MR. H. N. MOSELEY ON THE STRUCTURE OF THE STYLASTERTDHL 467 
the polygonal areas are viewed from the surface of the planula, they appear mainly 
composed of rows of nematocysts viewed end on, but partly also of the already 
described opaque rounded bodies (Plate 44, fig. 8). Some of the nematocysts con- 
tained in the ectoderm of the mature planula were observed to have their contained 
threads fully developed. 
Planulse were not examined in the fresh condition, hence the ciliation of their 
surface doubtless occurring was not observed. In the most mature planula investi- 
gated the endoderrn consisted of pigmented cells, like those of the endoderm of the 
mature coral, but evidently in a condition of rapid increase, and of oil globules of 
various sizes and fine granular matter. The endoderm mass did not show any trace 
of a central cavity, but appeared homogeneous and solid. The gonophore sacs seem 
to be permanent in Cryptohelia pudicci, and the production of planulse within them to 
be carried on as a continuous process. 
Growth by Budding . — -In ordinary growth of the coral by budding, every part of the 
coral surface would appear capable of producing complete cyclo-systems, for in one 
specimen procured a new cyclo-system has been abnormally produced as a bud from 
the upper surface of the lid of an older cyclo-system. 
General Remarks. 
Summaries of the characteristics of the Hydrocorallinse and their subdivisons will 
be given in the sequel under the heading' “ Classification.” A few further points are 
required to be noted here. The Hydroid affinities of the Stylasteridse need no discussion ; 
they are borne out by every item of structure. 
As in almost all Hydroids, the sexes are on distinct stocks, and these stocks, like 
those of Sertularins, have a tendency to grow in a flabellate form with alternate 
gemmation. In having the number of the tentacles borne by the gastrozooids regular 
in number in each species, possibly in each genus, the Stylasteridse differ from the 
Milleporidse, in which the number is variable. The connexion of an absence of the 
styles in the gastropores with a flask- shaped form of gastrozooid devoid of tentacles is 
remarkable. It occurs in apparently otherwise widely separated genera, Astylus and 
Pliobothrus. It is possible that the tentacles of the gastrozooids in all the genera 
would show traces at least of having knob-like or club-shaped ends were they able 
to be examined in the fresh condition. 
The gonophore sacs within the ampullae, as containing several distinct gonopliores, 
in several genera at least, seem entitled to the term “ gonangia,” according to 
Allman’s terminology. It seems uncertain whether the central mass in Astylus, 
from which the sperm-developing lobules are budded off, is to be considered as a 
blastostyle or not ; no definite spadices were observed within these lobules. 
The radiate arrangement of the coenosarcal canals around the sacs of the zooids, 
