80 



In allusion to this latter character I had long ago noted this form under the 

 provisional name C. limbata. Another peculiar character distinguishing the 

 present species is the abrupt contraction of the anterior extremity of the shell 

 which, in the dorsal or ventral aspect of the animal, looke like a sharply 

 pointed rostrum; hence the specific name proposed. 



Occurrence. I have met with this form occasionally in the environs of 

 Christiania, especially in shallow grassy creeks at the borders of lakes and for- 

 med by the higher level of the water in the lakes during the spring. Unlike 

 what is generally the case, male specimens of this form are more frequently 

 met with than females. 



Distribution. Sweden (Ekman), British Isles (Brady) Germany (G. W. 

 Muller), Bohemia (Vavra), Russia (Cronenberg). 



19. Candona marchica, Hartwig. 



(PI. XXXVIII, fig. 1). 



Gandona marchica, Hartwig, Sitzungs Berichte de Gesellsch. naturf. Freunde in Berlin 18 



Nr. 8, p. 183. 



Syn: Candona rostrata, G. W. Muller (part). 



Specific Characters. Female. Shell comparatively shorter and stouter 

 than in C. rostrata, though, seen laterally, of a somewhat similar shape, 

 greatest height as usual behind and considerably exceeding half the length, 

 dorsal margin somewhat ascending and joining the posterior edge by a bold 

 and quite even curve, ventral margin slightly sinuated, anterior extremity more 

 uniformly rounded than in C. rostrata, posterior blunted and less expanded 

 below; seen dorsally, oblong oval in outline, with the greatest width some- 

 what exceeding 2 /5 of the length, anterior extremity more pointed than t 

 posterior, but scarcely rostriform produced. Surface of shell, as in the pr 

 ceding species, densely hairy, hyaline borders however rather narrower. Stru 

 ture of the several limbs almost exactly as in C. rostrata. Caudal rami co 

 paratively shorter and stouter than in that species, with the apical claws more 

 unequal in length, the proximal one being very much shorter than the distal 

 one, which almost attains the entire length of the ramus. Genital lob 

 broadly rounded off behind. 



Male of somewhat larger size than female and rather like the male of 

 C. rostrata in the shape of the shell, though heving the hyaline borders in 

 front and behind conspicuously narrower. Prehensile palps of maxillipeds com- 

 paratively shorter and stouter. Caudal rami with the proximal claw much 







