94 Merriam Rediscovery of the Mexican Kangaroo Eat 



Remarks on the Accompanying Table. 



The table on the preceding page is believed to possess certain 

 advantages over the ordinary method of tabulating measure- 

 ments of mammals. It presents to the eye in the brief space 

 of four lines a summary of the average measurements, ratios, 

 maxima and. minima, and percentages of variation, by localities, 

 of 61 specimens, instead of covering a number of pages with the 

 detailed measurements of each individual. 



The usual object of measuring zoological specimens is to as- 

 certain one or more of the following facts : (1) the normal* size 

 of the animal; (2) the proportions (or ratios) of some of its 

 parts, and (3) the limits or extremes of variation in a large; 

 series of individuals (which may be expressed both in actual 

 maximum and minimum measurements and in percentages of 

 the normal). The accompanying table not only summarizes 

 this information for each locality in a single line, but also, by 

 bringing into sharp contrast corresponding data from different 

 localities, shows the amount of geographic variation in the 

 species. Tables of the ordinary sort may contain the material 

 from which these important facts can be ascertained, but the 

 labor of digging them out from the bewildering mass of figures 

 in which they are buried is so great that it is rarely undertaken. 



Note on Macrocolns halticus Wagner. 



A word is necessary, perhaps, concerning the Macrocolus halticus 

 of Wagner,f which has been a stumbling block to naturalists 

 lor many years, though its true position was correctly indicated 

 1 > v Baird thirty-five years ago. Baird's remarks were as follows : 

 "Although Wagner expressly states that there were no external 

 cheek pouches in his specimen, and that in consequence it 

 could not belong to Gray's genus, Dipodomys, yet the coincidence 

 in every other respect skull, teeth, skeleton, and external 

 form is so very intimate as to render it almost certain that the 



-'The normal of any measurement in the average or mean of that mea- 

 surement in a large series of adult individuals from the same locality. 

 In preparing such tables care should be taken to exclude all immature 

 and imperfect specimens. 



t Mn;-nrr)l.nx lifilticux A. Wagner, Wiegmaiin's Archiv. fiir Naturgesch- 

 ichte, 1846, 172-177. 



