﻿356 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



series 3.43 (3.4-3.5) ; least interorbital width 4.6 (4.5-4.9) ; weight 

 19 (16-22). 



Remarks. — It seems hardly logical that this gerbil, in view of the 

 apparent plasticity of the genus, could be the same subspecies in the 

 Nile Valley and in Algeria. However, owing to the lack of compara- 

 tive material, it is felt best to place the above specimens in this 

 subspecies. 



GERBILLUS PYRAMIDUM PYRAMIDUM (E. Geoffrey St.-Hilaire) 



Dipus pyramidnm B. Geoffeoy St.-Hilaire, Catalogue des mammifferes du 

 Museum National d'Histoire Naturelle, p. 202, 1803 (near Pyramids of Giza, 

 Giza Province, Egypt). 



Specimens examined. — Twenty-three. Fayum Province: 1 mile 

 northeast of Kom Aushim, 4; Sennuris, 3 (MVZ) ; The Fayum, 2 

 (MVZ). Giza Province: Abassia Fever Hospital, Cairo, 2; 3 miles 

 northeast of Mount Abu Eauwash, 5 ; 1 mile northeast of Mount Abu 

 Rauwash, 3. Nubia : Abu Simbel. 1 (MVZ) ; Amanda, near El Derr, 

 3 (MVZ). 



Description. — Upper parts Pinkish-Cinnamon, purest on sides, 

 flanks, cheeks and muzzle; hairs of the dorsum plumbeous at base, 

 finely tipped with black, remainder of hairs of body white at base; 

 entire underparts, dorsal and ventral surfaces of fore and hind feet, 

 supraorbital and postauricular spots, lower half of cheeks and muzzle, 

 and posterior ventral half of tail, pure white; tail above, same pure 

 color as on sides, shading in the posterior one-fourth to a penicillate 

 black tip ; ears finely covered with hair, margins of pinnae blackish ; 

 narrow black ring around eye. Tail not quite so long as head and 

 body ; hind feet relatively short. 



Measurements. — Two males from 1 mile northeast of Abu Rauwash 

 and two females from 3 miles northeast of Mt. Abu Rauwash meas- 

 ured, respectively : Total length 232, 255 ; 229, 252 ; length of tail 128, 

 135 ; 129, 139 ; length of hind foot 34, 35 ; 33, 33 ; length of ear from 

 notch 15, 15; 15, 15; occipitonasal length 31.5, 33.0; 29.9, 32.1; length 

 of palate 14.5, 15.0; 13.8, 14.5; length of palatal foramina 5.9, 6.0; 

 6.3, 6.1; length of auditory bulla 9.0, 9.7; 9.1, 10.0; crown length of 

 upper molar series 4.3, 4.3 ; 4.2, 4.2 ; least interorbital width 6.6, 7.2 ; 

 6.5, 6.8 ; weight 37, 56 ; 32, 42. 



Remarks. — In the series of specimens available at this time are 

 TV hat appear to be two color phases. However, when these animals 

 are examined critically, these "phases" are seen to be juvenile and adult 

 pelages. The juvenile pelage is darker than that of the adult and 

 appears to be retained longer than in most species of rodents. With 

 respect to pelage these darker animals appear to fit the description 

 of Gerhillus pyramidum tardbuli., and it is possible that this subspecies 

 is based on immature specimens of G. p. pyramidum. However, until 



