ENTOMOSTRACA OF MINNESOTA. 143 



Limnosiria 



"Si da. Pseudosida ,.Latona 



Holopedidas \. .' ,,-■'' 



^^^^ ^-.y ,Ddphnella 



"--, V 

 ■"- I 



I 



<SIDID/€> 

 I 



[ SimoQephalus 



^■1 lAO\HA-~--Cerioc/aphnia / ^Daphnia 



<LYNCODAPHNID/E> "^"-^Scahholeheris 



Bosmina Streblocercus Macrothri^^ -s^^ Lyncodaphnia 



Lathon'ura DrepanothriX^ ^v|^ iliocryptus 



1 V. 



I -s 



A cantho/eheris <^ly N C E I D/E > t 



_ I Leydi'Jici 



_ turycercus ^^ 

 Camptocercus / ^-' 



Alonopsis-'' ^/, ,'' 



lAlona) / 



Lynce'us Graptolebris 



I PleOroxusl^ 



Chydorus \ 



^ Monospilus 



part of the body, or at least forms a sac for the protection of the eggs. 

 This so called shell springs as a fold from the maxillary segment, and 

 is the most conspicuous and variously formed, while really least im- 

 portant, of the structural peculiarities. 



All Cladocera begin life with a single median eye, but some lose it 

 during later life. In one case it remains the only visual organ. 



The outer covering is in most cases changed by frequent moults. 

 The period of the moult is one of the most precarious in the life his- 

 tory of the animal. 



Although figures and brief descriptions of animals belonging to 

 this group are to be found in the works of Swammerdam, Leuwen- 

 hoek, Trembley and others of the older authors, Mueller* was the 

 first to produce a systematic work upon these in common with other 

 minute fresh water Crustacea. He may be called the father of the 

 study of micro- Crustacea. Jurine,t an eminent Swiss naturalist, was 

 the next to contribute important discoveries relating to these inter- 

 esting animals, though Kamdohr had given anatomical details of sev- 



♦Entomostraca, seu Insecta testacea, qure in aquis Daniic et Norvegire repcrit descripsif, etc. Otto 

 Friedrich Miilkr, 1785. 



t Monoc. qui se trouvent aux Envir. de Geneve. 



