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List of Genera from London Catalogue, marked by Mr H. C. Watson, (August 1855) showing the species, resembling each other, perhaps only 1 species, / those more probably 2 species / probably 2 species but connected by intermediate forms. / Genera. Rubus Rosa, Hieracium Salix & Carex, omitted from doubts in some cases & large numbers in others. The greater number of marks refer to species probably really distinct. Phanerogamous Plants

[List and calculations not transcribed]

This paper superseded by the later & fuller List.

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In the Loudon catalogue there are, (excluding those with same number repeated, & marked by*, but including the italics)

Genera 497 Species 1371

Subtracting Rosa on account of many doubtful species, & on account of genera being so large as to vitiate results, Rosa (with 4 sp. 13 sp.) Rubus (4) Hieracium (17) Salix (28) Carex (58) = 5 genera with 120 species

[calculations not transcribed]

Hence the each genus (with the subtraction of the above genera & all genera with single species which do not here come into play) give 4.27 species per genus. If Carex

Now Mr Watsons marked genera, have on average 5.95 species, or 1.68 more species to genus. (& many of these, viz 11/63 have more than a pair of closely allied species). If carex had been included & Hieracium &c had been included, the 5.95 wd. have been considerably increased. —

(To show that excess of 1.68 is considerable I may mention that (excluding the 5 large & doubtful genera as before) all the are of other genera, 492, include 1251 species, or only 2.54 species to genus. —)

It shd be stated that Mr Watson did not know object when he marked list.

There were 87 genera with 2 species each: if these be subtracted, as well as genera with 1 species (& the 5 doubtful large genera), then we have 145 & 817 species, so that each genus has 5.63 species. But in Watsons marked genera eleven have at least 3 species allied, & these eleven genera have 106, so that each genus has 9.63 species.