Fresh water Algse, &c. By A. W. Bennett. 5 



interwoven. Cells ellipsoidal or nearly globose, green, 5 /a in 

 diameter (about forty to the length of the envelope). Heterocysts 

 intercalary, very few in number, three to four in each envelope, 

 spherical, green, 6-7 jx in diameter. 



Several specimens obtained from a bog pool, Loughrigg Fell. 

 It bears some resemblance to N. minutissimum Ktz., but is much 

 smaller, and the trichomes are much less densely packed in the 

 hyaline envelope. According to Kiitzing all the free-swimming 

 Nostocs are attached at first ; but this does not seem to be the case 

 with this species. 



ALG^. 



Pediastee^. 



Pediastrum angulosum Ehrb. 



„ Boryanum Turp. 



„ Ehrenbergii A. Br. 

 Pediasteum oompaotum n. sp. Figs. 4, 5. 



Ccenobium oval and perfectly regular, 0*09-0 '16 mm. in 

 length (or probably more), rather more than half as broad as long. 

 Periphery composed of thirty-two lunate cells (in the smaller speci- 

 mens), with two somewhat divergent, very slender tapering, not 

 bidentate horns, quite as long as the cells themselves. Inner cells 

 irregularly polygonal and densely packed, without any lacuna, in 

 2-4 rows. Coenobium invested with a distinct gelatinous en- 

 velope. Endochrome yellow-green ; that of the peripheral cells of 

 a deeper colour, which gives the appearance, under a low power, of 

 a deep green border. Length of cells about 6 /x. 



Bog pools, Loughrigg, not infrequent. The perfectly regular 

 elliptical form, the much yellower endochrome, and the absence of 

 any interstitial spaces between the cells, give this Pediastrum a 

 very distinct appearance from all others with which I am ac- 

 quainted. In shape it resembles P. elli])ticum Ehrb. (judging 

 from Ealfs's figure), but differs widely in other respects. 



Uloteichace^. 



Hormiscia moniliformis Kabh. 

 „ cateniformis ? Ktz. 

 Ulothrix zonata Ktz. Grisedale, Cumberland. 



Confeevaoe^e. 



Conferva fontinalis Berk. 



„ tenerrima Ktz. 



„ bombycina Ag. 

 Microspora vulgaris Eabh. 

 floccosa Thur. 



