[11] LAKE SUPERIOR ENTOMOSTRACA. 711 



varied, that I can see, in any particular since its advent here, my speci- 

 mens from PAnse Bay, Marquette, and White Fish Point agreeing pre- 

 cisely with the specific descriptions and figures of P. E. Miiller,* Lillje- 

 borg,f and Schoedler.| Even the rudimentary legs of the fourth pair, 

 although more swollen than in Muller's and Lilljeborg's figures, are 

 similarly lobed, and bear the same armature ; and the coxal tuberosities 

 noted by Miiller are also present. 



My examples differ, on the other hand, from Leydig's plates and 

 descriptions in the presence of four curved spines instead of three at 

 the tip of each of the first three pairs of legs, and in the number of 

 plumose bristles on the antennoe, — seven on each ramus in ours, while 

 in Leydig's oculus there are eight on the outer ramus. These distinc- 

 tions of pediculus and oculus have already been noticed by Schoedler, 

 but subsequent writers have considered tbem insignificant, and bring 

 all known forms of Polyphemus under one specific name. 



In this country, this species has been reported previously from Mas- 

 sachusetts (Birge) and from Minnesota (Herrick). 



Family Leptodoridje. 



Leptodora hyalina Lillj. 



A beautiful and interesting species, likewise common to the northern 

 parts of both worlds, and equally abundant in both, occurred frequently 

 in my Michigan collections, although much more abundantly in Lake 

 Michigamme than in Lake Superior. Great numbers were taken in the 

 former lake, at the surface, on a bright day, with high wind, at 3 p. m. 



Family Lynceid^:. 



Eurycercus lamellatus O. F. M. 



Identical with the European species. Taken in Marquette harbor and 

 PAnse Bay. 



Acroperus leucocephalus Koch. 



From PAnse Bay. 

 Alona sp. 



A very few specimens of this difficult genus were taken, usually in 

 numbers too small for precise determination. A. oblonga P. E. M., and 

 ^others allied to modesta Hk., and quadrang ulata P. E. M., occurred at 

 Marquette and at White Fish Point, and still another form was taken 

 in Lake Michigamme. 



Pleuroxus procurvus ? Birge. 



Trans. Wis. Acad. Sci., IV (1877), p. 92. 



To this species I assign doubtfully a few specimens taken at Mar- 



* Daninark's Cladocera, p. 200. 



tDe Crustaceis ex ordinibus tribus Cladocera, Ostracoda et Copepoda, in Scania 

 occurrentibus, p. 62. 



t Neue Beitriige zur Natnrgeschiclito der Cladoceren (Crustacea Cladocera), p. 67. 



