Proc. Biol. Soc. Wash.. Vol. XXIV. 1911. 



I'l \TE I. 



Fig.l. 



Fig. 3. 



Fig. 1. Gambusia holbrookii, male. 

 Fig. 2. Gambusia holbrookii. female. 

 Fig. 3. Heterandria formosa, female. 

 (Much enlarged.) 



