Mr Greville on the Genus Ermeum. 79 
Ish, rough. Tubes much clustered together, sub-branched or 
lobed, summits rugged and deformed, of a pale pink colour un- 
der a strong power of the microscope. This plant is well mark- 
ed, and cannot be mistaken for any other species. It is con- 
fined to the under side of the leaf, and met with during the 
summer months in perfection. Of this island it has not yet been 
found a native. 
Erineum hetulinnm^ Rebent. 
Plate III. Fig. 8. 
E hypo- rare epiphyllum fulvo-ferrugineum saspe confluens, tii- 
bis brevibus variantibus plerumque sub-bicornibus aliquando 
turbinatis. — Gr. 
Erineum betulinum, Rebent. Prod. FI. Neomarcli. 
Albert, et Schw. p. 370. ( eoscl. part ) vid E. betulse. 
Moug. et Nest. No. 200. 
Hab. In foliis Betulae albse ; vere et gestate. 
Changes, as it advances to maturity, from white to ferrugi- 
nous, and lastly to a dark tobacco colour. Spots or tufts irregular, 
slightly immersed, sometimes confluent, on both surfaces of the 
leaf, but chiefly the under. Tubes dwarfish, very eccentric in their 
form, capitate or turbinate, but more frequently dividing at the 
top into two blunt j short, divaricate, horn-like terminations. 
This plant has been mistaken by Albertini and Schwieniz for 
an old state of E. hetula. Vid. what I have said under that spe- 
cies. I do not possess the Prod. FI. Neomarchicce, and the on- 
ly proof I have of this plant being described in that work, are 
the specimens published in that valuable collection the Stirpes 
Cryptogamce of Mougeot and Nestler, No. 200. As these plants^, 
however, have never been subjected to rigorous microscopical 
investigation, it is very possible that my E. tortmsum should 
have been confounded with the species in question, as both it and 
also E. hetula, are found on the leaves of the same tree. In 
spring and summer, this plant may be found in shady and moist 
places : my specimens were collected at Roslin. 
