58 GEOL. AND NAT. HIST. SUfiVEY 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 setne; the last joint of the pro- 

 topodite has a finger-like hyaline api^endage 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 eiseiii Lilljeborg. 



Plate X, Fig. 11. 



De Guerne and Richard '89. 



One of the largest species known. First segment of abdomen with 

 lateral spines. Caudal stylets short, hairy. Antennae 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 frauciscanus Lilljeborg. 



Plate VIII, Figs. 12, \Q. 



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, sjained laterally. Second abdominal seg- 

 ment very short. Caudal stylets short. Antennre reaching? to the 

 stylets, 25 jointed. The hook-like process of the antepenultimate 

 joint of the male antennne a litlle longer than the penultimate joint. 

 The form of the fifth feet chiefly separates this species from Dkq)fomus 

 similis Herrick. Collected in the vicinity of San Francisco, Cal., 

 by G. Eisen. 



