182 



U.S. NATIONAL MUSEUM BULLETIN 2 75 



Figure 40. — Distribution of the subspecies of Meriones libycus. 



The other two specimens representing Meriones robustus are much 

 darker and markedly larger in all external characters. 



Compared to Meriones caudatus, Meriones libycus differs in having 

 a markedly shorter tail with a less conspicuous pencil of brown rather 

 than black, smaller and less inflated auditory bullae, and suprameatal 

 triangles which are usually more nearly round in shape, rather than 

 elliptical, and imperfectly enclosed rather than completely enclosed 

 by enveloping processes of the supraoccipital and temporal bones. 



Remarks. Thomas (1902) referred specimens from various localities 

 of coastal Libya to Meriones shawi. More recently, Toschi (1954) and 

 Setzer (1957) also considered specimens from coastal Cyrenaica and 

 Tripolitania as subspecies of M. shavri. Setzer had no specimens of 

 shawi for comparison, and the above assignments were based largely 

 on the similarities of measurements between the Libyan specimens 

 and those of typical M. sham. I have examined those specimens 

 available to Setzer and additional series from other coastal localities 

 in Libya and find them all referable to M. libycus of Egypt. These 

 Libyan populations differ slightly from typical M. libycus from the 

 vicinity of the Nile and western coastal Egypt, but these differences 



