The skull of the male, in linear measurements, is approximately 13 (12-16) per cent smaller and 40 per cent lighter than in _M. e. richardsonii_. In relation to the basilar length, the skull averages slightly narrower, slightly shallower as measured in the vertical plane touching the posterior borders of the last upper molars, and the preorbital part is slightly longer. In skulls of females of _cicognanii_, linear measurements average 3 (0-6) per cent less, the weight is 16 per cent less and the teeth are 5 per cent shorter. In relation to the basilar length, measurements of the skull are approximately the same or slightly less in _cicognanii_.
In comparison with _bangsi_, the male sex in linear measurements of the skull and teeth averages 11 per cent less than in _bangsi_ from Aitkin, Minn., and 6 per cent less than in _bangsi_ from Elk River, but in relation to the basilar length the preorbital region is larger. The weight is approximately a fourth less. In females the measurements average less, some being the same, and in relation to the basilar length, the bullae are shorter and the skull is shallower. The weight is about the same.
_Remarks._--In January, 1838, in Charlesworth's Magazine of Natural History, C. L. Bonaparte proposed for three kinds of American weasels the names _Mustela cicognanii_, _Mustela richardsonii_ and _Mustela longicauda_.
In this paper Bonaparte indicates that he previously had written (for his Iconografia della Fauna Italica ...) an account of _Mustela cicognanii_ using this same name. Fasciola XXII of the Iconogr. d. Fauna Italica, presenting his account of _Mustela_, like the English paper was published in the year 1838. In his article in Charlesworth's Magazine, Bonaparte refers to his book published [used the past tense] in Rome but whether it actually appeared first I am unable to determine and hence am uncertain which of the two constitutes the original description.
Reference to the Italian account suggests as basis for the name _M. cicognanii_, (1) specimens possibly seen in the United States by Bonaparte, or (2) Godman's published account of the animal.
In the English publication, however, Bonaparte actually says that (1) he saw the small species in the Union [= United States]. Also, he (2) mentions his earlier written Italian account, (3) mentions that "all the [American?] naturalists" used the name _M. vulgaris_ for this animal, (4) incidentally mentions Godman's account, and (5) in naming two other American species cites accounts of them by Richardson. Also, Bonaparte in this English article makes clear that when he wrote [not necessarily published] his Italian paper he did not know of the existence of two of the three American species.