STATE GEOLOGIST. 57 



margin of the shell or is quite wanting. This longer form has the beak 

 slightly arched so as to resemble a "Roman nose." The anal spines 

 are less numerous (10-14 while typical D. pulex has nearly 20). 

 The young of this form, which may be called 



Daphnia pulex, var. nasiitus, (Var. n.) 



(Plate N. Figs. 1-4.) 



vary much among themselves but, in general, resemble the young 

 of the European form. 



Daphnia pulex has been mentioned by a number of authors in 

 America, Smith, Birge, Chambers and Herrick having noted its 

 occurrence in various parts ol the United States. D. ohtusa, Kurz, 

 is apparently only the spineless condition of the above or a related 

 species. No Daphnia is without the spine through life; such a 

 form would constitute a new genus at once. 



Sp. 4. D. sclioedleri, Sais. 



Seems to resemble D. pulex very closely but diifers in having 

 the lower margin of the head nearly straight, terminating in a short 

 straight beak. The spine springs from the middle of the posterior 

 margin. The anal spines are 14-16 in number. Length 2.33 mm. 



This name is applied by Sars to Schoedler's D. longispina which 

 is not D. longispina of Leydig. 



Sars' D. hastata is so insufficiently defined that it will probably 

 be necessary to drop it from the list. 



Sp. 5. Daphnia niiiinehaha, (Sp, n ) 



(Plate K, Figs. 1, 2; Plate L, Figs. 1, 2.) 



This species, which occurs in small pools in autumn (afiluents of 

 Minnehaha creek, etc.,) closely corresponds apparently to Sars' 

 Daphnia carinata but differs in numerous points. It, in fact, is more 

 nearly related to D. pulex than the group under which that species 

 is placed. 



The form is oval, arched above, narrowed posteriosly, terminat- 

 ing in a rather short spine which curves lightly upwards. In males 

 and young females the spine springs from the upper angle, but in old 

 females having many summer eggs the spine is nearly median- 

 The head is depressed, strongly arched and keeled slightly above 

 the eye, which occupies the extreme end of the forehead. The keel 

 of the head extends into a slight angle over the heart and continues 



