﻿MAMMALS FROM THE NILE DELTA REGION, EGYPT SETZER 361 



Measurements. — Averages and extremes of five males and two fe 

 males from Alexandria, Beliera Province, were, respectively: Total 

 length 398 (370-428), 415 (415) ; length of tail 195.4 (182-207), 196.5 

 (194^199) ; length of hind foot 42 (40-46), 40 (39-41) ; length of ear 

 from notch 19.6 (19-20), 19 (19) ; greatest length of skull 46.4 (44.5- 

 49.5), 27.2 (47.0-47.4); condylobasal length 41.1 (39.3-43.9), 41.8 

 (41.5-42.1) ; length of palate 22.3 (21.5-24.2), 22.2 (21.9-22.6) ; length 

 of palatal foramina 7.9 (7.4-8.4), 7.85 (7.7-8.0) ; alveolar length of 

 upper molar series 7.5 (7.4-7.6) , 7.4 (7.3-7.5) ; least interorbital width 

 6.6 (6.4-7.0), 7.0 (6.9-7.1); length of nasals 17.2 (15.8-19.3), 17.75 

 (17.5-18.0) ; greatest zygomatic width 22.7 (21.0-25.4), 22.85 (22.8- 

 22.9). 



Remarks. — As may be noted from the measurements, these rats show 

 a gi-eat amount of age variation. No effort was made to segregate 

 senile from subadiilt individuals for the purposes of measurement. 

 It is interesting to note that the averages of individuals from the four 

 areas represented are quite close to one another. There are no observa • 

 ble peculiarities in these introduced rats. 



RATTUS RATTUS (Linnaeus) 



Mus rattus Linnaeus, Systema naturae, ed. 10, p. 61, 1758 (Sweden). 



Specimens examined. — Thirty-four. Behera Province: Alexandria, 

 11. Daqahlia Province: 5 miles west of Simbillawein, 4. Giza 

 Province : Cairo, 11 ; Kafr Taharmes, 2 ; Talbia, 4. Suez Canal Zone : 

 Fayid, 2. 



Description. — Three basic color types of this species occur in the 

 Delta region. They are : (1) Blackish brown upper parts, with plum- 

 beous belly and hands and feet; (2) grizzled brown upper parts with 

 buff-tipped plumbeous-based hairs on the belly and brownish hands 

 and feet, the toes of both hands and feet whitish; (3) dorsal color as 

 in (2) but somewhat lighter, with underparts white, washed with 

 yellowish, the hands and feet whitisli. Tail longer than head and 

 body, but finely covered with hair; annulations pronounced; ears 

 large and rounded. Temporal ridges of skull more or less in the form 

 of a lyre, never parallel as in R. norvegicus; anterior upper molar 

 without accessory cusp. 



Measu.rements. — Averages and extremes of eight males and nine 

 females, all of the third color type, from several localities were, re- 

 spectively : Total length 412 (378-432), 406 (355-460) ; length of tail 

 227.5 (208-249), 224.2 (194-262) ; length of hind foot 36.5 (34-38), 

 35.6 (33-37) ; length of ear from notch 23.5 (21-25), 24.8 (24-26) ; 

 greatest length of skull 42.3 (40.6-44.3), 42.7 (39.6-46.6) ; condylobasal 

 length 36.9 (35.0-37.8), 36.7 (33.4-40.7) ; length of palate 19.6 (18.6- 



