50 
Ohio Biological Survey 
Collegia (Hill.) Web. in Wig. Prim. FI. Hols. 89. 1780. 
Transforming the algal-host colony into a squamulose or an irregu¬ 
larly foliose body, with the upper surface olivaceous, varying toward 
green or black and the lower surface somewhat lighter colored; thallus 
wholly mycelial and the hyphse more densely disposed toward the sur¬ 
faces ; hyphse hyaline, variously and often densely disposed, straight or 
curved, monopodially branched; rhizoids inconspicuous but commonly 
seen in sections; apothecia commonly scattered; disk varying from con¬ 
cave to convex, from light brown to dark brown, surrounded by a thalloid 
margin, which is rarely overgrown; exciple either densely mycelial or 
plectenchymatous, usually hyaline; hypothecium usually of interwoven 
hyphse, hyaline below to pale brown above; hymenium hyaline below to 
brown above; paraphyses hyaline at the base and tinged with brown 
toward the somewhat enlarged apex, simple or sometimes monopodially 
branched toward the apex or farther back, all species showing both 
simple and branched ones, the number of cells varying from 5 to 9, the 
length from 55 to 160 mic., the diameter from 1.5 to 4 mic.; asci clavate, 
the walls 9.5 to 2.5 mic. thick laterally and 5 to 13 mic. thick at the apex; 
spores hyaline, ellipsoid, muriform, 8 in each ascus, irregularly arranged. 
KEY TO THE SPECIES OF COLLEMA 
Attached to calcareous rocks. 
Spores usually less than 8 mic. wide.4. CoHema plicatile 
Spores usually more than 8 mic. wide.5. Collema furvum 
Not attached to calcareous rocks. 
On calcareous soil and on mosses, usually over calcareous rocks. 
Thallus and transformed algahhost colony 200 to 
750 mic. thick. 1. Collema pulposum 
Thallus and algal-host colony less than 100 mic. 
thick .2. Collema tenax 
On tree trunks.3. Collema microphyllum 
1. Collema pulposum (Bernh.) Ach. Lich. Univ. 632, pi. 14. f. 9. 1810. 
Lichen pulposus Bernh. Journ. Bot. Schrad. pi. 1. f. 1. 1799. 
Transforming the algal-host colony into a middle-sized, orbicular or 
more or less irregular body, which is 1.5 to 8 cm. across, 200 to 750 mic. 
thick, and closely attached to the substratum, with thick, entire or repand- 
crenate and often imbricated, rosulate lobes, which are often reduced in 
the central portions, to mere granules, with the upper surface olivaceous, 
