arms in 57048 B.M. is 11 centim. 
I Br number from 7 to 11, the usual number being 8. 
Their height is 1:4 millim. ; their width 3 millim. 
Li Bre9; 10; or aa 
III Br from 9 to 14. A 
IV Br from 12 to 26. 
V Br numbers noted 17 and 22. 
VI Br numbers noted 16 and 25. 
VII Br 15 observed. 
VILLI Br and 1X Br are so small 
and faint that it is difficult to make 
out their exact numbers. ‘The 
width of the finials is about °25 
millim. The distal portions of 
an arm-branch are figured here 
(fig. 6), to show that there is no 
suspicion of pinnules. 
Anal structures. — Anal « is 
hexagonal, resting on the hori- 
zontal upper side of post. B, in 
a line with RR, and supporting 
three plates, viz. a median proxi- 
mal plate of similar shape and 
a small plate on either side be- Fig. 9.—M. loreus. Distal end of 
tween it and the adjacent radials part of 1. post. Arm in 57048 
(r¢ and /t). B.M. (x 6% diam.) 
The Ventral Sac in 57048, 
where it is magnificently displayed, has a length of 7 
centim. At its origin it is 10 millim. wide, but rapidly 
increases to 18 millim. and then decreases very gradually. It 
is transversely compressed and is very flat. 
In its plan of structure this sac resembles those of Thenaro- 
crinus, Botryocrinus, and Dendrocrinus (what may be called 
the wickerwork-type, ‘Trautschold’s “ Angulosi”’). Seen 
from the posterior, 5 ridges are visible, which are from left to 
right as follows :—(1L) ridge starting from /t, (2) ridge starting 
from a plate intercalated between /¢ and median proximal 
plate, (3) median ridge, starting from median proximal plate, 
(4) ridge starting from ré, (5) ridge on right of ré ridge. 
There are probably three other ridges on the anterior side. 
This would make the number of ridges 8 in all, in which the 
genus would agree with Zhenarocrinus if not with others of 
the group. 
The ossicles are slightly ridged in the middle, and are 
