58 G. O. Sars. 



Gen. Alonella, G. O. Sars. 



Re marks. — The exact limitation of this genus, estab- 

 lished by the present author as early as the year 1862, appears 

 somewhat difficult, as it exhibits affinity to several other 

 Lynceid genera, on the one side to the genus Alona, on the 

 other to the genera Chydorus and Pleuroxus. I think, never- 

 theless, that it may be convenient to retain the genus in 

 the sense here adopted, though some authors still seem to 

 be unwilling to admit its value. 



No less than 7 different species belonging to this genus 

 have been observed in my aquaria. Three of these have been 

 previously described, whereas the other 4 are new to science. 



26. Alonella lineolata, n. sp. 



(PI. X, figs. 1, 1 a). 

 Specific Characters. — Female. Carapace, 

 seen laterally, broadly oval in outline, height almost equal 

 to the length, posterior extremity but slightly narrowed, 

 and evenly rounded, with the upper corner obsolete, dorsal 

 margin considerably more arched than the ventral. Head 

 slightly procumbent, rostral projection rather short. Surface 

 of shell sculptured with numerous delicate, curved striæ, 

 extending parallel to the dorsal margin and distinctly visible 

 even in the head, those of the carapace curving abruptly 

 downwards on the anterior part of the valves; lower edges of 

 the latter fringed with rather distant delicate setæ. Ocellus 

 much smaller than the eye, and placed somewhat nearer to 

 it than to the tip of the rostrum. Lip-plate with the lower 

 edge evenly curved. Caudal part rather large and oblong, 

 dorsal edge below the anal orifice almost straight, supra-anal 



