LIN D LEY'S NATURAL SYSTEM OF BOTANY, 9 



now employed was first sketched in the " Nixus Plantarum " 

 (1832), and afterwards in the " Key to Structural, Physio- 

 logical, and Systematic Botany"^ (1835), and is more fully 

 developed and illustrated in the work before us. He now 

 admits, as we have already seen, five primary classes, two of 

 which, however, are much smaller than the others and of sub- 

 ordinate importance, and may be considered as transition 

 classes, namely, Gymnospermce^ which connect Exogens with 

 the higher Acrogens, and Rhizanthce, which form the transi- 

 tion from Endogens to Acrogens of the lowest grade. The 

 great class Exogenm (^Dicotyledones of Jussieu) is divided 

 into three subclasses, namely : — 



1. Polyioetalm ; those with the floral envelopes consisting 

 of both calyx and corolla, the latter couiposed of distinct 

 petals. 



2. Mo7iopetal(B ; those with the petals combined in a mono- 

 petalous corolla. 



3. Incom.pl etce ; those always destitute of a corolla, the 

 calyx also often incomplete or absent. 



Thus far this mode of subdivision is nearly the same with 

 that of Jussieu ; Dr. Lindley, however, neglecting altogether 

 the character afforded by the insertion of the stamens, divides 

 the polypetalous orders into seven, and the Monopetalm and 

 Incompletce each into five sections or groups. As a specimen 

 of this plan, we copy the names of the groups of the first sub- 

 class, with their synoptical characters. 



1. Albuminosce. Embryo very considerably shorter and 

 smaller than the albumen. 



2. Uj^igy 1710 see. Ovary inferior, usually having an epigy- 

 nous disk. 



3. Parietosce. Placentation parietal. 



4. Calycosce. Calyx incompletely whorled ; two of the 

 sepals being exterior. 



5. SyncaiposcB. None of the characters of the other 

 groups, and with the carpels compactly united. 



^ This excellent little work consists of an augmented edition of the 

 author's Outlines of the First Principles of Botany, with a revised trans- 

 lation of the Nixus Plantarum. 



