ENTOMOSTRACA OF MINNESOTA. 65 



iated process. We do not find in this species that the claw of the 

 penultimate segment of the outer ramus is denticulate, though in some 

 stages or forms it may be. The apical segment is obsolescent and bears 

 two unequal spines. De Guerne and Richard figure an accessory spine 

 at the base of the apical segment. There is occasionally a slight ten- 

 dency for the inner ramus to appear obscurely two-jointed. The male 

 feet of the fifth pair are very long. The inner rami are both rather 

 long (longer than the segment of the outer ramus opposite which they 

 stand), one-jointed, and slightly ciliated apically. The terminal claw 

 of the right foot is short and slightly curved and denticulate toward 

 the apex interiorly. The preceding segment has a short accessory 

 spine. The segment bearing the two rami has a short spine laterally 

 and is bristly exteriorly. The terminal segment of the outer ramus 

 bears two spines and a few cilia, while the penultimate segment has a 

 ciliated process inwardly near its apex. The armature of the third 

 and fourth feet is similar, the apical segment of the outer ramus bear- 

 ing an external short spine, one long spine and two setie at the tip, 

 and three setse internally. Length of female 1.5 to 1.7 mm.) of male 

 1.4 mm. "^ 



Diaptomus tatricus Wierzejski. 



Plate X, Fig. 8. 

 Wierzejski '82 (lacinnlatus), and '83; De Guerne and Richard '89. 

 A large, stout form, with antennoe scarcely exceeding the thorax 

 nd the last segment of the latter produced into a large spindle-shaped, 

 protuberance. The antepenult joint of the male antenna with a hya- 

 line lamina. Inner ramus of fifth feet of the female short, obscurely 

 two jointed; those of the male curved. A tooth is found on the mid- 

 dle of the inner aspect of the basal segment of the left foot, and the 

 apical segment of the outer ramus is forcipate. Length 2.1 mm. 

 Color carmine red. 



Diaptomus coer ulcus Fischer. 



Plate IX, Fig. 7. 



S. Fischer '53 (Cyclopsina coerulea); Lubbock '63; Poggenpol '74; UJjanin '74; 



De Guerne and Richard '89. 



This widely distributed species has been very frequently con- 

 founded with D. castor, than which it is rather smaller and from which 

 it differs in possessing a lamina on the antepenultimate segment of the 

 male antenna. The anteunre reach the caudal stylets. The apical 

 segmei^t of the outer ramus of the fifth foot of the female is well de- 

 veloped and its inner spine is almost as long as the claw of the penulti- 

 mate joint. The inner ramus is two jointed and longer than the basal 

 joint of the outer ramus. The inner rami of the male feet are one- 

 jointed. Length 1.8 mm. 



