FRESH-WATER ALG^ OF THE UNITED STATES. 117 



Sab. — In fossis, Atlantic States. 



Four to six times longer than broad; from the front cylindrical, not attenuate at the tmncately 

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

 cytioderm striately punctate. 



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

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

 not apparent, but when 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 Ehode 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. granulatns, (Bb£b.) Ralfs. 



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

 Drnm.— t1/ = .0013". (.00155". R.) 



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

 p. 140. 



Hab. — Prope Philadelphia; 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 in two transverse rows. Sporangium orbicular, smooth, margin finely striated, placed 

 between the deciduous empty fronds. L. xiV- B. ^^V'- Archer. Pritchard's Infusoria. 



* 



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



T. grii^antenS; Wood. 



T. maximus, oblongus, diametro 3 plo longior ; apicibns hand attenuatis, late rotundatis ; suturis 

 profundis, lineafibus ; cytiodermate irregulariter granulato-punctato. 



i%am.— tI^/ = -0031". 



Syn. — T. giganteus, Wood. Proc. Acad. Nat. Sci., 1869. 

 Hab. — 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. 



Bemarhs. — 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. granulatus. 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. granulatus. 



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



