-I'HAEROZOSMA. 31 



not seem to admit of separation. The cells are often only 

 slightly inflated, sides nearly straight ; the spines, in young 

 condition nearly obsolete, or very small and straight, and the 

 glandular processes sometimes short, barely discernible, and 

 again so long that they lap over the cells. 



S. (Onychoneina) XORDSTEDTIANA, Turner. Plate XLIII, figs. 



9, 10. 



Cells forming filaments of fifty to sixty cells or more con- 

 nected by subcapitate claspers peculiar to the genus. Length 

 of cells 14 /Y. ; breadth 18 //. ; breadth of sheath 30-40 /*. 

 The rather unusual size, and that it has not been found 

 where other forms prevail, Mr. Turner considers evidence 

 of a distinct species rather than a merely young form. 



S. WALLACHII? Jacobsen. Plate IV, fig. 15. 



A peculiar form of which I found only two short speci- 

 mens in pond, Brown's Mills, X. J. They are not identical 

 with the form described by Jacobsen. I record the figures 

 of them provisionally until other specimens may be found 

 to verify a good species. 



Diameter 10-12 yu. 



S. SPINULOSUM? Delph. Plate IV, fig. 14. 



Another variety of which I found only a single specimen, 

 in a pond known as Chain Dam, Northampton Co., Pennsyl- 

 vania. In a Florida collection are numerous well developed 

 specimens, which agree with Delpont's diagnosis in being 

 really spinous. They have the form of cell, the measure, 

 and the arrangement of the spines, except perhaps that 

 there are more frequently only two, than three spines, on 

 the margin of each semi cell. A fine and distinct species. 

 If the granules of the figure (Plate IV, fig. 14) were drawn 

 out into short spines, the typical plant would be well repre- 

 sented. It is not the same, but near Delpont's described 

 form. 



Diameter 10 //. 



S. RECTAXGULARE, Wolle. Plate LX, fig. 9. 



Filament wide ; cells twice as wide as long, deeply con- 

 stricted in the middle ; semi-cells somewhat tapering near 

 the ends, producing acute-angled sinuses between the cells, 

 and between the semi-cells; ends truncate concave, and 

 angles often cuspidate. Membrane smooth. 



Diameter 50-55 //. ; thickness 18-20 jw. 



