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58 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
fifth foot two-jointed, more than half as long as the first joint of the 
outer branch, its apex clothed with a fringe of minute cilia; second 
joint of the outer branch ending in a stout, slightly curved: claw, 
which is slightly ciliated on the concave margin; last joint bearing at 
its apex a long, finely ciliated spine and one much smaller seta. 
MALE.—Antepenultimate joint of the right antenna armed with a 
plow-share shaped process, which is nearly half as long as the follow- 
ing joint, and has an obscurely fimbriated free margin. Inner branch 
of the fifth foot on the left side very small; outer branch slender, end- 
ing in two subequal finely pectinated sete; the last joint of the pro- 
topodite has a finger-like hyaline appendage on the inner margin, and 
there is a Similar but smaller organ in the same position on the right 
foot. Inner branch of the right fifth foot very small, pyriform, one- 
jointed, acuminate; terminal claw of the outer branch long, slender, 
subsigmoid. Length 1.1 mm. 
* Diaptomus eiseni Lilljeborg. 
PLATE X, Fie. 11. 
De Guerne and Richard ’89. 
One of the largest species known. First segment of abdomen with 
lateral spines. Caudal stylets short, hairy. Antenne short, reaching 
the lateral processes of the abdomen. Antepenultimate segment of 
right male antenna with a hooked process reaching beyond the end of 
the antenna. Inner ramus of the fifth foot of female obscurely two- 
jointed. The fifth feet of the male very unequal, inner rami two- 
jointed; basal joint of the right foot provided with a spiny process. 
Length 4.0 mm ; male 3.5 mm. This form is about the size of D. 
stagnalis, but seems quite distinct; it was found at Centreville, Cal. 
* Diaptomus franciscanus Lilljeborg. 
PLATE VIII, Fiaes. 12, 16. 
De Guerne and Richard ’89. 
A species of moderate size (2.3 mm.). Last segment of the thorax 
obtuse with minute spines. First segment of abdomen about as long 
as the rest of the abdomen, spined laterally. Second abdominal seg- 
ment very short. Caudal stylets short. Antenne reaching to the 
stylets, 25 jointed. The hook-like process of the antepenultimate 
joint of the male antenne a little longer than the penultimate joint. 
The form of the fifth feet chiefly separates this species from Diaptomus 
similis Herrick. Collected in the vicinity of San Francisco, Cal., 
by G. Hisen. 
