MR. H. N. MOSELEY ON THE STRUCTURE OF THE STYLASTERID2E. 4=29 
For the former the term “ gastrozooid ” is here adopted, and for the latter that of 
“ dactylozooid.” 
The pore m the corail um occupied by the gastrozooid is termed gastiopoie, and 
that of the dactylozooid “ dactylopore.” 
In the more highly differentiated Stylasteridse the pores are arranged in regular 
circular systems simulating the calicular systems of the Anthozoans in appearance. 
These systems are termed “ Cyclo-systems.” 
Structure of the Hard and Soft Parts in the several Genera of the 
Stylasteridse. 
(1.) GENUS SPOBADOPOBA (H. N. M.). 
This genus, hitherto unknown, I described in the Proceedings of the Royal Society, 
vol. clxxiii., 1876, p. 94, under the name Polypora , but as I have been informed by 
Mr. Etheridge, junr., that the name Polypora is already in use, I here change 
it to Sporadopora, which refers to the irregular scattering of the pores over the 
surface of the corallum. The genus is founded on a single species, Sporadopora 
dichotoma, obtained on one occasion only by the £ Challenger ’ off the mouth of the 
Rio de la Plata in 600 fathoms. 
Coiallum of Sporadopora dichotoma. 
The corallum or hard calcareous structure in this Hydroid occurs in the form of 
stout upright stems, which branch with tolerable regularity dichotomously to form 
a flabelliform expanse. The stem is usually nearly circular in section towards its 
base, but becomes compressed above in the plane of the fan, whilst the branches and 
branclilets forming the fan itself are very much flattened, so as to be more oblong 
than oval in transverse section. The number of branchings is few in number, only 
four or five at most. The flattened branches and branclilets coalesce at their adjacent 
margins. A figure of a well-grown but partly broken example is given on Plate 34, 
fig. 2, reduced to half the natural dimensions. 
Sometimes the stems are somewhat bent and irregular, as are also the flabellate 
expanses which they support. The height of the largest specimen obtained is about 
5§ inches, and the breadth of the fan about 5 inches. The diameter of the stem at 
its base is about 1 inch ; in slenderer specimens b inch to f inch. In one large 
broken and dead specimen the stem is 2 inches in diameter. The corallum is dense 
and heavy, and when macerated out from a living specimen is of a pearly white, and 
smooth and glistening in appearance (Plate 34, fig. 1). The surface is pierced by deep 
pores, which are simply circular in outline and of two kinds, large and small, and are 
scattered irregularly over it. The larger pores or gastropores are less numerous than 
