12 R. LUNDBERG, DEVELOPMENT OF THE DAPHNIDS. 



Daphnia mogna Straus & Lill.jeborg. whieh is evident from 

 the ronnd sliape of the body. The last iiamed author (Lillje- 

 borg)'") also oonsiders it as a synonym of magna. All Baird's') 

 iigs. of these species represent niore or less young specimens; 

 most advaneed is that one represen ted on the Pl. VI lig. 3 

 {Daphnia pidex). 



LsYDKi '-) suggests that he has found in the terminal set;« 

 of the antennte of the males a reliable characteristic distin- 

 guishing Daphnia magna and D. pulex from D. longispina. It 

 seems, however, to be rather donbtful, whether the eharac- 

 teristics mentioned by him may be regarded as snfficient 

 to establish a new species. indeed, his fignres of Daphnia 

 longispina (Ph 11. tigs. IM and 19) represent only young 

 forms of a male and a feinale. Besides. the former possesses 

 the tooth-like prominence, though situated further back. 

 IVIoreover. TjEYDi(i's '-) fignres of Daphnia ^^k^cx, Pl. iigs. 2 — 5, 

 disagree with those of the same species drawn by Fischer 

 and Lilljeborg. The last named author iigures, it is true, 

 only the abdomeii of the male Daphnia pulex (Pl. XVI, 

 tig. 10). bnt this tignre does not agree at all with Leydig's 

 tigs. '6 and ö. Pl. 1. Lilljeborg '") does not men tion anything 

 abont the large hair^- and scaly prominence on the addomen 

 of the male, which according to Zenker •') and Leydig ^'^) ought 

 to be characteristic for the male of this species, and which 

 was tirst stated by Fischer ^), Pl. VII. ^^. 12, as belonging 

 to the male af his Daphnia magna. 



In fact, only the above mentioned authors, Fischer. Zen- 

 ker and Leydig. have seen this stränge prominence. which 

 ouglit to be specially marked, as it is a most peculiar organ 

 which is not found in other forms of Daphnia. According to 

 my views, this prominence is nothing but the spine of the new 

 shell which is laid bare after the next exuviation. The named 

 authors obtained their specimens ju.st in a .state of exuviation; 

 disregarding this to be the case. they evidently believed that 

 this prominence belonged to the abdomen and drew it as it 

 was attached to this part of the body, which thus in Leydig's*2) 

 tignre (Pl. 1. tigs. 3 and 5) has a very stränge shape. Zen- 

 ker '•') describes such a thing on the abdomen of the male 

 Daphnia pulex, and Leydig, ^'^) who believes it to characterize 

 this species. emphasizes therefore that Fischer's ^) tignre 

 of the male Daphnia magna (Pl. VII, %. 12) represents 



