shape is rather as a Gulo ; but even the profile of the latter is here exag- 

 gerated. The prominence appears to be mainly due to enlargement of 

 the frontal sinuses, as may be seen in this specimen, on which the outer 

 tablet of the skull is abraded in places, exposing the interior. With 

 this general elevation is associated a notably higher arch of the zy- 

 goma ; but the bone itself is slenderer than in recent species at its 

 anterior portion, "where it is curiously narrowed vertically instead of 

 being laminar throughout. ISone of these characters obtain in any of 

 the numerous recent skulls examined, notwithstanding the great varia- 

 bility of the latter. 



The animal was the size of the common species. The skull in gen- 

 eral bulk is intermediate between various specimens of M. oii^jjliitim. 



The excellent figure, engraved by Nichols, of Washigton, from an 

 photograph on wood by Smillie, renders further descrii^tion unnecessary. 



MEPHITIS MEPHITICA, Bd. ex Shaw. 

 {M. americana or cliinga, of authors.) 



The cranium of no animal with which I am acquainted varies more 

 than that of the skuuk, and few exhibit such remarkable differences, 

 independently of age and sex. Some specimens are more than a fourth 

 larger than others, and twice as heavy ; and there is a corresponding 

 range of variation in contour. Compared with an ordinary ratio of 

 osteological variability, the discrepancies are almost on a par with those 

 exhibited by the coloration of the animal when set over against the more 

 constant markings of most animals. In the series of twenty or thirty skulls 

 examined, I find that the western ones, and esx)ecially those from the Pa- 

 cific coast, representing occidentcdis of Baird, are, as a rule, larger and 

 heavier than others, more widened and flattened behind, with stronger 

 and more flaring sagittal and especially occipital crests. But these 

 extremes shade insensibly into an ordinary pattern, and I can draw no 

 dividing line. Tables of measurements would show these variations, 

 though they would scarcely render that realizing sense of the discrep- 

 ancies that is found by laying the two extremes side by side. An aver- 

 age cranium, No. 3816, from New York, is selected for description, in 

 the course of which the variations of the whole series will be brought 

 under review. 



The greatest zygomatic width is to the length as 1 to 1.55, or slightly 

 less than two-thirds such length. A similar proportion is generally pre- 

 served. Viewed from above, the cranium presents a short, tumid, rostral 

 portion, high at the nose, tapering on either side, but with a protuberance 

 indicating the course of the canine tooth in the bone, subtruncate in 

 front, with large subcircular nasal aperture, in this view much fore- 

 shortened. The rostrum is about a third of the whole length, if meas- 

 ured from extreme front to anterior root of zygoma ; the zygoma, and 

 then the rest of the skull, being, respectively, another third. In other 

 skulls, the rostrum is shorter than this, and less vaulted. The general 

 convexity of the rostrum continues on to the forehead, in the broad, 

 smooth, iuterorbital space. Supraorbital processes are very slight, 

 being only indicated in a little bulging at the front, where the anterior 

 forks of the sagittal crest come to the brim of the orbit. There is thus 

 scarcely any definition of the orbit from the general temporal fossa. 

 The point of greatest constriction of the skull is considerably behind 



