BIHANG TILL K. sv. VET.-AKAD. HANDL. BAND 20. AFD. IV. N:0 2. 11 



developed inncro . The Daphnia 2)7<Iea-gvoi\\) was thus divided 

 by O. F. MtiLLER ') (wlio did not meution tbe Hyalodaphma- 

 forms) into two species. pennata and louffispina. For the 

 latter De Geer's M. pukx was a synonym (in spite of Mul- 

 ler's figure). Straus ^ a) distinguishes tliree forms of Daplmia : 

 Da2)hnia pidex (wliicli lie makes synonynions with MtJLLER's 

 Daphnia pennata), his new species Daplmia magtia ai-nåDaphnia 

 longispina O. F. Muller. The differences lietween Straus's 

 pulex and nuif/na partly consist in the size (the former 4 mm., 

 the låter 5 mm.) partly therein that his pulex has a short 

 spine and the fnllgrown one only a blunt prominence, while 

 his magnu has a straight permanent spine. His hnigispina is 

 distinguished by the coneave outline of the head beneath, by 

 a permanent spine and by smaller size, only 1^ 2 mm. Straus's 

 pulex and magna are, however. as can easily be seen from 

 the figures as well as from the diagnosis. only tlie same 

 species though in different ages. 



.Jurine's ■') iJajiJniia pulex is different from Straus's species 

 with the same name and is an aberrant form, which is evident 

 from the concavity of the rostrum. S. Fischer^) in his first work 

 incorporates the three species in Dapluiia niag'na. In his låter 

 works (**a and *^ b) he proposes all three again as independant 

 species, but then he confounds Daphnia magna dii\å2ndex. so that 

 his figs. 1 and 3, Pl. III. oi pulex (^ b) are Straus'!^ Daphnia tnagria 

 (yonng ones) but his magna, fig. 2 and 5, on the other hand 

 is a DajJmia pidex, as is already stated by Lilljeborg ^"). In 

 the same work. Bull. Soc. Nat. de Moscon 24. 2, (Pl. Ill, tig. 4) 

 FiscHER has drawn a y<mng female of Daphuia pulex with a 

 wartlike excrescence on the neck instead of the triangulär 

 prominence. His longi!<pina from South Russia (* c), Pl. III, 

 fig. 1 — 4, is a »longispine , yonng form, which lie believes to 

 correspond with O. F. ]VIi!LLER's longispina and which Leydig ^-) 

 regards as synonymous with his species of the same name. 

 Bairi) ') mentions Deiplnda magna and longispina as var. a 

 and [j of Daphnia pulex. and established two new species, 

 Daphnia psitfaeea and Daplmia Sehccfferi. His Daphnia pulex, 

 tar. (i magna (Pl. XI, fig. o) is evidently only a variety 

 tending to what (I. O. Särs ^"^ a) låter has called Da^^/mm 

 aqiiilina; and Baird's^) Da])hnia psitfaeea (Pl. XI, figs. 3 and 

 4) is nothing but a young (of magna':'). Dapthnia Sehcefferi 

 Baird is also a young form, but deviates somewhat from 



