58 DESMIDS OF THE U>'rTED STATES. 



Var. TUEGiDUir, (fig. 11). WoUe. Shorter and stouter, often 60 n. 



Of frequent occurrence In pond waters, Maine to Florida. 



The number of whorls varies from 12-16 in a semi-cell. 

 In living condition the cells are green, but more commonly 

 they are found of brownish red color. 



Plate X. fig. IS. This illustration given as another of 

 many forms in which this species often occurs. The third 

 diverging process of the apical termination not always 

 evident. 



W. X. Hastings, Rochester, Xew Hampshire, reports this 

 form frequent in the Cocheco River. 



D. GEACiLE, (Triploceras gracile\ Bail. Plate XIII, figs. 3, 6, 7, S. 

 Differs from the last in usual smaller size of cell, smaller 

 and more acute tooth-like prominences of the whorls. 

 Diameter 2(t-2S j^., exceptions, up to 40 //. 



Habitat the same as the former. 



The whorls appear to be composed of a double series of teeth, 

 but frequently the second row is barely evident. Fig. 3 is of 

 unusual size. Fig. 7 represents a condition of dissolution ; 

 the contents have escaped, and the parts constituting the cell 

 have separated, contracted and assumed a partially inverted 

 position. 



Gemts. CALOCTLIXDErS. D. By. 



Cells straight, cylindrical, ends rounded or truncate : semi- 

 cells without basal inflation, or longitudinal plication: chloro- 

 phyl parietal or axillary. 



C. Ealfsii. (Kg. ). Kirch. ( Cosmai-ium cylindricum. Ealfs). Plate 

 XT, fig. 17. 

 Cells cylindrical, about twice as long as wide. Semi-cells 

 subquadrate in front view, broadest at the extremity : cytio- 

 derm more or less granulated. 

 Diameter about 24 //. 



Pools fresh water, Pennsylvania and New Jersey. 



C. De Baeti. Arch. Plate XLT, fig. 12. 



A specimen from ^Minnesota, the typical form, unlike the 

 one fig. 5. Plate XT, which is more like a form of C. Cu- 

 cumis: the constriction is not deep, linear, but merely a 

 shallow notch, hence De Bary classified it vrith Pleurotaenium. 



