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F. E. PEABODY AND J. M. SAVAGE 



specifically distinct. Generally the distribution pattern is like that of 

 Sceloporus graciosiis (Fig. 12). The foothill alligator lizard, preferring 

 warmer, drier habitat than the northern alligator lizard, ranges 

 completely around the Great Valley and broadly up and down the 

 California Coast. However, there is subspecilic differentiation, which 



COERULEUS 

 35 



'ANCESTRAL SPECIES 

 SONORAN ALLIGATOR 

 LIZARD 



Fig. 13. Patterns of distribution for northern alligator lizard, Gerrho- 

 notus coeruleus, and related Sonoran alligator lizard, Gerrhonotus kingi. 

 Filter effect of coastal corridor is clearly apparent. 



has highly interesting boundaries. Gerrhonotus muUicar hiatus webbii 

 ranges the southern California Coast and up the Sierra Nevada, but 

 is differentiated from the northern California subspecies precisely in 

 the position of the marine barrier postulated earlier. This coinci- 

 dence would be unimportant were it not for the fact that insular 

 representatives of the two subspecies (Fig. 14) are also separated — 

 multicarinatus occurring on four islands north of the mainland 

 boundary, webbii on three islands south of the boundary. There is 



