ake BOTANICAL GAZETTE. [octoper 
lection made at the “Ledges” is not yet completed, enough has been 
dohe so that data for comparison are at hand. The “Ledges” 
have an extent of about two miles along a tributary of the Des Moines 
river and are fully 15™ high in.some places. They are well shaded 
in,many places and bear a higher plant flora quite different from that 
about the society especially studied above, and including such 
moisture-lovers as Camptosorus rhizophyllus, Woodsia obtusa, Asa 
rum canadense, Impatiens aurea, Anemone quinquejolia, Arisaema 
Dracontium, Adicea pumila, Aralia racemosa, Conocephalus conic, 
and a species of Grimaldia or Preissia; while the conditions at other 
points are more xerophytic and bear a number of ferns, composites, 
and trees or shrubs. The lichen species of the “Ledges” are for the 
most part quite widely distributed upon the rocks, so that the whole 
number recorded is about the same as for the riprap. The list is as 
follows: 
Usnea barbata Fr., infrequent; Ramalina calicaris farinacea (L.) Fr,, fre . 
- R. calicaris fastigiata (Pers.) Fr., infrequent; Parmela Borreri Tut 
common; P. crinita Ach., frequent; P. caperata (L.) Ach., infrequent, F268 
= eae (Schreb.) Nyl., infrequent; P. speciosa (Wulf.) Nyl., rare; Peltier 
canina (L.) Hoffm., frequent; P. canina spuria (Ach.) Tuck., rare; Senechoblastus 
(Collema) nigrescens (Ach.) Stizenb., rare; Collema pulposum (Bernh.) Ach, 
rare; Leptogium chloromelum (Sw.) Nyl., infrequent; Pannaria nigra 
Nyl., common; Amphiloma (Pannaria) lanuginosum (Ach.) Nyl. abundant; 
Acarospora bi canara) fuscata oligocarpa Nyl., rare and new to Iowa; a 
muralis (Schreb.) Schaer., rare; Placodium  aurantiacum (Lightf.) Naeg. 
Hepp, frequent;*P. cerinum (Ehrh.) Naeg. & Hepp, infrequent; P. seve 
(Ehrh.) Naeg. & Hepp, frequent; P. citrinum (Hofim.) Leight., rare; P 
velata (Turn.) Nyl., rare; Urceolaria scruposa Ach., ; 6 preng.) 
common; C. caespiticia (Pers.) Flk., rare; C. pyxidata ee spurl 
Fik., frequent; Bilimbia (Biatora) trachona (Flt.) Fink, at ee 
(Ach.) Arn., rare; Dermatocarpon (Endocarpon) pusillum Hedw., ¥. viridula 
Verrucaria muralis Ach., common; V. nigrescens Pers., frequent) 
Ach., rare and new to Iowa; V. fuscella Fr., rare. 
A comparison of the list above with that for the TipraP ee 
resemblance. The ‘most striking difference is the occ — 
shade- and moisture-loving lichens in the society at the ‘ ‘uel 
which are absent from the riprap society. These shade 
lichens are the Collemas, the Leptogium, the P annariay 
‘aca The next most conspicuous difference is 
