FRESH-WATER ALGJE OF THE UNITED STATES. 117 



Ilab. — In fossis, Atlantic States. 



Four to si.x times longer than broad; from the front cylindrical, not attenuate at the truncately 

 rounded ends ; viewed laterally fusiform, attenuated from tbe middle to the rounded ends ; 

 cytioderm striately punctate. 



Remarks. — The central constriction is more apparent in the lateral than front 

 view. When the frond is full of endochrome the punctae on the outer wall are 

 not apparent, hut vvlien it is empty they are seen to be small, and closely arranged 

 in stria-like rows. This species extends through all the Atlantic sea-board States. 

 Prof Bailey has found it in South Carolina and Florida, as well as in llhode Island. 

 I have collected it in Centre County, of this State. 



Fig. 3, pi. 21, represents an empty half frond of this species; 3 a the outline of 

 the frond. 



T. g^raniilatus, (Breb.) Ralfs. 



T. habitu Tetm. Brebissonii, sed major et cytiodermate irregulariter granulato-punctato. (R.) 

 Diam.—^\-s" = mU". (.00155". R.) 



Syn. — T. granulalus, (Brebisson.) Ralfs. Rabenhorst, Flora Europ. Algarum, Sect. III. 

 p. 140. 



Hab.—Pvo\w. Philadelpbia ; "Wood. Rhode Island; (S. T. Olney.) Thwaites. South Caro- 

 lina ; Bailey. 



Frond somewhat longer than T. Brebissonii, about five or six times longer than broad ; in both 

 f. V. and s. v. fusiform, the constriction a very shallow groove, ends with a hyaline lip-like 

 projection extending beyond the notch ; endochrome with a longitudinal series of large 

 granules; e. f. punctate, the puncta scattered, except near the constriction; where they are 

 disposed iu two transverse rows. Sporangium orbicular, smooth, margin finely striated, jilaced 

 between the deciduous empty fronds. L. -j-^iy"- B. ■^\^". Archer. Pritchard's Infusoria. 



Remark. — Fig. 8, pi. 12, represents this species magnified 450 diameters. 



T. g^iganteiis, Wood. 



T. maximus, oblongus, diametro 3 plo longior ; apicibus hand attenuatis, late rotuudatis; suturis 

 profundis, linearibus; cytiodermate irregulariter granulato-punctato. 



Diam.—^IW = .0031". 



Syn. — T. giganleus, Wood. Proc. Acad. Nat. Sci., 18G9. 



Ilab. — In stagnis, Centre County, Pennsylvania. 



Very large, oblong. 3 times longer than broad ; with the ends not attenuate but broadly rounded ; 

 suture profound, linear ; cytioderm irregularly granulately punctate. 



Remarks. — I found this beautiful desmid in a stagnant pool in Bear Meadows, 

 Centre County, in the month of August. It is very different in its outline from 

 its nearest ally, T. (jranulatus. The diameter is preserved uniform until near the 

 end, where there is an alteration in the line of the margin, so as to cause 

 some contraction, which is, however, wanting in some specimens. The ends are 

 therefore broad and obtuse. The size is also double that of T. gramdatus. 



Fig. 7, pi. 12, represents a frond of this species magnified 260 diameters. 



