IDMOXEA. 
149 
of some palaeontological generic names in a different sense from 
that for which they were proposed. 
The simplest of the Cretaceous Idmonids, or at least the species 
which most nearly resembles the Jurassic ‘ species ’ of Idnionea, is 
a Lower Greensand Bryozoan from Berkshire, described by Sharpe 
as a Lopholepis. That ‘ species ’ appears to be nearly allied to 
I. triq^uetra, and is succeeded by some Tipper Cretaceous ‘ species ’ 
which differ mainly by the prominence of the peristomes. These 
adnate, banded species are analogous in the Idmonid series to 
Frohoscina in the Diastoporid series. Phalangella, the Idmonid 
analogue of Berenicea, is represented by a species P. radians (iN’ov.). 
Filisparsa is similarly represented by Crisina. In addition to 
these groups there is a further series with more specialized zoaria, 
which is not represented in the Diastoporidae. Thus, Retecava has 
a well-developed axial rod on the reverse face. In Reticrisina 
the zoarium is reticular, and consists of laterally compressed 
branches. In Bituhigtra the zooecia open in biserial rows. 
In his treatment of this family M. Pergens attaches great 
importance to some tubes which frequently occur on the reverse 
side of the zoarium, and which he calls “ canaux de reuforce- 
ment.” * He gives no definite suggestion as to their morphological 
character, and his own figure of these canals in Idmonea cenomana ^ 
shows that they are the smaller proximal portions of zooecia. The 
canals on the left-hand side of Pergens’ figure expand as they 
approach the obverse face at the other end of the figure. These 
tubuli in other cases are probably rudimentary zooecia. Thej^ occur 
in the genus Retecava^ where they form the reverse axial rod. 
IDMONEA, Lamouroux, 1821. 
Synonyms. 
Idmonea, Lamouroux, 1821. 
non Idmonea of Busk, Hincks, and neontologists. 
Beptotuhigera, pars, d’Orbigny, 1852. 
Lopholepis {non vou Hagenow), Sharpe, 1854. 
Eeptoclausa, d’Orbiguy, 1854. 
^ Pergens: Ke vision, p. 311. 
2 Ibid. p. 344. 
