SOME DESMIDS OF THE UNITED STATES. 305 
98. COSMARIUM RACIBORSKII, Lagerh. in Ofvers. K. Sv. Vet.- 
Akad. Forh. 1887, no. 8, p. 537.—0C. Nordstedtii, Racib. 1884. 
Long. 48 p; lat. 53 u; lat. isthm. 20 p. 
Hab. Laconia, N.H., occasional. 
99. C. woxowazuM, Lund. in Nov. Act. Soc. Scient. Ups. 
Ser. III. vol. viii. no. ii. p. 32, t. 7. f. 11. 
Var. TRISTICHUM, n. var. (Fig. xylogr. 4.) 
Var. granulis 9 in centro semicellularum in seriebus trans- 
versis 3 ordinatis. 
Long. 32 u; lat. 36 u; lat. isthm. 11 p; crass. 20 p. 
Fig. 4.—Cosmarium monomazum, Lund., var. tristichum, n. var. X 150. 
a, front view ; b, vertical view; c and d, different arrangements of the 
central granules. 
Hab. Whitmore Lake, Mich. (H. J. no. 452). 
The granules in the centre of the semicells vary somewhat in 
number and arrangement ; the central one or one of the outer 
ones may be doubled, or the middle one of the basal row may be 
wanting, 
100. C. TAXICHONDRUM, Lund. l. c. p. 39, t. 2. Ê. 18. 
Var. PrpeNTULVM, Lagerh. in Ofvers. K. Vet-Akad. Forh. 
1885, no. 7, p- 237, t. 27. f. 8. 
Long. 32-34 u; lat. 30-32 u; lat. isthm. 8 p; crass. 16-17 p. 
Hab. Seattle, Wash. 
101. C. PSEUDOTAXICHONDRUM, JVordst. in Üfvers. K. Vet.- 
Akad. Förh, 1877, no. 3, p. 20, t. 2. f. 5. 
Var. FLORIDENSE, n. var. (Pl. 18. fig. 1.) . 
Var. egregia, apicibus semicellularum angustioribus et retusis 
(angulis apicalibus leviter productis), serie transversi verrucarum 
