SOME DESMIDS OF THE UNITED STATES. 281 
7. Mesorzntum ENDLICHERIANUM, Nig. Gatt. Einz. Alg. 
p. 109, t. vi. B. 
Lat. 10-12 u; 2-4 times longer than the diameter. 
Hab. Palo Alto, Calif., abundant iu small pool (H. J. no. 588). 
IV. CYLINDROCYSTIS, Menegh. 
8. C. AMERICANA, n. sp. (Pl. 18. figs. 5, 6.) 
C. magna, circiter 23-plo longior quam lata; cellulis eylin- 
dricis, in medio distincte constrictis, apicibus rotundatis (semi- 
eireularibus); membraná achroá; pyrenoidibus magnis singulis 
in centro semicellularum, chromatophoris conspicue radiantibus. 
Long. 52 u; lat. 22-21 y. 
Hab. Ithaca, N.Y. (H. J. no. 499). 
This species appears to be sufficiently distinet from C. diplo- 
spora, Lund., the cylindrical cells and semicircular apices being 
quite characteristic. It resembles Penium rufescens, Cleve, in 
form, but it is a little smaller and has a colourless membrane ; 
moreover, the chlorophyll is arranged as in Cylindrocystis. 
9. C. ANGULATA, West & G. S. West, in Trans. Linn. Soc. 
Ser. II. Bot. v. p. 237, pl. 13. ff. 25, 26.—C. tumida, Wolle, Alg. 
U. S. p. 23, pl. 56. ff. 7, 8, non F. Gay. 
A rather smaller and proportionately narrower form : long. 62 y; 
lat. 21 u; lat. isthm. 20 p- 
Hab. De Land, Florida (H. J. no. 590). 
V. PENIUM, Bréb. 
10. P. Crever, Lund. in Act. R. Soc. Scient. Ups. Ser. IIT. viii. 
no. 2, p. 86, t. v. f. 11. 
Long. 75-90 u; lat. 30-33 p. 
Hab. Seattle, Wash. (H. J. no. 637). 
"The smallest specimens are about one fourth smaller than 
Lundell's original measurements, but they resemble his figures 
exactly.” 
11. P. ANNULARE, West, in Journ. Bot. xxix. Dec. 1891, p. 354, 
t. 815. f. 5, 6. 
Hab. Chester, S.C., common (H. J. no. 628). 
“A peculiar form with the constrictions barely visible; lat. 25 p. 
Must be a form of this species." 
This plant is now known from Maine, Pennsylvania, Louisiana, 
and South Carolina. 
