Fresh-water Algse, &c. By A. W. Bennett. 9 



The occurrence of five out of tlie seven British fresh-water Ulvaceae 

 in the Cornwall list, all absent from that for Westmoreland, is probably 

 due to the proximity of the sea. Of greater interest is the observa- 

 tion of several species of microscopic Protophyta which may be included 

 in the family Characiaceae, using the term in its larger sense. This, I 

 have little doubt, is due to the lower latitude ; and it is probable that 

 further search, and a better acquaintance with this class, might lead to 

 the discovery of a number of new and interesting forms. Among the 

 beautiful Pediastrese and Sorastreee I have had the good fortune to meet 

 with four very interesting species which have not hitherto been observed 

 in Britain, one of them new to science, as also a very striking Oscillaria. 

 The greater number of the Desmidieae were gathered in pools on the few 

 peat-bogs above referred to. Comparing them with my experience of 

 the Lake District, I must note the comparative absence of the larger 

 species, especially Micrasterias, Xanthidium, Holocystis, the larger 

 Euastra, and the whole of the filamentous forms, though this applies 

 more to the comparative paucity of individuals than to a reduction in 

 the number of species. On the other hand, the larger Cosmaria and 

 Closteria were quite as frequent, while the genera Penium and Docidium 

 were more abundant, at least as far as the number of individuals is con- 

 cerned. I was also struck with the large number of extremely minute 

 forms belonging to the genera Cosmarium, Sfaurastrum, and Arthro- 

 desmus, some of which, I cannot doubt, represented species hitherto 

 undescribed.t 



PEOTOPHYTA. 

 Pkotococcaoe^ (including Palmellace^). 



Eremosphsera viridis dBy. 



Glceocystis vesiculosa Nag. 



* „ ampla Ktz. 

 Botryococcus Braunii Ktz. 

 Rhaphidium falcatum Cooke. 



* „ aciculare Br. Bog pool, Mawgan. 

 Protococcus viridis Ag. 



*Chlorococcum frustulosum Carm. Boscastle. 



„ gigas Griin. 



*Polyedrium tetrahedricum Nag, Bog pool, Mawgan. 

 Scenedesmus acutus Mey. 



„ quadricauda Breb. 



* „ obtusus Mey. 



Not unfrequent in bog pools. I do not find the character by any 

 means constant that the cells are always " remote from one another " ; 

 their contact is frequently as close as in S. acutus. 



Characiage^. 

 *Apiocystis Brauniana Nag. Fig. 1. 



This interesting organism was seen only once, attached to Zygnema 

 insigne in a mill-dam in the valley of the Grannel. It appears to have 



t The names of new species are again printed in small capitals, those of species 

 new to Britain in italics. 



