68 G- 0. Sårs. 



35. Chydorus Poppei, Richard. 



(Pl. XI, figs. 2, a— c). 



Chydorus Poppei, Richard, Entomostracés de l'Amérique du Sud. 

 Mém. Soc. Zool. France 1897, p. 296. 



Specific Characters. — Female. Carapace 

 rather tumid, sub-globose, height fully equal to the length, 

 posterior extremity narrowly truncated, dorsal margin boldly 

 arched, ventral considerably bulging in the middle. Head 

 about as in C. Barroisi. Shell extremely thin and fragile, 

 though sculptured as in that species, the curved striæ of 

 the anterior part of the valves being easily observable; in- 

 fero-posteal corners, on the other hand, rather different, be- 

 ing rounded off and without any trace of a denticle. Lip- 

 plate with only very slight traces of the strong serrations 

 found in C. Barroisi. Caudal part built upon the same type 

 as in that species, marginal denticles, however, more numer- 

 ous, some of the proximal ones being considerably elongated ; 

 caudal claws with 2 distinct denticles at the base. Colour 

 whitish, pellucid. Length af adult female 0.30 mm. 



Remarks. — This form was briefly noticed in the 

 above-mentioned paper by Mr. Richard from some badly pre- 

 served specimens collected by Mr. C. O. Poppe, at Lunache, 

 Chili. As observed by Mr. Richard, it is nearly related to 

 C. Barroisi, so nearly, indeed, that at first I only believed it 

 to be a variety of that species. On a closer examination, 

 however, some well-marked differences are found to exist, 

 proving it to be in reality specifically distinct. Among these 

 differences may especially be named the total absence of 

 a denticle at the infero-posteal corners of the valves (see figs. 

 2, 2 c), which, on the other hand, is constantly found in 

 C. Barroisi (see figs. 1, 1 b), and the presence of an addi- 

 tional denticle at the base of the caudal claws (see fig. 2 a). 



