52 NEW AMERICAN ALG.E. 



months the symptoms steadily increased in severity, confining him 

 almost entirely to the house and garden. His death at Perth on 

 December 8rd, 1894, is a heavy blow to the study of the Zoology 

 and Botany of Scotland, and a grief to those who had the privilege 

 of personal friendship with him, and who knew his sterling worth 

 as a man. j. w, h. Trail. 



NEW AMERICAN ALG^. 

 By W. West, F.L.S., and G. S. West, A.R.C.S. 



Pediastrum duplex Meyen. (P. pertusiun. Kiitz.), var. gracil- 

 LiMUM, n. var. Var. cellulis gracillimis, periphericis arcuatis cum 

 processibus duobus longis tenuibus emarginatis ad apices; cellulis 

 reliquis 4-radiatis ; lacunis permagnis. Diam. usque ad 87 fi. 



This variety is similar to var. reticulatum Lagerh. (Bid rag till 

 Banned. Stockholmstr. Ped., Protoc, PalmelL, Ofvers. af K. Vet.- 

 Akad. Fork., 1882, p. 56, t. ii. f. 1), but the cells are much more 

 slender, the processes narrower and with emarginate apices, and 

 the spaces between the cells are very much larger. 



Tetraedron tortum, n. sp. T. magnum, irregulariter tri- 

 angulare, contortum, lateribus curvatis, convexis, subconvexis, vel 

 concavis sed in medio leviter convexis; angulis leviter productis, 

 spina longa valida acuta vel acutissima ad angulum unumquemque 

 instructa ; membrana crassa glabra. Diam. sine spin. 73-81 /x, 

 cum spin. 108-117 /x; crass, circ. 42-44 /x. 



The large size, peculiar bent and twisted triangular form, fur- 

 nished with the strong spines at the angles, distinguish this 

 species from all others. 



Radiofilum apiculatum, n. sp. E. cellulis transverse elliptico- 

 vel rotundo-rhomboideis, angulis lateralibus subapiculatis, cellulis 

 conjunctis arete in fills longis flexuosis. Contentum chlorophyllosum 

 cellularum cum pyrenoidibus magnis singulis. Long. cell. 4-4-4 /x; 

 lat. cell, cum apic. 4*6-5-6 fx. 



The smaller somewhat rhomboidal cells with lateral apiculations 

 distinguish this species from the only other one of the genus, viz., 

 R. conjimctivwn Schmidle (Aus der Chloroph.-Fl. der Torfstiche zu 

 Virnheim, Flora oder allg. Bot. Zeitung, 1894, Heft 1, p. 47, 

 taf. vii. f. 4, 5). The filaments of R. apiculatum are long and 

 flexuose, as distinguished from the short fragile filaments of R. 

 conjiinctivum; moreover, the cells are not so remote as in the latter 

 species, and are arranged more or less in pairs, the minute apiculi 

 on the cells of each pair often being directed slightly towards each 

 other. 



The material was not in the living state, but traces of a 

 gelatinous investment with a radiating structure were observed. 



