NEW PUBLICATIONS. 395 



We have in our two last volumes noticed the first and second parts 

 of the ' Compendium ' respectively. These comprehended the distri- 

 bution of the natives, " denizens," and " colonists," whilst this third 

 part consists of a separate list, including the " aliens," the " casuals," 

 and, hardly to be separated from the last, the errors, and tlie extinct 

 plants. These are treated on a formula much less full than that era- 

 ployed for the natives ; the area in provinces is given, and references 

 to books in which additional information will be found, as well as a 

 few special localities. "We are somewhat sorry to see that the hope 

 we expressed (Vol. VI. p. 375), that the exotic distribution of the 

 introductions would have been indicated, has not been fulfilled ; it 

 would have been especially useful in the case of these plants, which are 

 in such large numbers making their appearance, to know from what 

 quarters they come. This class of plants is every day increasing, many 

 are becoming commoner, and some already form a prominent feature 

 in the vegetation of the districts round our large towns. The ques- 

 tions arise in each case, how did this species get here and from where, 

 what does its presence mean, and what is to be its future history ? 

 How much interest lies in the solution of such problems is seen in a 

 recently-published paper* by M. Andre Devos — in which, by the way, 

 Mr. Watson's terms for the classes of naturalized plants are adopted — 

 on the introduced plants of Belgium, where the history and exotic 

 distribution of many species are examined. What strikes one with 

 regard to not a few of these plants is, that they play so much the same 

 part under similar conditions everywhere, — cosmopolitans, in short, 

 and scarcely more native in one country than another. It is easy to 

 put all such species into an appendix, and determine to more or less 

 ignore them, but they continually force themselves on our attention. 

 We confess to a rooted objection to all appendices and supplementary 

 lists ; it seems to us more rational, as it is certainly more convenient, 

 to give all in one series, of course typographically distinguishing the 

 native from the naturalized species. The defence which is reasonably 

 urged by those (upon whom Mr. Watson is somewhat severe) who put 

 on record the occurrence of mere casuals is, that it may become a 

 matter of importance to know when, where, and by whom they were 

 first noticed, if, as is by no means uidikely, any should spread and be- 

 come a de facto part of the vegetation of Britain. Such facts, how- 

 * Bulletin de la Soc. Eoyale de Bot. de Belgique, 1870, pp. 5-122. 



