OF ARTS AND SCIENCES. 69 



containing the genera in question. Nuttall's Genera of North Ameri- 

 can Plants appeared as a whole in the year 1818, the copyright 

 bearing the date of April 3 of that year. 



A. iNVOLUCRATA, Eiigehii. 1. c. Uiiibella foliis quasi involucrata. 



c. Folia angustissiina : caules huniiles insigniter ramosi: cuculli lanceolato- 

 subulati longissimi, basi eoncavi. 



A. MACROTis, Torr. Bot. Mex. Bound. 164, t. 45. A peculiar species. 



d. Folia ovata seu oblonga, pubescentia vel glabella : caules erecti 1-2-pedales : 

 cuculli oblongi, antheris 2-3-plo longiores, apice iategerrimo rotundato. 



1. Cuculli involuto-concavi, supra medium a processu corniformi apice incurvo 

 vel inflexo exserto liberi : foUiculi toruentosi vel pubescentes. 



A. ovALiFOLiA, Decaisne in DC. A. variegntn var., Hook. Fl. Bor.-Am. ii. 

 252, t. 141. A. Nuttallitna, Gray, Man. ed. 2, non Torr. — Tlie habitat, " Cali- 

 fornia," assigned to tiiis si^ecies by Decaisne, stood in the way of its identifica- 

 tion. Tlie following, from a more south-westerly district, which I confounded 

 with it, appears to be quite distinct. 



A. Hallii. Puberula, niox glabrata : foliis crassiusculis ovato-seu oblongo- 

 lanceolatis subacutis basi rotundatis brevi-petiolatis, costa valida, venis leviter 

 adsceiulentibus rectis subtus proniinulis : umbellis multifloris paucis corymbosis 

 pedunculatis ; corollse viridiilo-albae purpiirascentis lobis oblongis : cucuUis elon- 

 gato-oblongis inteyerrimis basi liastato-bigibbosis cornu sicajfornie parum super- 

 antibus. — .1. oral ifoliu, Gray in Proc. Acad.Philad. 1863, 75. — Colorado; near 

 Denver, E. Hall, no. 480. Upper Arkansas River, T. C. Porter. In aspect this 

 most resembles A. Snllirainii. The follicles are not known; but the anther- 

 wings are destitute of the corniculations at the basal angle which are conspicu- 

 ous in the latter species. 



A. OBOVATA, Ell. Sk. i. 321. A well-marked species, with somewhat the 

 aspect of Acerates viridiflora. The anther-wings are manifestly bicorniculate at 

 the salient basal angle. Tlie hoods are dorsally somewhat hastately bigibbous 

 above the short contracted base, and from the gibbosity are narrowly wing- 

 appendaged upward and inward for some distance : the inner margins of the 

 hood entire, straight, and so involute as to meet vertically for almost tlie 

 whole length : at the very base inside is a pair of short and roundish fleshy 

 internal auricles. The abruptly inflexcd apex of the horn is subulate and 

 traversed with a dorsal groove or channel. 



2. Cuculli a latere complanati, solidi, margine ventral! petaloideo-bilamellato, 

 lamellis semi-obovatis, parte dilatata cristam subconformem eroso-trun- 

 catam includente, angulo interno processu subulato breviter exserto api- 

 culato. 



A. NYCTAGiNiFOLiA. Scabrido-puberula ; caule ut videtur pedali adsurgente : 

 foliis ovatis subrhombeis basi in petiolum sat longum contractis, venis adscen- 

 dentibus : umbellis axillaribus 4-8-floris brevissime pedunculatis ; pedicellis 

 petiolo a?qni!ongis ; corolla viridula semipollicari, lobis oblongis ; cucullis erectis 

 antheris subtriplo longioribus : columna sub corona vix ulla : antherarum alls 



