Vol. II, Pt. I] VAN DENBURGH— GALAPAGOS TORTOISES 261 



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 v^ith 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. 



The actual measurements of the tortoises in the collection 

 of the Academy will be given under each species. For pur- 

 poses of comparison I have made charts showing each dimen- 

 sion as found in all the races represented. The males and 

 females are charted on separate lines. Each medium-sized or 

 adult specimen is represented by a dot, while the young are 

 indicated by crosses. Certain combinations of these measure- 

 ments are also charted. 



