[403] THE ALG^E 167 



Docidium minutum Ralfs. 



Pleurotcenium ? minutum (Ralfs.) Delponte. 

 In freshwater near Prince William Sound. 

 Diameter 1 1 /*, length 135 /*. 



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



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

 Diameter 32 /i, length 32 /z without the spines. 



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



In a freshwater pond near Cook Inlet. 



Diameter 55 /z, 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 Si//, 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 iS//, length 32^. 



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



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

 Diameter 40^., length 65/1. 



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



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

 Diameter i6-iS/z, length 17-18 /a. 



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

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

 Diameter 10-14 //., length 18-22/7.. Very close to the variety suban- 



gustatitm 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 /z, length iS//. 



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

 In freshwater near Kukak Bay. 

 Diameter 32/7., length 54 A*. 



Cosmarium venustum (Breb.) Arch. 



In a freshwater pond near Seldovia, Cook Inlet. 



