2 Transactions of the Society. 



from bog pools at a comparatively low elevation. On the whole, they 

 were not so rich as those made in the Loughrigg district, but some 

 interesting forms were obtained.* 



PEOTOPHYTA. 



Protococcace/E (including Palmellace;tc). 



Glceocystis ampla Ktz. 



Scenedesmus obtusus Mey. 



Homospora mutabilis Breb. Figs. 1-3. 



As, according to Dr. Cooke, this interesting plant has at present 

 been observed only in Ireland, as far as these islands are concerned, a 

 figure is appended. The completely unbranched gelatinous sheath is 

 about 37 "5 /u, in diameter, and rounded at both ends, usually quite 

 straight, but sometimes with a knee-shaped bend, as in fig. 1. The 

 pseudocysts are globular or elliptical, about 20-25 fi long by 15-20 //, 

 broad, with bright green and strongly granular endochrome, frequently 

 exhibiting rudimentary transverse bipartition (fig. 2). They are 

 either in close contact or with an evident space between them. In 

 only one instance (fig. 3) were the pseudocysts seen in two rows 

 within the sheath. It was observed only in gatherings from a bog 

 pool near the Bowder-stone, but was there abundant. 



Acanthococcus anglicus n. sp. Fig. 4. 



Of this interesting genus, first separated by Lagerheim, as many 

 as fourteen species have been described and figured by Keinsch.t I 

 have already noted (see this Journal, 1887, p. 12) the occurrence of 

 several of these forms in this country ; the one now described I am 

 unable to identify with any of Keinsch's species. It occurs in isolated 

 individuals, the stiffly gelatinous or cellulose membrane of which is 

 irregularly spherical, varying between 65 and 95 //. in diameter, and 

 is distinctly laminated or folded in several layers, and prolonged into 

 long slender colourless protuberances, from one-third to two-fifths the 

 diameter of the globe. These spines are sufficiently solid to be dis- 

 tinctly bent by passing diatoms or animalcules, thus being clearly 

 distinguished from the very much more fluid envelope which, in some 

 desmids, is also not unfrequently raised into spine-like prominences. 

 The cell-contents are bright green and granular. This species corre- 

 sponds very closely in size and in the structure of the cell-membrane 

 with Keinsch's A. insignis, which, however, is described as without 

 spines ; but I cannot but think it probable that they are different 

 stages or conditions of the same organism. It is larger than any of 

 Keinsch's spined species, coming nearest to A. Eystrix, but differs also 

 in the nature of the cell- wall. At first sight it resembles Eremosphsera 

 viridis dBy., but is somewhat smaller, and at once distinguished by 



* The names of new species are printed in small capitals ; those of species new 

 to Britain in italics. 



t Ber. Dentsch. Bot. Gesell., 1886, pp. 237-44. 



