Culex (subgenus Mochthogenes). (figs. 1, 2).In the subgenus Mochthogenes, only the pupa of Culex (M.) inconspicuosus, Theo., has been described.Since one of us (M.P.) has obtained the immature stages of all the known species, including C. (M.) castor, De M., we take advantage of this opportunity to give a key to the pupae. The pelts were all obtained from specimens bred in isolation at Yangambi, Belgian Congo, and the resulting adults identified by means of the male terminalia.The terminal hairs of the paddle appear to be absent in the pelt of C. (M.) castor, but this may be due to accident, although no scars are to be seen.KEY TO THE PUPAE.