520 Arthur : New species of Uredineae 



being in strong contrast to the normal deep green of the imma- 

 ture cone. The scales of the cone become cemented together, 

 and show no tendency to separate when mature and dry. After a 

 time the sori open by breaking away the superposed tissues, and 

 the whole surface is covered with the orange-yellow spores. As 

 the cones become old and dry the powdery surface fades to white. 

 There is no peridium, and consequently the species is not placed 

 in the genus Peridermium. The species differs from Caeoma 

 conigemim Pat., found in Mexico by P. Maury, in having spores 

 with much thinner and less verrucose walls. There is much 

 probability that these two species of Caeoma are the aecial forms 

 of species of Bubakia, the rust on Croton. This is assumed from 

 the fact that all known coniferous species of Caeoma belong to the 

 Uredinatae, so far as their life histories have been ascertained. 

 They have been previously collected only on leaves of Abies and 

 Larix as aecia of species of the true genus Undo {Melampsora of 

 most authors). Two other American genera under this subfamily 

 are known, PJiysopella and Bubakia, and of these the latter, judging 

 by geographical distribution of its species, is the most likely to be 

 associated with these species of Caeoma on Pimts, for the rust is so 

 unlike those on Abies and Larix that it is not likely to belong to 

 the same telial genus. 



Aecidium Herrerianum sp. no v. 



0. Pycnia hypophyllous, in small groups, i mm. or more 

 across, surrounded by aecia, inconspicuous, subepidermal, almost 

 wholly immersed, honey-yellow becoming dark-brown, flask- 

 shaped, 80-1 10/^ broad by 80-100 fx high; ostiolar filaments 

 40-55 ft- long. 



1. Aecia hypophyllous, gregarious, crowded, cylindrical, long ; 

 peridium pale-yellow, margin erect, lacerate, peridial cells rhom- 

 boidal, 32-48^ long, considerably overlapping, outer wall much 

 thickened, 10-15/i, transversely striate, inner wall thinner, 4-5 fi, 

 moderately verrucose ; aeciospores globoid, often angular, large, 

 23-26 by 27-33 /i, wall pale cinnamon-brown, thick, 3-4^, 

 moderately verrucose. 



On Scnecio salignus DC, Hacienda of San Joaquin, District of 

 Tulancingo, State of Hidalgo, Mexico, May, 1906, A. L. Herrera 

 of the Comision de Parasitologia Agricola ; communicated by E. 



