Distribution of the Species. 



191 



Diaptomus sanguineus . . 

 1 1 leptopus 



1 ' pallidus ... . 



1 l sicilis 



' ' ashlandi . . . . 



< < minutus .... 



' ' oregonensis . . 



Epischura lacust?Hs 



Limnocalanus macrurus 

 Cyclops americanus .... 



brevispinosus . . . 



navus 



pulchellus 



parens 



leuckarti 



signatus 



modestus 



fluviatilis 



serrulatus 



phaleratus 



bicolor 



Jimbriatus 



Pelagic. 



T . , , I Stag- 

 Ljlt \°- j nant 

 raL Pools. 



x 



X 



X 

 X 

 X 

 X 



X 



X 

 X 



X 



X 



X 



X 

 X 

 X 



None of our species is peculiar to this immediate region, and 

 it is probable that they are widely distriouted over the north- 

 ern part of the United States and the southern part of British 

 America. Indeed, the copepod fauna of North America resem- 

 bles very closely that of Europe and northern Asia. This fact 

 has already been remarked by Prof. Birge in regard to the 

 cladocera, and it seems no less true of the copepoda. Many of 

 our species are identical with those of Europe, even in the 

 minutest details, as in the case of Cyclops leuckarti Sars. In 

 other cases the structural differences are slight, and it is very 

 probable that we should consider them of only varietal value, 

 were we acquainted with the limits of species variation. That 

 the species should be identical, or nearly so, over such a wide 

 extent of territory is not at all strange when we remember 

 how easily the living animals and their eggs may be trans- 

 ported by water-fowl. Most of the forms, too, seem to readily 



