322 



PROCEEDINGS OF THE ACADEMY OF 



nizable forms, if there be more than one. Various species have 

 been proposed and recognized. As these 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 the two spe- 

 cies, commonly supposed to be distinguished by size and propor- 

 tions, intergrade in these respects. The specimens are arranged 

 without reference to locality, according to the chief point in ques- 

 tion, namely, length of tail. 



Measurements. 



Current 

 Number. 



4970 

 S436 

 4S71 

 4970 

 8437 

 947S 

 4970 

 4970 

 4971 

 7349 

 7341 

 2627 

 2626 

 262S 

 1072.i 

 7348 



Locality. 



Cape St. Lucas. . . . 

 Ft. Whipple, Ariz 

 Cimarron, N. M. . 

 Cape St. Lucas. . .. 

 Ft. Whipple, Ariz 



(Unknown) 



Cape St. Lucas.... 



(Unknown) 



Platte Valley 



Ft. Heading, Cal. 



"California" .. 



Mouterey , 



Ft Tejon, Cal, 

 "Rocky Mts.". 

 Average 



Sex 



d 

 J 



2 

 ? 



d 

 ' 

 ? 

 d 



From tip of Nose to Tail to end of 



$ 

 d 

 d 



d 

 V 

 ? 





0.90 



i "66 



0.85 



1.00 

 0.83 

 0.95 



90 



0.90 

 090 

 SO 



1.00 

 1.00 

 0.95 

 0.92 



m 



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 

 1.44 



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.S0 

 1.70 

 1.61 



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 

 4.06 



5.00 

 5.00 

 5.00 

 5.25 

 5 25 

 5.50 

 5.75 

 5 75 

 5.75 

 5.75 

 5.75 

 5 80 

 600 

 6.10 

 6.75 

 7 00 

 7.00 

 5.79 





6 00 



5 75 



6.25 



6 75 

 6.75 

 6.75 

 6.50 

 7.00 



7 00 

 7.75 

 7 75 

 S.00 

 6.85 



L'gth of 



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 



Nature of 

 Specimen. 



Ale. 



Fresh. 



Ale. 

 tt 



Fresh. 

 Ale. 



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 dimensions. The specimens range, by mi- 

 nute 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 1.35 to 1.70, settling at an average of 1.58. 

 It will be observed that the lengths of tail and feet bear no con- 

 stant ratio to each other, some specimens with relativeby smallest 

 feet having relative^ the longest tails. It will further be evident 

 that absolute lengths of tail and feet are not indicative of geo- 

 graphical limitations ; for the specimens which are arranged in 



