REPOET ON THE POLYZOA. 
Ill 
tion of such an appellation for a species of a genus nearly all of whose members are in 
some sense reticulated seemed absurd, and I consequently retained the Linnean appellation. 
The minute characters assigned to it in the “ Catalogue ” having to a great extent been 
adopted by others, it may perhaps be advisable not now to change the appellation, but to 
retain it for that particular member of the Linnean genus, as has been done by Prof. 
Smitt. As regards the specific appellation here adopted, and which I have ventured to 
propose for the large Mediterranean Retepora, though Dr. Solander’s name “ foraminosa ” 
might perhaps have been employed, the doing so would have involved a good deal of 
confusion with other forms, whilst the term itself is objectionable on the same grounds 
as that of “ reticulata.” In order, therefore, to prevent confusion becoming worse con- 
founded, I have thought it convenient to employ a name which could give rise to no 
ambiguity, and at the same time include a recognition of the merit of the eminent 
naturalist who first described the species. 
But another consideration also arises with regard to this form, which appears to me to 
render it doubtful whether, after all, the Mediterranean and Atlantic species here described 
may not be merely a variety of Retepora elongata of d’Orbigny and of Smitt, an arctic form 
for which at one time I proposed the name of Retepora wallichiana. The points of agree- 
ment, at any rate, between Retepora elongata and Retepora imperati are apparently of 
greater importance than those in which they differ. For instance, they both agree in 
the absence of fissure or stigma on the front of the ooecium, and in the want of any labial 
fissure or suboral pore, or any avicularian armature about the peristome, which in both 
though wavy is quite entire and much raised on the sides 
so as to become canaliculate in the older zooecia, but is 
never thickened or fissured. The anterior rostriform 
avicularia are alike in both, though comparatively larger 
in the Mediterranean form. Both have the beak hooked 
like a parrot’s and both have a very broad, lanceolate, or 
subtriangular curved-pointed mandible ; and what is of 
great importance, the operculum in both is of the same 
peculiar conformation. In most species that I have 
had an opportunity of examining, the operculum is more 
or less semicircular or subcrescentic, consisting, in fact, 
mainly of a semicircular chitinous bow filled in by a 
thin membrane, the lower border being more or less 
simply membranous, whilst in Retepora elongata and 
Retepora imperati, as in the three succeeding species belonging to the same subsection, 
it is of a suborbicular or elliptical form, bordered all round, except for a small space 
at the bottom, by a thick chitinous ring, as shown in the accompanying figures in 
which (B) represents the operculum of Retepora elongate t from Spitzbergen, and (A) that 
A A 
A B 
i/\ 
yy\V 
jjl 
1 1 CjMy \ 
/I 
k ^-A\\ 
/p •> 
D(Q) 
aO 
Fig. 19. 
A, R. imperati. 
B, R. elongata. 
