Tol. 55.] OF THE EOCK-FISSUEE AT IGHTHAM. 425 



to the use of the specific name of M. Ahhotti by Mr. Waterhouse ^ 

 for a small mouse from Trebizond, and courteously suggested that I 

 should give some other name to this fossil ; this I have done in a 

 note to the Zoological Society,^ naming it Mus Leiuisi^ in order that 

 it may still be associated with its discoverer, Mr. Lewis Abbott. 

 The species is now represented by several additional examples of 

 lower-jaw rami with teeth. 



15. MicROTUs AEVALis, Pallas. 



The occurrence of this species is confirmed by the discovery of 

 several portions of one skeleton. The number of angles to the 

 front lower cheek-teeth shows that it must belong to either 

 M. agrestis or M. arvalis ; and the presence of only five angles to 

 the second upper cheek-tooth prevents its reference to the first of 

 these. 



16. MiCEOTUs NIVALIS (?), Martins. (Mpine Yole.) 



The front lower cheek-tooth of this species is not always to be 

 clearly distinguished from extreme forms of M. glareolns ; but 

 among the very many examples of the latter species which have 

 been obtained by all the collectors from the Ightham fissure, there 

 are several which have the inner part of the anterior prism well- 

 <developed, so that five inner and four outer angles maj' be counted. 

 It seems highly probable, therefore, that these are the remains of 

 Microtus nivalis. 



17. MusTELA VFLGAEis, Briss. fWeasel.) 



In my earlier paper ^ some very small bones were recorded as the 

 variety minuta of this species, and other equally small bones have 

 since been obtained ; but in addition to these we now have skulls 

 and limb-bones belonging to several individuals that correspond in 

 size with the common weasel. It must now, therefore, be included 

 in this fauna. 



18. MusTELA PTjTOEitrs, Linn. (Polecat.) 



Besides the specimens found by Mr. Lewis Abbott, skulls and a 

 number of limb-bones have been secured by Mr. Frank Corner and 

 Mr. A. S. Kennard, which correspond in all particulars with those 

 -of the normal polecat, and undoubtedly represent that species. 



19. MusTELA EOEUSTA, Newtou. (Giaut Polecat.) (PI. XXVIII, 

 figs. 1-6.) 



In my earlier paper a humerus and some other bones of a large 

 Mustela were made the type of this species. Since then, additional 

 bones have been found which add much to our knowledge of this 

 form. Mr. Frank Corner and Mr. Kennard obtained from the 

 collateral fissure, which they call the ' small horse fissure,' a 

 liumerus even larger than that originally figured, as well as a 



1 Proc. Zool. Soc. 1880, p. 61. ^ jj^i^ 130,9^ p ^^^ 



3 Quart. Journ. Geol. See. vol. 1 (1894) p. 201. 



