548 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 47. 



MONOSTYLA CLOSTEROCERCA Schmarda. 



Monostyla closterocerca Murray, Journ. Royal Micr. Soc, 1913, p. 357, pi. 15, 



fig. 39. 

 ? Monostyla tmncata Turner, Bull. Denison Uiiiv., vol. 6, 1892, p. 62, pi. 1, 

 fig. 11. 

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

 (2), common; creek flowing into Camacho Reservoir (3), common; 

 Rio Grande Reservoir (5), few; Rio Trinidad, above Agua Clara 

 (10), few; at Escoval (11), few. 



This species does not have the fusiform toe figured by Schmarda 

 and Murray; the toe is parallel-sided for about half its length and 

 from there tapers rapidly to a long, slender point. 



MONOSTYLA HAMATA Stokes. 



In collection from a creek flowing into Camacho Reservoir (3), 

 common; stagnant pool at Empire (4), common; Rio Grande 

 Reservoir (5), few; Rio Trinidad, above Agua Clara (10), common; 

 at Escoval (11), few. 



MONOSTYLA DECIPIENS Murray. 



In a pool near the railroad between Black Swamp and Gatun (2), 

 few; creek flowing into Camacho Reservoir (3), rare; Rio Grande 

 Reservoir (5), few. 



MONOSTYLA FURCATA Murray. 



Abundant in a pool near the railroad, between Black Swamp and 

 Gatun (2); creek flowing into Camacho Reservoir (3), rare; stag- 

 nant pool at Empire (4), abundant; Rio Grande (6), rare; Rio 

 Trinidad, about 1 mile from mouth (9), few; above Agua Clara (10), 

 few; at Escoval (11), few. 



MONOSTYLA OBTUSA Murray. 



Among water plants near the railroad bridge, Gatun Lake, rare; 

 stagnant pool at Empire (4), common; Rio Grande Reservoir (5), 

 common; Rio Trinidad, above Agua Clara (10), few. 



MONOSTYLA RUGOSA, new species. 



Plate 24, figs. 4-6. 



The ovate body is short, very broad, and excessively thick. The 

 anterior margins of the lorica are nearly straight and almost coin- 

 cident; there are no anterior spines. The broadly ovate dorsal plate 

 is shghtly truncate posteriorly; the width is greater than the length 

 and its anterior margin is narrower than that of the ventral plate. 

 The dorsal markings are very deep and the fields of the two anterior 

 rows irregular, while the third and fourth row are fairly regular. 



