137 



Colour very similar to thp.t in P. vidua, the ground-colour of the shell 

 being pale whitish, and the band-like patches very dark, almost black. In 

 addition to the 3 patches found in the said species, a 4th patch is to be traced 

 close to the hind extremity of the valves. 



Length of adult female 0.65 mm. 



Male unknown. 



Remarks. This form has generally been confounded with the preceding 

 species, to which it certainly bears a close resemblance. Dr. Kaufmann has 

 however pointed out some well-marked differences, which prove it to be in 

 reality specifically distinct. I have raised both these forms together from a 

 parcel of dried mud kindly sent to me by Mr. Johansen and taken from a 

 pool near Ottawa, Canada. On examining more closely the specimens abound- 

 ing in my aquaria, I at once became aware of the marked difference between 

 these 2 forms in the shape and sculpture of the shell, making it very easy 

 to distinguish them, the one from the other, even at a rather low magnifying 

 power. 



Occurrence. This species is rather frequently met with, both in small 

 pools and at th* borders of greater lakes, and I have taken it as far North 

 as Matsjok in East Finmark. In its behaviour the animal agrees with the 

 preceding species, being however comparatively more active in its movements. 



Distribution. Switzerland, and probably in many other places of Europe, 

 North America. 



57. Pionocypris obesa (Brady & Robertson). 



(PI. LXIV, fig. 2). 



Cypridopsis obesa, Brady & Robertson, Ann. Mig. Nat. Hist. Ser. 4, Vol. Ill, p. 12, 



PI. XVIII, figs. 5-7. 

 Syn: Cypridopsella tumida, Kaufmann. 



Specific Characters. Female. Shell of a very obese appearance, seen 

 laterally, broadly ovoid in shape, greatest height in the middle and exceeding 

 Ve of the length, dorsal margin boldly arched, with indication to an angle in 

 the middle, ventral margin slightly sinuated and distinctly bowed in the oral 

 region, anterior extremity broadly rounded off, posterior somewhat narrower 

 and obtuse at the end; seen dorsally, broadly ovate in outline, with the 

 greatest width behind the middle and considerably exceeding the height, 

 anterior extremity obtusely pointed, posterior evenly rounded off. Surface of 

 shell finely hairy, and of a somewhat dull appearance, being very distinctly 



17 Crustacea. 



