NO. 9 hedrick: some lichens from American tropics 185 



Thallus thin to moderately thick, smooth to minutely chinky and 

 becoming powdery, ashy to greenish gray, brighter green when moist, 

 hypothallus indistinct; apothecia minute to small, 0.05-0.1 mm. across, 

 round to elongated, several to many immersed in round to irregular thal- 

 loid warts, the disk flat, black; hypothecium brown, the apothecial wall 

 scanty and not well defined ; paraphyses hyaline below to brownish above, 

 branched; asci broadly clavate, 96 x 32 fi, the wall somewhat thickened 

 above; spores 4-8, hyaline, oblong, 33-40 x 9-15 n, muriform, 9-11-septate 

 transversely and 1-2-septate longitudinally, the cells cubical. 



On maritime rocks, Tortuga Island, April 13, 1939, Wm. R. Taylor, 

 39-731. Type deposited in the herbaria of the Allan Hancock Foundation 

 and of the University of Michigan. The species previously described in 

 this genus were growing on wood. M. caesiella Miill. Arg. and M. Can- 

 dida Miill. Arg. have a whitish thallus and spores 20-28 x 6.5-7 /n. M. ir- 

 regularis Miill. Arg. has a yellowish white thallus and spores, one in each 

 ascus, 65 X 23 /i. M. saxicola is found on rocks, has a greenish white thal- 

 lus and spores 33-40 x 9-15 /t, which separate it from the other species. 



ROGGELLAGEAE 



Roccella Babingtonii Mont. — On twigs, Tortuga Island, April 13, 

 1939, Taylor, 39-733. 



GOENOGONIAGEAE 



Coenogonium linkii Ehrh. — On twigs in forest, Golfo Dulce, Costa 

 Rica, March 26, 1939, Taylor, 39-726. 



GOLLEMAGEAE 



Leptogium denticulatum Nyl. — Specimen sterile; so identification 

 doubtful — on twigs in forest, Golfo Dulce, Costa Rica, March 26, 1939, 

 Taylor, 39-725. 



LEGANORAGEAE 



Lecanora varia (Ehrh.) Nyl. — On bark of trees, Port Parker, Costa 

 Rica, March 24, 1939, Taylor, 39-722. 



PARMELIAGEAE 



Parmelia latissima Fee. — On trees, Islas Secas, Panama, March 27, 

 1939, Taylor, 39-727. 



