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CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



It is unfortunate that we have no specimens of the 

 Chatham Island species for comparison, as good differ- 

 ences no doubt exist; but owing to the nature of the type 

 description, exact comparison is impossible. The differ- 

 ences (shorter tail and ears) given by Allen cannot be 

 relied upon, as Waterhouse's measurements were evidently 

 taken from a dried skin and are not comparable with those 

 of Allen's alcoholic specimens. Our measurements in the 

 flesh are also of little value in this connection. 



We found this mouse very abundant on Barrington 

 Island. It was found inhabiting crevices among the loose 

 lava rocks and burrows and runways beneath bushes and 

 brush piles. In habits it appears to be somewhat diurnal 

 and was as often seen at midday as at other times. 



Measurements of Oryzomys bauri. 



Measurements of Skulls. 



