398 PROCEEDINGS OF THE AMERICAN ACADEMY 



the latter hue soon prevails, and becomes at length, in the fully de- 

 veloped dichotomous lichen, olivaceous-brown. Within, the branches 

 are hollow, as in the last, the wall being clothed with a thin web of 

 medullary filaments. Apothecia either lateral, and clearly sessile, 

 or terminating branches, when they appear sometimes as if stalked ; 

 the shining, chestnut disk at length equalling the crenulate, thalline 

 margin. Spores in eights, in cuneate-clavate spore-sacks, spheri- 

 cal, like those of the last ; but occurring also, now and then, a 

 little oblong. Dufourea ryssolea, Ach. Lichenogr. p. 525 (not, as is 

 affirmed in the Index Dillenianus of Professor Fries, Lich. Eur. p. 

 468, the plant of Dill. Hist. Muse. p. 545, t. 82, f. 4, which seems 

 clearly to be Cetraria Richardsonii, Hook.), from Siberia, appears 

 almost to approach, so far as the brief character goes, to some less de- 

 veloped states of the present, but is really, according to Dr. Nylander 

 (Syn. p. 397) a Parmelia, nearly related to P. oUvacea ; the branches 

 of D. ramulosa being in fact, as already remarked, mostly hollow, or 

 in the narrower forms only very loosely webby within, and by no 

 means, as Acharius describes his plant, " s?<ifistulosi, tela bombycina 

 farcti." But I possess a lichen from Tyrol, collected by Funk, (prob- 

 ably Dufourea muricata, Laur. in Sturm D. FI. 2, 24, t. 12, but my 

 specimen, instead of being straw-colored, is rather olivaceous-brown, 

 often more or less white-pruinose,) which possibly difiers from the next 

 (as Laurer's is said to) in having a rather looser medullary web, or in 

 being even subfistulous, and in other respects sufficiently resembles 

 specimens of Dadylina ramulosa. The last-named lichen is clearly 

 congenerical with Dadylina arctica, and it also nearly approaches the 

 next. 



Dactylina madreporiformis. Lichen madreporiformis, Wulf. 

 in Jacq. Coll. 3, t. 3, f. 2. Dufourea, Ach. Lichenogr. p. 525 ; Syn. 

 p. 247 ; Koerb. Parerg. p. 15 ; Nyl. Syn. p. 287. Cladonia, Schajr. 

 Spicil. p. 48, & Lich. Helv. n. 85. Evernia, Fr. Lichenogr. p. 25. 

 Cetraria nivalis, var. madreporiformis, Schaer. Enum. p. 14. On the 

 earth, on alpine ridges east of Middle Park, Rocky Mountains ; sterile ; 

 Dr. C. C. Parry. Thallus softish, turgid, about an inch in height, 

 rather sparingly, subdichotomously divided ; the branches short, lacu- 

 nose-uneven, obtuse, ochroleucous ; the medullary filaments rather 

 closely filling the interior, which is seldom subfistulous. Apothecia 

 unknown. Readily distinguishable from the others by its paler color, 

 and from the last by its simpler habit, and more compact medullary 



