5 5 2 Bulletin American Museum of Natural History. [Vol. XIX, 



Muskrats, like most other mammals, continue to increase 

 in size after maturity is reached, the skull increasing some- 

 what in linear measurements and especially in massiveness. 

 The type of F. spatulatus is given as "yg. ad.," and no other 

 specimens from the type region are referred to. If the 

 character, "size small," is based on this specimen, this com- 

 parative statement should be eliminated, as shown by the 

 following table of comparative measurements, giving the 

 principal dimensions of the seven largest Muskrat skulls in 

 the Museum series of considerably over one hundred specimens. 

 They are all very old examples, and range much above the 

 average, doubtless, for the several forms they represent. 

 This is at least true of the New York and New Jersey series. 



COMPARATIVE MEASUREMENTS OF SKULLS OF MUSKRATS. 



No. 98567, U. vS. Nat. Mus., type of Fiber spatulatus Osgood. Lake 

 Marsh, N. W. T. (measurements from Osgood, /. c.). 



No. 20768, Am. Mus., Shesley, B. C. 



No. 16422 and 16421, Am. Mus., Kettle River, B. C., near type 

 locality of Fiber osoyoosensis. 



No. 16204 and 16205, Am. Mus., Newport, Nova Scotia. 



No. 8541, Am. Mus., Hastings, Westchester Co., N. Y. 



No. 15980, Am. Mus., Paterson, N. J. 



Mr. Anderson says (MS. notes): "On September 5 a single 

 muskrat was shot on the marshy edge of a small lake about 

 a mile from Shesley; another was shot at, but not secured. 



