^8 NATURAL HISTORY BULLETIN. 



LEPTOGIUM [Fr.) A-yl. 



L. LACERUM [Szc.) Fi' . Calcareous rocks among mosses^ 

 and also on dead wood. Fayette. Bremer. 



L. PULCiiELLUM [Ach.) JVyl. Dead trees in moist wooded 

 ravines. Fayette, Bremer, Clayton. Linn. 



L. TREMELLOiDEs (Z.) Fr . Calcareous rocks. Fayette. 

 This lichen seems to be rare in Iowa, and was always 

 found sterile. 



L. ciiLOROMELUM [Siv.) Kyi. Calcareous rocks. Fayette^ 

 Clayton. 



L. MYOCHROUM [FhrJi., Srlucr.) Tuck. Trees. Fayette, 

 Cla^'ton. 



Fam, LECANOREI. 



PL AC ODIUM {DC:) Xaeg. and He pp. 



P. ELEGANS [Link.) DC. Calcareous rocks. Fayette. Clay- 

 ten. Winneshiek, Johnson, Linn. 



P. ciNNABARiNUM {Ac/i.) Aiiz. Calcareous rocks. Fay- 

 ette, Clayton. Johnson. Linn. Winneshiek. 



P. wiCROPHYLUiNUM Tiick. Dead wood. Fayette, John- 

 son, Floyd. PlacodiiDU ccrimim var. pyracea grows in the 

 same habitat, and it is often ver}^ difficult to distinguish 

 between the two. 



P. ciTRiNUM (Ilojfin.'] Lcighl. Calcareous rocks. Fayette, 

 Johnson. Linn. 



P. AURANTiACUM {^Lig/ilf.) Kacg: and IIcpp. Trees and 

 rocks. Fayette, Bremer, Cla3ton, Winneshiek. Dickinson, 

 Story, Shelby. Johnson. Linn. 



P. CERINUM [Hcdiv.) Xaco. cnid IIcpp. Trees. Fayette, 

 Clayton, Bremer, Shelby, Johnson. Linn. Stor}', Winne- 

 shiek. 

 One form of this species seems to be quite widely distrib- 



