“…In some cases, inferences based on geological data or events recorded in historical times, were made as to the time when secondary contact was established. These complexes include two ecologically distinct morphs of sticklebacks, Gasterosteus aculeatus, in British Columbia (Hagen, 1967); toads, Bufo woodhousei x B. fowleri, in Texas (Meacham, 1962); anurans, Geocrinia laevis x G. victoriana, in Victoria (Littlejohn, Watson, and Loftus-Hills, 1971;Littlejohn and Watson, 1973, 1974; anurans, Litoria ewingi and L. paraewingi, in Victoria (Watson, Loftus-Hills, and Littlejohn, 1971;Watson, 1972;Gartside, 1972;Littlejohn, 1976); whiptail lizards, Cnemidophorus tigris gracilis x C. t. marmoratus, in Arizona and New Mexico (Zweifel, 1962;Dessauer, Fox, and Pough, 1962); leopard lizards, Crotaphytus wislizenii X C. silus, in California (Montanucci, 1970); chromosomal races of the Sceloporus grammicus complex of iguanid lizards in Mexico (Hall and Selander, 1973); orioles, Icterus galhula galbula X I. g. bullockii (Sibley and Short, 1964;Rising, 1970Rising, , 1973, flickers,Colaptesauratus auratus x C. a. cafer (Short, 1965), and towhees, Pipilo erythrophthalmus erythrophthalmus x P. e. arcticus (Sibley and West, 1959), on the Great Plains; grackles, Quiscalus quiscula quiscula X Q. q. versicolor, in eastern and southeastern United States (Huntington, 1952;Yang and Selander, 1968); titmice, Parus bicolor x P. atricristatus, in Texas (Dixon, 1955); towhees, Pipilo erythrophthalmus X P. ocai, in Mexico (Sibley, 1954) (Thaeler, 1968).…”