South Americaii Rotifera. By J. Miirraij. 347 



120 fjL, greatest width 110 /x, of dorsal plate 100 //,, of anterior 

 margin 65-70 /x, length of toe 70-75 yu,. The dorsal plate is 

 a short ellipse, truncate at each end. The anterior margin is a 

 very slight excavation, with a deeper depression in the middle 

 line. The anterior spines are incurved, and there is a slight con- 

 striction between them and the swelling of the ventral plate. The 

 sulcus is deeper than usual. The toes have slight shoulders, but 

 these are often indistinguishable in dorsal view. There is no 

 wrinkling or faceting of the surface. 



C. curmcornis is distinouished from C. luna, which is about 

 the same size, by the narrower form, narrower dorsal plate, wider 

 anterior margin with more prominent spines, and the longer toes. 

 It has some resemblance to C. niiida, but that has strongly faceted 

 dorsal surface, and the shorter toes are more distinctly clawed. 

 C. affinis Levander {4.5) is about the same size, but has a straight 

 anterior margin with smaller spines ; the plates are longitudinally 

 ridged or faceted, the toe is not curved, and the ventral plate is 

 narrower. 



Habitat. — Pond in Praca Kepublica, Eio de Janeiro. 



Cathypna iiitida sp. n. Plate XIY, figs. 24a-24Z>. 



Specific Characters. — Fairly large, egg-shaped ; dorsal plate 

 narrower than ventral. Anterior margins nearly coincident, nearly 

 straight, bounded by spines with broad base and incurved points. 

 Dorsal surface deeply symmetrically wrinkled. Posterior segment 

 large, bearing two conspicuous curved masks. Toes slender, 

 straight, sharply shouldered and clawed. 



Des€riptio7i. — Length of contracted lorica 150 /^, of dorsal plate 

 115 /jl, greatest width 110 /x, of dorsal plate 105 /x, of anterior 

 margin 65 /a, length of toe 70 yu,. The dorsal plate is egg-shaped, 

 truncate at both ends ; the margins become obscure before reach- 

 ing the anterior margin. The lateral and posterior sulci are deep. 

 The wrinkling of the dorsal plate, while its pattern may be homo- 

 logous with the regular hexagonal faceting of the group of species 

 resembling C. ploenensis (So) has departed far from the original 

 type. The posterior segment bears marks which I cannot elucidate, 

 hut peculiar to the species. The margins of the toe are not 

 straight, but show various expansions and contractions. The 

 shoulder makes a sharp point. 



C. iiitida has no near relative. It may be said to belong to a 

 group of species of which C. luna is the type, having strongly 

 shouldered toes. It most resembles C. cnrvicornis, Plate XIY, 

 fig. 22, but the ornamented skin distinguishes it. 



Habitat. — Fresh-water pond in Prafa Eepublica, Pdo de Janeiro, 

 April 1912. 



