ENTOMOSTRACA OF MINNESOTA. 61 
D. pallidus, from which it differs in possessing a hook on the right 
male antenne. The antenne exceed the caudal sete and are very 
slender; that of the male on the right side bears a curved plate or 
hook which in my specimens is decidedly shorter than the following 
joint, though said to be equal to it by De Guerne and Richard. The 
fifth feet of the female resemble those of pallidus. The inner rami of 
the male fifth feet are two jointed in the type, but both Marsh and I 
find forms with one-jointed rami. The terminal claw of the right 
foot is long and geniculately curved, the accessory spine of the pre- 
ceding segment is near the distal one-third, the inner ramus is (in our 
‘form) quite slender, longer than the basal segment of the outer ramus. 
The terminal joint of the left foot is rounded and ciliated, as well as 
furnished with two spines. Length of larger forms 1.4 mm., male 
considerably less. Our small form is 1.1 mm. long and may prove a 
subspecies, though agreeing with Marsh’s figures. Compare also D. 
siciloides, the western representative of this small form. 
Diaptomus baccillifer Koelbel. 
PLATE X, Fia. 2. . 
Wierzejski ’82 (D. gracilis var. d and b); Koelbel ’85; Wierzejski ’87 (D. mon- 
tanus); De Guerne and Richard ’89. 
A small species encountered in high latitudes and altitudes of 
the old world, Siberia and the Alps being the chief stations, is not 
well distinguished from its allies. The antenne reach the stylets, and 
in the male the geniculate antenna has a strong process on the ante- 
penult joint. The internal rami of the fifth feet are more or less dis- 
tinctly two-jointed, being very short in the female. The inner ramus 
of the left foot in the male is fused with the preceding segment, and 
near its base is aspine. The outer ramus of the same foot is forcipate. 
Length 1.0 to 1.5 mm. 
* Diaptomus shoshone Forbes. 
PLATE V, Fia. 11. 
Forbes 793. 
‘‘A very large and robust species. Thorax broadest in front, 
across the maxille, tapering gradually, with little convexity to the 
posterior third. In the female the angle of the last segment is bifid, 
both projecting points being minutely spinose at the tip. The first 
segment of the abdomen is laterally expanded; the expansion of the 
left side with a minute spine at the apex behind; that on the right 
produced at the same point into a small, rounded tubercle, 0.03 mm. 
in length, about as broad as long, making this first segment somewhat 
unsymmetrical.”? ‘‘Egg mass very large, obovate (narrowest for- 
ward). Right antenna of male robust, the last two joints without 
special appendages, antepenultimate with a long inarticulate process 
at its outer apex, extending beyond the tip of the penultimate and to 
