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STATE GEOLOGIST. 59 



a great deal of diversity of opinion as to the value of this name. 

 Not that there is any doubt of the existence of a widely distributed 

 form which in general is that intended by Leydig and others, but 

 the variation is so great that the possibility remains that more 

 than one species is included under the one title. 



P. E. Mueller recognizes two varieties depending chiefly upon 

 the length of the spine. 



D» lacustris^ Sars, is nearly related, if not a variety of the above. 



Sp. 8. Daphnia rosea, Sars, 



(Plate K. Figs, 10-12.) 



Tn form very like D. longispina, this species, which is the only 

 representative of this smooth-clawed, unkeeled group yet found in 

 America,might perhaps be appropriately re-united with that species, 

 but, as there seems little doubt of the identification with Sars' va- 

 riety, as above, I prefer to use his name. 



Body oval, moderately ventricose; head of moderate size, lower 

 margin nearly straight; eye situated in the anterior prominence. 

 The beak is not very prominent. The upper outline of the head 

 is slightly concave above the eye or rather less convex. The head 

 is separated from the body by a marked depression. The spine of 

 the shell springs from the upper angle or is quite wanting. The 

 post-abdomen is of moderate size, somewhat narrowed toward the 

 end. The claws are smooth, the anal spines nearly equal, straight, 

 about 14 in number. The abdominal processes are not coalesced 

 or but slightly so. Length 1.50 mm. to 2.0 mm. The species was 

 collected sparingly in a large gathering of D. pulex from a small 

 lake in early spring. 



The size and conformation of the abdominal processes is very 

 variable and the long and very slender spine is frequently absent, 



Sp. 9. Daphnia similis, Claus. 



The description of this species, which was bred in confinement 

 from eggs brought in mud from Jerusalem, I am, unfortunately, 

 unable to quote. Judging however, from the figures which alone I 

 now have access to, it belongs in the group of D. longispina^ though 

 in many particulars it resembles D. schsefferi. The form is elon- 

 gate, the spine short and springing from the upper margin. The 

 antennule of the female is very large and flagellate, while that of the 

 male is like that of D. schaefferi. The flagellum and hook of the 

 first foot of male are rather small. 



