144 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



eral species. Gruithuisen, a little later, gives further details of 

 Daplmia sima (Simocephalus). The work of Milue Edwards gives a 

 resume of what was known regarding these animals in that period. 

 Soon afterwards the work of Baird became the beginning of a new 

 era, and the study of the minute Crustacea sprang into importance at 

 once. The Scandi vanian peninsula being the birthplace of the science, 

 it is proper that the most exhaustive work on the group should be 

 performed there. 



The most important of the later writers are Leydig, Schoedler, 

 Fischer, Lilljeborg, P. E. Mueller, Sars, Weismann, Clans and Kurz. 



The complete bibliography of the subject up to Mueller's time is 

 found in Baird' s British Entomostraea; the greater part of the later 

 bibliography is to be found in P. E. Mueller's DanmarWs Cladocera. 

 A few only of the more important works are here mentioned, the com- 

 plete list elsewhere given making repetition unnecessary. 



Lilljeborg, ]]'., De Crustaceis ex ordinibus tribus, (or) Om de inom Skane forekom- 

 mande Crustaceer af ordningarna Cladocere, Ostracoda och Copepoda. 



This valuable work is particularly good on the Cladocera, but is unfor- 

 tunately without Latin descriptions; so that the Swedish text is a 

 hindrance to its usefulness. It is chiefly of historic value now. Large 

 8vo. Lund, 1855. 



Leydig, Fr., Naturgeschichte der Daphniden. 



The most magnificent work published on this group. 



S'lrs, G. 0., Om Crustacea Cladocera, iagttagne iOaiegnen af Christiania, 1862. 



This valuable work is difficult of access, printed on thin paper and 

 without illustrations. A second paper by the same author in 1863 

 is mentioned, but I have never seen it. 



Schoedler, J. E., Neue Beitriige zar Naturgescbicte der Cladoceren, 1863. 



One of the most important works on the Lynceidce. 



Sars, G. 0., Norges Ferskvands'irebsdyr Cladocera ctenopoda, 1865. 



The best work on the Sidldce, etc. 



Mueller, P. E., Danmark's Cladocera. 



One of the most useful books on the subject. Especially good on Lyn- 

 ceidce and Bosminidce. 



Grobben, C, Zar Eatwicklungsgescbicbte d. Moiua rectirostris, 1789. 

 Weismann, Beitriige zur Naturgscb. der Daphnoiden, Leipzig, 1876-79. (Valuable on 

 tbe pbysiology.) 



The American literature may be catalogued in a few lines. The 

 first descriptions and figures with which I am familiar are those in 

 the Beport of the United States Fish Commision, 187'4, where S- I. Smith 



