i 



AUSTRALIAN CLADOCERA. 



however, merely as a variety, and in a subsequent paper, more- 

 over, he describes and figures, under the name of EHzhIhUkp 

 far. fifiifi-mKh-ofu,-'. another very remarkable form, which, as 

 pointed out also by Mr. Schoedeler 1 , undoubtedly represents a 

 very distinct new species. The latter author is however most 

 assuredly wrong in regarding the type-form as identical with the 

 European species X. rrhihis, having apparently been led to this 

 opinion chiefly by the similar form of the ocellus. In 'fact the 

 present species exhibits in its general habitus a much greater 

 resemblance to another northern species, the S. serrtihilns of 

 Koch, from which it however may be readily distinguished, not 

 only by the different form of the ocellus, but also by (he rounded 

 front and the absence of denticles on the posterior edges of the 

 valves. 



Description. — The length of the adult female does not 

 much exceed 172 mm, and the species is thus considerably smaller 

 than the preceding. 



The carapace, as seen laterally (PI. 2, fig. 6), is rather 

 broad, irregularly oval in form and somewhat dilated in the post- 

 erior part. It terminates, as in the European species 8. ser- 

 ntlatm, with a well defined triangular prominence, obtuse at the 

 tip, and located exactly in the longitudinal axis. The dorsal 

 edge of the carapace is but slightly arched and posteriorly bends 

 with a sharp curve abruptly down to the posterior projection. 

 The inferior edges of the valves are slightly sinuated in the 

 middle and join the somewhat oblique posterior edge by an even 

 curve. The head, as seen laterally, exhibits a similar oblique 

 triangular form as in the preceding species; but the front is 

 narrowly rounded, not as in that species subangular, and the 

 inferior edge deeply concaved posteriorly, joining the recurved 

 rostral projection without aDy intervening notch. 



The sculpture of the shell is exactly as in the preceding 

 species, and the posterior part of the dorsal edge exhibits a si- 

 milar armature of small appressed denticles, not continued along 



1 Zur Naturgeschichte der Daphniden. 1877. p. 17. 



