[15] 



LAKE SUPERIOR ENTOMOSTRACA. 



715 



L'Anse Bay, August 14, 1 p. in., pier, shallow water, somewhat weedy 

 and dirty. A swift stream entering about a quarter of a mile above. 

 Still. Sun and shower. A good collection. 



Diaptomus sicilis, common. 



imperfect us, common. 

 Canthocamptus, sp., very few. 

 Cyclops thomasi, few. 



gyrinus, a few. 



pectlnifer, several. 

 Polyphemus pediculus, many. 

 Leptodora hyalina, several. 

 Eurycercus lamellatus, few. 

 Acroperus leucocephalus, few. 



Alona, sp., several. 

 Pleuroxus procurvus, a few. 

 Chydorus globosus, a few. 

 Bosmina longirostris, several. 

 Scapholcberis mucronatus, several. 

 Daphnia intexta, several. 

 Simocephalus vetulus, few. 

 Sida crystallina, abundant. 

 Holopedium gibberum, several. 



White Fish Point, August 15, shallow water, sandy bottom, sun, 

 high wind. Fair collection. 



Diaptomus sicilis, common. 



imperfectus, common. 

 Cyclops thorn asi, abundant. 

 Polyphemus pediculus, several. 

 Leptodora hyalina, a few. 



Alona oblong a, a few. 

 Alona, sp., a few. 

 Chydorus sphcericus, few. 

 Bosmina longirostris, few. 

 Daphnia intexta, several. 



Lake Michigamme, August 8, 3 p. m., sun, high wind, 

 and about 15 feet below. Very large collection. 



At surface 



Diaptomus sicilis, common. 



imperfectus, common. 

 Epischura lacustris, common. 

 Canthocamptus, sp., a few. 

 Cyclops edax, a few. 

 Leptodora hyalina, many. 



Alona, sp., a few. 

 Chydorus sphojricus, a few. 

 Daphnia intexta, several. 



Iwvis, rare. 

 Daphnella brachyura, very abundant, 

 below the surface. 



The facts now known concerning the animal life of the Great Lakes 

 furnish an insufficient basis for a final discussion of the origins of this 

 fauna, but may nevertheless serve to indicate the general lines within 

 which such a discussion must proceed. There are three such principal 

 origins possible 5 some of the Great Lake species may have made their 

 way directly from the sea, undergoing meanwhile more or less modifi- 

 cation; others may be a part of a general north-temperate fauna, 

 whose formerly continuous area of distribution has been broken up by 

 changes of level and climate, with consequent organic differentiation ; 

 and others may have had an independent southern and southwestern 

 origin, possibly reaching back, in some instances, to a South American 

 starting-point. 



Too little is as yet known concerning our southern Entomostraca, or 

 even those of our Atlantic and Pacific coasts, to make it possible to 

 point out with any assurance the elements of the Great Lake fauna 

 which are to be referred to these origins, and we can only undertake to 

 show which are related to the much better known fauna of the lakes of 

 northern Europe. 



Three of the four Calanidre now reported from our Great Lakes are 

 so closely related to those of European lakes as to leave not the slight- 



