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



Diaptomiis gracilis Sars. 

 Plate IX, FiCx. 1. 

 Sars '64; Gruber '78, Rehberg 'SQi; Daday '8o^; De Guerne and Richard '89. 

 This very widely distributed species is scarcely over 1.0 mm. long 

 and very slender. The antennae are much longer than the whole 

 body. The stylets are short, and the first segments of the abdomen are 

 armed with strong spines. The inner rami of the fifth feet are one- 

 jointed in both sexes, in the female shorter than the basal segment of 

 the outer ramus. The apical joint of the outer ramus is well- 

 developed and bears two spines, one of which is as long as the claw. 

 The inner ramus of the right foot of the male is very long, reaching 

 nearly to the base of the claw. There is a curious, conical, ciliated 

 process from the inner aspect of the outer ramus of the left foot. 



Diaptoinvis orientalis Brady. 

 Plate X, Fig. 5. 

 Brady '86; De Guerne and Richard '89. 

 There seems to be some doubt whether the various collections from 

 Ceylon and Australia really pertain to the same species. 



The last thoracic segment is rounded and armed with short spines, 

 as is the first abdominal. The second abdominal segment is very 

 short. The caudal stylets are short, with loug seta?. The antennse 

 reach the stylets. The antepenultimate segment of the male antenna 

 bears a long hook. The terminal segment of the outer rami is distinct 

 (not so figured by Sars), the inner ramus as long as the basal segment 

 of the outer. Inner rami of male fifth feet very short and one-jointed. 

 Length 1.3 mm. 



• Dlaptonius stagnalis Forbes. 



Plates III; XIII, Figs. 11, 13. 



Forbes '82; Herrick '82 (D. giganteus), and '84; De Guerne and Richard '89. 



This species was described by Professor Forbes and the writer at 



almost the same time, but as the former's description appeared in a 



periodical it was more promptly distributed and deserves priority. 



A very large species, resembling D. castor, the place of which it 

 takes in America. Greatest width in front of the middle. The an- 

 tennae scarcely extend beyond the thorax. The first segment of the 

 thorax is separated by a suture, as is the last, which is greatly pro- 

 duced laterally and bears two spines. The first abdominal segment is 

 much longer than the rest of the abdomen. The caudal stylets are 

 very short and broad, divaricate, and ciliated externally. The caudal 

 setse are large, short and profusely plumose. The egg sac is large and 

 spherical. In the male the abdomen is slender and five-jointed. The 

 five joints preceding the hinge of the right male antenna are very 



