64 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



the right side distally a broad blunt process. Antennse reaching the 



caudal setiE; that of the male on the right side bearing a lamella and 



hook on the antepenult segment. Inner rami of fifth feet in the female 



two-jointed, outer ramus three jointed. Tbe inner rami of the fifth 



feet of the male are curiously modified, and we must refer to the 



figures. 



Diaptonms zachariasi Poppe. 



Plate X, Fig. 6. 

 Poppe '86; De Guerne and Richard '89. 

 A species closely resembling D. leptopus and found in Silesia. While 

 the last segment of the abdomen is not dilated it is ornamented with 

 two spines. The inner ramus of the fifth feet of the female is two- 

 jointed and armed at the apex with three spines, and is somewhat longer 

 than the basal joint of the outer ramus. At the base of the claw of the 

 outer ramus is a strong tooth. The apical segment is distinct and bears 

 two spines. The figures of the male foot are not entirely satisfactory, 

 but the inner ramus of the right leg is said to be rudimentary, short 

 and two-jointed, while that of the left leg is one jointed but quite long. 

 The apical joint of the left foot is forcipate. The antepenult segment 

 of the male antenna has a hyaline plate which is scarcely hooked dis- 

 tally. Length of female 1.8 mm. Like our B. leptopus this species is 

 brilliantly but variously colored. 



* Diaptomus leptopus Forbes. 1882. 



Plates II; IX, Fig. 9. 



Forbes '82; Ilerrick '84 (D. loiigicornis var. leptopus); De Guerne and Richard '89; 



Marsh '93. 



This species, which is one of the commonest in small lakes in Min- 

 nesota, is widely distributed in the Mississippi Valley. While not 

 large it is generally ornamented with brilliant coloration bands, of 

 which the j)urplish suffusion of the tip of the antennae and abdomen 

 are most constant. Marsh found it of a brownish red color much as 

 D. sanguineus. We find it during the summer quite pellucid except 

 for the purple markings. The body is stout with the head and last 

 two thoracic segments fused. The last thoracic bears on either side 

 one or two small spines. The abdomen is short, the last two segments 

 being fused; the first segment bears a small lateral spine on either side. 

 The female antennre do not extend to the end of the caudal setse and their 

 spines are short. The right male antennaj is strongly geniculate and 

 spined. The antepenultimate segment bears only a very inconspic- 

 uous hyaline lamina but no hook or process as stated by Forbes and 

 by De Guerne and Richard. The fifth foot of the female is short, with 

 an inner ramus scarcely shorter than the antepenultimate segment of 

 the outer ramus and bearing at the tip two subequal spines and a cil- 



