348 PROCEEDINGS 01' SOCIETIES. 



either Cooke or Corda, except Sf //nanus stemonitis, Corda, from 

 which it differed in the fact that the stem, instead of being simple 

 and surmounted by a cylindrical head of concatenated spores, 

 was divided into numerous branches, each terminated by a head 

 of spores, the way in which the threads of the stem passed into 

 the branches strongly reminding one of the divisions of some 

 tendons. A specimen was subsequently shown to Mr. Yize, and 

 by him to Mr. Phillips, of Shrewsbury, and both concur in con- 

 sidering it a branched form of the species named. As its claim 

 to specific rank is doubtful, Mr. Pirn would suggest that it be 

 called Stysanus stemonitis, Corda, var. ramosa, Pim. 



A new Micrasterias from 8cotland,foricarded by Mr. J. P.Bisset, 

 Banckory. — Mr. Archer exhibited a new Micrasterias, kindly 

 sent to him from Scotland, by Mr. J. P. Bisset of Banchory, near 

 Aberdeen, and collected by that gentleman on the Dee-side. This 

 presented denticulations like those of M. denticulata, with some 

 of the contour of M. angulosa, but seemed well distinguished by 

 the possession, on each front surface, near the base of each semi- 

 cell, of a curved series of circular groups of bead-like mark- 

 ings, of which the central group was the largest, the external 

 ones being the smallest. These seemed to Mr. Archer to be 

 composed of leaflike prominences, and the groups he supposed, 

 were it possible to view them laterally, would be seen to stand 

 out as crown-like elevations, somewhat comparable to those, say, 

 4)i Xanthidium armatum, but most likely not by any means so 

 prominently — that is to say, the component bead-like markings 

 did not appear as dots or even granules, but, as he said, thin leaf- 

 like projections. Mr. Bisset referred to other " markings," but in 

 the specimen, owing probably to the presence of the cell-con- 

 tents, no others could be noticed. These examples formed a 

 portion of a set of two or three slides of species carefully selected 

 and exquisitely mounted by Mr. Bisset — one contained six species 

 of Micrasterias, represented by one example of each, M. rotata, 

 M. denticulata, M. truncata, M. papillifera, M. angulosa, and the 

 new species. 



Section of Spine of Mespilia gtohulus, exliilited. — Mr. Mackin- 

 tosh exhibited a cross section of the spine of Mespilia globulus, 

 which had been kindly sent him by Dr. Giinther, P.R.S. The 

 greater portion of the spine was composed of reticulations with 

 thick trabecules, tlie periphery being formed of a single row of 

 solid wedges, whose form was almost that of an equilateral 

 triangle. 



Peculiar condition of Rivularia. — Dr. E. Perceval "Wright ex- 

 hibited sections from examples of lUvularia, showing a peculi- 

 arity in certain of the component filaments, consisting in the fact 

 that these presented a clavatc expansion in place of the ordinary 

 tapering, inside which expansion the ceils formed indefinite 

 groups, not linear series. Possibly, in function these might be 

 coa)parable to the mamillale branches of such forms as Stigo- 

 nema mamillosum, in which, however, the cells remain in single 



