500 General Notes. [ August, 
a corresponding range 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.” These variations are 
described somewhat in detail, in connection with a general description of 
the cranial characters of the species. 
Dr. Coues recognizes among the Mephitine the three genera Mephitis, 
Spilogale, and Conepatus. The two first named differ not at all in their 
dental formule, while Conepatus has usually been considered as lacking 
the minute first premolar present in the others. Dr. Coues, however, 
affirms that it is present as a rule, though always minute, but is often 
either deciduous or abortive, and never functionally developed. Hence 
the main differences appear to relate to the general contour of the 
skull, for while Dr. Coues has described each form with great detail he 
has failed to give a contrasted summary of the differences that severally 
characterize these so-called genera, — an omission that detracts consid- 
erably from the availability of an otherwise excellent paper. While 
Mephitis and Spilogale seem to be hardly generically separable, Conepa- 
tus presents wider differences, especially in respect to the characters of 
the lower jaw. i . " 
No synonymy is formally presented in this connection, but it is men- 
tioned incidentally that the M. occidentalis of authors is inseparable from 
M. mephitica. Of Mephitis proper only the single recént species mephit- 
tea is mentioned ; of Spilogale, a single species only is noticed, putorius 
Linn., based on Catesby (= to the M. Zorilla, bicolor, and interrupta of 
recent authors), and of Conepatus also but a single species (marputto 
Gmel. = mesoleuca Licht.). 
The supposed new fossil species here described seems to present no 
very tangible features. Its size is stated to be intermediate between 
various specimens of the recent M. mephitica, the only ostensible charac 
ters hence being th@excessive tumidity and angulation o 
the skull, and the vertical narrowing of the zygoma anterio 
of the normal tumidity of the frontal region, and especially the tendency; 
so readily seen in any large series of the skulls of the common per 
to a diseased and abnormal enlargement of this part, this alle, 
acter has much less weight than it would otherwise have. 
rly. In view 
GEOGRAPHY AND EXPLORATION. 
account 
Tue Istamus or TeEnuanTEPEC. — We extract the pppoe we 
from Sumichrast’s notes on the birds of the isthmus in the fou the 
letin of the United States National Museum. The contraction © i 
American continent between the ninety-fourth and ninety- operly, 
of longitude west from Greenwich forms what is called, quite imp" th of 
perhaps, the Isthmus of Tehuantepec, whose width between the mou ik 
the Rio Coatzacoalcos and the Bay of Ventosa is about one banger: 
eighty miles. 
fc 
f the vertex of 
y-fifth degree? 
