Alcjse of the English Lake District. By Wm. West. 739 
T regulare Kiitz. ( Polyedrium tetraedricum Nag.). Bn. 
forma pachyderma. 
Forma membrana crassissima. 
Lat. 31-35 p; crass, membr. 2-2*5 p. Bn. 
T. gigas (Wittr.) Hansg. 
forma obtusa. 
Forma angulis abrupte obtusis. 
Lat. 27-42 p. Kirk Fell, 
var. mamillata var. n. Fig. 53. 
Yar. major, angulis mamillatis. 
Lat. max. 92 p. Bn. 
T. enorme (Balfs.) Hansg. R., Bn. 
ClaSS PHYCOCHROMACEiE. 
Sub-class Nostochinese. 
Order Nostocace^:. 
Genus Nostoe Vauch, 
*N. paludosum Kiitz. Bn. 
N. muscorum Ag. Amongst mosses, Scandale. 
N. humifusum Carm. B. 
N. microscopicum Carm. [N. rupestre Kiitz. N. hyalinum Benn. 
(N. opalinum Benn.)]. Bn., R, H., Bt., Deepdale. 
Genus Anabsena Bory. 
A. sp. Crass, cell. 7*5-8 p; crass, heterocyst. 8*5-9 p. Bn, 
Order Rivulariace.e. 
Genus Dichothrix Zanardini. 
D. Orsiniana (Kiitz.) Bornet et Flab, (Revis. des Nostocac. 
Heterocyst., p. 376). Langdale. 
Genus Gloeotrichia J. Ag. 
G. Pisum (Ag.) Thuret. Pike of Bliscoe. 
Order Scytonemace^:. 
Genus Microchsete Tbur. 
*M. diplosiphon Gomont var. cumbrica var. n. 
Yar. cum articulis prope basem 7*5-8 p crassis, apicem 
versus 3 p crassis ; vagina exteriore 23-30 p crassa ; hetero- 
cystis intercalaribus diametro 4-plo longioribus. 
Crass, vag. inter. 6*5-9 p\ long, heterocyst, intercal. 
22-24 p, lat. 5*5 p. C. 
No freshwater species of this genus has hitherto been recorded 
for Britain, The form seen had the trichomes occasionally inter- 
rupted. 
