006MARIUM. 75 



Var. TDMIDUM, Wolle. Plate XVII, rigs. 3-5. 



In outline, front view, very near'' '. Botryti8,yel entirely unlike 

 it in Bide and end views, which show a central inflation. Found 

 it in only one locality in a meadow pool, near Bethlehem, Pa. 

 Further observation may prove ir a distinct species. 



C. Brebjssonii, Menegh. Plate XIII. Bgs. 10, 11. 



Cells somewhat longer than broad; Bemicells semiorbicular, 

 rough with conic -pine- or granules; end view elliptic or oval. 

 Diameter 1565 //. 



Cells generally larger than C. margariiiferum ; semicells 

 nior' oval, but separable only by the armor of conicalgranules. 

 Nol bo frequent as the preceding, but appears to be widely 

 distributed. 



C. CON8PEE8UM, Ralfs. Plate XIV, figs. 1,2. 



(Vll> somewhat longer than broad, quadrilateral, angles ob- 

 tusely rounded; constriction deep, produce- a linear notch on 

 each side ; granules pearly, large, depressed, giving a crenulate 

 appearance to the margin. 

 Diameter 50-73 u, 



A beautiful and conspicuous Bpecies, frequently found in 



large iiumher.-: it is easily distinguished by it.- large size and 

 quadrangular form. 



C. TETRAOPHTHALMUM, Kg. Breb. Plate XIII, fig. 13. 



Cells one-third to one-halt' longer than broad; Bemicells 

 semiorbicular somewhal elevated, rough with pearly granules 

 which give a crenate appearance to the margin ; chlorophyl 

 masses two, often very conspicuous. 

 Diameter 6078 n. 



Rather common. The semicells are usually near in form 

 to two-thirds of a circle. The transverse view La broadly 

 elliptic. The four chlorophyl nuclei, which are frequently 

 very prominent, two in each semicell, probably suggested 

 the name, four-eyed. 



C. tNTERMEDIUM, Delp. Plate XIII, fig. 12. 



Cells very near the preceding (O. tetraophthalmum,) some- 

 what smaller, semicells more absolutely semiorbicular, not so 



elevated. 



Diameter 45-50 . 



Habitat same as the preceding. 



