5 - 1*. pulverulentll, (Schreb.) Nyl. On trees, rare and hardly 
fertile. 
/>. leucoleiptes, Tuck. On rocks, rare and sterile. 
6. P. stel laris, (L.) On trees and rocks, common. 
b. aipol/'a , Nvl. On rocks, rare. 
7 - P. astroidea, (Fr.) Nyl. On trees, rare. 
8. P# tribacia, (Ach.) Tuck. Very common on elms* 
9. P. llispida, (Schreb.. Fr.) Tuck. On trees, and stones in walls. 
10. P. Cfesiil, (Hoffm.) Nyl. On rocks. Referred here by Tuck- 
erman : but the specimens are hardly characteristic. 
11. P. obscura, (Ehrh.) Nyl. On trees, rocks, and mosses. 
b. endococcina , (Kbr., Nvl.) On trees. Nyl. in Japan, p. 33, 
distinguishes this from the var. endochrysea , Hmp., in which the 
thallus is lemon-colored within. 
12. P. setosa, (Ach.) Nyl. On ash in swamps. 
13. P. adgllltiliata, (Flk.) Nyl. On trees. I have not been able 
to find among my specimens the var. pyrithrocardia Mull., Flora , 
1880, p. 278, said to have occurred among specimens sent him by me. 
Exslc., Lojka, n. 162. 
9. PYXINE, Fr., Tuck. 
* 1. P. Frostii, Tuck. On shaded sides of rocks. Rare and ster¬ 
ile, 1864. 
2. P. sorediata, Fr. On trees and rocks. Seldom fertile. 
10. UMB1LICAIUA, Hoffm. 
1 . U. Mllllleilbergii, (Ach.) Tuck. On rocks, common. Once 
on rail, Weymouth. Exsic., Lojka, n. 14. 
2. U. Dillenii, Tuck. On rocks, reaching a large size. Sterile 
here, but fertile in Weymouth and Quincy. 
3. u. [Mist lllata, (L.) Hoffm. On rocks, common, and very 
rarely on bark and dead wood. Exsic., Lojka. n. 12, in my set. but 
called in Sched. U. Pennsylvanica. 
b. papulosa , Tuck. On rocks. 
