MR. H. N. MOSELEY ON THE STRUCTURE OF THE STYLASTER1M. 457 
massed around a spadix, as in Sporadopora. The process of development was not 
closely followed in the present species. 
(7.) GENUS A STYLUS, Gen. Nov. (H. N. M.). 
I have formed the above genus for a Stylasterid with regular cyclo-systems, dredged 
off the Meangis Islands in 500 fathoms. The coral is, like Cryptohelia, devoid ol 
styles in both kinds of zooids, and differs in structure in no important particular from 
this genus, with the exception that it has no solid lid-like covering overhanging the 
mouths of the zooid pores. It possesses, however, a curious tongue-like process deeply 
seated in the calicle, which probably is the homologue of this lid. 
Corallum of Astylus subviridis.'" 
The corallum (Plate 34, fig. 4) consists of a short stem, which breaks up into a few 
primary branches. These, with their slender secondary branches and branchlets, 
which are very few in number, ramify in the same plane, and form a small flabellum. 
The stem and branches are circular in transverse section throughout then- length, 
except where distorted by the presence of zooid cyclo-systems upon them. They are 
composed of a hard and compact pearly- white calcareous tissue, the outer surface of 
which is marked by a series of conspicuous fine rounded ridges, which separated by 
shallow grooves follow the directions of the stem and branches with parallel course, 
each ridge preserving its integrity for a long distance, except on the pore-bearing face 
of the flabellum, where the ridges are interrupted by the prominent cyclo-systems. 
The branches are somewhat swollen at the points where cyclo-systems are attached to 
them. The whole corallum is, as in other Stylasteridse, permeated by networks of 
canals. The axes of the branches are traversed by bundles of large main canals, which 
place the cyclo-systems in relation with one another. 
The cyclo-systems are all, with one exception, which is evidently abnormal in the 
present specimen, placed on one face of the flabellum, with then - axes at right angles 
to its plane. The systems appear as globose bodies, with flattened tops, which are 
much wider in diameter than the branches on which they rest, and stand out promi- 
nent and entirely free from one another, at regular intervals along the course of the 
branches. The globose appearance of the systems is due to their being each encircled 
by a broad prominent zone of confluent ampullae, which zone has a rounded surface, 
rendered somewhat irregular by the occasional prominence of individual ampullae. 
Immediately above this zone, the edge of the summit of each system appears as a 
delicate lamina, which slightly overhangs the outer wall of the system all around 
(Plate 35, fig. 8). The summits of the systems are circular in outline, with a series of 
* The Hydroid here named Astylus subviridis was referred to in my abstract paper on the “ Structure 
of the Stylasteridas ” (Proc. Roy. Soc., 1876, p. 95), as “a Stylaster resembling Cryptohelia.” 
3 N 2 
