Distribution of the Species. 
191 
Pelagic. 
Litto¬ 
ral. 
Stag¬ 
nant 
Pools. 
Diaptomus sanguineus .. 
4 4 leptopus .... 
44 pallidus .... 
44 sicilis . 
4 4 ashlandi .. . 
44 minutus .... 
4 4 oregonensis .. 
Epischura lacustris .... 
Limnocalanus macrurus 
Cyclops americanus .... 
4 4 brevispinosus .. . 
4 4 navus . 
44 pulchellus . 
44 p arcus . 
4 4 leuckarti . 
4 4 signatus . 
4 4 modestus . 
4 4 flumatilis . 
4 4 sermdatus . 
4 4 phaleratus . 
4 4 bicolor . 
4 4 fimbriatus . 
None of our species is peculiar to this immediate region, arid 
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 
