SACCOMYID^E— DIPODOMYINJ3— DirODOMYS. 



537 



posed and recognized. As they rest mainly upon size and proportions, these 

 points will be first discussed. 



The following tables of measurements of a series of Dipodomys, fresh 

 and alcoholic, will serve to show whether or not two species, commonly sup- 

 posed to be distinguished by size and proportions, intergrade in these respects. 

 The specimens are arranged without reference to locality, according to the 

 chief point in question, namely, length of tail. 



Table V. — Measurements of seventeen specimens of Dipodomys. 



2~ 



Locality. 



■I 070 

 8436 

 4871 

 4970 

 8437 

 0478 

 4970 

 4970 

 4970 

 7349 

 7344 

 2637 

 2626 

 2028 

 10725 

 7348 



Cape St. Lucas 



Fort Whipple, Ariz. 

 Cimarron, N. Mex... 



Cape St. Lucas 



Furl. Whipple, Ariz. 



(Unknown) 



Cape St. Lucas 



do 



.do . 



(Unknown) 



Platte Valley 



Fort Reading, Cal . 

 do 



" California " ... 



Monterey 



Fort Tejon, Cal . 

 " Rocky Mts.".. 



A vera go . 



From tip of nose to 



1.00 

 0.85 



1.00 

 0.85 

 0.95 

 0.90 



0.90 

 0.90 

 0.80 



1.00 

 1.00 

 0.95 



1.45 



1.55 

 1.35 



1.40 

 1.40 

 1.50 

 1.45 



1.40 

 1.35 



1.25 



1.60 

 1.60 

 1.45 



1.55 

 1.90 

 1.75 

 1.45 



1.55 

 1.50 

 1.60 

 1.55 



1.60 

 1.55 

 1.40 



1.75 

 1.80 

 1.70 



3.50 

 4.25 

 4.50 

 3.50 

 4.50 

 4.75 

 3.75 

 3.75 

 3.75 



4.50 

 3.35 

 3.25 

 5.00 

 5.09 

 4.25 

 4.50 



Tail to end ^ th of _ 

 of— 



5.00 

 5.00 

 5.00 

 5.25 

 5.25 

 5.50 

 5. 75 

 5.75 

 5.75 

 5.75 

 5.75 

 5.60 

 6.00 

 6.10 

 6.75 

 7.00 

 7.00 



6.00 

 5.75 



6.25 



6.75 

 6.75 

 6.75 

 6.50 

 7.00 



7.00 

 7.75 

 7.75 



8.00 



6.85 



fl 



1.35 

 1.55 

 1.55 

 1.40 

 1.50 

 1.60 

 1.40 

 1.40 

 1.45 

 1.60 

 1.55 

 1.60 

 1.60 

 1.60 

 1.70 

 1.70 

 1.70 



1.58 



y, 



Alcoholic. 



Fresh. 



Alcoholic. 



...do. 

 Fresh. 

 Alcoholic. 



...do. 



...do. 



...do. 



...do. 



...do. 

 ...do. 



...do. 



...do. 



...do. 



...do. 



...do. 



The foregoing table of measurements of only 17 specimens, all adult, 

 suffices to prove an uninterrupted gradation in size of every part of the body 

 and its members. There is no break whatever in any of the absolute dimen- 

 sions. The specimens range, by minute fractions of the inch, from 3.25 to 

 5^00 inches in length of head and body, averaging about 4.00. The tail vertebrae 

 range from 5.00 to 7.00 inches, averaging about 5.75 ; with the hairs, the tail 

 is from 5.75 to 8.00 inches, averaging a little less than 7.00. The hind foot 

 runs from 1.85 to 1.70, settling at an average of 1.58. It will be observed 

 that the lengths of tail and feet bear no constant ratio to each other, some 

 specimens with relatively smallest feet having relatively the longest tails. It 

 will further be evident that absolute lengths of tail and feet are not indicative 



