266 PROCEEDINGS OF THE AMERICAN ACADEMY 



of forms in this instance also. The material thus named occurring in 

 America includes at least two, and perhaps three forms ; one, which 

 for convenience we will call lacerata, x, is found abundantly in this 

 vicinity and further to the eastward on the fruit, stems, and less fre- 

 quently on the leaves, of Amelanchier and Cratcegus, during June and 

 July, wholly disappearing by the end of the latter month. A second 

 form, lacerata, y, infests the leaves of Cratcegus, and does not appear 

 until early in August ; while a third and smaller form, lacerata, z, is 

 found abundantly on Pyrus mains simultaneously with it. 



The first of these (lacerata, x) is very similar to Oersted's figure of 

 lacerata, and is identical with the European carfOfMla of Baguis, dis- 

 tributed in Herb. Critt. Ital. II. 732, and in Myc. Univ. 1326, while 

 it occurs under lacerata in various other exsiccati on Cratcsgus, and 

 seems undoubtedly distinct from the forms y and z, of whith the first 

 is usually considered the more typical form of lacerata, while the sec- 

 ond is referred with some doubt to the same species. In general ap- 

 pearance it bears a superficial resemblance to penicillata and pyrata ; 

 but although the peridium tends to become finely shredded, the shreds 

 are straight, diverging only slightly, without any tendency to curl out- 

 wards as in these species ; nor is this tendency observable in single 

 cells. The spores are large, having a diameter of about 27 /^, while 

 the peridial cells are long and narrow, about 90 X 16/x, the outline 

 broken by fine, not very distinct ridges, the striae somewhat obscure 

 and horizontal. 



In the forms y and z, the spores are smaller, about 20 ju, in di- 

 ameter, while the peridial cells are smaller and broader in proportion 

 to their length, about 20 X 65 /a, with a tendency to a rhomboidal 

 shape; the ridges are deep and sharply cut as a rule, with the striae 

 clearly marked and running obliquely in two directions ; those above 

 the median line, where the strite are horizontal, running in a plane 

 nearly at right angles to those below it. The two forms seem nearly 

 identical microscopically ; the spores and peridial cells of z are per- 

 haps slightly smaller, but otherwise it differs from y only by its smaller 

 size and faded yellow color. 



It should be remarked, that, from a microscopic point of view, the 

 Rcestelia obtained on Crataegus after sowing G. clavariceforme was 

 identical with the form x ; while in habit it resembled y very closely, 

 the peridia being but slightly lacerate. It must be remembered, how- 

 ever, that the cultures were not exposed to the weather, being kept 

 indoors during their whole development, and that, had they been ex- 

 posed to rain and wind, a different habit might have supervened, as was 



