396 Wisconsin Academy of Sciences, Arts and Letters. 



in general, and include both names. In no case have I found the head 

 directed so horizontally forward as in Schoedler's figures of C. rectiro- 

 stris* Nor are the posteal teeth so large. Our form more nearly resem- 

 bles that figured by Matile.| In the other form, the head is more depres- 

 sed, the macula nigra larger than the eye, and the ventral margin of the 

 valves is concave. I have found no specimens connecting the two forms 

 and have therefore identified them as above. 



In both species I have found individuals in which the beak was trun- 

 cate, resembling that part in C. Lilljeborgii, Schdl., as figured by Hellich, J 

 or C. latirostris, Kurz.§ The shell markings differ from those figured by 

 any author. If a cast shell is examined without cover glass and not 

 covered by water, a reticulated area is seen in the anterior part of the 

 valves just below the middle. From this radiate most of the striae. 

 These are in front parallel to the anterior edge of the shell and the 

 direction gradually changes until they are parallel to the ventral edge. 

 Sixteen or more striae run out on the ventral edge of the shell. The long- 

 itudinal striae anastomose occasionally and those on the dorsal part of 

 the valves do not bend downward into the reticulated area. I have never 

 f Qund specimens reticulated all over with quadrangular meshes as Hel- 

 lich (1. c, pp. 76-77) figures them. 



Species 63. Polyphemus pediculus, De Geer. 



This species I have found very rarely. Only two or three specimens 

 have been discovered at long intervals. Zacharias!| notes that this ani- 

 mal is distinctly northern in its range. My observations confirm his 

 conclusion. I find it quite abundant in a small collection from northern 

 Minnesota. Herrick also describes it as plentiful in Minnesota . As I 

 have often searched vainly for it here, I believe that this locality must 

 be close to the southern limit of its range. The same is probably true of 

 Holopedium gibber urn, Zad. 



Species 64. Leptodora hyalina, Lillj. 



I quote this species by its old name, without passing on the correct- 

 ness of the change to L. Kindtii, Focke. Focke's paper is inaccessible to 

 me. Leptodora is very abundant in all our lakes. It grows to a large 

 size and specimens 18-21 mm. in length are not rare. 



* Schoedler. J. E. Neue Beitrage zur Naturgeschichte der Cladoceren, 1853. PL III, fig 50. 

 t Matile, P. Die Cladoceren der Umgegend von Moskau. 1890. PI. IV, fig.26. 

 t Hellich, B. Die Cladoceren Boehmens, 1877, p. 77, fig. 37. 

 § Kurz, W. Dodekas neuer Cladoceren, 1874, PI. II, fig. 9. 



ii Zacharias, O. Die Fauna des grossen und kleinen Teiches in Biesengebirge, Zeit. Wiss. 

 Zool. Vol. XLL, p. 492. 



