COSMARIUM. 69 



and convex apex, containing each one chlorophyl nucleus ; 

 cytioderm distinctly punctate. 

 Diameter 24 /*. 



Denmark, and other ponds, New Jersey. 



C. SEXANGULARE, Lund. Plate XIX, figs. 8, 9. Plate LX, 



fig. 13. 



One-fifth part longer than wide; constriction deep; sinus 

 linear within and widening outwardly. Semi-cells more 

 or less hexagonal- elliptic; ends truncate, sides obtusely 

 rounded ; end view elliptical ; side view circular. Cytio- 

 derm finely punctate. 

 Diameter 25-42 //. 



Occurs frequently in ponds, Pennsylvania, New Jersey. 

 The hexagonal feature of the semi-cells is not always as dis- 

 tinct as described ; in the figures 8 and 9 it was inadvertently 

 omitted altogether, nevertheless, they represent a common 

 form of the species. 



C. DEPRESSUM, (Naeg. ', Lund., not Bailey. Plate LXI, figs. 10, 



11, 12. 



Cells usually slightly shorter than wide ; constriction deep; 

 sinus widening outwardly ; semi-cells compressed oval ; the 

 long sides flattened, the others rounded; one chlorophyl 

 mass in each. Membrane finely punctate. 

 Diameter 20-25 p. 



Frequent in pond, Spring Lake, N. J. They are smaller in 

 size than the European form ; otherwise identical. 



Bailey in his contribution, describes another plant under 

 the same name. Naegeli's description has claim of priority, 

 hence must stand. In order to avoid further confusion, I 

 change the name of the former, and in honor of the author 

 call it C. Baileyi. 



C. BAILEYI, Wolle. (C. depressum, Bailey.) Plate XIX, figs. 



17, 18. 



"Elliptical, binate, division in the plane of the longest 

 axis. Segments entire, nearly twice as long as broad, 

 rounded above, very much flattened at base;" cytioderm 

 punctate. 

 Diameter 36-48 /u. 



Florida, (Bailey); and ponds, Mount Everett, Mass. 



"This species resembles C. bioculatum, Breb., but the seg- 

 ments are much closer together, and are angular, not rounded 

 at the basal extremities." Compare Note under C. depression. 



