236 



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



A considerable series of specimens is in the collection 

 from Iguana and Tagus coves and Elizabeth Bay, Albe- 

 marle Island; Wreck Bay, Chatham Island; and Duncan 

 Island. From the last locality this is the only known rodent, 

 but on Albemarle and Chatham it occurs with M. alexan- 

 drinus, with which form it apparently intergrades in both 

 coloration and skull characters. In no locality in the archi- 

 pelago do any species of Mus occur with the indigenous 

 species of Oryzojnys and JVesoryzomys. This is probably 

 due to the extermination of these latter species by hardier 

 introduced forms of Mus, and by cats. 



Measurements of Mus rattus. 



Mus alexandrinus St. Hilaire. 



Mus alexandrinus St. Hil. Descr. Egypt, v. 2, 1815, p. 733. 

 Musjacobice Waterh. Zool. Voy. Beagle, v. i, pt. 2, 1840, p. 34. 

 Mus decumanus AW&n, Bull. Am. Mus. Nat. Hist. v. 4, 1892, p. 48. 



