vine: notes on British eocene polyzoa. 
159 
1. DiTTOSARiA Whetherellii, Busk. Geol. Mag., vol. iii., p. 4, 
pi. xii., %. 3. 
Allied to Gemellaria loricata, but the orifice of the Zooecia is 
much smaller and nearly round. Mr. Busk says that " the wall of 
the cell is sparsely punctured so as at first sight to suggest a suspicion 
that the species may belong to the cyclostomatous sub-order, but 
close examination of the orifice will show, I think, signs of the ar- 
ticulation of an operculum, were not the ventricose form of the cell 
itself a sufticient indication of the true place of the species." 
Habitat : On Stone ? 
Horizon : London Clay, Highgate. Collection of N. T. Wetherell. 
Family MEMBRANIPORIDiE. 
2. Membranipora Lacroixii, Busk. Geol. Mag. vol. iii., 1866. 
Lacroixii, Savigny, Egypt, pi. 10, fig. 10. 
„ Lacroixii, Busk, B. M. Cat. p. 60, pi. 69. 
„ Lacroixii, Hincks, B. M. Pol. p. 129, pi. xvii. 
Flustra distans, Hassall, Johnston. 
,, Peachii. Couch. 
Conopeum reticulum. Gray. 
There are in the Eocene rocks fragments of a species of Meiii- 
bmiiipora allied to, if not identical with, this widely distributed 
form. Mr. Busk, in describing three species of Polyzoa from the 
London Clay at Highgate,''' says, "I am unable to perceive any 
essential difference between the form here represented and the 
existing species {M. Lacroixii). ... In general aspect and mode of 
growth, . . . the two agree very closely. The only distinction I am 
able to draw between the Eocene and recent form, as exemplified in 
a specimen now before me, collected by the late Mr. W. Thompson, 
of Belfast, at Portmarnoch, consists in the somewhat greater thick- 
ness of the septa in the former. The two agree also in the circum- 
stance that in the septa of the more worn cells there is an appearance 
of minute distant pores, which is quite in accordance with the exist- 
ence in very perfect specimens, of extremely delicate marginal spines. 
Habitat : On Shells and Stones, &c. 
* Geol. Mag. 1866, vol. iii., p. 2. 
