740 
Transactions of the Society. 
Genus Scytonema Ag. 
S. Cookei sp. n. 
[S. natans Cooke (Brit. Fresh w, Alg,, p, 265, pi. 105, fig. 2) 
non Breb.]. 
Crass, fil. 18-24 yu ; crass, trich. 6-7 fi. Langdale. 
This species belongs to the section Euscytonema Bornet et Flah. 
(Revis. des Nostocac. Heterocyst., p. 86) ; it has the sheath composed 
of parallel strata and has distinct dissepiments. S. natans Breb. does 
not belong to this genus, it is the same as Plectonema mirabile Thur. 
(vide Bornet et Flah., l.c. p. 113). As Cooke’s description of the 
species which he places under S. natans Breb. agrees with the Lang- 
dale plant, I propose to call it S. Cookei. 
S. figuration Ag. H., C., Pike of Bliscoe. 
S. crustaceum Ag. \Petronema fruticulosum Thwaites.] Bo. 
Genus Tolypothrix Kiitz. 
T. tenuis Kiitz. [T. pygmea Kiitz.; T.flaccida De Bary.] Bn., 
H,, Hk., Crummock Water. 
Genus Desmonema Berk, et Thwaites. 
D. Wranqelii (Ag.) Bornet et Flah. (Revis. des Nostocac. Hete- 
rocyst., p. 127). 
[ Calothrix Dillwynii Kiitz. ; Desmonema Dillwynii Berk, et 
Thw.] 
var. minor var. n. 
Yar. trichomatibus angustioribus. Lat. trich. 5-6 fi. 
Langdale. 
Exactly similar to the typical form but smaller. 
Order Sirosiphoniace^:. 
Genus Stigonema Ag. 
S. ocellatum (Dillw.) Thur. R. 
S. panniforme (Ag.) Bornet et Flah. Pike of Bliscoe. 
8. minutum (Ag.) Hass. Bo. 
8. turfaceum (Eng. Bot.) Cooke. Bt., Langdale. 
S. mamillosum (Lyngb.) Ag. Langdale. 
Order Oscillariace^. 
Genus Oscillaria Bose. 
0. tenerrima Kiitz. Near Keswick, near Cockermouth. 
0. leptotricha Kiitz. Bassenthwaite Water, near Cockermouth. 
0. subfusca Yauch. Bn. 
0. tenuis Ag. H., Bn., Sk., C. 
0. limosa (Roth) Ag. Bo., Yale of Newlands. 
0. nigra Yauch. H., Bn. 
0. FrolicJiii Kiitz. Bn. 
0. princeps Yauch. Bn., C., Hk, 
