6 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser, 



second to third marginals is the straight width at the level 

 of the lateral margins of the sutures between the second and 

 third marginal plates of each side. The middle height is 

 the vertical distance between the board or table and the middle 

 of the third vertebral plate, and is taken with a square and 

 spirit-level. The front height is taken in the same manner 

 at the nuchal notch. The height to marginals is the vertical 

 distance from the table to the lower border of the marginal 

 plates at about the middle of the plastral bridge. The plastron 

 is measured with a tape along the median line, the tape is not 

 pushed into plastral depressions and when the plastron is 

 notched the projections are not measured. 



San Francisco, 



November 18, 1907. 



