1893.] NATURAL SCIENCES OF PHILADELPHIA. 463 



Dicoccum nebulosum E. & E. 



On Fraxinus Americana, Sept., '93, Wisconsin. (Dr. J.J. Davis). 



Hypophyllous, spots none. Conidia obovate-oblong, olivaceous, 

 1 -septate, 11-13x4,", apiculate below, -rounded above sessile, like the 

 preceding species scarcely constricted, and with the septum above the 

 middle, but differing in the absence of any spots and smaller conidia, 

 which form faint olivaceous, more or less confluent patches, without 

 any distinct hyphae. 



Cladosporium nigrellum E. & E. 



On bark of R. R. ties, Nuttallburg, West Va. Oct., 1893. (L. 

 W. Nuttall, No. 172). 



Hyphae densely tufted, septate, subequal, 150-200x5-6//, tufts 

 effused, subconfluent, forming a black, velvety coat extendiug over the 

 surface of the bark indefinitely, with the same habit as Maerosporium 

 nigrellum C. & E. Conidia smoky hyaline, becoming pale brown, 

 variable in size, the smaller ones ovate, continuous or uniseptate, 

 6-8 x 5,", the larger ones oblong-elliptical or subcylindrical, 2-3-sep- 

 tate, 12-15 x 5-6,". 



Clasterisporium olivaceum E. & E. 



On old com stalks (Zea Mays), Newfield, N. J. May 14, 1893. 



Forms a thin, dark olive layer (becoming nearly black), composed 

 of much branched, creeping hyphae, hyaline at first, becoming 

 brownish and closely appressed to the matrix. Conidia cylindrical, 

 4-8 -septate, constricted at the septa, obtuse, 20-25x6,"., arising 

 directly from the creeping hyphae without any visible pedicel. 



Cercospora exotica E. & E. 



On leaves of some cultivated water lily in an aquarium on the 

 World's Fair Grounds, Chicago, 111. Oct., 1893. (E. F. Smith). 



Spots epiphyllous, orbicular, small (2-4 mm.), dirty-brown, with 

 or without a slightly raised border. Hyphae densely fasciculate, 

 subolivaceous, simple or with a short, rudimentary branch above, 

 25-40 x 22-3,". Conidia slender, linear, multiseptate, hyaline, 

 80-150 (exceptionally 190)x3-3 2; ", nearly straight. 



Closely allied to C. nymphaeacea C. & E. , but hyphae and 

 conidia twice as long as in that species. The tufts become effused and 

 appear like a lead-colored, thin tomentum, covering the central part 

 of the spots. 



