02 DUBLIN UNIVEKSITY 



1. — C. bicornisy n. s. Plate IX., Figs. 2 and 2a. 

 The only known species. 



This genus supplies another link in the beautiful chain of modifica- 

 tions in the arrangement of cells in pairs furnished by the Gemellariadae. 

 By combining one of the peculiar characters of Notamia with a genera, 

 appearance closely resembling Dimetopia, it affords another reason for 

 retaining Notamia in the group, bearing, in fact, with the exception of 

 the total absence of avicularia, the same structural relation to Notamia 

 which Dimetopia bears to Gemellaria. The lower half of each pair is 

 contracted and tube-like, the two tubes of which it is composed sepa- 

 rating and curving over the walls of the inflated triangular upper half 

 of the pair immediately beneath it. The ccencecium is thus formed of 

 two incorporated, independent rows of pairs of cells, all the cells of each 

 row being in the same plane, but at right angles to all the cells of the 

 other row. This somewhat complicated structure might be better un- 

 derstood if the reader would imagine another exactly similar double- 

 stem incorporated at right angles with Pig. 2a, Plate IX. 



The cell- mouth is small, nearly horizontal on the upper surface of 

 the cell. The margin is thickened, rising at the outer angles of the nearly 

 straight lower lip into a pair of strong, incurved, blunt spines. The cell- 

 wall seems to consist of two membranes, and round the lower lip and at 

 the base of the spines there are a few small, oval and round, fenestras, 

 passing apparently through one layer only. A small, granular, perforated 

 papilla rises immediately below the cell-mouth, the oval aperture pass- 

 ing right through the cell- wall. 



The ovicell is immediately above and behind the mouth of the cell, 

 cemented against the triangular side of the pair of cells above, subsphe- 

 rical, slightly compressed, and beautifully marked, as if stamped with a 

 miniature clam-shell. 



The ccencecium is very calcareous, forming delicate pure white, 

 bushy tufts, about half an inch high. 



It occurs sparingly with Cellularia cuspidata and Dimetopia comuta, 

 parasitical on Catenicella ventricosa. 



Bass's Strait ; Dr. Harvey. And on Catenicella hastata. New Zea- 

 land ; Dr. Joliffe. 



