444 THE ZOOLOGISY. 
posterior tubercle. First lower molar with a well-developed inner 
tubercle at the base of the main cusp. 
As Blasius has remarked, the differences of proportion are 
less, conspicuous when a skull of an aged example of M. foina is 
compared with that of a young M, sylvatica than when indiyiduals 
of the, same age are contrasted; nevertheless they are always 
present to an appreciable degree. In his figures Blasius has 
represented a further distinction, in the form of the transverse 
ridges of the soft palate; but I have not had an opportunity of 
testing the constancy of this feature; nor have I sufficient 
materials for any original observations on the distinctive marks 
of the American and Siberian Martens, as to which I can only 
refer the reader to the descriptions of Drs. Couest and Midden- 
dorff.t On the whole, it may be said that the most striking and 
trustworthy of the characters enumerated above are, externally, the 
colour of the under fur, and, internally, the comparative breadth 
of the skull and the shape of the upper molar.§ 
Having thus cleared the ground as to the synonymy and dis- 
tinguishing marks of the two European Martens, we come to the 
question whether both of them whabit our own islands. Every work 
hitherto published on the British fauna has either stated or 
assumed that both forms are natives; and almost, every one has 
represented the white-breasted Martes foina (the Common Marten 
of the Continent) as being also the prevailing species in Britain. 
Several, however, of our best zoologists have expressed grave 
doubts as to the specific distinction of the two forms, or have 
even denied that they could be separated as constant varieties. 
This will be evident from a glance at the pages of the, principal 
writers on the subject. ) 
Passing oyer the older writers, who merely copied the accounts 
of Gesner and Aldrovandus, we may come at once to Pennant, 
who describes Justela foina as ‘The Martin,’ distinguishing ‘The 
Yellow-breasted Martin’ as a distinct species, of which he says 
*« Fur-bearing Animals,’ pp. 59 —96, pls. ii., iv. 
t+ ‘Reise in Sibir. ii. Th. ii. pp. 68, 69, pl. ii. figs. 1—6. 
} It should be observed that Dr. Severtzoff has stated that our European 
Martens are “not fully differentiated” in Eastern Turkestan, and has described 
some skins which he saw there as a new species, Mustela intermedia (Turkestanskie 
Jevotnie, p. 80; Ann. and Mag. Nat. Hist., 4th ser. xviii. p. 46); but as he obtained 
no skulls, much weight cannot be laid on his observations. 
