(257) 
However similar in the characters of their apothecia, the evidence is 
to me insufficient that Verrucaria umbrina can be traced into Endocarpon 
pusillum, or V. clopima into E. pulvinatum, Th. Fr.; and the points of 
approach between the two groups may be said perhaps to be no greater 
than those to be found between Rinodinaand Physcia. And on the other 
hand the finally indeed blackening, but not carbonaceous perithecium may 
serve to keep Staurothele apart from Verrucaria sect. Polyblastia ; of 
which V. theleodes, Sommerf. (Sporodictyon, Mass.) is so important a type. 
The group before us is marked by the commonly conspicuous, excipular 
relation of the thallus to the immersed apothecia; but agrees in this as 
well with Segestria as with Trypethelium ; the monocarpous species of 
which latter genus (as JT. uberinum (Fée) Nyl., and T. meristosporum, 
Mont.) now closely approach in habit, as does the last-named also in the 
spores, to the present. 
As many as seven species, all rupicoline, have been reckoned by some 
European writers as referable here ; but the distinctions are slight, and 
the whole perhaps are included in Verrucaria umbrina, Nyl. (Pyrenoc. 
p. 21) as understood by him. This author has since indicated, as belong- 
ing here, his V. suwbumbrina (Lich. Scand. p. 269), The other species are 
North American; the whole genus being northern, though recurring in 
one of its forms in the Himalayah (Ny]l). 
S. Drummondii (Verrucaria, Tuckerm. Obs. Lich. 1. ¢. 6, p. 286) well 
distinguished on the light-gray lime-rock (Kingston, Canada, Mr. Drum- 
mond) upon which it grows, by the orbicular, dark-brown patches (5-9™™- 
in diameter) which are radious at the circumference of its verrucose 
thallus, is a much finer lichen than Dermatocarpon Ambrosianum, Mass. 
(Lich. Ital. n. 30) and the spores, so far as these have been yet observed 
(0,080-40™™- long, and 0,011-20™" wide) are smaller. There can however 
be no doubt that the two plants are closely allied to each other, and to 
S. umbrina. —— And the same remark must be made of another North 
American Stawrothele, which yet I cannot but distinguish. SS. circinata, 
Tuckerm.,! occurring abundantly on the lime-recks of Trenton Falls, 
dissected as much as possible from the external parts,” to the microscope, ‘‘cyl- 
indrical, straight spermatia, measuring 0,005-0,007™™- in length, upon simple 
sterigmata,” made their appearance, as if originally included within the perithecium. 
1 Staurothele circinata (sp. nova) thallo ecrustacco orbiculari tenni contiguo 
levigato 1. dein rimoso, ambitu zonato, olivaceo-fusco, hypothallo fuscescente fim- 
briato; apotheciis (0™™., 3-0™., 7 lat.) concentrice dispositis protuberantibus. 
perithecio mox denudato nigro, amphithecio ulbo. Spore 1-2ne, ellipsoidew, muri- 
formi-multiloculares, fusce, longit. 0,034-46™-, crassit. 0,016-20™™. On the 
lime-rock at Trenton Falls, N. Y. The rounded patches exceed at length an inch 
in diameter. As the patches increase in size, successive lines of growth appear 
more or less clearly at, and give a zonate aspect to the circumference ; the outer- 
most of these lines being a pale, but finally darkening hypothalline fringe. At the 
centre the crust becomes chinky, and finally falls away. 
33 
