Desmidiece.] INFUSOEIAL animalcules. 253 



Iff Margin of segments crenate ; surface not granulate. 



CosiTAiauir Jleneghinii. — Exceedingly minute ; smootli, deeply con- 

 stricted ; segments sub-quadrate; sides and ends bier enate. Transverse 

 view elliptic. (l-853rd.) 



G. crenatmi. — Punctate, deeply constricted; segments crenate, 

 and flattened ; spines of orbicular sporangia very short. Smaller 

 than C. margaritiferum ; end view elliptic. The depressed ends 

 distinguish this species from the next. (l-474th.) 



C. unduhtum. — Deeply consti'icted ; segments semi-orbicidar, cre- 

 nate; sporangia Avith elongated spines. Transverse view elliptic. 

 (P. 13. f. 33. 34.) f. 34 shows the sporangium. 



t f t Frond ivith pearly granules, ivhich give a denticulate appearance 

 to the margin. 



C. tetraophthalmum. — Compressed, deeply constricted ; segments 

 semi-orbicidar, rough with pearly granules ; hence margin crenate. 

 Lai'ger than C. margaritiferum. Transverse \-iew broadly elliptic. 

 Spoi'angia large, -\Aith branched spines. 



C. ovale. = Euastrum carinatum (Ehr.) — Large elliptic ; deeply 

 notched, linear; segments with a marginal band of pearly granules; 

 disc punctate. Granules confined to the margin, in 3 to 6 rows, 

 leaving the disc free. Length 1-1 39th. 



C. Botrytis. = Euastrum lofrytis and E. angulosuni (Ehr.) — Gra- 

 nulate ; with a deep linear constiiction ; segments in fi'ont view, trun- 

 cato-triangidar ; end view elliptic. Margin denticulate. Sporangia 

 orbicular, spines elongated, and slightly divided at the apex. 

 (l-460th.) 



C. margaritiferum. = Euastrum margo/ritiferum (Ehr.) — Rough, 

 with rounded pearly granules ; segments semi-orbicidar, or reni- 

 form ; end view elliptic ; notch linear. Sporangia orbicular, enclosed 

 in a granulate cell, usually somewhat angular. 



The rough fi'ond distinguishes it from C. crenatum and C. undu- 

 latum ; its rounded ends from C. botrytis, and its less angular shape 

 from C. conspersum. Size variable. (P. 2. f. 126.) 



C. Brehissonii. — Compressed, rough with conic spines, or granules ; 

 segments semi-orbicular ; end view elliptic. Larger than C. marga- 

 ritiferum ; notch deep, Unear ; gi'anules or spines longer than broad. 

 (1 -285th.) 



