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University of California Publications in Zoology [Vol.12 



Fig. L. Posterior view crania of Castor canadensis leucodonta and Castor 

 subauratus subauratus. 1 Note the different outline of the 

 foramina magna; the difference in the external auditory meatus, 

 and in general massiveness of crania. Approximately natural size. 



a. Castor canadensis leucodonta, no. 12107. 9. Mus. Vert. Zool.; 



Alberni, Vancouver Island. British Columbia. 



b. Castor subauratus subauratus, no. 12654, 5, Mus. Vert. Zool.; 



Grayson, San Joaquin River, Stanislaus County, California. 



teriorly approximate the line in some specimens, in others fail of 

 doing so by several millimeters; frondator, no. 60354. 2.6 mm.; 

 351)46, 3.3 mm.). 



- In rigs. J. K, and L comparison has been made between Castor s. 

 subauratus and Castor c. leucodonta instead of Castor c. pacificus. For 

 textual comparison of cranial characters of leucodonta and pacificus see 

 pp. 442 to 14*;. They differ in nasal outline, breadth of hamular blades, and, 

 as a rule, in the condition of occipital crest. 





