CENSUS OF SPECIES. 379 



mailing a distinelioii between the questioned and unquestioned species, 

 quite appropriate to the objects of tbe census list. All those plants 

 which stand as species in that list, but which are treated as varieties in 

 the ' Handbook,' are distinguished by the names of the species, to which 

 they are referred by Mr. Bentham, being added at the ends of their 

 lines. Conversely, the nos. of the varieties are added to the lines of the 

 species in which they are sunk by Mr. Bentham. It should perhaps be 

 observed, that in some few cases those references of Mr. Bentham have 

 not been adhered to with rigid exactness. For example, Bromus seca- 

 liniis, commutatus, and mollis of the census list are united under the 

 name oi Bronnis arvensis in the 'Handbook'; B . secalinus hehng there 

 given as the typical form, even though its chief peculiar characters are 

 alleged to arise " from being cultivated with the corn." In this 

 instance, instead of adhering to the ' Handbook' (impossible, as no B. 

 arvensis is recognized among the British plants, by the Cybele) B. 

 mollis has been referred to after the names of the other two species, 

 sccalinus and commutatus. In other instances Mr. Bentham sinks 

 British alleged species under foreign species, the names of which do not 

 appear in the list, and consequently cannot be referred to. Such is the 

 case with Euphorbia portlandica, sunk under the continental E. segetalis, 

 but necessarily therefore allowed to stand as an unquestioned species in 

 the census list. 



' Bentham's Handbook' and ' Babington's Manual' may be contrasted 

 against each other, and will afford a striking illustration of that " un- 

 certainty of species " before commented upon in pages 35 to 43. It 

 seems impossible to doubt that book-species are to a great extent (if not 

 wholly) conventional and optional, when we thus find two competent 

 botanists differing by one-fourth or one-fifth (320 in 1175 or 1495) of 

 the flora of a small country so much investigated as that of Britain. 

 The references to Mr. Bentham's views have been substituted in the 

 census list in the place of somewhat similar intimations discarded for 

 them. It was first intended to add one or other of these four terms to 

 each of the species, — 



aggregate, segregate, dimidiate, integrate. 

 As before explained, the term ' aggregate ' is used for a species which 

 is believed by various botanists to include several real species, like 

 the Ranunculus aquatilis or Rubusfruticosus of Linneus. The term 

 'segregate' is also used in former pages, to express a species or variety 

 severed from au aggregate, and regarded iu the one way by some 



