1885.] 



CLADOCERA. 



9 



L 



On the Structure of the Ephippia and the Development of 

 the Ephippial Eggs in Daphnia Lnmholtzii, n. sp. 



(Pl. 1, figs. 1-10). 



It has been mentioned above, that one kind of ephippia 

 occurred in great numbers in the Australian mud, and that these 

 ephippia could at once be recognized as belonging to a pecu- 

 liar species of Daphnia, subsequently domesticated with suc- 

 cess in my aquaries. This species, which I have named after 

 the Norwegian traveller, Mr. Lumholtz, whose kindness enabled 

 me to'prosecute these investigations, will further on be described 

 in detail Here, I purpose merely describing the structure 

 of the ephippia of the species together with the development of 

 the so-called winter-eggs, having found that former investiga- 

 tions do not give satisfactory information concerning these points 

 in the natural history of the Cladocera. 



The ephippia of the present Australian Daphnia differ in 

 certain respects not a little from those of most of our indige- 

 nous species. In but one species, Daphnia magna Strauss, do 

 we meet with a similar arrangement of the two ova contained 

 in the ephippium, their ampullæ having an obliquely transversal 

 position to the axis of the ephippium. The size of the ephippia 

 found in the mud was somewhat variable, the length of the 

 valves measuring from 1,00 mm to 1,50 mm. In a lateral aspect 

 (Pl. 1, fig. 1), they exhibit an oblong-oval, or rather irregular- 

 quadrilateral form, the dorsal side being the longer and the two 

 opposite angles rounded off. Along the dorsal edge occurs a 



