452 MR. H. N. MOSELEY ON THE STRUCTURE OF ' THE STYLASTERID2E. 
in various ways. One edge of the summit of the system is frequently elevated above 
the other, and this elevation is on the side of the same face of the flabellum in all the 
calicles ; whilst the dactylopores, on the opposite margin of the system, are frequently 
more or less aborted. This condition forms a step towards that occurring in Crypto- 
helici, where all the cyclo-systems have their mouths turned towards one face of the 
flabellum. The cyclo-systems in the present species are also frequently elongated in a 
direction in the plane of the flabellum, and in the case of those systems which are 
placed at the sides of the main branches, parallel with the line of extension of these 
branches. 
Besides being permeated completely by fine canals, the coenenchym of the pore 
systems is excavated by numerous rather large lacunar cavities, especially near the 
base of the style and place of origin of an ampulla (Plate 35, fig. 3). 
The ampullae appear, on both faces of the branclilets, as conspicuous rounded 
prominences, set in groups, and often fused together into large papi Hated masses. 
They do not occur on the flabellar faces of the main stem or branches. They present 
internally a nearly spherical cavity, which communicates freely by openings with the 
canal systems of the coenenchym (Plate 35, fig. 3). 
Soft Structures of Stylaster densicaulis. (Plate 40.) 
Ccenosarc . — The outer surface of the coral generally and of the cylindrical cyclo- 
systems, is invested by a continuous surface layer of coenosarc (Plate 40). This layer 
dips down to line the dactylopores, and form the small tubulate sacs of the contained 
zooids, and also is reflected into the wide cavity of the gastropore, the inner lining of 
which is the greatly expanded sac of the gastrozooid, which zooid, deeply seated at 
the bottom of the sac, occupies a very small area of its space (Plate 40, A). Be- 
neath the surface layer the coenosarcal meshwork forms a fine reticulation of smaller 
canals, and a similar fine reticulation lies immediately beneath the lining membrane 
of the gastropore (Plate 40). In the walls of the cyclo-systems, between these two 
finer reticulations, a series of larger canals form an intermediately placed network, in 
which the branches have a general direction parallel to the axis of the gastropore, and 
form a direct communication between the bases of the dactylozooids and the large 
canals which spring from the bases of the gastrozooids. Offsets of this reticulation 
pass up into the canals in the interior of the pseudosepta. The three reticulations 
described are intimately connected together by abundant anastomoses. In Plate 40, 
B B, the interior of a zooid cyclo-system is represented with the sac of the gastro- 
pore and superficial lining network removed, in order to display the connexions of 
the deeper reticulation with the dactylozooids, and its general arrangement. The 
connexions of the reticulations with one another are well seen at the cut edges of 
the bisected zooid systems, as shown in the plate. 
A tortuous and complicated mass of large canals springs from the bases of the 
