310 DECADES OF FUNGI: 
Forming minute jet-black crowded sori which are at length 
almost confluent. Stroma consisting of decumbent branched 
threads. Spores at first consisting of a pellucid simple obo- 
vate cell, which gradually acquires an oblong form (the pe- 
duncle being entirely obliterated) and divided regularly by 
numerous transverse and vertical septa ; occasionally a few of 
the lower septa are oblique. ks 
A very pretty object under the microscope. The true 
Sporidesmium atrum which appears to be a rare species also 
occurs at Ohio. It was, however, common at Prag as 
M. Corda informs me, till the wooden palisades were de- 
stroyed. 
Tab. XII, fig. 3. a. Flocci. 4. Spores in various stages of 
growth. c. Portion of spore. All more or less magnified. 
93. Oidium simile, n. sp. Effusum submembranaceum 
fulvum filis ramosiusculis ; articulis ultimis subglobosis. (Tab. 
XII. f. 4.) 
-. On decayed wood, Jan. Ohio. No. 147. T. G. Lea, Esq. 
Forming a deep tawny pulverulent but somewhat membra- 
naceous stratum on decayed wood which to the outward eye 
exactly resembles Oidium fulvum, but distinguished by its 
subglobose not oblong articulations. The fructifying joints 
arise either from a direct transformation of the ultimate joints, 
or from the central constriction of the subterminal. 
Tab. XII, fig. 4. a. Flocci with spores. 5. Spores; more 
or less magnified. 
94. Septonema spilomeum, n. s. soris parvis punctiformi- 
bus; filis ramosis; articulis oblongo-ellipticis scabriusculis 
triseptatis. (Tab. XII, f. 5). 
On fence rails. March. Ohio. No. 92. T. G. Lea, Est 
Forming little scattered sori about the size of a poppy- 
seed; threads branched ; articulations oblongo-elliptic triseP~ 
tate; one or more of the septa occasionally containing an oil- 
globule; border of articulations pellucid, rough with little 
scabrous prominences, "e. 
Very distinct from the other species in the punctiform 
habit, and in the nature of the articulations. 
= 
