Fresh-water Algse, &c. By A. W. Bennett. 13 



to round themselves off, the endoclirome becoming at the same time 

 darker in colour (a, fig. 13), possibly the commencement of the forma- 

 tion of reproductive resting-cells. 



My plant agrees very closely with Nageli's description and figure 

 (Gatt. Einzell. Algen, p. 96, t. v. B. f. 4). It was observed only on the 

 wet sides of a well at Tintagel, where it appeared to be abundant. It is 

 recorded from several places in Germany. 



SORASTRE^, 



*Coelastrum sphericum Nag. Bog pools, fi-equent. 

 *Coelastrum cuhicum Nag. Fig. 14. 



Coenobium free-swimming, about 45 yu, in diameter, composed of 

 eight cells arranged in a cube. The front view shows a rectangular 

 space in the centre surrounded by four nearly spherical cells, very 

 obscurely hexagonal in outline, 22 • 5 /it in diameter, with homogeneous 

 bright green endochrome. Each cell has two blunt shallow hyaline 

 processes at the outer corners, and there is also a shallow hyaline band 

 in the sinus between each pair of cells. 



I cannot find that this very pretty organism has been seen or 

 described except by its discoverer (Nageli, Gatt. Einzell. Algen, p. 97, 

 t. V. C. f. 2), whose figure is evidently imperfect. Kabenhorst is cer- 

 tainly in error in identifying it with G. sjjJiericum, from which it is 

 abundantly distinct. In bog pools, Mawgan, apparently not uncommon. 



*Selenasteum bifidum n. sp. Figs. 15 and 16. 



Coenobium free-swimming, nearly spherical in outline, about 60 fi 

 in diameter, composed of 8-16 cells. Cells bright green, somewhat 

 broadly lunate, all with their apices pointing outwards, narrowing 

 towards each apex, which ends in two straight hyaline processes, from 

 one-fifth to one-sixth the length of the cell, about 35 /a long (without 

 the spines) by 15 /^ broad. 



The genus Selenastrum, distinguished by its lunate cells, has been 

 hitherto represented in our flora only by the doubtful species 

 S. Bihrianum Keinsch. The present species comes near to S. gracile 

 Eeinsch, but is distinguished by the cells being broader in proportion to 

 their length, and bidentate at the apex instead of simply falcate. It 

 was seen frequently in gatherings from bog pools, Mawgan. 



*Sorastrum lidentatum Reinsch. Bog pool, Mawgan. 



PANDORINE.E. 



*Eudorina elegans Ehrb. 



In a roadside ditch, Eoche, among Zygnema insigne, very abundant ; 

 also in running water and in bog pools, Mawgan. In none of a 

 large number of individuals under observation was a red " eye-spot " 

 detected. 



*Gonium pectorale Miill. 



Eoadside ditch, Eoche, with the preceding. "When observed it was 

 always swimming with the " frond " placed vertically. 



