293 
hyaline punctations is difficult to make out. They seem to be be- 
tween the granules in the longitudinal rows. Diam.=72 y; length 
=90n. Fig. 32. 
C. pseudoprotuberans Kirch. New Baltimore, Mich. Rare. 
Typical. Diam=32y; length=36; isth—1op. West re- 
ports this from Maine. Fig. 24. 
* C. costatum Nordst. (522.) Wake Forest, N.C. Scarce. 
Diam.= 32 #; length=42 ; thick.=21 y; isth—=12y. This bears 
some resemblance to C. sub-speciosum var. validius Nordst., but is 
much smailer and with less numerous and larger crenae on the 
margin. Fig. 31. 
* C. Gotlandicum Wittr. Burlington, Kans. Occasional. 
Diam.= 28 ; length= 36; isth—=9oy. This may be the same as 
C. rectangulare Grun. (in Rab. Fl. Eur. Alg.),and in that case the 
latter name should prevail by the right of priority, but it seems to 
me that the identity of the two is not positively proven. This is 
reported as occurring in Nebraska’. Fig. 26. 
* C. granatum Breb. var. sub-granatum Nordst. (341.) Ann 
Arbor, Mich. Occasional. Diam.—25 p; length=36y; isth— 
Sp. Fig. 16. 
* C. Paulense (Borgesen). (C. polymorphum Nordst. subsp. 
Paulense Borgesen). 277. Duval Co., Fla. Scarce. At the sug- 
gestion of Prof. Nordstedt I raise this to specific rank, as it seems 
to differ sufficiently from C. polymorphum Nordst. Diam.= 36 p; 
length=50 y; isth—10y. Slightly smaller than Borgesen’s speci 
mens and differing slightly in the position of the granules, but 
seemingly not distinct. In very clear specimens one can see that 
the wall is hyaline punctate between the five large granules on the 
front. Fig. 17. : 
*C. pericymatium Nordst. (445). Ithaca, N. Y. Occasional. 
Differing from Nordstedt’s figures’ in its deeper constriction in 
side view, but otherwise the same. Diam.=28y; length=5op; 
thick=26y; isth—24y. Fig. 28. 
*C. porrectum Nordst. (360.) Burlington, Kans. Frequent. 
‘8 Contr. from Bot. Dept. of Univ. of Nebraska. New Series III. 46. 14 Je. 1892. 
9 Nordstedt,O. Desmidieae Arctoae. Ofvers. K. Vet. Akad, Forh. 1875: pi. 
7. f. 26. 1875, 
