C06MARIUM. 59 



C. SCENEDESMUS, Delp. Plate L, figs. 7, 8, 9. 



Cells Hiioorh. not as long as broad, depressed, constriction 

 deep. Bin us narrow linear; semi-cells subsemicircular, base 

 nearly straight, ends a depressed arch, angles rounded ; end 

 view elliptic; side view circular. 

 Diameter 32-38 u. 



Reminds stronglj of C Phaseoltu, l>ut has no reniform 

 base, and do central inflation. Sinn- of fig. 7 too much am- 

 pliated. 

 ( Occurs frequently. 



C. quadratum, Ralfs. Plate XVIII, figs. 8,9, 10. 



Smooth, deeply constricted at the middle ; semi-cells in fronl 

 view quadrate, with a slight protuberance on each side above 

 the base, giving the sides a retuse appearance, .*i ultI<~ rounded ; 

 chlorophyl in larger forms usually divided into two masses. 

 Diameter, smaller form -<> 23 ". larger form 10 u. 

 Ponds, Pennsylvania, rather rare. 



The apices of the two forme differ; the smaller ones an 

 more or less retuse, and Lhe larger ones convex, lie' length 

 ef each i- twice the diameter. 



C. ANCEP8, Lund. Plate Will. fig. I I. 



Small, tii 1 1 twice as long a- broad, hexagonal-oblong ; sinus 

 narrow linear ; side view oblong \\ it h sides slightly emarginate ; 

 apices rounded ; semi-cells quadrate, rather longer than broad, 

 tapering moderately from base to end; end view sub-circular. 

 Membrane smooth ; isthmus half the diameter of the cell. 

 Diameter 17-ls u.\ length 1560 u. 



Tin; only plant I have found to barmouize with this de- 

 scription, van collected by J. I). Smith in Florida. It 

 agrees very well except in length, being nearly equal to three 

 diameters. 



C. parvulum, Breb. Plate XVIII, fig. 12, 13. 



Cells small, ovate elliptical, lightly constricted, apices trun- 

 cate, two to nearly three time- as long a- wide; margins 

 entire, or sometimes lightly crenulate ; semi-cells short conical, 

 broadly truncate or sometimes with apex retuse ; cytioderm 

 smooth or finely punctate. 



Diameter 18-22 a. 



Florida, collected by J. D. Smith. 



