OF ARTS AND SCIENCES. 35 



the interposition of as many delicate and scabrous awns, the latter of 

 nearly the length of the cylindrical akene. 



Flaveria chlob^folia, Gray, PI. Fendl. 88. Among the abun- 

 dant specimens of this well-marked species in Palmer's Mexican col- 

 lection (682, 2083), one was noticed in which most of the flowers had 

 a pappus of four oblong and entire paleee ! 



PoROPHYLLUM FiLiFOLiUM. Caulibus 6 radice perenni gracillimis 

 simpliciusculis rigidulis monocephalis ; foliis omnibus alternis flliformi- 

 bus plerisque pollicaribus, summis parvis ; involucro brevi-campanulato 

 8-9-phyllo, bracteis lato-oblongis obtusissimis crassiusculis flores (raul- 

 tos) purpurascentes sequantibus ; tubo corollse fauce subinfundibuli- 

 formi cum dentibus ovatis 2-3-plo breviori ; acheniis gracilibus apice 

 baud angustatis pappo subparco barbellulato parum longioribus. — 

 Northern Mexico, in the Sierra Madre, south of Saltillo, Palmer, G88, 

 mixed in the distribution with a little Thelesperma subsimplicifolium. 

 Belongs to the section which contains P. scopcanum and P. amplexi- 

 caw/e ; but with more dilated throat to the corolla. The last-named 

 two species are remarkable for the slender corolla, of which the greater 

 part is a narrow tubular throat, raised on a decidedly shorter proper 

 tube, and surmounted by very short and blunt teeth. In this they 

 agree with Ghrysactinia. 



PoROPiiYLLUM Ervendbergii. P. TiuleraU var. elUptico sat sim- 

 ilis, multo minus ; foliis omnibus oppositis oblongis ; capitulis gra- 

 cillimis 10-15-floris; involucro semipollicari. — P. ellipticum, var. 

 Gray, Proc. Am. Acad. v. 184. — Wartenberg, Mexico, Ervendberg, 

 no. 75.* 



Dysodia and the genera nearly allied to it are of difficult limita- 

 tion. A I'enewed study of nearly all the species concerned obliges me 

 to modify the view adopted by Bentham in the Genera Plantarura, 



* A few Mexican species may be noted as follows : — 



PoROPHYLLDM viRiDiFLORUM, DC, to wliicli Hartweg's no. 147 has rightly 

 been referred, comprises P. Lindenii, Schultz Bip., if Hemsley has correctly 

 identifiecl Seemann's with Hartweg's plant. 



PoROPHYLLUM Seemanni, Scluiltz Bip. Bot. Herald, 308. Seemingly a 

 variety of this, with narrower and mostly attenuate-acute or acuminate leaves 

 (the base tapering into a petiole) is a plant from " ^lexico, Tale," long ago 

 received from duplicates of Herb. Hooker. By the elongated corolla tube it 

 belongs to the same group with the broad-leaved petiolate species. 



PoROPiiYLLXJM OBTusiFOLiUM, DC, we know only from the specimens of 

 Mendez. It appears to be truly perennial, has the involucre eitlier bright violet- 

 purple or sometimes greenish, the leaves mainly tapering somewliat into a 

 petiole ; the limb of the corolla deeply 5-partedinto oblong-lanceolate lobes, and 



