PITTIER: CAESALPINIACEOUS trees of PANAMA 469 



This abrupt transition brings in as new elements of the flora 

 several genera known heretofore as represented exclusively in the 

 Amazonian Hylea or in the eastern part of South America. The 

 presence of these species in a district separated from regions 

 of identical climatic conditions both by imposing mountain 

 ranges and the semixerophytic belt of Colombia and Venezuela 

 constitutes a most interesting problem, the solution of which 

 may not be reached until the interlocking slopes and valleys 

 of Colombia and Venezuela have been thoroughly explored. 

 Among such Panamanian representatives of Brazilian genera one 

 species each of Stachyarrhena, Cassupa, Browneopsis, and Colig- 

 nonia has already been detected, while many others are certain 

 to appear during the further progress of the work of identifying 

 and naming the extensive collections now at hand. In the pres- 

 ent paper, 3 more species, belonging to 2 genera, are described 

 under the names Peltogyne purpurea, Centrolobium yavizanum, 

 and Centrolobium patinense. Furthermore, an undescribed spe- 

 cies of Dilodendron has been collected in the hilly region of the 

 Chucunaque Valley, while the forests of Darien in general have 

 furnished an unusually strong contingent of Lecythidaceae, 

 among them 1 species of Couroupita, 4 of Lecythis, 3 of Esch- 

 weilera, and 2 of Gustavia. 



Another interesting fact never brought out before is the con- 

 siderable development, along the Pacific coast, of the mangrove 

 formation, and the presence in the inner part of the tidal-belt 

 of a characteristic tree allied to the mora of Guiana and never 

 described. Besides being of importance as an ecologic element, 

 this species enjoys the peculiarity of possessing the largest known 

 dicotyledonous seed. It also is described below under the name 

 D itnorphandra megistosperma. 



Centrolobium yavizanum Pittier, sp. nov., ramulis juvenibus foliisque 

 pube molli ferruginea evanescente dense vestitis, petiolis communibu.s 

 teretibus, longitudinaliter striatis, stipulis ovatis, obtusis, extus dense 

 villoso-lanatis, intus pubescentibus, folioli^ membranaceis, breviter 

 petiolulatis, ovatis vel elliptico-lanceolatis, argute acuminatis, basi 

 rotundatis, leviter emarginatis, supra glabrescentibus, hifra glabratis, 

 ad costas venasque rufo-villosis ; floribus . . . . ; legumine pri- 

 mum glanduloso-tomentello dein glabrato, aculeis partis seminiferae 



