196 REVIEWS. 



find them in all the flower-buds now examined. But before 

 adopting the genus it may be well to examine the Photinice 

 generally. Photinia, of which P. serndata is the type, is 

 characterized as having imbricative aestivation, and Decaisne's 

 diagram represents it as regularly (i. e., quincuncially) so. 

 But in P. prunifolia and in P. Bhnnel we find occasionally 

 only one exterior petal, and the four others successively over- 

 lapping in the " contorted " way ; and in one of Wallich's 

 specimens of P. integrifolia the first flower-bud inspected 

 showed the " contorted " aestivation complete. This is also 

 the case in P. duhia (in one of Hooker's and Thompson's 

 Khasyia specimens), and this Decaisne refers to Eriobotrya, 

 which has imbricative aestivation. Next is Pourthiaea, a new 

 genus of eleven Japanese and Indian species, the type being 

 Photinia arguta, villosa, Icevis, etc., and the character, among 

 others, " aestivatione contorta." But we as commonly find 

 one petal wholly exterior. So we think it evident that the 

 jestivation of the corolla furnishes no characters for the divi- 

 sion of the genus Photinia. 



Finally, as to the proper stone-fruited genera, Pyracantha 

 is adopted from J. Rcemer for Cratcvgus Pijracantha and 

 an allied Indo-Chinese species, and placed near Cotoneaster ; 

 and a character not before used is introduced, namely, the 

 position of the cotyledons, which in this genus are, as regards 

 the rhaphe, accumbent. 



There are eight plates, six of them filled with admirable 

 dissections, neatly done upon stone by Riocreux from the 

 author's sketches. 



ENGELMANN'S NOTES ON THE GENUS YUCCA.^ 



Tnis modest title comprises the principal results of Dr. 

 Engelmann's long study of a diflicult genus of plants. Pur- 

 suing his botanical investigations now for many years only 



* Notes on the Genus Yucca. By George Engelmann, in Trans. St. Louis 

 Acad. iii. St. Louis, 1873. (American Journal of Science and Arts, 3 ser., 

 vi. 4C8.) 



