MONOGRAPH OF THE GENUS PYRUS. 195 



of the disk. Pyrus, Tourn., is thus brought clown to the 

 Pear ; and this, as Decaisne had formerly announced, to a 

 single collective species, of six geographical proles or forms. 

 We continue to write Pyrus from old habit and custom, not 

 doubting, however, that Pirus is the correct orthograjjhy. 



Of Amelanchier, following Lindley, there are enumerated 

 twelve species, six for the Old World and six for North 

 America, and there are names for four more. Without being 

 able to clear them up (and no wonder), Decaisne thinks that 

 they may be distinguished into at least three groups, charac- 

 terized by the distinct or united styles, and the glabrous or 

 downy ovaries. We are continually impressed with the idea 

 that there must be three or four American species, and the 

 seeds may aid in their definition. But thus far the characters 

 elude investigation. Peraphyllum, Nutt., referred by Ben- 

 tham and Hooker to Amelanchier, has not been studied by 

 Decaisne. When he examines the excellent specimens in 

 flower and in fruit, which Mr. Siler has supplied from south- 

 ern Utah, he will conclude that the genus must certainly be 

 reinstated. The likeness is only in the peculiar structure of 

 the fruit. 



As respects the remaining genera, the difference between 

 this monograph and the disposition in Bentham and Hooker's 

 " Genera Plantarum " is mainly this : Eriobotrya, with its bac- 

 cate fruit (what is termed endocarp reduced to a soft pellicle), 

 large turgid seeds with thickened cotyledons, and undulate 

 petals, is upheld as a good genus ; Heteromeles is adopted 

 from J. Roemer for the Californian Photinia arbutifolia, 

 and a second (probably not good) species, H. Fremontiana, 

 is added. The characters appear to be the 10 instead of 20 

 stamens, in pairs opposite the calyx-lobes, their filaments 

 dilated at base and somewhat monadelphous. In the tabular 

 conspectus the petals are said to have " prefloraison tordue," 

 but in the generic character it is " aestivatione imbricativa vel 

 convolutiva," the latter term with the French botanists mean- 

 ing the same as imbricated, only more enrolling. The diagram 

 represents the whole five petals with one edge covered, ^. e., 

 " tordue " or contorted (or, as we say, convolute), and so we 



