31 



Perithecia scattered, flattened. Microthyrium. 



Perithecia stromatic. Lasiohotrys. 



3. Perithecia subglobose, appendiculate. Meliola. 

 ■ Perithecia subglobose, not appendiculate. Dimerosporium. 



Perithecia flattened. - Asterina. 



Perithecia elongated, subulate, etc. Capnodium. 



Mycelium massive, coarse. Scorias. 



DIMEROSPORIUM, Fekl. 



Symb. Myc. p. 8g. 



Perithecia superficial, subglobose, subastomous, membranaceo- 

 carbonaceous. Mycelium copious, black, bearing conidia. Asci short, 

 8-spored. Sporidia didymous, hyaline or brown. 



D. piilchrum, Sacc. P. Ven. II, p. 299. 



Apiospovium pulckrum, Sacc. iu Thum. M. U. No. 52. 

 Exsicc. Rab. F. E. 2149, 2684.— Thum. 1. u. 



Mycelium mostly epiphyllous, dark brown, often nearly covering 

 the surface of the leaf. Conidia lateral on the branches of the my- 

 celium, at first spherical with two septa at right angles to each other, 

 and then 4-celled, at length dark brown, many-celled and more irregu- 

 lar in shape, 20-25 fi diam. With these are also subfalcate, 3-septate, 

 hyaline conidia 35-40 x 8-9 [i, not constricted at the septa. Peri- 

 thecia scattered among the mycelium, clear yellow-brown, 80-100 /x 

 diam. Asci elliptical, 46 x 30 fi, 8-spored. Sporidia elongated-ovate, 

 uniseptate, constricted in the middle, hyaline, 22x11 fi. 



Only the conidial form has yet been found in this country, but 

 this is quite common west and southwest, from Iowa to Texas, on 

 leaves of Cornus, Fraximis and other trees. 



D. Collinsii, (Schw.) 



SphcEria Collinsii, Schw. Syn. N. Am. 1512. 

 Dimerosporium Collinsii, Sacc. Syll. I, p. 54. 

 Sbhcsria papilionacea, B. & C. Grev. IV, p. 106. 

 Sphceria Russellii, B. & C. Grev. 1. c. (sec. Cke. Grev. XV, p. 82). 

 Exsicc. Thum. M. U. 849.— N. A. F. 488.— Rab. P. E. 3541- 



Mycelium brown-black, septate, crustaceous, hypophyllous, cover- 

 ing the whole surface. Perithecia black, globose, closely aggregated, 

 150-160 p.. Asci cylindric-clavate, 8-spored, 45-60 x 10 p. Sporidia 

 hyaline, oval, uniseptate, 2-seriate, 12-15x3-4 fi. 



On leaves of Amelanchier Canadensis, and A. alnifolia, New 

 York, Massachusetts, Prince Edward's Island, and Sierra Nevada 

 Mts., California. 



