144 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
eral species. Gruithuisen, a little later, gives further details of g 
Daphnia sima (Simocephalus). The work of Milne 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 Scandivanian 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, Claus and Kurz. 
The complete bibliography of the subject up to Mueller’s time is 
found in Baird’s British Entomostraca; the greater part of the later 
bibliography is to be found in P. E. Mueller’s Danmark’s Cladocera. 
A few only of the more important works are here mentioned, the. com- 
plete list elsewhere given making repetition unnecessary. 
Lilljeborg, W., 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. 
Surs, G@. O., Om Crustacea Cladocera, iagttagne i Omegnen 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 Beitrage zur Naturgeschicte der Cladoceren, 1863. 
One of the most important works on the Lynceide. 
Sars, G. O., Norges Ferskvands<rebsdyr Cladocera ctenopoda, 1865. 
The best work on the Sidida, ete. 
Mueller, P. E., Danmark’s Cladocera. 
One of the most useful books on the subject. Especially good on Lyn- 
ceidee and Bosminide, 
Grobben, C., Zar Eatwicklungsgeschichte d. Moina rectirostris, 1789. 
Weismann, Beitrage zur Naturgsch. der Daphnoiden, Leipzig, 1876-79. (Valuable on 
the physiology. ) 
The American literature may be catalogued in a few lines. The 
first descriptions and figures with which I am familiar are those in 
the Report of the United States Fish Commision, 1874, where 8. I. Smith 
iar. 
