ENTOMOSTRACA OF MINNESOTA. 97 
First Foor. 
ex. 2 spines. ex. 1 seta. 
Outer ramus | 2 sete. Inner ramus P 1 spine, 1 seta. 
in. 2 sete. in. 3 se‘. 
SECOND AND THIRD FEET. 
ex. 2 spines. ex. 1 seta. 
Outer ramus |e 1 spine, 1 seta. Inner ramus {ae 1 spine, 1 seta. 
in. 3 sete. in. 3 sete. 
FOURTH Foot. 
ex. 2 spines. ex. 1 seta. 
Outer ramus i 1 spine, 1 seta. Inner ramus me 2 spines. 
in. 3. sete. in. 2 sete. 
“The fifth foot is two jointed, the basal joint is short and bears a 
tubercle carrying a seta 0.06 mm. long, the terminal segment is terete 
and bears a spine 0.10 mm. long apically ana another as long upon the 
middle of its inner side. The cement gland is of peculiar shape, 
resembling that of C. parcus exactly. The last segment of the abdomen 
is Spiny upon the posterior margin above. ‘The color is usually pale, 
but may be ornamented with bluish suffusions. 
‘*Though closely allied with the species in America identified with 
Sars’ C. oithonoides there can be no doubt that two forms occur, this 
one being nearly exactly like the species described by Hoeck as ( 
leeuwenhekii. The description and drawings are given as a basis upon 
which to distinguish other allied species. The form from the Southern 
States originally called ©. tenuissimus is probably this species, though 
possibly distinct.’’ 
I have quoted our own original descriptions, correcting misprints 
in the armature of the feet, which was, however, correctly given in 
the figures. Schmeil’s figure of the armature of the antenne is faulty 
in not representing the teeth upon the lamina although the excision 
is clearly shown. 
The form described in the previous edition as C. oithonoides Sars, 
has not been re-examined and I am inclined to believe that it is but a 
small pelagic form or variety of the typical C. leuckarti. Cyclops oitho- 
noides is essentially a brackish water form and with its variety hyalina 
Rehberg, and ©. dybowskii Schmeil, constitutes a very close group 
whose members are quite variable and occur under such conditions as 
to lead one to suppose that they constitute a compound specific group 
whose members have not yet attained their autonomy. 
The original description of the American form is appended: 
‘“‘This most interesting species occurs under peculiar circumstances. 
It is perhaps the rarest member of the genus, and seems, beyond a 
doubt, nocturnal in its habits. It was first found by Sars in saline 
water, and named, on account of its slender form, from the marine 
Oithona. A similar species which, though about half as large, is 
hardly distinct, was found by Rehberg near Bremen. Rehberg men- 
