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other names. When examined in the fresh state, it may at once be recognised 

 from the other indigenous Cypridae by the bright yellow colour of the shell, 

 and the same characterising colouring is also found in all the other known 

 species of the present genus. 



Occurrence. This is perhaps the most common of our fresh water Ostra- 

 coda, occurring often in great abundance in ponds and ditches during the 

 greater part of the year. Though more generally keeping at the bottom, the 

 animals are at times seen swimming about in the water with great dexterity. 

 The exlusive parthenogenatical reproduction of this form seems to me to be 

 indubitable. I have examined immence numbers of specimens, both from 

 Norway and from abroad, but have never come across even a single male 

 specimen, arid I have also watched the species in my aquaria for many suc- 

 sessive generations with the very same result. True, Dr. Varra describe what 

 he believe to be the male of this form; but I am by no means assured that 

 the specimen examined by him had in reality belonged to the present species. 

 In some other species more or less closely allied to the present one, are indeed 

 male specimens not rarely met with, and I have examined this sex in both of 

 the 2 South African forms; H. capensis (G. W. Muller) and H. anrea G. O. Sars. 



Distribution. Throughout Europe, Central Asia, North and South Africa, 

 North America, Brazil. 



Gen. 23. Dolerocypris, Kaufmann, 1900. 



Generic Characters. Shell very narrow and elongated, with both extremi- 

 ties rather produced. Valves somewhat unequal, the right overlapping the 

 left both in front and behind, edges unarmed; inner duplicatures very broad. 

 Antennae well adapted for swimming. Maxillae with both the masticatory lobes 

 and the palp narrowly produced. The other limbs on the whole of normale 

 structure. Caudal rami rather powerfully developed, with the apical claws 

 very unequal in length, both coarsely denticulated, dorsal seta very small a 

 attached near the end. 



Remarks. This genus was proposed in the year 1900 by Kaufmann, to 

 include Cypris fasciata O. Fr. Muller, and has been admited by the more 

 recent authors. In addition to the European species described below, 4 other 

 nearly allied species have in recent times been recorded from more south 

 latitudes. 



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