The baculum in Microtus ochrogaster—orientation and variation with age.
Shape of baculum most resembled that of Ochrotomys and Calomys.
The total length of the baculum, considered together with its shape, serves to identify to species all specimens examined by me.
There the species differ in color, in the shape of the skull, and in the size and shape of the baculum.
The baculum does not, however, suddenly reach its maximum maturity.
The development of the baculum has been studied by Callery in Mesocricetus auratus and by Ruth in the laboratory rat.
Voles of the genus Microtus vary in the structure of the baculum almost as much as do the lemmings.
Maximum development of the baculum is reached late in the reproductive life of the hamster.
It should be noted that not all species can be keyed out on the basis of the baculum.
The development of the baculum in Microtus ochrogaster was studied in 32 specimens of various ages.