112 FRESH-WATER ALG^ OF THE "UNITED STATES 



Fusiform, straightish, or very slightly curved, the ventral side often a little concave in the 

 middle, 9-10 times longer than broad, moderately attenuated at each end; the apices trun- 

 cately rounded ; cell-membrane reddish-brown, thick and firm, distantly profoundly striate, 

 and very minutely but distinctly granulate or areolate; median sutures very distinct, 

 4-10 in number. 



Remarhs. — I found this species growing in a quiet pool of pure water, in a wild, 

 deeply wooded ravine, near Danville, Central Pennsylvania. It was in great 

 abundance, forming a translucent greenish jelly, one or two gills of which might 

 have been readily gathered. Unfortunately, I had no microscope with me and 

 cannot, therefore, determine at all as to the arrangement of the endochrome, the 

 carbolic acid, used as preservative, having entirely disarranged this by the time I 

 got the fronds upon a slide. The empty frond is of a reddish-brown color. The 

 membrane is quite thick and firm, and is marked with very prominent broad striae 

 or grooves. In a number of cases I have counted these and always found nine 

 present upon one face of the frond. There are also upon the surface numerous 

 minute markings not fairly visible with a lower power than a y^th objective. 

 Under this glass they appear as minute punctations. An eighth resolves them 

 into granules mostly of an oblong shape, arranged more or less regularly in longi- 

 tudinal rows. Very generally, each side of the stria or groove has a close row of 

 larger and more distinct granules forming a sort of border to it. In truth, the 

 surface of the frond is covered with broad longitudinal bands of these granules, 

 and the narrow smooth spaces between them constitute the stria spoken of. This 

 species is very closely allied to G. turgidum, Ehkb,, agreeing pretty well with it in 

 general outline and size. I think, however, the peculiar markings upon the 

 membrane are sufficient to separate it, and do not doubt that if fresh specimens 

 were at hand, differences would be found to exist also in the arrangement of the 

 cell-contents. The turning up of the ends, generally so marked in C. turgidum, 

 is mostly entirely absent in this species, rarely there is some tendency to it. 



Fig. 6, pi. 11, represents in outline a frond magnified 160 diameters; Fig. 6 a, 

 the end of an empty cell, magnified 1375 diameters; the color of this is, perhaps, 

 a little too dark. 



C. lineatnm, Ehbb. 



C. valde elongatum, gracile, quater vicies-tricies longius quam latum, distincte striatum, e 

 medio recto cylindrico ntrinque valde attenuatum, apices versus leviter incurvum, obtuso- 

 truncatum; vesiculis chlorophyllaceis in quoque crure 20-21, in seriem unicam axilem dis- 

 tributis ; locello parvo, ab apice remoto, corpusculis 10-12 impleto. (R.) 



Diam.—s^jys" = .0015". 



Syn. — G. lineatum, Eheb. Rabenhorpt, Flora Europ. Algarum, Sect. III. p. 130. 



Bob. — Pennsylvania, Wood. 



Very much elongate, slender, distinctly striate, from the centre straight and cylindrical, at each 

 end very greatly attenuate, apex bent, slightly incurved, obtusely truncate; chlorophyl glo- 

 bules 20-21 in each limb, placed in a simple axillary series; vacuole small, remote from the 

 apex, containing from 10-12 corpuscles. 



Remarks.— The American forms agree well with the above description ; some 



