DUBLIN MICROSCOPICAL CLUB. 445 



the recent genera just quoted, if not identical therewith." The 

 accompanying figures of specimens exhibited show plainly, for 

 example, that the genera Cymopolia and Polytrypa may be 



Cymopolia and Polytrypa. 



YiG. 1. — Transverse section of a morsel of the calcareous tube of Cymopolia 



rosarhm, Lamr., showing the canals which receive the whorl of cellule s 



and the central sporangial cavity. 

 Fig. 2. — Transverse section of Poli/tri/pa elongata, Defrance, showing the 



same portions. 

 Fig. 3. — Part of a whorl of cellules of Cymopolia rosariim, separated from 



the calcareous tube by acid, a, Wall or central cellule; b, first row of 



cellules ; c, terminal whorl of cellules, in the centre of which is D, the 



axillary sporangium. 

 Fig. 4.— Exactly the same parts in Polytrypa elongata, obtained from a 



mould. 



united ; for the typical species thereof oflfer in every respect the 

 same generic characters, and there is even a difficulty to find for 

 them sufficiently distinct specific characters. Under the deno- 

 mination 0?" 8iplio7iece verticillatce,^' M. Munier-Chalmas unites 

 (1) " Those greeen-spore bearing algse arranged by Harvey in the 

 family of the Dasycladese ; (2) All those fossil genera related to 

 Larvaria, Clypeina, Polytrypa, Acicularia, Dactylopora, and 

 TJteria. This group at present contains over fifty genera, which 

 are for the most part to be met with in the triassic, Jurassic, cre- 

 taceous, and tertiary strata. In the number of those actually 

 living there is a notable falling off, there being not more than 

 the seven following genera : — Dasycladus, Halicoryne, Cymopolia 

 (with two sub-genera, Polytrypa and Decaisnella,^ g-ii-)' Polj- 

 physa, Acetabularia, Neomeris, and Bornetella,- g.n." [Doubt- 

 less a few more genera of recent forms yet remain to be de- 



' TjTpe,- Dactylopora eruca, Parker. 

 ^ Type, Neomeris nitida, Harv. MS. 



