[285]

In Waterhouse's list of 62 aberrant genera, including 472 [illeg] species, each genus has an average 7.61 species.

(If genus Brachicerus be removed, with its 172 species, then each genus wd have 4.91 species.

18/62 (= .29) of the above 62 species have only one species. In whole Catalogue the genera with single species are 252/660 = .38 - The fewness of the aberrant genera with single species is singular, considering that the average number of these species to each genus is 7.61. Whereas in whole Class it is 10.17. - I presume that species have been crowded together, when very few, more than when many, then if 20 species agreed closely, & 1 less closely this wd be more likely to be generically separated, that if there was only 1 of the 20 preserved. Waterhouse fully admits that Brachycerus & Microcerus with 8 species shd be taken out of his lists of Aberrant

Feb. 55

[286]

This list of Waterhouses' aberrant genera, shows those such generally confined in ranges. Those having wide ranges, having also many species. So that co-selection of large genera & wide range, shown even here.