Dipodomys phillipsi Gray. 95 



cheek pouches must have been overlooked, especially as we are 

 particularly informed that the specimen was in very defective 

 condition as preserved in alcohol. The species was probably 

 identical with that described by Gray, viz : D. phillipii, which 

 appears to be the one common in Mexico." * It should be borne 

 in mind, however, that at the time Baird wrote (in 1857) all of 

 the kangaroo rats were referred to Dipodomys, the genus Perodipus 

 (containing the 5-toed species) not having been established until 

 ten years later, f That Wagner's animal could not have been a 

 Perodipus is clear from the statement that it had only 4 toes on 

 the hind foot, and by other details of the original description. 

 On the other hand, that it was a true 4-toed Dipodomys is shown by 

 Wagner's original description, which includes a detailed account, 

 with measurements of the skull and skeleton ; J by his drawing 

 of the skeleton (natural size), published a little later, and by his 

 drawings of the teeth, contained in the supplement to Schreber's 

 Saugthiere (tab. 239, E.). 



The genus being disposed of, the species now conies up for 

 determination. The fact that Baird referred it to D. phillipsi of 

 Gray, in which he was followed by Coues, is of no weight, since 

 both of these authors included under this head not only several 

 very distinct species 3 but also species belonging to both genera. 

 Nothing is known of the source of the specimen save that it came 

 from Mexico. Three species of the genus are now known to 

 inhabit Mexico, namely, D. phillipsi, D. spectabiUs, and D. mer- 

 riami. D. spectabiUs may be at once eliminated because of its 

 much larger size, leaving only D. phillipsi and D. merriami be- 

 tween which to choose. Wagner's measurements of the skull 

 and skeleton give a total length of 269 mm. and a length of tail 

 vertebra) of 168. His external measurements of the body and 

 tail added together make a total of 279 mm., an excess of 10 mm. 

 over the length of the skeleton, as usual when the bod}^ and 

 tail are measured separately, the length of the body overlapping 

 the point from which the tail measurement begins. Allowing 



* Baird, Mammals of North America, 1857, 409. 



fFitzinger, Sitzimgsber. math.-nat. classe, K. Akad. Wiss. A\ 7 ien, i,vi, 

 1867, 126. 



J Macmcolus halticus A. Wagner, Wiegmaim's Archiv. fur Naturgesch- 

 ichte, 1846, 172-177. 



\ Beitrage zur Kenntniss der Siiugethiere Amerikas, II Abth., 1848, 319 

 und 332, pi. vn (Abhandl. d. II, Cl. d. k. Ak. Wiss V, Bd. II). 



