138 Mr. 0. Thomas 07i 



Ti/pe. Adult male. B.M. no. 12. 12. 12. 1. Original 

 number 21. Collected 12tli March, 1912. 



Besides the two specimens of this species obtained by 

 Sr. Budin, there are in the Museum three skunks from 

 Cachi, Salta, collected by Herr J. Steinbach, two at least of 

 which are clearly referable to the same form. The third is 

 much more extensively marked with white, but is probably 

 only one of the aberrations which have to be set aside in 

 studying this difficult and variable group. 



2. Mus musculusj L. 



S . 32, 33, 35 ; $ . 34. Maimara. 2300 m. 

 " Caught in meadows far from houses, in thorn hedges. 

 Kot common, either in fields or houses." — E. B. 



3. EVgmodontia laucJia muscuUna^ subsp. n. 



S . 12, 13, 18 ; ? . 4, 6. Maimara. 2230 m. 



Very similar to S. Argentine E. laucha, but larger. 

 General colour above rather paler, drab-grey ; under surface 

 greyish white, with a slight drabby tinge. Wiiite post- 

 orbital patch less conspicuous. 



Skull decidedly larger than is normal in E. laucha, though 

 unusually large examples of the latter may just attain the 

 size of small specimens of E. I. musculina. Supraorbital 

 edges unbeaded, as in laucha, those of E. callosa having 

 distinct beads. 



Dimensions of the type (measured in flesh by collector) : — 



Head and body 100 mm. ; tail 98 ; hind foot 21 ; 

 ear 16. 



Skull : greatest length 2G ; condylo-incisive length 23*5 ; 

 zygomatic breadth 13-8 ; nasals 11"3 ; interorbital breadth 4 ; 

 breadth of brain-case ll'l ; palatilar length 10*8 ; palatal 

 foramen 5'9 ; upper molar series 3*6. 



JIah. As above. 



Type. Adult male. B.M. no. 12. 12. 12. 9. Original 

 number 18. Collected 12th March, 1912. 



I have been in some doubt as to whether this mouse ought 

 not to be called a separate species, as its skull is so much 

 larcer than that of ordinary Buenos Aires specimens of 

 E. laucha. But both forms seem to vary a good deal in 

 size, while there are no other distinctions o£ importance, and 

 therefore it may, for the present, be attached to E. laucha 

 in order to emphasize its difference from the still larger 

 E. callosa^ in which supraorbital beads are developed in old 

 examples. 



