1883. ] . Zoology. 209 
Claus, Dana, Leydig, Jurine, Baird, Fischer, Miller, Lubbock, 
Boeck, Brady, Heller, Lilljeborg, Sars, Uljanin,etc. As yet, how- 
ever, it is too soon to say how far this similarity may extend. 
Confining ourselves, for the present, to fresh-water forms, a recent 
opportunity for comparison of American with European Copepoda 
has confirmed our impression that a large number of species will 
be found identical". It seems, indeed, somewhat astonishing at first 
A Diaptomus, believed to be identical with D. castor in typical 
as well as several varietal forms, occurs throughout Minnesota from 
the shores of Lake Superior to near its southern boundary and in 
Ulinois. Another species believed to be nearly allied to a Scandi- 
navian species is known from Minnesota, Wisconsin and the neigh- 
borhood of East St. Louis, Illinois. Cylops serrulatus Cls., with 
similar variations to those noticed by Claus (Op. cit., p. 85) and 
Brady (Op. cit., vol. 1, plate 22) occurs as our most abundant 
species, 
It may be observed that Brady’s work is so strictly systematic 
that his figures are frequently little more than schematic, and lack 
the life-like character of those in the earlier work of Claus. It 
_ Would seem that some of the species of Cyclops described by Dana? 
are identical with the above, although details are wanting to identify 
positively. Without delaying to discuss the question opened as to 
‘ whether these widely separated forms have all diverged from a 
-Primitive geographical center or have arisen independently from 
; original marine prototypes, as suggested to the writer by Professor 
=~ 4#uckart, we may remark that the former theory is rendered pos- 
_ sible by the fact that the feathers of water-fowl often form a vehicle 
l the transportation of even larger crustacea. ; 
; the Phipods, for example, are transported hundreds of miles under 
) feathers of geese. While it is unlikely that these larger crus- . 
fans or their eggs would survive a long aerial journey, it is 
quite certain that the eggs of Cyclops would pass many hours or 
‘ven days without being destroyed. On the other hand, it seems 
wena : : 
ae Copepoda of Minnesota. Rep. Geol. Surv. Minn. 1881. 
Ga. fe Wilke’s Exploring Exp. Crustacea. 
*Siel and Kdlliker, Zeitschrift. 1872, p- 293. Packard; synopsis of Phyllo- 
Pod crust = N. A. U.S. Geol. and Geng. Surv. of Col. 1873. p- 614, etc. 
