ENTOMOSTRACA OF MINNESOTA. 73 
mentioned and bears two teeth. The terminal segment of the left foot 
is expanded and carries two movable spines and a spur; according 
to Richard’s drawing the spines are dentate and there are accessory 
ciliar pads along the inner aspect of the outer ramus. The inner 
ramus is longer than the basal segment of the outer ramus and is cili- 
ated apically. 
* Diaptomus pallidus He rick. 
PLATES LY; Pies. 1-6; VY, Fie. 10; XT, Fie: 17. 
Herrick ’83 and ’84; De Guerne and Richard ’89; Marsh ’93; Turner ’92. 
De Guerne and Richard in their monograph quite overlook the 
original figures and description, for the remarks in Microscopic Ento- 
mostraca cannot be regarded as a scientific description. It is not to 
be wondered at that it is considered insufficiently described. This 
was to be expected from these authors, but is more remarkable from 
Marsh, who had the paper of 1883 before him but fails to note the 
figures and description, which, though poor (being prepared on a rail- 
road journey), are diagnostic in respect to the armature of the fifth 
feet. The credit of completing the description belongs to Marsh. 
A slender species of medium size. Cephalothorax widest near the 
middle; head partially separated by a suture; last cephalothoracic seg- 
ment fused with its predecessor, armed with one or two minute spines 
on either side. First abdominal segment long as remainder; second 
segment shorter than the third. Stylets twice as long as wide. The 
antennee are longer than the sete or at least reach beyond the end of 
the stylets. Right male antenna without special armature. The ter- 
minal segment of the outer rami of the fifth foot of the female is obso- 
lescent and bears two unequal spines. The claw is short and moder- 
ately curved. The inner ramus is as long as the basal joint of the 
outer ramus and bears two long curved spines and a few cilia. The 
fifth feet of the male are nearly equal, neglecting the claw of the right 
which is of moderate length and geniculately curved. The accessory 
Spine is Short and near the apex, while a small tooth is situated about 
at the proximal one third of the inner aspect. The inner ramus of the 
right foot reaches about to this tooth. The armature of the outer ramus 
of the left foot is peculiar and was not correctly figured by myself or 
Marsh. Fig. 2 of the plate is a camera drawing of the usual appearance. 
Fig. 6 is drawn so as to interpret the appearance. There is a movable 
claw, blunt at the tip and bearing a knob on the inner aspect which 
fits into the concavity of a basin-shaped projection whose outline is 
mistaken for a curved claw in most lights. Fig. 6 was taken from a 
specimen found in Lake Minnetonka. In general, the species prefers 
clear water. Fig. 1 represents a subimago form, with the first set of 
