THE FAUNAS
We have mentioned elsewhere that three different mammalian faunas occur in Washington. These may be described as follows.
1. The Great Basin Fauna. This fauna is best typified by such genera as Perognathus and Dipodomys. Species that, at least in Washington, are confined to this fauna are:
| Sorex merriami | Tamias minimus | |
| Myotis thysanodes | Perognathus parvus | |
| Myotis subulatus | Dipodomys ordii | |
| Pipistrellus hesperus | Onychomys leucogaster | |
| Antrozous pallidus | Reithrodontomys megalotis | |
| Taxidea taxus | Lagurus curtatus | |
| Marmota flaviventris | Lepus californicus | |
| Citellus townsendii | Sylvilagus nuttallii | |
| Citellus washingtoni | Sylvilagus idahoensis |
The break between the Great Basin Fauna and the other two faunas is extremely sharp, probably as a consequence of a sharp break in the flora.
2. The Pacific Coastal Fauna. The mammals of the humid coastal district range from the Fraser River, British Columbia, southward to the vicinity of Monterey Bay, California. In Washington typical genera are Aplodontia, Neurotrichus and Scapanus. The following species are typical of the Pacific Coastal Fauna in Washington:
| Neurotrichus gibbsii | Tamiasciurus douglasii | |
| Scapanus townsendii | Sciurus griseus | |
| Sorex trowbridgii | Clethrionomys californicus | |
| Sorex bendirii | Microtus townsendii | |
| Marmota olympus | Microtus oregoni | |
| Tamias townsendii | Aplodontia rufa |
Some species which range outside this faunal area have strongly marked races confined to it. Glaucomys sabrinus oregonensis and Lepus americanus washingtonii are examples. The Pacific Coastal Fauna is a forest fauna. Like the Great Basin Fauna, it reaches its northern limit of distribution in Washington and is better represented farther south. Unlike the Great Basin Fauna, the break between the Pacific Coastal and the surrounding fauna is not sharp, because forests continue into the more boreal faunal areas to the north and east. There, some mingling of coastal and Rocky Mountain faunas occurs.