4 R. TiUNDBERG, DEVELOPMENT OF THE DAPHNIDS. 



the pond had beeu refilled in the .spring. Låter in the summer, 

 however, I suceeeded in reeovering thera in the lowermost of 

 the small ponds of the station which had been kept drv 

 during the winter and the greater part of the sumnier, bnt 

 which was lilled with water in Angnst. A few weeks after- 

 wards I found the same Daphnia again thongh not aggregated 

 in siich dense swarms. Even hei'e niales. females and yonng 

 ones were observed, but the larger specimens were mostly 

 less advanced in the development. thns inaking the series, 

 bronght together during the previous summer. complete. 



I have called the attention to the cireurastances nndei- 

 whieh the colleetions and observations were made, as they 

 niay be of importance in deciding whether the forms belong 

 all to the same species or not. 



Referring to the outline drawings* which accompany the 

 text, 1 will at tirst describe what 1 found and point out the 

 conclusions which may be drawn from them, and then I intend 

 to criticise tlie views pronounced by other investigators. 



The smallest specimen 1 found is that showu on Pl. 1, 

 lig. 1. a young one which probabh' has jnst left the matrix 

 and on which the spine can be seen. but not yet any tooth on 

 the neck. The fig. 2 (larger scale) represents an older stage, 

 thongh the above mentioned tooth on the neck is still wanting. 

 But in the specimens represented by the figs 3 — 5 (ligs. 3 and 

 4 smaller scale than 5) the tooth is very eonspicuons. This 

 tooth-like process is drawn in the fig. (!. thongh more en- 

 larged. The fig. 7 is the sketch of a slightly older specimen. 

 where the outline (»f the back has become more convex, re- 

 sulting that the spine has moved nearer to the median axis 

 of the body. All these yonng specimens are females. Sonie 

 older ones are drawn in the figs. 9 — 14 and on a couple 

 of these. figs. 11 12. the beginning of an ephippium oi' 

 ontgrowth is eonspicuons. In all these older females the spine 

 has disappeared so that only a lilunt prominence is left. A 

 fullgrown male specimen is represented in the fig. 13. 



All these figures are drawn from specimens belonging to 

 the collection of 1892. Considering that the stages between 

 the young and old ones are wanting, the series from that 



* The drawings are made with the help of Al)be"3 Zeichenapparat iC 

 Zeiss, Jena) but not all with the same power. See the explanation of the 

 figures. 



