108 PROCEEDINGS OF SOCIETIES. 



is the result of a outgrowth of either a terminal cell of a filament 

 or a lateral cell of a filament ; that the involucral whorl is itself 

 composed of a series of verticillately-arranged ramuli, which are 

 advanced a good way in their development ere they burst asunder 

 the cell-wall of the containing terminal cell, which ramuli develop 

 on their inner surface a series of bud-like projections, which 

 develop into oval, sac-like forms, the contents of some of which 

 develop into tetraspores, and of others into a series of daughter- 

 cells, which latter equal the autheridial-cells. The^e daugliter- 

 cells discliarge their contents by means of an exceedingly well- 

 marked, tube-like prolongation of their cell-wall, which projects 

 out for some distance beyond the cell-wall of the mother-cell, 

 giving this large cell an appearance as if it were filled with a 

 number of Olpidium-like forms. 



Such a development seemed to be as yet unnoticed in any of 

 the Plorideae, and seemed to point to rather a high differentiation 

 in this species. The peculiar endings of the ramuli and their 

 trichomes, also to be seen in this species, were also apparently 

 undescribed. 



New Sjjecies of Stauroneis. — Eev. E. O'Meara exhibited an 

 undescribed form of Stauroneis, found by him in stomachs of 

 Ascidiaus dredged at Moukstown, Co. Dublin, by Mr. H. W. 

 Mackintosh, of which the following is a detailed description : — 



Stauroneis MacJclntoshii. — Valve linear elliptical, acuminate 

 towards the ends, stauroform band broad, very slightly expanded 

 towards the margin ; strife cbscure, slightly radiate, not extending 

 to the ends ; on front view frustule linear, very slightly con- 

 stricted in the middle ; considerably depressed at ends ; length 

 •003G, breadth -0008. 



JSuastrum divaricatujn, Luudell, new to Britain, exhibited. — 

 Mr. Archer exhibited Euastrum divaricatum, Lundell, new to 

 Britain. The examples were taken in liannoch Moor, in Scotland, 

 on a recent tour in company with Dr. Barker. This is an 

 extremely pretty and well-marked little species. 



