536 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.47. 



while this does show a smooth lorica and is without the three indenta- 

 tions of the posterior body segment, these characteristics occur 

 frequently among Isthmian specimens which are undoubtedly speci- 

 fically identical with Mr. Murray's 0. curvicornis. The dorsal facet- 

 ting figured for 0. nitida is nearly always present; the posterior 

 indentations of C. lofuana are less frequent, but occur in otherwise 

 typical specimens, as does also the partly retracted anterior margin 

 of this species. 



Tlie most distinctive pecuHarities of Lecane curvicornis are best 

 seen in a lateral view, compare plate 17, figure 3. The ventral plate 

 is divided by a transverse fold, in front of which it is very deep and 

 convex; the posterior section is nearly flat and correspondingly 

 shallow. The toes have a short, sharp double curvature at the base; 

 the posterior portion is slightly decurved. The spines at the base 

 of the claw are at an angle of about 45 degrees with the body, so that 

 a slight displacement makes them invisible, especially as they are 

 very small and indistinct. 



LECANE LEONTINA (Turner). 



Canihypna leontina Turner, Bull. Denison Univ., vol. 6, 1892, p. 61, pi. 1, fig. 12. 



In Black Swamp, near the railroad bridge (1), few; stagnant pool 

 north of the raihoad bridge over Black Swamp, few; pool near the 

 railroad, between Black Swamp and Gatun (2), common; sluggish 

 stream in savannas between Panama and Old Panama, rare; creek 

 flowing into Camacho Reservou' (3), common; Rio CocoU, above 

 lake, rare; stagnant pool at Empire (4), abundant; pond east of 

 canal at Empire (8), few. 



LECANE NANA (Murray), 



Cathypna nana Murray, Joum. Royal Micr. Soc, 1913, p. 353, pi. 14, fig. 29. 



From a pool near the railroad, between Black Swamp and Gatun, 

 abundant. 



LECANE PLOENENSIS (Voigt). 



Distyla ploenensis Voigt, Zool. Anz., vol. 25, 1902, p. 679. 

 Cathypna affinis Murray, Joum. Royal Micr. Soc, 1913, p. 346. 



A small variety of this species, about two-thirds the usual size, 

 with rather indistinct markings, occurs on the Isthmus. My speci- 

 mens were identified by Mr. Murray as identical with the animal he 

 found at Rio de Janeiro. It was found in the following collections: 

 Slow stream in tlie garden of the Isthmian Canal Commission, Empire, 

 rare; pool near the railroad, between Black Swamp and Gatun (2), 

 rare; creek flovvdng into Camacho Reservoir (3), few; stagnant pool 

 at Emphe (4), few; pond east of canal at Empire (8), rare; Rio 

 Trinidad, about a mile from mouth (9), rare. 



