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 Eichard'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 pallicUis He rick. 



Plates IV, Figs. 1-6; V, Fig. 10; XIII, Fig. 17. 



Herrick '83 and '84; De Guerne and Richard '89; Marsh '93; Turner '92. 



De Guerne and Eichard in their monograph quite overlook the 

 original figures and description, for the remarks in Microscopic Ento- 

 viostraca 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 

 antennae are longer than the setiB or at least reach beyond the end of 

 the stylets. Eight 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 



