CIXDSTERIUM. 13 



C. lineatuMj Ehrb. Plate VI, fig. 16. 



Long, straight and cylindrical in the centre, ends greatly 

 attenuated and slightly incurved, apices obtusely rounded, dis- 

 tinctly striate; chlorophyl globules, about twenty in each 

 semi-cell, placed in a single axillary series : vacuoles small, 

 remote from the apices. 



I Hameter 2 1 36 ". 



Pennsylvania, New Jersey, and probably every State. 



C. i'i' orum, Breb. Plate V 1 1 . fig. I . 



Moderately arched, 1216 diameters in length, gradually 

 tapering from the centre to one-fourth or one-fifth of largest 

 diameter; ends rounded; vacuole small. Cvtioderm fineh 

 striate. Zygos]>ores angular in European specimens. 



I tiameter 3 I 1 1 " 



Occurs occasionally in sluggish waters, Pennsylvania and 

 Nt w Jersey. This form is separated from C. striolatum, 

 mainly by the larger cumber of Btriae; the one has 1215 

 and the other 20 30 



C. A.REO] \ ri m. Wood. Plate VII, figs. 3, I. 



Fusiform, straightish, or ven slightly curved, the ventral 

 side often a little concave in the middle; 910 times longer 

 than broad, moderately attenuated at each end ; the apices 

 truncate^ rounded; cell-membrane reddish brown, thick and 

 firm, distant!} profoundly striate, and verj minutely l>ut dis- 

 tinctly granulate <r areolate ; midian sutures very distinct. 

 1-K> in number. 



I h'ameter 6( u. 



Dr. Wood remarks: "I found this species growing in a 

 quiet pool uf pure water, in a wild, deeply wooded ravine. 

 near Danville, Central Pennsylvania. It was in great, abund- 

 ance, forming a translucent greenish jelly, one or two gills of 

 which might have been readily gathered." " This species is 

 very closely allied to C. titrr/ithtm. Khrh.. :t li i i 1 1 lt pretty 

 well with it in general outline and size. I think, however, 

 the peculiar markings upon the membrane are sufficient to 

 separate it." "The turning up of the ends, generally so 

 marked in C. turgidum is mostly entirely absent in this 

 specie-, rarely there is some tendency to it." 



