Streblocerus serricaudatus. 303 



not notably stout. All setae usually appear smooth but some- 

 times there are visible very fine teeth on the basal seta and 

 scattered hairs on the others. 



The eye is of moderate size, as is the macula nigra. The lat- 

 ter is quadrangular in shape. The intestine is straight and 

 there are no hepatic coeca. The first foot in the female has a 

 strong hook. The labrum carries a strong triangular process. 



Two species of this genus are known, Bunops serricaudata, 

 Daday,* and the present form which I have called Bunops scuti- 

 frons, sp. nov. 



The species are distinguished by the fact that in B. serri- 

 caudata the crest is serrated posteriorly, while in B. scutifrons 

 the crest is smooth. Length 0.8-1.3 mm. ; height 0.5-0.8 mm. ; 

 transparent. 



The species was found in lake Kawaquesaga at Minocqua, 

 in shallow water among Utricularia, and also in ditches near 

 outlet of lake Wingra, Madison. This species is the subject of a 

 separate paper in this volume by Miss. H. Merrill, of Mil- 

 waukee. For the detailed description of the animal, reference is 

 made to this paper. 



Streblocerus serricaudatus, Fischer. 



This species, hitherto not recognized in the United States, 

 I have found in a marshy pool at Rhinelander, Wis., in shallow 

 water at Minocqua, Wis., at Washington Harbor, Isle Royale, 

 and in collections from Quissett, Mass. It is therefore probable 

 that it is widely distributed in the northern part of this country. 



My specimens agree very closely with the descriptions and 

 figures of Matile ('90, p. 34). The antennules bear on the con- 

 vex side four strong sensory setae and have no cross rows of hairs. 

 On the ventral edge of the shell are numerous stout, stiff setae, 

 apparently immovable. Between these are others, more slender 

 and movable, which ordinarily project inward and so guard the 

 opening between the valves. The post-abdomen also agrees with 

 the description of Matile. 



* Macrothrix serricaudata, Daday. ('88, p. 105, P. II, f. 46-48.) 

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