Part 1 (2/2)

At least twelve of these are insular or local forms perhaps derived from some other species; for example _Microtus coronarius_, an insular form derived from _Microtus longicaudus_; _Microtus provectus_, considered by Chamberlain (1954:587) and by Wheeler (1956:176) as a subspecies of _Microtus pennsylvanicus_; and _Microtus ludovicia.n.u.s_, a close relative of _Microtus ochrogaster_.

All North American genera have been studied. Of the genus _Microtus_ in North America, all subgenera but _Orthriomys_ and all species but the following nine, have been studied: _M. (Orthriomys) umbrosus_, the insular _M. (Stenocranius) abbreviatus_, _M. (Microtus) breweri_, _M.

(Microtus) nesophilus_, _M._

[Ill.u.s.tration: FIGURES 2-13. Bacula of microtines. Unless indicated otherwise views are (_a_) of the dorsum, (_b_) the right side, and (_c_) the proximal end with the dorsal surface upward. Exact localities are given in accounts of species concerned.

2. _Lemmus trimucronatus_, 50678, Point Barrow, Alaska.

3. _Dicrostonyx groenlandicus_, 50539, Porcupine Lake, Brooks Range, Alaska.

4. _Dicrostonyx groenlandicus_, 52524, Point Barrow, Alaska.

5. _Synaptomys cooperi saturatus_, WBQ 3-C-454, 3 mi. S Demotte, Indiana.

6. _Synaptomys cooperi paludis_, 13716, Meade County State Park, Kansas.

7. _Phenacomys intermedius celatus_, SA 2044, Quebec.

8. _Phenacomys intermedius intermedius_, WBQ 3-C-309, 5.4 mi. S Moran, Teton Co., Wyoming.

9. _Clethrionomys rufoca.n.u.s_, 60438, 1 mi. NW Oho-ri, Korea, (_d_) ventral view.

10. _Clethrionomys gapperi_, 42108, 31 mi. N Pinedale, Wyoming.

11. _Clethrionomys rutilus_, 42865, 5 mi. NNE Gulkana, Alaska.

12. _Clethrionomys occidentalis_, FWS 30, Mary's Peak, Benton Co., Oregon.

13. _Clethrionomys glareolus_, 67100, Zermatt, Valais, Switzerland.]

[Ill.u.s.tration: FIGURES 14-25. Bacula of _Microtus_. Unless indicated otherwise views are (_a_) of the dorsum, (_b_) the right side, and (_c_) the proximal end with dorsal surface upward.

14. _M. pennsylvanicus_, 42439, 1 mi. S, 2 mi. E Eagle Nest, Colfax Co., New Mexico; abnormality perhaps owing to injury; dorsal view.

15. _M. pennsylvanicus_, 42306, 5 mi. N, 26 mi. W Saguache, Colorado; dorsal view.

16. _M. pennsylvanicus_, 43043, 20 mi. NE Anchorage, Alaska, ventral view.

17. _M. pennsylvanicus_, 42430, 1 mi. S, 2 mi. E Eagle Nest, New Mexico.

18. _M. agrestis_, 67102, Gryon, Switzerland.

19. _M. monta.n.u.s amosus_, 62241, 1/2 mi. E Soldier Summit, Wasatch Co., Utah.

20. _M. monta.n.u.s na.n.u.s_, 57470, 2 mi. N, 2 mi. W Pocatello, Idaho.

21. _M. monta.n.u.s fusus_, 42307, 5 mi. N, 26 mi. W Saguache, Colorado.

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