290 Birge — Notes on Cladocera. 



B. On new or rare species of Cladocera chiefly from Northern 

 Wisconsin. 



MOINA AFFINIS, Sp. nov. 



Plate X, Figures 1, 3, 5, 7, 8, 12, 13, 14. 



Female. — The head closely resembles that of M. rectirostris r 

 Jur. , being somewhat rounded anteriorly, having a deep de- 

 pression above the eye, and being without an angle on the ven- 

 tral margin posterior to the an.tennules. As seen from above, 

 the head is rather long and narrow and shows the supraocular 

 depression very distinctly The outline of the sides of the 

 head is slightly concave in the middle and the sides round over 

 evenly into the anterior margin. The valves are fringed on the 

 margin with setae more closely set than in M. rectirostris, and 

 are marked by transverse, anastomosing lines, giving an ap- 

 pearance to the shell somewhat like that of a Simocephalus. 

 These markings can be seen when the shell is examined un- 

 covered and without water, and also, by careful manipulation, 

 under a cover-glass. These striae resemble those of M. Lillje- 

 borgii, Schdl. as figured by Lilljeborg, ('53,* p. 38, pi. II, f. 4f.), 

 and still more closely those of M. propinqua, Sars, as described 

 and figured by him. ('85, p. 31, pi. VI, f. 1.) 



The structure of the legs agrees exactly with that of M. rec- 

 tirostris, as described by Gruber and Weismann. ('77, p. 70-72.) 



The post-abdomen has a relatively long post-anal portion,, 

 which is armed with 9-11 serrate teeth and a bident longer 

 than the adjacent tooth. The caudal claws have a pecten of 

 12-15 teeth at the base and are denticulate. 



The ephippium contains one egg whose long axis is parallel 

 to that of the body. The ephippium is densely reticulated over 

 its entire surface. 



The antennules are of moderate size, being apparently some- 

 what smaller than the figures of M. rectirostris would indicate 

 for that species. The usual anterior sense-hair is placed a 



* For fall titles of papers, see the list at the end of this article. 



