110 PRESH-WATER ALG^ OP THE UNITED STATES. 



at the ends, which are truncate and often somewhat fuscous ; membrane very distinctly striate, 

 when empty somewhat fuscous ; chlorophyl globules 5-7 (in each limb); vacuole placed in 

 the bent apex, moderately large, including 12-20 corpuscles. 



Remarks. — The measurements given are those of Prof. Rabenhorst. Our Ame- 

 rican forms agree well with them. 



C. angnstatum, Ktz. 



C. gracile, sublineare, diametro 16-18 plo longius, ad polos levissime attenuatum, apicibus late 

 truncatis; costis longitudinalibus paullulum prominulis 4-5, interstitiis circiterjj^'" latis; 

 vesiculis chlorophyllaceis in quoque cruro 6-1 ; locello ab apice subremoto mediocri, corpus- 

 culis 12-20 impleto. (R.) 



Diam.—^y—i^" = 0.00081"— 0.0010". (R.) 



Syn. — G. angustatum, Ktz. Rabenhorst, Flora Europ. Algarnm, Sect. III. p. 126. 



Eab. — In aquis quietis, prope Philadelphia, Pennsylvania. Wood, Rhode Island. Bailey. 

 New Hampshire. (Lewis) 



C. slender, sublinear, 16-18 times longer than broad, very slightly attenuate at the ends, which 

 are broadly truncate ; with from 4-5 somewhat prominent longitudinal ribs, the interstices 

 about 55n"' broad ; chlorophyl globules in each limb 6-7 ; vesicle subremote from the apex, 

 moderate, containing from 12-20 corpuscles. 



C. jnncidum, Ralfs. 



C. elongatum, anguste lineare, diametro 20-35 plo longius, leviter arcuatum, utroque polo vix 

 attenuatum ; apicibus truncatis ; cytiodermate luteolo, interdum longitudinali|;er striate. 



Diam.— j^Vir" =0004". 



Syn. — G. juneidum, Ralfs. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 127. 



Hab. — In fossis. South Carolina. (Ravenel) In lacu Saco, New Hampshire. (Lewis) 



Elongate, narrowly linear, 20-35 longer than broad, slightly bent, scarcely narrowed at the 

 ends ; apices truncate ; cytioderm yellowish-brown, sometimes longitudinally striate. 



Remarhs. — I am indebted to Prof. Ravenel for specimens of this species, by 

 whom they were found on the slimy surface of a half dried-up ditch, associated 

 with numerous other desmids. The specimens are all smaller than the measure- 

 ments of Rabenhorst, but much larger than those given by Mr. Ralfs. None of 

 the plants have any chlorophyl granules — a circumstance probably simply depen- 

 dent upon the stage of their development. The longitudinal striae are in none of 

 the specimens very distinct, and in many cannot be demonstrated. 



Since writing the above I have seen specimens collected by Dr. Lewis in " Saco 

 Pond," near the Crawford House, New Hampshire. 



Mr. Archer (Pritchard's Infus., p. 749) lays stress upon the fronds being straight 

 in the middle, with the ends curved downwards ; but I have seen numerous speci- 

 mens in which the curve was through the whole length. 



Fig. 2 o, pi. 12, represents one of the specimens collected by Prof. Ravenel in 

 South Carolina. 



2. Gellulse cylindricse, dorso plus minus convexae, venire subplanse, nunquam ventricoso 

 — injiatae. 



