186 
Journal of Mycology 
[Vol. 12 
spicuous stromata, but as a rule one side has fewer spots; some¬ 
times it is the upper surface of the thick fleshy leaf, sometimes 
the lower that shows more conspicuous and abundant infection. 
The fungus is a species of Plowrightia apparently unde¬ 
scribed. Tracy and Earle published, in the Bulletin of the Tor- 
rey Botanical Club, March 1901, p. 187, a species of this genus 
under the name of Plowrightia circumscissa, which they gave as 
occurring “on languishing leaves of some aloe (Agave sp. ?),” 
collected in Florida. When this was compiled by Saccardo for 
the Sylloge the host name “Alo.e” was omitted and the entry 
was made as follows: “in foliis languidis Agaves spec.” Some 
of the material from Tracy and Earle’s type No. was kindly fur¬ 
nished me from the Missouri Botanical Garden where, Prof. 
Tracy informed me, his collections had been sent. After thus 
passing through Dr. Trelease’s hands I find the host given on the 
label as Yucca gloriosa (Y. aloifolia). It seems certain therefore 
that Tracy and Earle’s host is not an Agave as mine is. At any 
rate my Plowrightia is very different, both in microscopic char¬ 
acters and especially in the appearance and disposition of the 
stromata. Compare Fig. 1, which shows two spots of the fungus 
here in question, and Fig. 6, which presents a portion of a leaf 
affected by Plowrightia circumscissa Tracy & Earle. A specimen 
of my material sent to Prof. Tracy elicited the reply: “Very dif¬ 
ferent from mine.” 
Another fungus somewhat similar in outward appearance to 
the Plowrightia, also collected in Guatemala, is shown in Fig. 7. 
It is Colletotrichum agaves Cav. No evidence was found to verify 
the suspicion at first entertained that the two might be forms of 
one and the same life cycle. Hedgecock reports (Annual Report 
of the Missouri Botanical Garden, 16:153-6. 1905) a study of 
this fungus, and he says “no ascigerous stage was found.” 
The technical description of the Plowrightia is given below. 
I have selected the specific name in honor of Mr. G. F. William¬ 
son, of Guatemala, whose courtesies materially assisted in the 
botanical explorations both of 1905 and 1906. Mr. R. A. Young 
assisted in the study of the fungus and he and Mr. L. A. Hawkins 
prepared under my direction the illustrative drawings. 
Plowrightia williamsoniana Kellerm. n. sp. Stromata 
rupturing the epidermis, prominent, globular to sub-quadrangular 
or oblong, J-j- mm. high, \-2 mm. long, arranged concentrically 
in five to ten (or more) somewhat irregular rows, the inner larger, 
the outermost poorly developed and scarcely lifting the epidermis, 
forming at first a definite suborbicular or oblong spot, but later 
fusing with adjacent affected areas, in many cases finally occupy¬ 
ing nearly or quite the entire leaf. 
The stromata are at first reddish yellow, becoming gradually 
brown, and finally black, the surface minutely papillate, the sub- 
