()."?H ON A VKI.LOW VARIirrV OK MI'S ItA'lTUS. [Apr. 10, 



.Sknll broad ;iiul iiat, very like that of M. nuoidarinits on a 

 smaller scjile. Hrain-case square, with well-marked angles, but 

 the ridges little developed. Anterior palatine foramina of about 

 e][ual breadth throughout, those of mamlarimis broad in front, 

 naiTOwing behind. 



Incisors markedly lighter than in ma7idaHnus, their faces 

 orange to the tips. Molar pattern about as in M. mandarinas ; 

 m^ with 4 spaces, three outer and thi-ee inner saUent angles ; 

 »>?, with 7 spaces, 5 inner and 4 outer angles. All triangles 

 separated from each other except in m^. 



]^imensions of the type, measured in the flesh : — 



Head and body 95 mm. ; tail 23; hind foot 17 ; ear 7. 



Skull: condylo-basal length 24-6 mm.; greatest l)readth 15"2 ; 

 nasals 7*0 X 3'1 ; interorbital breadth 3*5; palatilar length 13 '2; 

 diastema 7*1 ; palatal foramina 4*1 ; upper molar seiies (crowns) 

 5-8. 



Hah. Mts. 12 miles N.W. of Ko-lan-chow, Shan-si. Alt. 

 7000'. 



^T/jDe. Adult male. B.M. No. 9.1.1.178. Original number 1950. 

 Collected 5 June, 1908. 



This Yole was i-eferied to M. rnandao-ivus M.-Edw. in my last 

 paper *, but by the kindness of Prof. Trouessart I have had an 

 opportunity of re-examining the skull of that species, and I find 

 it to agree in every detail with two specimens noAv sent from 

 Shang-chou, S.E. 8hen-si, and to differ equally from the Ko-lan- 

 chow foi-m, which therefoie needs describing. 



If, however, this identification be accepted, it throws some 

 doubt on the asserted locality of " Mongolie chinoise" for ?»««- 

 darinus, and 1 think it not impossible that the type really came 

 from S. Shen-si, where David made a small collection, after 

 getting his Mongolian series. 



M. jnhnnnes is readily distinguishable from JA. viandarinus 

 by its pah'r colour and markedly smaller skull. 



]\Tr. J. Lewis Bonhote, M.A., F.L.S., F.Z.S., exhibited a yellow 

 variety of Mas ratius. This individual had been bred from two 

 wild-caught examples of Mus raitxs tectormn from Egypt. The 

 long hairs on the upper parts, which are normally black, weie 

 colourless and the shorter body-hairs had grey l)ases witli yellow 

 tips. So far as he knew, this was the first recorded example of a 

 vellow rat, which was a colour (juite unknown to fanciers and 

 was never met with by Crampe or Donca.ster. who had conducted 

 colour-bi-eeding experiments on rats. Although it was not defi- 

 nitely stated, these experiments had pi obably been carried out with 

 Mns nwvegicns. A careful search thrftugh the large series of 

 ^fu8 rattus in the Museum also failed to bring to light any j'ellow 

 forms. 



" P. Z. S. IflOP, p. OTH. 



