CYCLOPIDiE AND CALANIME OF MICHIGAN LAKES. 9 



Diaptomus Reighardi, sp. nov. 

 Plate I, figs. 1-4. 



The first segment of the cephalothorax is considerably shorter than the 

 second. The first two segments form nearly half the length of the cepha- 

 lothorax. The last segment is armed behind with two very minute spines. 



The first segment of the abdomen of the female is elongated, nearly 

 equal in length to the remainder of the abdomen and the furca. It is 

 dilated laterally and in front and bears two rather small lateral spines. 

 The second segment is. about one-third shorter than the third. The third 

 segment is slightly shorter than the furca. 



The antennae reach the end of the furca. The right antenna of the 

 male is swollen anterior to the geniculating Joint; the antepenultimate 

 joint has no appendage. 



The outer ramus of the fifth foot of the female is two- jointed. The third 

 joint is represented by the customary two spines. The inner ramus is 

 one-jointed; it is somewhat longer than the first joint of the outer ramus, 

 and is armed at tip with minute setae and two spines. 



In the right fifth foot of the male the basal joint is quadrangular, about 

 one-half longer than broad. The length of the first joint of the outer 

 ramus is about equal to its width. The second joint is elongate, concave 

 on its inner margin; at about one-third of its length there is a minute 

 spine on its inner margin; the rather long lateral spine is situated at about 

 two thirds of its length. The terminal hook has a single abrupt angle at 

 about one-half its length. The inner ramus is one- jointed and equals in 

 length the first joint of the outer ramus. 



The left fifth foot of the male reaches a little beyond the middle of the 

 second joint of the outer ramus. The basal joint is about as broad as 

 long, and is somewhat shorter than the basal joint of the right foot. The 

 first joint of the outer ramus is about as broad as long, its distal end con- 

 siderably narrower than the proximal. The second joint is about twice as 

 long as the first, and the tip is expanded into two finger-like processes, of 

 which the outer is much the larger and is armed on its inner surface with 

 a pad bearing minute setae. The inner ramus extends to rather less than 

 one-half the length of the second joint of the outer ramus. 



Length of female, 1.1395 mm.; male, 1.0248 mm. » 



This species, which is nearly related to D. oregonensis, is yet readily dis- 

 tinguished by the characters of the male fifth foot. I found it in the 

 collections from only three localities, — the North Lake on Beaver Island, 

 Intermediate Lake, and Crooked Lake. 



I have named this species in honor of Professor Reighard who has, 

 directly and indirectly, done so much to increase our knowledge of lacus- 

 trine faunae. 



