218 Mr. D. Don's Descriptions of new Genera and Species 



cumference are clearly nothing more than the scales composing 

 the inner series of the involucrum. The plumose pappus com- 

 pared with that of the inner floret of the partial capitula of 

 Polyachyrus, a genus hereafter to be described, the form and 

 structure of their corolla, the outer lamina of which is tra- 

 versed in both by four distant slender nerves, and the habit of 

 the plants themselves, show that there is a considerable degree 

 of affinity between these two genera. 



Ptilurus. 



Flosculi aequales. Pappi radiis plumosis, duplici serie dispositis. 

 Involucrum subsequale. 



Involucrum duplici ordine poly-(18 — 20)phyllum, subaequale : 

 foliolis ovato-lanceolatis, trinerviis, apice membranaceo 

 acuminato radiatis. Receptaculum nudum. Flosculi omnes 

 hermaphroditi, tubulosi, bilabiati, aequales ; labio exteriore 

 ligulato, 4-nervio, obtuse tridenticulato ; interiore bipartite, 

 demum revoluto : segmentis linearibus, obtusis, binerviis. 

 Anthera coalitae, basi longe bisetosce : setis simplicibus : 

 appendicula lineari-lanceolata, acuta. Stigma bipartitum : 

 laciniis semicylindricis, recurvis, apice dilatato-truncatis, 

 pruinosis. Achenia elliptico-oblonga, compressa, dense pa- 

 pilloso-glandulosa, apice angustata, disco parvo. Pappi 

 radiis crassiusculis, eleganter phimosis, mollissimis, duplici 

 ordine digestis, basi dilatata imbricatis ! deciduis. 



Herba perennis, humilis, ccespifosa, facie Dauci v. Athamantse, 

 setulis erectis, glanduliferis, copiosissime instructa. Radix 

 fusiformis, raynosa. Caulis erectus, teres, subramosus, tri- 

 uncialis, vix calami scriptorii crassitie. Folia supradecom- 

 posita, dense glandulosa, pollicaria v. sesquipollicaria : seg- 

 mentis linearibus, obtusis, sesquilineam longis. Petioli foliis 

 longiores, ?naxime dilatato-membranacei ; inferiorum foliorum 



la t lores 



