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in its outer part, with the dactylus quite short, hamiform curved and exhibiting 

 at the base inside a knob-like prominence. Copulative appendages with both 

 terminal lappets lanceolate in shape and nearly equal-sized. 



Colour in both sexes transparent white, with a fainte yellowish tinge. 



Length of adult female scarcely exceeding 0.60 mm. 



Remarks. This form was briefly announced by the present author in 1890 

 under the manuscript name lacustris proposed by Lilljeborg. The validity of 

 the species has however not been admitted by Dr. Aim, who regards it as 

 merely a slight variety of C. ophthalmica. In order to settle this question, I 

 have subjected both these forms to a renewed detailed examinarion, and have 

 thereby convinced myself on their specific distinctness. 



Occurrence. I have found this form very abundantly in severals of our 

 larger lakes, down to very codsiderable depths. Though the animals are well 

 equipped for swimming, they keep constantly near the bottom, over which they 

 move in the usual manner. 



Distribution. Sweden (Lilljeborg). 



Group 4. Notodromides. 



Remarks. In accordance with Dr. Kaufmann, I refer to this group the 2 

 anomalous genera Notodromas Lilljeborg and Cyprois Zenker, which, though 

 rather sharply defined the one from the other, yet exhibit some characters in 

 common not found in the other groups here recorded. To these genera may 

 moreover be added the genus Newnhamia King, which evidently is closely 

 allied to Notodromas, and the genus Hungarocypris Va'vra, which shows some 

 relations to Cyprois. Only the 2 first-named genera are represented in the 

 Fauna of Norway. 



Gen. 14. Notodromas, Liiljeborg, 1853. 



Generic Characters. Shell short and stout, with the dorsal face evenly 

 vaulted, ventral flattened and exhibiting in the middle a sharply defined navi- 

 cular area, surface of valves otherwise quite smooth. Eye distinctly divided 

 in the middle so as to appear double. Antennae well adapted for svimming, 

 the posterior ones with the penultimate joint distinctly subdivided in both sexes, 

 the 3 outer joints remarkably slender and narrow, apical claws imperfectly 

 developed. Mandibles of normal structure. Maxillae with the palp of moderate 



