38 G. 0. Sårs. 



Gen. Streblocerus, G. O. Sars. 



Remarks. — This genus was established by the pre- 

 sent author as early as the year 1862, to comprise a small 

 Norwegian Macrothricid, S. minutus G. O. Sars, which, how- 

 ever, has turned out to be identical with a form previously 

 described by S. Fischer as Daphnia serricaudata. No other 

 species has subsequently been noticed, and it may therefore 

 be of interest to have some information of a nearly allied 

 species from Brazil. 



13. Streblocerus pygmæus, n. sp. 



(PI. VI, figs. 13—17). 

 Specific Characters. — Female. Carapace 

 very tumid, seen laterally of a rounded form, height some- 

 what exceeding the length, dorsal margin boldly arched, 

 ventral angularly curved in the middle, posterior extremity 

 blunted. Head rather large, and defined above from the 

 carapace by a well-marked, though small depression, its dors- 

 al margin evenly curved, rostral projection rather prominent, 

 lower margin smooth and slightly incurved in the middle, 

 inferior edge of lip-expansion, however, minutely serrate. 

 Surface of shell, especially towards the dorsal face, sculp- 

 tured with very conspicuous scale-like ridges, lower edges 

 of valves setiferous. Eye well developed; ocellus small and 

 placed at some distance from the eye, close to the tip of the 

 rostrum. Antennulæ and antennæ almost exactly as in the 

 type species. Tail, however, differing conspicuously in the 

 fact of the upper part of the dorsal edge not being serrate, 

 but clothed with a row of delicate hair-bunches; caudal 

 claws minutely denticulate throughout their whole length. 



