Lake Distriet: Interlacustrine Area. 395 
Cladonia gracilis erg Se occurs on shaded talus and is found typically 
along the north shore of Lake Superior. 'The face of the bluff above the Cain is covered with 
species of a Cetraria, rn na, Buellia, Usnea, a Alectoria, Evernia and 
Pannaria, while the talus below is covered with a perfect maze of Cladonia res . gracilis 
var. dilatata, C. cristate ar a, C. verticillata var, evoluta, C. furcata var. paradoxa, c. EEE 
var. apolepta, C. fimbriata var. subulata, C. fimbriata var. radiata, C. bacillaris, C. deformis, C. pyxi- 
data, C. cenotea, C. coceifera, C. squamosa, C. caespiticia, C. uncialis, C, rangifera, C. sylvatica 
and C. alpestris with species of li Peltigera strieta and Parmelia. 
donia rangifera Association. This is best developed on the east side of Hat 
Point near Grand Portage. Talus Bioeke- occur here overgrown with coniferous trees and the 
whole talus block floor is covered with a rich growth of Cladonia rangifera, €. alpestris, C. syl- 
vatica, C. uncialis, C. amaurocraea and Stereocaulon paschale with these in another ee 
Lecanora Association. This occurs on exposed granitic boulders. The most constant 
u > this association in Minnesota are Physcia caesia, Placodium cerinum, ii um vitel- 
m, Lecanora rubina, Lecanora cinerea, Lecanora xanthophana, Rinodina sophodes, Buellia 
petraea, 
Lecanora ealcarea-contorta Association®!). The lichens of this association have 
small thalli closely adnate, or even more or less hypolithie oceuring on exposed limestone, viz., 
Placodium vitellinum var. aurellum, Lecanora subfusca, Lecanora calcarea var. contorta, Lecanora 
privigna var. pruinosa, Rinodina Bischofhi, Bien pusillum, Verrucaria nigrescens, Verrucaria 
muralis. 
3. Limnoplankton- and Lake-Formations. 
Plankton Formation. The plankton of Lake Erie according to JULIA SNOW °) 
consists of the following algae; being much the same species as in Europe: 
Confervoideae. Scenedesmus. 10 spec. 
Stigeoclonium tenue Kg. Coelastrum, ap 
Aphanochaete repens A. Br. Pediastrum, 3 spec. (and 4 var.), 
Cladophora glomerata Kg. Staurogenia, age 
Hormidium, 2 spec. Kirchneriella, 2 spec. (and 2 var.). 
Golenkinia fenestrata Schräd. 
Siphophyceae. Ophiocytium capitatum Wolle. 
; ; Characium ambiguum A, Br. 
Protosiphon botryoides Kg. Polyedrium, 3 spec. 
3 Dictyosphaerium, 2 spec 
| Protococcoideae. Tetraspora natans Kg. 
Volvox globator Ehrb. Schizochlamys gelatinosus A. Br. 
Eudorina elegans Ehrb. Botryococcus Braunii Kg. 
Pandorina morum Bory. Gloeocystis ampla Rabh. 
Chlamydomonas, 3 spec Nephrocytium Agardhianum Nag. 
Hydrodictyon utrienlatum Roth. Oocystis, 3 spec. 
shore at Lake of Woods. Minnesota Botanical Studies Bulletin Parts X and XI: 1007—1012; 
Fınk, Bruce: Some talus Cladonia Formations Botanical Gazette XXXV: 195—208 March 1903. 
1) Bruck Fink gives a minute and detailed classification of lichen associations too detailed 
for even brief mention here. See Minn oh Botanical Studies second ser. pages 1, 215, 277, 657 etc. 
2) Snow, Jura W.: The plankton Algae of Lake Erie. Bulletin U. S. Fish Commissio n XXH 
1902: 371—393- 
