MR. H. N. MOSELEY ON THE STRUCTURE OE THE STYLASTERIDHD. 
4G3 
As far as the form and arrangement of the branches is concerned, the corallum oi 
Cryptohelia differs in no important particular from that of Astylus subviridis which 
has just been described. The striae on the surface of the branches are in the present 
form finer and run for shorter courses than in Astylus subviridis, and well marked 
prominent ridges are not formed between them. 
Regular cyclo-systems are present in Cryptohelia which are all turned towards one 
face of the flabellum. Their mouths are not elevated above and isolated from the 
surfaces of the branches as in Astylus , but the branches swell vertically as well as 
horizontally where cyclo-systems are present, and the ccenenchym of the branch thus 
rises in a gradual curve to the level of the margin of each cyclo-system (Plate 35, fig. 7). 
There are from about fifteen to twenty-two dactylopores in each cyclo-system, in form 
and arrangement almost identical with those of Astylus subviridis. 
The margin of one side of each cyclo-system is raised up into a stout projection, 
which is inclined slightly over the mouth of the system for a short distance. After 
running this inclined course the projection spreads out into a thin broad lamina, with 
a rounded border, which extends horizontally over the mouth of the cyclo-system aud 
hangs as a lid or cover over its entire extent (Plate 35, fig. 7). The inclined portion 
of the projection is stout and thickened, and is strengthened by being continuous at 
its base with the adjacent coenencliym of the branch. It is thickened to the greatest 
extent in the direction towards the centre of the cyclo-system, and so much so that 
its substance projects within the cavity of the upper chamber of the gastropore as 
a prominent ridge. This ridge becoming gradually less marked as it descends, is con- 
tinued downwards to the margin of the aperture leading from the upper to the lower 
chamber of the gastropore, and appears as a prominent thickening of the wall of the 
upper chamber in this region (Plate 35, fig. 7, A). The dactylopores are aborted and 
absent in the region of the cyclo-system overgrown by the base of the lid. The lateral 
margins of this base are often grooved by dactylopores on either side, which have the 
appearance of having been pushed aside, as it were, by the growth of the projection. 
The thin horizontal lamina constituting the lid of the cyclo-system is often not quite 
smooth in surface but somewhat undulate or crumpled as it were. The lids are all 
directed with great regularity towards the tips of the branches on which the cyclo- 
systems to which they belong rest ; the supports of the lids arising from the sides of 
the cyclo-systems nearest the origins of the branches. 
The gastropores are divided into two chambers as in Astylus. In the present form 
the lower chamber is relatively smaller than in Astylus subviridis. Its communications 
with the dactylozooids are closely similar to those in Astylus (Plate 35, fig. 7). The 
opening between the two chambers in Cryptohelia is circular, not horseshoe-shaped as 
in Astylus. 
Ampullae occur only in connexion with the cyclo-systems in Cryptohelia pudica. In 
the female specimens examined by me, only one ampulla is developed in connexion 
with each system. It may lie on either side of the system, but not on the back of the 
MDCCCLXXV III. 3 O 
