472 Miscellancous. 
The agents by which the perforation is effected are sti]] unknown 
to us; we have been unable to detect siliceous corpuscles in the ex- 
cavations of the Terebripore—a circumstance which of itself would 
suffice to distinguish them from the terebrant Sponges (Cliona, 
Thoosa), even if their organization were not infinitely superior. 
Until we acquire fuller information, therefore, we shall assume that 
the perforation is due to a chemical action. 
In the commencement of this memoir we shall indicate a serious 
gap. We have been unable to study the animals whose habita- 
tions are described. In excuse we may say that the existence of 
their excavations is tolerably evident, and that the cells of the living 
Terebripora of the French coasts are scarcely 0°09 millim. in 
length. 
The systematic arrangement of our Bryozoa is consequently 
founded upon the form of their cells, their grouping, and develop- 
ment—characters which are sufficient for their identification. 
The genus Terebripora was established by A. d’Orbigny for two 
Bryozoans collected during his voyage in South America—one on 
the coast of Peru, the other at the Falkland Islands. D’Orbigny 
indicates that this genus differs from all others in its class by its 
cells hollowed out in the very substance of shells, their arrangement _ 
being identical with, and their mode of production similar to, those 
of Hippothoa. Since the publication just referred to, no author has 
made mention of the Zerebripore. 
The investigations which I have undertaken upon the terebrant 
Sponges in a fossil state led me incidentally to ascertain how widely 
the Terebripore are diffused in the Secondary and Tertiary beds. I 
have detected four or five species in the former, and as many in the 
latter. Their presence in the middle Tertiary beds of Touraine and 
the Astésan led me to expect that this genus was perhaps not yet 
extinct in the European seas, when, in September 1865, I collected 
in the harbour of Arcachon (Gironde) an oyster perforated by a 
colony of Terebripore. The same species occurs in the Medi- 
terranean. 
From the examination of this specimen it is easy to rectify some 
incorrect statements made by D’Orbigny, who represented the aper- 
_tures of the cells as round, whereas they are furnished with a notch 
of greater or less extent—a character of great importance in the 
classification of the Bryozoa. 
Besides Terebripora, I have found, on the coasts of the Gironde 
and the Charente-Inférieure a Bryozoan belonging to the same 
family and having the same habits, but differing in having its cells 
alternate and borne upon alternate axes. It leaves upon the shells 
elegant impressions resembling the ramifications of the Sertularia. 
I propose to name it Spathipora. 
The living Spathipore are not numerous. I know only two spe- 
cies—one from the coasts of France and of the Mediterranean, the 
other from the Pacific; but the former does not differ notably from 
a Bryozoan which has perforated with its colonies the shells of the 
Faluns of Touraine. 
