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



Cyclops uniang^iilatus Cragin. 



Cragin '88; Herrick '84. 

 Cragia was not conversant with the description of G. parcus, with 

 which his description agrees save in one point. It differs from G. 

 parens in having three inner set^B on the terminal joint of the outer 

 ramus of the first foot. It would be officious to suggest a possible 

 oversight here, but G. parens has only two in type specimens (though 

 in all this group the corresponding ramus of the second foot has three 

 setffi), so that at present the two must be kept distinct. 



* Cyclops leuckarti Claus. 

 Plates XVI; XVIII, Figs. 1, a-j; XXIV, Figs. 2-6. 



Claus '57 and '63; Sars '63; Poggenpol '74 (simplex); Uljanin '75 (tenuicornis); Hoek 

 '78 (leeuwenhcekii); Herrick '83 (tenuissimus) and '84 (simplex and leuckarti); 

 Daday '85 (simplex, pectinatus, and leuckarti); Vosseler '86 (simplex); Herrick 

 '87 (simplex); Thallwitz '90 (simplex); Lande '90 (simplex); Schmeil '91 and '92; 

 Richard '91; Forbes '91 (edaxj; Brady '91 (scourfieldi) ; Marsh '92. 



"Description of the Female: The form is very slender, an 

 average individual measuring between 0.95 and 1.0 mm. exclusive of 

 the caudal setse. The following detailed measurements of a specimen 

 measuring 0.976 mm. will serve to exhibit the proportions of the parts: 

 First thoracic segment 0.30 mm., second segment 0.08 mm., third seg- 

 ment 0.08 mm,, fourth segment 0.056 mm., fifth segment 0.024 mm.; 

 first (apparent) abdominal segment 0.16 mm,, second segment 0.08 

 mm., third segment 0.048 mm.; caudal stylets 0.088 mm,, outer seta 

 0.08 mm., outer median 0.30 mm,, inner median 0,46 mm,, inner 0.20 

 mm., dorsal 0,06 mm.; the lateral seta is 0.036 mm. from the end. 

 The antennfe reach nearly to the base of the thorax when reflexed, and 

 are quite strong. They resemble those of G. tenuicornis in several par- 

 ticulars, but since it is desirable to distinguish this species with the 

 greatest possible accuracy, the following numbers are given to express 

 the relative length of the several segments, beginning with the first: 

 jZO, gS, 33, 4IO, 5?, e4, 7II, 85, 95, io5, ^T, i^'^, ^gS, ^46, 15IO, jg^^? 

 i7l4. The fourth, eleventh, fourteenth and fifteenth segments bear 

 the longest sette. The last two segments are armed with a knife-like 

 ridge similar to that found in G. tenuicornis. This ridge is serrulated 

 on the last segment, and near the end is cut by a deep incision so that 

 the terminal part is like a hook notched upon its convex outer part. 

 The antennules are slender and but moderately spinous, the first 

 three segments being almost exactly equal (0.06 mm,), while the ter- 

 minal segment is as long as the basal segment of the antenute (0,08 

 mm,). The lab rum is armed with thirteen small teeth. The larger 

 maxilliped is pearled on the posterior margin of its largest segment. 

 The armature of the terminal joints of the feet is as follows: 



