34)4 PROCEEDINGS OF SOCIETIES. 



be no doubt but that the E-hizopod shown on Prof. Schulze's plate 

 and referred by him to that species appears again to be quite a 

 different thing ("social" in habit, no doubt) and to appertain 

 more probably to Plagiophrys and not to Gromia (Microgromia) . 

 Mr. Archer had long since discovered his own error in referring 

 the densely crowded state of Microg. socialis to a distinct genus ; 

 he hoped however for an opportunity ere long to furnish a resume 

 of the recent matter on these rhizopods in general, and submit 

 the reasons which seemed to him to sustain the opinion as to 

 the foregoing forms here enunciated. 



A very small form of Cosmarium SolmiensejJjuiideW, exMbifed. — 

 Mr. Archer drew attention to a very small form of Cosmarium 

 Sohniense, Lundell, not probably more than one half the linear 

 dimensions of the ordinary form. So great a diiference in the 

 dimensions of examples in a single species of the Desmidieae, 

 unlike Diatomacese, was rare to note, for ordinarily in the former 

 the variations in dimensions oscillated between certain rather 

 limited extremes. These examples (probably owing to being 

 taken at the " dead " period of the year) showed the cell-contents 

 very starchy in appearance and the radiate (Penium-like) ar- 

 rangement of the chlorophyll-mass to be seen in the larger form 

 of Cosmarium Solmiefise, Lundell, was not evident. In this small 

 form the general contour in all respects agreed with that of the 

 larger, except that the little undulations on the lateral margins, 

 as they approach the somewhat drawn-out upper angles, were 

 rather less pronounced. The ordinary form seems in Ireland 

 to be very scarce, yet widely spread, as Mr. Archer had taken 

 it now at Bray Head, "Tooles Rocks " and "Rocky Valley " (Co. 

 Wicklow), Townland of Clashnasmut (Co. Tipperary) ; the 

 present (very small) examples were from the " Rocky Valley," 

 near Bray, where also the larger form occurs. 



