294 MESSRS. W. WEST AND G. S. WEST ON 
Euastrum mediocre, circiter 1j-plo longius quam latum, 
profunde constrictum, sinu angusto-lineari extremo ampliato; 
semicellule truncato-pyramidate, angulis basalibus latissime 
rotundatis, lateribus superioribus retusis, apicibus late truncatis 
retusisque, argulis superioribus rotundatis; a latere vise trun- 
cato-ovate apice retuso; a vertice vise ellipticw, polis acute 
rotundatis, ad medium utrobique leviter sed late inflate; mem- 
brana granulata, granulis numerosis subconcentrice ordinatis. 
Long. 65-85 u; lat. 60-71 p; lat. apic. 27-33 p; crass. 42 p. 
Hab. Near Orono, Maine. Ponds, Pennsylvania. Evanston, 
DI. (H. J. no. 80). Waverly, Mass. (H. J. no. 21). 
Distrib. Canada and North Wales. 
After examining large numbers of this species from various 
localities and finding its characters quite constant, we are now 
convinced that it is certainly distinct from E. verrucosum, under 
which species Joshua placed it as a variety. Cosmarium pro- 
tractum, Wolle (l. c.), also evidently belongs to this species. 
Joshua’s figure is more accurate in outline than that of Wolle, 
but shows too few granules. The specific name ‘simplex’ could 
not be adopted as this name has already been given to two 
species of this genus. 
56. E. verrucosum, Ehrenb.; Ralfs, Brit. Desm. p. 79, t. 1l. 
f. 2. 
Var. atatum, Wolle, Desm. U. S. p. 101, t. 26. f. 4. 
Hab. Baton Rouge, Louisiana (H. J. no. 321). 
Var. nEDUCTUM, Nordst. in Act. Univers. Lund. xvi. p. 9, t. 1. 
f. 14. 
Long. 64 ye; lat. 60 p. 
Hab. Wake Forest, New Connecticut (H. J. no. 529). 
XII. MICRASTERIAS, 4g. 
57. M. arcuata, Bail. in Smithson. Contrib. ii. Art. 8, p. 9^ 
t. l.f. 6 (1851); Nordst. in Ofvers. K. Vet.- Akad. Fork. no. 3 
(1877), p. 22-23 cum fig. xylogr. II. 1, 2 c. 
Var. GRractiis, West & G. S. West, in Trans. Linn. So 
(Bot.) v. p. 238, pl. 13. f. 27. 
Long. 73 p; lat. 121 p; lat. isthm. 10 p. 
Hab. De Laud, Florida. 
58. M. PINNATIFIDA, Ralfs, Brit. Desm. Pp- 77, t. 10. f. 3.— 
Euastrum pinnatifidum, Kiitz. 
c. Ser. IL 
