Counts of the chromosomes of 17 spp. and varieties of plants related to maize gave the following numbers: Euchlaena mexicana, n = 10, 2n = 20; E. perennis, n = 20, 2n=40; Tripsacum dactyloides, collected at Angleton, Texas, and Manhattan, Kansas, n=18, 2n = 36; T. dactyloides, collected at Atchison, Kansas, n = 18; T. dactyloides, collected at Nacogdoches, Texas, New Haven, Conn., and Miami, Florida, n = 36, 2n = 72; T. dactyloides, collected at Alpine, Texas, n = 36; T. laxum, n = 36, 2n = 72; T. latijolium, n = 36, 2n=72; T. pilosum, n = 36, 2n = 72; Coix aquatica, 2n = 10; Coix lachryma-stenocarpa,2n = 20; C. lachryma-jobi, 2n = 20; Sclerachne punctata, 2n = 20; Polytoca barbata, 2n = 20; Manisuris cylindrica, n=9, 2n=18. Manisuris cylindrica is usually regarded as a member of the tribe Andropogoneae, rather than the Maydeae, the tribe to which maize belongs. If this classification is correct there are representatives of both tribes having 9 and 10 chromosomes, or multiples of these numbers. This fact agrees with the hypothesis that the 2 tribes are related through Tripsacum and Manisuris.