H R. LUNDBERG. DEVELOPMENT OF THE DAPHNIDS. 



all of the juvenile forms.* K. A. Ramdohr ^) was the first 

 to observe the develo2)ment of Daphnids in acpiaries, but tells 

 nothing uew about the changes of form. However, seeing that 

 he refers O. F. Muller's figure to a juvenile form, he appa- 

 rently was acquainted witli such changes. The låter in- 

 vestigators, H. E. Straus *) and Louis Jurine, ^) whose splendid 

 works were published both 1820, exhibit that the females are 

 sexually ripe before they are fuUgrown, acoording to Straus 

 after the fourth and according to Jurine after the third 

 exuviation. The last mentioned anthor pursued their deve- 

 lopment through the lirst juvenile stages and seemingly even 

 farther, but he did not give any account of them beyond these 

 stages. He emphasized, liowever. that they are subject to 

 changes of form during the development, and he regarded 

 Daphwia longispina only as a young Daphnia pulex. Such 

 men of science as S. Fischer. **) Liévin, '^) Baird, '^) and W. 

 LiLLJEBORG ^^) also regarded it to be either a young or a 

 variant form. S. Fischer was the first to call attention to 

 and to draw. ^) Fl. Vill, tig. 8. a young with the tooth- 

 like prominence on the neck, whieh he found both in males 

 and females. In his work on the Daphnids, published in 1860, 

 Leydig ^-) also paid very little attention to the yonnger forms. 

 Nevertheless he lias given a sketch of a young with the 

 »Haftorganv on the head. Pl. I, fig. 7, the purpose of which 

 he did not understand. I have not been able myself to see 

 such an orgauv in the specimens examined by me, nor have 

 I found it mentioned by any other investigator. 



At that time the entomostraca began to be looked for 

 not only in ponds and small lakes but even in larger waters. 

 The discoveries made by Leydig, Lilljeborg and Zaddach of 

 such interesting forms as Biithotrephes^ Lepfodora and Holo- 

 jjedium induced other naturalists to continue these investiga- 

 tions. G. O. Särs ^^) and Ed. Schcedler ^^) enriched the fauna 

 with a number of new species, though some of these hardly 

 can be considered so in the light of modern criticism. Earlier 

 authors had especially turned their attention to an explana- 

 tion of the anatomy and histology of these animals. for which 

 studies they so suitably lend themselves by their transparency; 



* He supposed the Nauplius stages of the Cyclopids to reiiresent genera, 

 distinct from the adult specimens and seems not to have Husj)ected any chan- 

 ges of form during the development of the Entomostraca. 



