[17] 



LAKE SUPERIOR ENTOMOSTRACA. 



717 



fereuces uow apparent are indeed constant ; if the presence or absence 

 in the adult of that rudiment of the larval eye known as the pigment 

 speck, a slight increase or decrease in the size or number of teeth on 

 the caudal claws, the presence or absence of a suture between two suc- 

 cessive an tennal joints, and other equally trivial differences, serve really 

 to distinguish animal groups which have been separated from each 

 other by the physical division of their area of distribution, we shall have 

 additional illustrations of the rise of specific and other distinctions as an 

 indirect consequence of simple isolation. 



INDEX. 



[Note. — The references are to page figures in brackets.] 



Page. 



Acroperus leucocephalus 11,15 



Alona 11, 15 



oblonga 14, 15 



Birge, Professor 1 



Bosinina longirostris 12, 14, 15 



Calanidao 2 



Canthocamptus 7, 14, 15 



Chydorus globosus 12, 15 



rugulosus 12,14 



sphaericus 12, 14, 15 



Cladocera 10 



notes on 1 



Copepoda 2 



Cyclopidoe 7 



Cyclops agilis 10, 14 



edax 9, 15 



anatomy of 9 



gyrinus -, 7,15 



anatomy of 8 



pectinifer 10, 15 



thomasi 7, 13, 14, 15 



Daphnella brachyura 14, 15 



Daphnia intexta 14, 15 



laevis 14, 12 



pellucida 13 



pulex 13 



retrocurva, var. intexta 13 



Daphniidae - 12 



DJaptomu.s gracilis 2 



imperfectus 14, 15 



pallidus 2 



sicilis 2, 14, 15 



Page. 



Diaptomus sicilis, anatomy of 3 



var. imperfectus 3 



Episthura lacustris 4. 14, 15 



anatomy of 5 



nevadensis 4 



nordcnskioeldi 4 



Eurycercus lamellatus 11, 14, 15 



Ilarpactidai 7 



Holopedium gibberum 14,15 



Kellicott,Dr 2 



Keweenaw Bay 1 



L'Anse ] 



Leptodora byalina 11, 14, 15 



Leptodoridae 11 



Limnocalanus macrurus 14 



var. auctus 6 



anatomy 

 of.... 7 



Lynceidae n 



Marquette 1,4 



Menominee River l 



Michigammo Lake 1, 4, 7 



Pleuroxus procurvus 11, 14, 15 



Polypbemida) 10 



Polyphemus pediculus , 10, 14, 15 



anatomy of 10 



Scapholeberis mucronatu 12, 15 



Sida crystallina 14, 15 



Simocephalus vetulus 15 



Smith, S.I l 



White Fish Point l 



