Apr 5, 2018
I think.
Case must be that one generation then should be as many living as now. To do this & to have many species in same genus (as is) requires extinction. Thus between A & B immense gap of relation. C & B the finest gradation, B & D rather greater distinction. Thus genera would be formed. — bearing relation [continues on p. 37] to ancient types. — with several extinct forms for if each species an ancient (1) is capable of making 13 recent forms, twelve of the contemporarys [sic] must have left no offspring at all, so as to keep number of species constant.