"s* 
SACCOMYIDAIi—DIPODOMYIN 4i—DIPODOMYS. eT | 
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. 
3 aA From tip of nose to— ae end Length of— a 
=3 = E 
et e 
Ba ; a 
2 Locality. , é re 3 Be 
2 Bl Sean I St be | Ce itada | Bets 2 
(é) na!) A S a > g a ion] A 
4970 | Cape St: Lucas.......-..--..--.---es-e-ee--ee- oS | 0.90 | 1.45} 1.55 | 3.50 | 5.00 |......]...... 1.35 | Alcoholic. 
8436 | Fort Whipple, Ariz Cill| betes) eae 1.90 | 4.25 | 5.00 | 6.00 |...... 1.55 | Fresh. 
4871 | Cimarron, N. Mex........... 9 | 1.00 | 1.55 | 1.75 | 4.50 | 5.00 | 5.75 |...... 1.55 | Alcoholic. 
4970) | (Cape St. LCase: --< ..2 25.025. can ene ewes c acne 9 | 0.85 | 1.35 | 1.45 | 3.50 | 5.25 |......]...... 1.40 |....¢0. 
8437 | Fort Whipple, Ariz.....-...--.---..--.--- SSC lhye tll Becca| terse Seas 450) 5,20) 63250 lene ee 1.50 | Fresh. 
947) (WD RCL I epeoeooseeecd Ae SnOecr SL Gsecsriase | £2.00) 1) 15:40)! 1555) (74279) 5.100) | 2222 eee 1. 60 | Alcoholic. 
ACTON @aneiste NGAS = oc... cs<+cceewcecsonccnncncn -~ 9 102855) 3.40) | 2 50003.75. 15.75) 1//6..75) =... 1. 40 do. 
4970 | .-.-.. G0) SecA SSB esas tenes eSo0e ss saAeCSSEEESeae od | 0.95 | 1.50 | 1.60 | 3.75 | 5.75) 6.75 |...... 1.40 |....do 
4970 | --.--- AUS consoted sahsc ee sea a9 so pOb ED soeea ae od | 0.90 | 1.45 | 1.55 | 3.75} 5.75 | 6.75 |...... 1.45 |. ...do. 
7220 || (HUST ee bol Ee re ee ee eae 5.75 | 6.50 |....-- 1.60 |..2.do 
PIM PIatLo Valen. - seco ss ccc a~--sce2-~2 nee e= 2 | 0.90 | 1.40 | 1,60 | 4.50 | 5.75 | 7.00 }...... 1.50 do. 
aon ehonilteading Cal... a scence soaee se. = F | 0.90 | 1.35 | 1.55 | 3.35 | 5.60 |....-.]...... 1. 60 do 
26264 -..<.- 0) 3 c4e25 = boc! so AH Ben eSAC AREAS of |.0.80 | 1.25 | 1.40 | 3.25) 6.00 |......]...... 1.60 |....do 
eateeel |) SULG PUN Oy chr HS ee een eee ees see||ess¢cq| bscead esse 5.00 | 6.10 | 7.00 |...... 1. 60 do 
TAF B an || WUC) Gn eae oo SSeeeo oe ee Bao ae Ses eSeSaSseeS o | 1.00 | 1.60 | 1.75 | 5.09 | 6.75 | 7.75 |...... 1.70 do, 
7348 | Fort Tejon, Cal 9 | 1.00 | 1.60 | 1.80 | 4.25 | 7.00 | 7.75 |...... 1.70 do 
Sessea MR OOK VA Mts Vanes cones <2 cenccaecccccce-vces7 a] 9 ||0:95)|| 1..45\|' 4. 70)|'4:50,||'7.00.| 8.00 |.-2<--] 1.70 do 
J STRIGS s esecaooctoeconcenoeo OEE | Reese 0.92 | 1.44 | 1.61 | 4.06 | 5.79 | 6.85 |...... 1.58 
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 1.35 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 
