92 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
The points of difference consist in the fact that the antenn# are 
shorter than European viridis, reaching only to the second instead of 
to the third thoracic segment, and that the armature of fourth feet are 
very unlike the figures and descriptions of European authors. Brady 
is the only author who figures these parts, and these figures are evi- 
dently careless, for the antennze on the same plate have a supernu- 
merary joint. We have examined a number of specimens of this spe- 
cies from distant parts of the United States, and find, with Marsh, the 
armature constant or but slightly variable. The proportions of the 
apical spines of the inner ramus of the fourth foot are the reverse of 
those given in his figure. The size varies remarkably, passing into 
the large variety. 1.4 mm. is an an average measurement exclusive 
of setee. 
Var. b. *Cyeclops ingens Herrick. 
PLATE XXYV, Fias. 1-8. 
This is the largest form yet encountered in America and is rarely 
seen. It is asimple exaggeration of the last, there being no obvious 
distinctions except the size. It is occasionally over 4.0 mm. long in- 
cluding the sete or about 3.0 mm. excluding them. 
It may be noticed that the males of this group have a well-devel- 
oped sixth foot. The antenne are strongly modified and amply spined, 
as shown in the figure. A series of hyaline plates near the joint are 
well developed. 
*Cyclops vernalis Fischer. (Fide Schmeil.) 
Fischer 53; Sars ’63(C. lucidulus); Claus ’63 (C. elongatus); Heller ’70 (C. elongatus); 
Rehberg ’801 (C. elongatus and C. lucidulus); Cragin ’83 (C. elongatus); Herrick 
84 (C. elongatus and lucidulus); Daday ’85° (C. lucidulus); Sostaric ’88 (C. luci- 
dulus); Schmeil ’91 (C. elongatus) and ’92; Richard ’91; Brady ’91(C. elongatus). 
We cannot, of course, enter the perplexing synonomy which has 
been very carefully studied by Schmeil, and we hope that it may now 
be considered settled. The not quite unexpected discovery that a 
17-jointed species may, under certain conditions, become 18-jointed 
rests on the same kind of evidence which Schmeil rejects in respect to 
our own statements in the case of other species, and offers a certain 
probability in favor of the frequent occurrence of imperfectly mature 
but oviparous females, which he rejects without making the necesary 
investigation by which he might easily have convinced himself of its 
reality. However, we are fain to accept the evidence that C. elongatus 
Claus is but a ‘‘post imago”’ of C. lucidulus Sars. Still it is not to be 
forgotten that other species may sporadically develop 18 jointed an- 
tenn and then might lay claim to be considered C. elongatus. 
