ENTOM03TRACA OF MINNESOTA. 79 



lateral spine situated at the distal end. The terminal hook has the 

 symmetry of the curve broken by two rather abrupt angles, and its 

 inner margin is armed with fine serrulations. The inner ramus is 

 one-jointed, and reaches about half the length of the second joint of 

 the outer ramus. 



"The left fifth foot of the male reaches to about the middle of the 

 second joint of the outer ramus of the right. The first joint of the 

 outer ramus is as broad as long. The second joint is armed at tip 

 with two finger-like processes, and both joints are armed within with 

 minute hairs. The inner ramus is one jointed, and nearly equal in 

 length to the outer ramus. Length of female, 1.2 mm,; male, 1.1 mm. 



"This species was found in some material kindly furnished to me 

 by Professor E. A. Birge. The collections were made in January and 

 February, 1893, in small lakes and ponds in Mississippi. It was the 

 only Diaptomns in the collections, and was found in nearly all of them. 

 It will be noticed that it bears a somewhat close resemblance to D. 

 graciloides Sars." 



* Diaptomiis birgei Marsh. 

 Plate XLVII, Figs. 4-6. 



"Of moderate size. The first segment of the cephalothorax is nearly 

 equal in length to the three following, 



"The first segment of the abdomen of the female is as long as the 

 remainder of the abdomen and the furca. It is much dilated in front. 

 The second segment is nearly twice as long as the third, and about 

 equal in length to the furca. The second and third joints are very 

 closely united. 



"The antennte extend to the end of the furca. The right antenna 

 of the male is much swollen anterior to the geniculating joint; the an- 

 tepenultimate joint is produced on its distal end into a short, blunt 

 process, which makes very nearly a right angle with the longitudinal 

 axis of the joint. 



"The outer ramus of the fifth foot of the female is two-jointed, the 

 third joint being represented by two spines. The inner ramus is one- 

 jointed, hardly as long as the first joint of the outer ramus, and 

 armed at the tip with minute sette and two rather long spines. 



"The basal joint of the right fifth foot of the male is elongated, tra- 

 pezoidal in form, it greatest breadth being at its distal extremity. 

 The first joint of the outer ramus is broader than long, armed on its 

 inner margin with a broad, thin expansion of the integument. The 

 second joint is elongate, broader at base; the lateral spine is situated 

 at about the middle of its length, is long and stout, and armed on its 

 inner margin with fine serrulations. The terminal hook is slightly 



