In the New World pouched rats (Geomyidae) the pouches open externally on the cheeks.
The American pouched rats, or pocket-gophers, constitute the third section, Geomyoidea, with the single family Geomyidae.
In the highly specialized mastoid region of the skull, the North American Oligocene Protoptychus approaches to Dipopodomys, while the contemporary Gymnoptychus and Entoptychus likewise appear referable to the Geomyidae.
On the other hand, the scaly-tailed squirrels (Anomaluridae), the jumping-hares (Pedetidae), and the strandmoles (Bathyergidae) are exclusively African; while the sewellels (Haplodontidae) and the pocket-gophers (Geomyidae) are as characteristically North American, although a few members of the latter have reached Central America.
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