448 MR. O. THOMAS ON SMALL [Nov. 20, 



" This species is rare in Duval County, and I have not seen more 

 than one pair in one place ; they build very comfortable nests of grass 

 lined with feathers, cotton, or wool ; these nests are very firmly put 

 together, and look like those of some birds except that they have two 

 openings ; they are easily seen placed high on the top of some prickly 

 cactus, or on a branch of some smooth tree or bush, where skunks 

 and weasels seldom try to climb. I had a few of them in confine- 

 ment, but they did not breed. They are the most active animals I 

 ever saw — monkeys are slow compared with them ; they can jump 

 from the wires on one side of the cage, turning as they spring, and 

 catch on the other side again and again, as fast as one can count. 

 They vary greatly in colour, independently of season or locality, 

 being sometimes as bright as Cricetodipus fiavus and sometimes as 

 sombre as Mus musculus." — W. T. 



15. DipODOMYS AGiLis coMPACTUs, True \ 



a. Ad. al., $ . 



b. Skull and dried foot. 



Head and Forearm 



body. Tail. Hind foot, and hand. Ear. 



a 98 122 33= 27 lO-l 



Mammas 1 — 2 = 6. 



Skull — Basal length 26 millim ; greatest length from tip of nasals 

 to back of bullae 36"4 ; greatest breadth (across bullae) 22-1 ; nasals, 

 length 13"5; interorbital breadth 13; interparietal, length S'O, 

 breadth 2-6 ; greatest diameter (obhque) of bullae 14-4 ; palate, 

 length 16 ; diastema 8 "5. 



These specimens a[)pear to represent a race of D. agilis so decidedly 

 smaller than the typical form as to merit subspecific distinction, 

 especially as the reduction in size is correlated with a decided differ- 

 ence in the relative development of the bullae. 



As to the difference in size, Mr. True ^ has given a table of the 

 measurements of ail the alcoholic specimens of Dipodomys preserved 

 in the United States National Museum. In this table only one of 

 the eleven five-toed specimens has a hind foot measuring less than 

 39 millim., and this one, No. 2621, comes from Coahuila, Mexico, 

 and therefore probably belongs to the present subspecies. All the 

 other specimens have hind feet ranging from 39 to 45 millim. in 

 length, including the claws. 



^ The above account was in tj'pe when I received Jlr. F. W. True's " De- 

 scription of Dipodomys comjMctus, a new species of Rodent from Padre Island, 

 Texas " (P. U. S. Nat. Mus. si. p. 169, 1888). The form described by Mr. True 

 and that obtained by Mr. Taylor are, no doubt, the same, although no mention 

 of the skull -characters is made by the former. 



^ With claw, 35. The dried foot of specimen h measures 31 millim. without 

 and 33 with its longest claw. 



^ P. U. S. Nat. Mus. ix. p. 411 (1886). In this admirable paper the distinction 

 in the number of toes between D. phillipsi and I), agilis is first pointed out, and 

 useful series of measurements and localities are given for both forms. 



