216 PEOCEEDINGS OF THE AMERICAN ACADEMY 



Silphn, stylus sterilis Silphit, vel summo apice bifida : ovarium inane. 

 Achenia obovata, crassa, obcompresso-turgida, dorso subconvexo uni- 

 nervia, ventre subangulata, costa prominente superne in den tern cras- 

 so-subulatum rigidura porrectum desiuente, marginibus dentato-alatis 

 (nempe ala siiiuato-iucisa nunc jiluripartita, lobis suminis cartilagiueis 

 auriculiformibus forte ad pappum referentibus), basi nee bractea sua 

 involucri nee paleis internis adnata. 



DuGESiA Mexicana. Herba bumilis e radice perenni, facie Chry- 

 sogoni, foliis pinnatifidis hispidulis EngelmannicB (sed plerisque oppo- 

 sitis), acbenio dente interno instructo Lindheimerce, sed Sllphio potius 

 affinis, acbenio crasso (maturo tuberculato-scabro) scbizoptera insignis. 

 — Lindheimera Mexicana, Gray, Proc. Am. Acad. xv. 34 ; Hemsl. 

 Bot. Centr. Am. ii. 141. San Luis Potosi, Parry ^ Palmer; but 

 collected much earlier by Dr. Schaffner. This might seem to be re- 

 ferable to the obscure genus Schizoptera of Turczaninow ; but the 

 involucre and slender tube to the sbort ligules attributed to that genus 

 indicate something different, perhaps more like Guardiola.* — This 

 genus is named in honor of Professor Alfred Duges, of Guanaxuato, 

 Mexico, a zealous zoologist, from whom we have recently received a 

 collection of the plants of that part of the country. 



Parthenium confektuji. Herbaceum, pube adpressa substrigosa 

 canescens et hirsutum ; radice ignota forte perenni ; caulibus 1-2-peda- 

 libus sat validis subsimplicibus usque ad apicem foliosis ; foliis circum- 

 scriptione obovato-oblongis bipinnatifidis, segmentis lobisque brevibus 

 crebris obtusis, vel pinnatilobatis lobis paucies crenato-incisis ; capitu- 

 lis perplurimis corymboso-cymosis confertis; involucro canescenti- 

 pubente ; pappi paleis parvulis oblongis. — Plains of Coahuila, Mexico, 

 near Parras, Gregg, 1847-9, Palmer (no. G48), 1880. Belongs to 

 the section formed for P. Jlysterophorus (but pi-obably the root 

 perennial), which species indeed approaches it in a canescent and 

 simpler-leaved variety (var. lyratum), of the same region, no. 316, 

 Wright, no. 647, Palmer, &c. The present species, now confirmed by 

 Palmer's specimens, was long ago collected by the late Dr. Gregg. 



* Chrysogonum ViRGiNiANUM, L. It Still appears that this is the only 

 species of the genus, although a rather variable one. The akenes at maturity 

 fall away from the receptacle, carrying the involucral bract behind and the 

 bracts of two or sometimes three sterile tlowers in front : so the genus belongs to 

 the Parthenioid group, along with Berlandiera, Engelmamua, &c., and not with 

 Silphium, where Bentham placed it, liaving combined it witii Moonia, Arn, and 

 taking the character in these respects from that truly distinct Indo-AustraUan 

 genus. 



