228 111^ J. LEWIS BONHOTE OX 



distingnished from the foregoing, as it is a larger and stouter 

 animal, more closely approaching Psmnmomys in general build. 

 In colour it is darker than M. crassus, the dark tips to the hairs 

 being longer and much more conspicuous, especially on the tail. 



The skull is more stoutly built and slightly longer, the extra 

 length being almost entirely due to the longer molar series. 



The teeth themselves, except in size, resemble those of 

 M. crassus. 



The most obvious skull-difference, however, is to be found in 

 the auditory bullae, which are much smaller and do not extend 

 beyond the back of the skull. 



The measurements of this specimen have been given under the 

 preceding species to facilitate comparison. 



The skull-measurements are as follows : — Greatest length 

 40 mm., basal length 35, greatest breadth 23 ; palatal length 19 ; 

 diastema 11 ; length of bullpe 15 ; length of molar series 6. 



PsAMMOMYS OBESUS Oretzschm. 



Psammomys obesus Cretzschmar, Riipp. Atlas, p. 58, pi. 22 

 (1828); deWint., Anders. ZooL Egypt, Mamm. p. 274 (1902); 

 Bonh. P. Z.S. 1909, p. 793. 



Three specimens of the typical form from Maryut, L. Egypt. 



MUS RATTUS TECTORUM Savi. 



Mus tectorum Savi, Nov. Giorn. Pisa., Feb. 1825. 



Mus rattus Linn. ; de Wint., Anders. Zool. Egypt, Mamm. p. 274 

 (1902) ; Bonh. P. Z. S. 1909, p. 793 ; id. ibid. 1910, pp. 638, 651. 



Mr, Nicoll shot an example of this form some distance up a 

 tree. I have been trying to obtain evidence as to which of the 

 two forms of Mtis rattus climbs trees or whether both do it. 

 This is the first definite evidence that tectorur)i is the climber, 

 although there is a certain amount of indirect evidence on that 

 point (see P. Z. S. 1910, p. 655). The question which requires 

 settling is, does M. r. alexandrinus usually climb trees? On this 

 point there is no evidence, direct or indirect. In confinement 

 both forms climb with equal facility. 



Mus MUSCULUS GENTiLis Branfcs. 



Mus gentilis Brants, Muizen, p. 126 (1827). 



Mus Diuscuhis Linn. ; de Wint., Anders. Zool. Egypt, Mamm. 

 p. 277 (1902); Bonh. P. Z. S. 1909, p. 794. 



Two examples of this race of House-mouse, in which the hairs 

 of the under parts are white to their bases, were brought back by 

 Ca.pt. Flower from Khartoum in the autumn of 1910. 



Mus MUSCULUS, albino var. 



Mr. Nicoll received from his correspondent Signor A. J. Balboni 



