426 standley: omiltemia 



served pelecypods, no fossils of diagnostic value have been found 

 in it in Wyoming. From its stratigraphic position conformably 

 between the Park City and Chugwater formations, and from 

 its relation to the Woodside and Thaynes formations in Idaho, 

 which are classified as Lower Triassic, it is inferred that the Din- 

 woody formation is either Permian or Lower Triassic or both. 

 The name is derived from the canyon of Dinwoody Lakes, in the 

 Wind River Range, where the formation is completely exposed, 

 and has been measured in detail. 



BOTANY. — Omiltemia, a new genus of Riihiaceae from Mexico. 

 Paul C Standley, U. S. National Museum. ^ 



From the large collections of plants obtained in Mexico a few 

 years ago by Mr. E. W. Nelson, of the Biological Survey, many 

 new species have already been described. A large and probably 

 the most interesting portion of the material, however, still re- 

 mains to be identified. One specimen, in particular, from the 

 State of Guerrero has come to the writer's attention in the course 

 of his revision of the Rubiaceae for the North American Flora. 

 This plant, although not possessing any very unusual charac- 

 ters, can not be placed satisfactorily in any of the known genera 

 of the tribe Rondeletieae, the group to which it evidently belongs. 

 Consequently it is described here as a new genus, Omiltemia. 



The tribe Rondeletieae is a large group, chiefly North Ameri- 

 can in distribution, many of whose genera are based upon rather 

 slight differences. Omiltemia falls in the subdivision with con- 

 torted corolla lobes, and is related as closely to Deppea and 

 Lindenia as to any genera, from both of which, however, it is 

 distinguished by the long, exserted filaments. Deppea, more- 

 over, has a short, funnelform or subrotate corolla, and Lindenia 

 a very long, salverform one. In its general appearance Omiltemia 

 is very unlike any of the genera of its tribe. The red tubular 

 corolla is suggestive of Manettia, to which the type specimen 

 was once referred, but that genus differs widely in its winged 

 seeds and scandent habit. 



1 Published by permission of the Secretary of the Smithsonian Institution. 



