( 224 ) 
in which the confluence of parts is carried further than in Chiodecton, a 
similarly difform, compound apothecium, resulting wholly from the con- 
fusion of proper exciples (pseudo-stroma') and this differs possibly in no 
respect from the warts of Arthonia, except that while in the latter the 
hymenium, or synhymenium, is assumed to be simple, and undistinguish- 
able into hymenia, the distinctness of these may more or less be made out 
in species of the former. This is all; and it may well hereafter prove 
that Eschweiler’s cited observation was in fact a vaticination; and that 
Mycoporum, as here taken, is only Arthonia finally understood. And 
with due respect to the learned monographer of the latter genus, I shall 
venture to add that A. ambiguella, Nyl. (Lindig Herb. N. Gran. n. 827) 
appears almost as referable to the one group as the other. 
As respects the spores, Mycoporum, Nyl., is well associable with that 
group of Arthonie which finds its complete expression in A. spectabilis, 
Flot. (-Arthothelium, Massal.) and Koerber’s reference of JZ. elabens to 
this group (Parerg. p. 261) though certainly disputable from the stand- 
point of present views of Arthonia-structure, as compared with If. pycno- 
carpum, may yet prove an anticipation of the ultimate verdict. 
Beside VU. elabens of Flotow, Nylander has indicated three European 
species, the minuteness of which will probably long obscure their real 
distribution; and two better developed tropical ones. Of these, one of 
the latter only is known as yet as North American; but either, or all the 
others, may prove also to occur. 
ML. pycnocarpum, Nyl. (in Prodr. Fl N. Gran. p.111; & in Herb. 
Lindig, n. 891) an inhabitant of Mexico (Nyl. Enum. Gén.) as of other 
parts of tropical America, is common, on various barks in the northern 
states (determ. Nyl.) and was found in North Carolina by Schweinitz 
(Herb. Fries). It offers very commonly the aspect of a minute (as if col- 
lapsed, or at length confluent compound) Verrucaria, but passes finally 
into variously difform, trypethelioid warts, the minute, rounded disks of 
which simulate ostioles. Spores in eights, in pyriform, or now oblong 
thekes ; oblong-ovoid or oblong (constricted at the middle) from quadri- 
locular with entire cells becoming muriform-multilocular (transverse 
series of cells 8-12, longitudinal 2-3) fuscescent or decolorate; 0,023- 
0,043™™- long, and 0,009-0,016™™- wide. The spore-character of the genus, 
based in part upon species unknown here, is yet, it will be seen, far from 
imperfectly represented by the differentiation of the spore of our Mfyco- 
porum. 
1 Sarcothecium, Massal. Mem., is equivalent to Stroma. Pseudo-sarcothecium, 
Koerb. Parerg. p. 394, which ‘ entsteht erst durch das Zusammenfliessen der einan- 
der eng gendherten Fruchtgehduse in Verlaufe des Wachsthums derselben’ is on 
the other hand practically equivalent to Pseudo-stroma. The concluding part of 
Dr. Koerber’s work had not reached the writer, at the time the latter term sug- 
gested itself, and was introduced, as above, into his text. 
