Differs from E. ruficaudus ruficaudus , E. r. simulans , E. cinereicollis , and E. quadrimaculatus , in being shorter, proportions as in E. q. quadrivittatus ; from E. speciosus , E. panamintinus , E. umbrinus , E. palmeri , and E. bulleri , in base not markedly widened, angle formed by tip and shaft larger; from E. alpinus , E. minimus , E. townsendii , E. sonomae , E. amoenus , E. dorsalis , and E. merriami , except for smaller size, as in E. q. quadrivittatus .
— from The Baculum in the Chipmunks of Western North America by John A. White
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