Part 2 (2/2)
The specimen of _Clethrionomys rufoca.n.u.s_ figured by Ognev (1950:97) resembles my specimen in the presence of three well ossified processes.
Ognev's specimen differs however in the lack of a proximal notch on the median process, the lesser proportion of the stalk included in the basal enlargement, the more posterior position of the point of greatest width, and the presence of a concavity in the posterior profile of the stalk in dorsal view. These differences in the stalk may be owing to a difference in age (my specimen perhaps being older).
_Specimen examined_: One from 1 mi. NW Oho-ri, 6 M., Korea, 60438.
Phenacomys intermedius Merriam
Figs. 7 and 8
Baculum: Stalk slender, greatest length (2.9 mm.) 2-1/4 to 2-1/2 times greatest breadth, 4 times greatest depth; three well-developed ossified processes, median one almost 1/2 length of stalk, curved, broad basally and slightly larger in all dimensions than either lateral process; lateral processes flattened distally, curved; base of stalk well developed, basal tuberosities medially confluent or separated by medial emargination, posterolateral faces flattened or rough; emarginations in the four adults examined; posterior profile in dorsal view bluntly pointed or flattened except for emargination posterially, abruptly curved at point of greatest width; shaft arising broadly from distal side of base of stalk; in end-view hour-gla.s.s shaped, medial constriction p.r.o.nounced, both dorsal and ventral concavities deep; shaft having relatively straight but distally convergent sides; at mid-point of stalk, 1 to 1-1/2 times as wide as deep; tip bluntly rounded, or slightly inflated.
The specimens from Quebec differ from the one from Wyoming in smaller size, relatively smaller lateral digital processes, larger more medial basal emargination, and slender shafts. The baculum of _Phenacomys intermedius_ differs much from that of _Phenacomys longicaudus_, described by Hamilton (1946:381) and by Dearden (1958:547). Dearden states that the three bacula examined by him of _Phenacomys longicaudus_ differ markedly from the specimen described by Hamilton. It seems to me that in major features the resemblance is greater between the specimens of _Phenacomys longicaudus_ examined by these two authors than between their specimens and specimens of other microtines, including _Phenacomys intermedius_. Neither Hamilton nor Dearden record the exact localities of capture, the collections in which the specimens are deposited, or the catalogue numbers of specimens. Consequently verification of identifications and observations is difficult.
_Specimens examined_: Five, of two subspecies; _P. intermedius intermedius_, 5.4 mi. S Moran, Teton Co., Wyoming, 3-C-309, collection of W. B. Quay; _P. intermedius celatus_, four (including one immature specimen) from Authiernord, Abitibi-ouest Co., Quebec, specimens in collection of Bristol Foster designated by numbers 2041-2044 of S.
Anderson's field catalogue. Smith and Foster (1957:107) were of the view that _Phenacomys ungava_ (including the above specimens from Quebec) may be specifically distinct from _Phenacomys intermedius_.
Ondatra zibethicus (Linnaeus)
Not figured
Baculum: In the single specimen examined, less mature than that figured by Hamilton (1946:384), the digitate processes are cartilaginous, the basal tuberosities are less well developed, and the shaft is slenderer throughout. The cartilaginous processes are of the same proportions as ossified processes in the figure mentioned. The shaft is also convex ventrally in lateral profile. The view of the side here considered to be anatomically the ventral side (adjacent to the urethra) is labelled dorsal view in Hamilton's specimen.
_Specimen examined_: One, from Reserve, Brown Co., Kansas, 72405.
Microtus (Herpetomys) guatemalensis Merriam
Figs. 42 and 43
Baculum: Stalk moderately elongate, greatest length (3.5 mm.) 2-1/3 times greatest breadth, spatulate, flattened throughout, greatest thickness 1/3 millimeter; three ossified processes; median process having three cornered base, curved dorsally, wider than high, 1/4 to 1/5 greatest length of stalk; each lateral process bent at middle, as long as median process, compressed laterally; base of stalk curved dorsally, tuberosities marginal, hence narrow, lateral excavations of tuberous margin not confluent medially; in end-view ventral concavity broad, no dorsal concavity, medial constriction but slightly less than greatest thickness (not depth); shaft wider than high throughout, at mid-point more than 3 times as wide as high; tip of shaft slightly inflated both laterally and dorsoventrally; lateral profile gradually sloping anteriorly from widest point of stalk.
Specimen number 65921 (Fig. 43) differs from number 65895 (Fig. 42) described above. Terminus of shaft of number 65921 has lateral lobes from which arise lateral cartilaginous processes; median terminal ossification irregular in shape, smaller, imbedded in terminally bilobate cartilage.
In the spatulate flattened stalk these two specimens are much alike. An immature specimen, number 65908, is smaller (length of stalk 2.6 mm.) also flattened and spatulate, has the terminal processes cartilaginous, the lateral processes bent medially, and proportions as in the adult.
The baculum shows no noteworthy resemblance to that of any other species of North American _Microtus_; on the other hand the differences between _M. guatemalensis_ and some other species are no greater than the differences between certain species included in the subgenus _Microtus_.
The baculum neither strengthens nor weakens the case for subgeneric rank for _M. (Herpetomys) guatemalensis_.
_Specimens examined_: Three from Guatemala; 65895 (2 mi. S San Juan Ixcoy), 65908, (3-1/2 mi. SW San Juan Ixcoy), 65921 (10 mi. E, 4 mi. S Totonicapan).
Microtus (Arvicola) richardsoni (DeKay)
Figs. 38 and 39
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