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On the Characters and Affinities of certain Genera chiefly he- 

 longing to the Flora Peruviana. By Mr David Don, 

 Librarian to the Linnean Society, Member of the Imperial 

 Academy Naturae Curiosorum, of the Royal Botanical So- 

 ciety of RatisboD, and of the Wernerian Society of Edin- 

 burgh, &c. 



A HE object of the present memoir is an attempt to illustrate 

 some of the more obscure genera published in the Flora PerU' 

 viana et Chilensis, a work containing a rich fund of interesting 

 materials ; but which, from its plan, it is much to be regretted, 

 is, in many instances, unavailable for the purposes of science, 

 the descriptions being often too meagre, and the details of the 

 plates rarely sufficient for determining satisfactorily the classifi- 

 cation of the new genera therein proposed. The examination, 

 however, of authentic specimens in the Herbarium of Ruiz and 

 Pa von, has rendered a task comparatively easy, which otherwise 

 would have been very difficult, if not wholly fruitless. To il- 

 lustrate the characters of groups already established, and to de- 

 termine their several stations in the system of Nature, is of 

 much more importance to the advancement of science, than the 

 discovery of new species, or the forming of new combinations. 



I cannot hope to have been equally fortunate in all cases ; 

 but if I have succeeded, even in an approximation to ascertain- 

 ing the characters and affinities of these genera, my utmost ex- 

 pectations will be fulfilled. 



CLEOMELLA, Decand. 

 Syst, Linn. HEXANDRIA MONOGYNIA. 

 Ord. Nat. CAPPARIDE^, Juss. 



Calyx monophyllus ! 4-fidus : laciniis ovato-oblongis, mucronatis (ut in /o- 

 liis /) integerrirais. Petala hypogyna, laciniis calycinis alterna, elliptico- 

 oblonga, obtusa, subcamosa, venosissima, integerrima : ungue brevissimo. 

 Stamina 6, sequalia, glandulae elevatae magnae truncatse inserta : filamenta 

 subcapillaria, glabra: antheree longae, Hneares, subtetragonae, obtusae, 

 biloculares, basi insertae, ad floris expansionem spiraliter revolutae I lo- 

 culis parallelis, bivalvibus, sutura longitudinali exteriiis dehiscentibus. 



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