THE ALG^ 403 



Docidium minutum Ralfs. 



PleurotcEniwn? juinuiuin (Ralfs.) Delponte. 

 In freshwater near Prince William Sound. 

 Diameter 1 1 //, length 135 M- 



Arthrodesmus convergens Ehrenb. (Plate xliv, fig. 14.) 



In a freshwater pond near Seldovia, Cook Inlet (422). Rare. 

 Diameter 32//, length 32/2 without the spines. 



Xanthidium antilopaeum (Breb.) Kuetz. (Plate xliii, fig. 38.) 



In a freshwater pond near Cook Inlet. 



Diameter 55 /M, length 55 // including the spines. The spines near 

 the apex of the semi-cells are more nearly straight than in the figures 

 given of this species. 



Xanthidium armatum (Breb.) Ralfs. (Plate xliv, fig. 18.) 



In a freshwater pond near Virgin Bay, Prince William Sound. 

 Diameter 81 /x, length 128^. Most of the spines are bifurcated, 



with the points divergent. 



Cosmarium granatum Breb. (Plate xliii, fig. 8.) 

 In a freshwater pond near Seldovia, Cook Inlet. 

 Diameter i8^«, length 33 /a. 



Cosmarium constrictum Delp. (Plate xliii, figs. 33, 34.) 



In a freshwater pool near Virgin Bay, Prince William Sound (300). 

 Diameter 40 /i, length 65 //. 



Cosmarium bioculatum Breb. (Plate xliii, fig. 28.) 



Common in a freshwater pond, Seldovia, Cook Inlet (422). 

 Diameter 16-1S/2, length 17-18 />t. 



Cosmarium hammeri Reinsch. (Plate xliii, fig. 7.) . 



In a freshwater pond near Seldovia, Cook Inlet (422). 



Diameter 10-14 /y, length 18-22/^. Very close to the variety ^M^aw- 

 gustatum of Boldt. The angles are a little more acute than in the 

 type ; the apex of the semicells is very emarginate. 



Cosmarium depressum (Naeg.) Lund. (Plate xliii, fig. 17.) 

 In a freshwater pond near Seldovia, Cook Inlet. 

 Diameter 16-20//, length 18, a. 



Cosmarium holmiense Lund. (Plate xliv, fig. 28.) 

 In freshwater near Kukak Bay. 

 Diameter 32//., length 54//. 



Cosmarium venustum (Breb.) Arch. 



In a freshwater pond near Seldovia, Cook Inlet. 



