164 LEPTOGITJM. 



etc. New York, Peck. New Jersey, Austin. Pennsylvania, 

 Michener. Ohio, Lesquereux. Illinois, Hall. Maryland and 

 Virginia, Tucker man. South Carolina, Eavenel. Florida, Aus- 

 tin. Alabama, Peters. Louisiana, Hale. Texas, Wright.- 



The two forms differ much as the two conditions of L. marginel- 

 lum ; or as Wright Lick. Cub. n. 6 from n. 7 of the same collec- 

 tion. The first of the last-named is not indeed to be well-dis- 

 tinguished from the present species, unless when fertile, a may 

 also be compared with L. Tremelloides, but is readily seen to 

 differ in its (at least finally) rigid, and always strongly wrinkled 



thallus. b now occurs (Florida, Austin) in a state (f. fusis- 



porum) otherwise undistinguishable, with spores at length per- 

 fectly fusiform, reaching 48 mic. in length, and with 8-10 entire 

 spore-cells. But this is only another instance of the anomaly 

 noted elsewhere in Collema flaccidum (Gen. pp. 88, 91), and 

 these elongated spores not only revert to acuate-ovoid ones, but 

 exhibit now a divided spore-cell, suggesting at once the sub- 

 muriform stage. 



18(&). L. adpressum, Nyl.; thallus, as described, and apothe- 

 cia, offering no differences from L. ckloromelum ; but the fusi- 

 form, 10-locular spores measuring *^ mic. Nyl. Syn. 1, p. 131. 



On bark, Orizaba, Mexico (F. Mutter), Nylander I. c. 1858. 



At the same station, Dr. F. Mohr. Thallus, in Dr. Mohr's 



specimen, which though small cannot well be diverse from Ny- 

 lander's lichen, larger and lighter coloured than that of L. clilo- 

 romelum f. fusisporum, and the apothecia larger. The spores 

 (measuring ^ mic.) scarcely differ at all, and also now shew a 

 divided spore-cell, but are longer, and their anomalous features 

 perhaps better marked. There can certainly be no question that 

 the cited form of L. chloromelum sufficiently explains the present 



lichen. L. Brebissonii, Mont, emend., Syll. p. 378, with an 



ample, sub-monophyllous thallus, otherwise similar, as the plant 

 is in the apothecia, to L. chloromelum, from which neither Mon- 

 tagne nor Nylander at first separated it, differs yet, like L. ad- 

 pressum, in its long -fusiform or even acicular, 8-12-locular 

 spores, measuring 56-64 mic. in length (Hepp.), and has occurred 

 in France, in the Canaries, in India, in Surinam, and in Tahiti 

 (Montagne), but is not as yet known as North American. 



19. L. bullatum (Ach.) Mont.; thallus orbiculate, middling 

 to ample, membranaceous, at length rigid, sharply wrinkled; 



