5 It supplies classifications which are of greatest heuristic and explanatory value in most branches of biology, e.g., evolutionary biochemistry, immunology, ecology, genetics, ethology, and historical geology. A sound classification is the indispensable basis of much biological re- search. It is a prerequisite for the application of the comparative method. All aspects of living organisms are of interest to systematists who adopt -- Simpson's (1%1:7) definition of the field as "the scientific study of the kinds and diversity of organisms and of any and all relationships among