530 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.47. 



rests upon the dorsal points of the foot spines, as shoMTi in the lateral 

 view. The anterior edge of the dorsal plate is strongly convex and 

 has a single pair of spines at the side of the antennal sinus ; the ventral 

 edge has a wide and shallow median notch. Both dorsal and ventral 

 plate is moderately convex. The lateral antennae are unusually 

 stout and project through simple holes in the dorsal plate, very close 

 to the edge of the lorica. 



Total length of lorica, 105 //; width over lateral spines, 100 /i; 

 width of anterior edge, 60 fi; depth of body, 42 //. 



TyiM. — Cat. No. 16570, U.S.N.M., from a pond west of Rio Chagres, 

 at Bohio, w^here the species is common. 



BRACfflONUS FALCATUS Zacharias. 



This excessively variable species occurs on the Isthmus in an 

 almost infuiite variety of forms. It is recorded from the following 

 locaUties: Stagnant stream mider old bridge, Old Panama, abundant; 

 Gatun Lake, enormous numbers; Mindi Reservoir, few; bayou of 

 French Canal, 2 miles south of Gatun, common. 



BRACmONUS PATULUS Miiller. 



Brachionus militaris Ehrenberg, Abh. Akad. Wisa., Berlin (for 1833), 1834, 

 p. 199. 



A very small, but otherwise normal form occurs occasionally on 

 the Isthmus: Stagnant stream imder old bridge. Old Panama, few; 

 stagnant pool at Empire (4) , common ; back water of Rio Chagres at 

 Las Bocas del Gatun, few. 



BRACmONUS PATULUS MACRACANTHUS (Daday). 



Plate 17, fig. 1. 



Noteus militaris macracanthus Daday, Zoologica, Heft 44, 1905, p. 119, pi. 7, 

 figs. 3-5. 



This form is common in weedy ponds everywhere in the Canal 

 Zone. A peculiarity in the position of the lateral antennae deserves 

 notice; in the typical, short-spined form the antennae are on the inner 

 edge of the lateral spines, as figured by Cohn, while in macracanthus 

 they are on the spines, about one-third the length of the spine from 

 the j^sterior end, where there is a decided "knee." In Daday's 

 figure a projecting knob is shown, which is no doubt the antenna, 

 or rather, it is in the position of the antenna. The form macra- 

 canthus was found in collections from: Stagnant stream under old 

 bridge, Old Panama (probably Rio Alcorobo), common; slough in 

 savannas near pohce station on road to Old Panama, common; 

 Gatmi Lake, abundant; creek flowing into Camacho Reservoir (3), 

 common; Rio CocoH, above reservoir, few; stagnant pool at Empire 

 (4), abundant; Rio Grande (6), few; pond at Bohio (7), few- pond 

 at Miraflores (12), common. 



