346 Transactions of the Society. 



Length of contracted lorica 180 /t, greatest width 130 ix, of 

 anterior margin 70-75 fx, of posterior process 40 ^, length of toe 

 120 yLt. The dorsal and ventral plates are exactly coincident in 

 width, except towards the anterior margin, where the dorsal is 

 narrower. Both anterior margins are deeply incised in flat V's, 

 the ventral a little deeper, the outline undulate. Both lateral and 

 ventral sulci are very deep. The " tail " varies in form, being 

 sometimes nearly straight, sometimes simply excavate, sometimes 

 excavate in double curve, as figured. 



Daday {SJf.) describes a variety hisinuata, and I am strongly 

 inclined to think that his C. hiloha, C. incisa, as well as the animal 

 he identifies as C. appendiculata Lev. are all to be regarded as 

 varieties of D. leontina, in spite of the differences of size. His 

 figure of (7. appendiculata shows toes quite unlike Levander's 

 animal. The tail-process varies considerably in form and depth 

 of incision. 



Habitat. — Fresh- water pond in Botanic Gardens, Kio de Janeiro. 

 A narrower variety in Prapa Eepublica, Kio (Plate XIII, fig. 21c). 



The lateral view (Plate XIII, fig. 21&) shows the hyaline plates 

 in front of the lorica proper, which are hidden in contraction. 



Cathypna affinis Levander (4^). 



This species I have not figured, as my drawing of the one 

 example found is incomplete. The student may refer to Levan- 

 der's figure. 



The lorica is narrowly oval, rounded behind, the frontal margin 

 broad, almost quite straight, bounded by small spines. The ven- 

 tral plate is slightly narrower. The dorsal plate is obscurely faceted 

 or ridged longitudinally. The toes are long, straight, very acute, 

 without shoulder or claw. 



Habitat. — Pond at Quinta Boa Vista, Eio de Janeiro. Had I 

 not found this animal I might have identified the next species on 

 my list {C. curvicornis) as Levander's species, despite several 

 differences. The two are quite distinct, and the animal from Boa 

 Vista is closest to Levander's. 



C. curvicornis sp. n. (Plate XIV, fig. 22). 



Specific Characters. — Fairly large, oblong ; dorsal plate narrower, 

 truncate behind, lateral sulcus deep ; anterior margins coincident, 

 excavate in broad shallow V, bounded by two little spines. Pos- 

 terior joint small, rounded. Toes slender, half the length of 

 contracted lorica, outcurved, acuminate at point, sharp, not 

 shouldered. 



Descrijjtion. — Length of contracted lorica 140 //,, of dorsal plate 



