270 
ME. A. W. WATERS ON SOME 
examination by Mr. Busk ” ; who would have placed it, she 
considered, under Hornera if lie had noticed the ovicell. 
In Idmonea I believe the ovicell is only known in I. radians, 
Lam., I. atlantica , Forbes, I. gracillima , Busk, I. concava*, Reuss, 
I. serpens, L., I. eboracensis, Busk, I. radicata , Kirkpatrick ; and 
in all is on the anterior surface ; but both in Idmonea and Hor - 
nera the position may be axillary, or far away from the bifurca- 
tion ; and the position in relation to the axils can seldom or never 
be looked upon as characteristic. I have before me a MS. list of 
130 Idmonece , some of them synonyms, though all have been con- 
sidered as separate species ; but only in the few cases mentioned 
is the ovicell described. An ovicell has been figured by Ilagenow 
as Coelophyma granulata on il Idmonea ” lichenoides , Goldf. ; but 
I am not sure that this is a true Idmonea. 
From a list of 74 species of Hornera , it seems that the ovicell 
is only known in H. frondiculata , Lam., H. folia cea, MacGf., 
H. violacea, Sars (practically dorsal), H. galeata, Sm., H. robusta, 
MacGr., H. ramosa, MacG., H. lichenoides , L.f Goldstein (Trans. 
Roy. Soc. Yict. 1881, pi. ii. figs. 6, 7, 8) has named a ‘Chal- 
lenger’ specimen from Marion Island H. subdubia, with “ ovi- 
cells but from the figure it might be Hydrocorallina. Reuss 
has described as Coelophyma striata an ovicell which, as pointed 
out by Manzoni, probably belongs to H. hippolyta , Defr. In 
all these cases the ovicell is dorsal, forming a distinct chamber ; 
and this is also the case in Hornera fissurata. In this last it 
is longitudinally ridged, and in the furrows are pits, giving, 
when not calcined, an areolated appearance. 
The position and nature of the opening of the ovicell is most 
important, often, in fact, more so than the shape of the ovi- 
cell. The opening is, however, formed after the ovicell is com- 
* Not described ; but a recent specimen from Naples has the ovicell as a 
raised chamber at the bifurcation. It nearly encloses one of the series, and 
the ovicellular opening is by the side of the series. In another specimen 
there is a slight central inflation between the series ; but this does not seem to 
be mature. 
t I find that II. lichenoides, L., occurs in Naples, together with IL frondi- 
culata, and has an ovicell with a rib down the middle, as figured by Smitt 
and Alder, whereas Hincks figures a transverse rib. It has been looked upon 
as an exclusively northern form ; but the ‘ Challenger ’ found it off Monte 
Video ; and, as mentioned, it lives in the Mediterranean. Among the ‘ Chal- 
lenger ’ material in Edinburgh I have since seen the ovicells on specimens from 
Simon’s Bay. These have a central rib, and also a transverse one from the 
ovicelluiar opening to the median rib. 
