537 



KEY TO THE EUROPEAN SPECIES OP SICISTA. 



Least depth of rostrum behind incisors about equal to 

 breadth of rostrum in same region ; crown area of »i' 

 about four times that of premolar ; sides distinctly 

 more yellow than back, with rather noticeable 

 line of demarcation (Roumania) S. lorigcr, p. 537. 



Least depth of rostrum behind incisors decidedly greater 

 than breadth of rostrum in same region ; crown 

 area of «t' about three times that of premolar ; sides 

 essentially concolor with back (Hungary, Denmark, 

 south-eastern Norway) S. iri^onrz, p. 539. 



SICISTA LORIGER Nathusius. 



18-40. Sminihus lorigcr Nathusius in Nordmann, Demidoff's Voyage dans 



la Russie M6ridionale, iii, p. 49 (Odessa). 

 1840. Sminthus nordmanni Keyserling and Blasius, Wirbelth. Europas., 



p. 38 (Crimea). 



Type Jocalifi/. — Odessa, Russia. 



Geographical distrihution. — South-western Russia, eastern 

 Roumania, Bulgaria ; limits o£ range not known. 



Diagnosis. — Least depth of rostrum behind incisors about 

 equal to width of rostrum in same region ; crown area of m^ 

 at least four times that of premolar ; sides distinctly more yellow 

 than back, with rather well-defined line of demarcation. 



External characters. — General appearance essentially as in 

 Mus musculus, but size less (about as in 3Tus spicilegus), and body 

 more slender ; tail slightly longer than head and body, obscurely 

 four-sided, the fine hairs not concealing annulations (of which 

 there are about twenty to the centimeter at middle of tail) and 

 not forming any decided pencil at tip ; ear moderately large, 

 extending a little beyond eye when laid forward, its outline 

 simple, ovate, its posterior border with lai'ge thickened lobe at 

 base, capable of completely closing the meatus, its anterior 

 border with minute though evident sub-basal notch and projec- 

 tion ; both surfaces of ear densely clothed with sliort hairs ; 

 basal lobe conspicuously tufted ; anterior border of no.stril 

 thickened, a small wart beneath it ; space between nostrils 

 narrow, crossed by a well developed vertical ridge ; upi:)er lip not 

 grooved in front ; feet more slender than in Mus musculus and 

 its allies, the fingers and toes longer relatively to palm and sole ; 

 front foot with thumb reduced to a mere tubercle to support the 

 short but evident blunt nail ; third digit longest, fourth slightly 

 shorter, second extending to middle of third, fifth just beyond 

 middle of fourth, j^ads as in Mus musculus ; hind foot with 

 relative lengths of digits as in Mus musrulus, the second, third 

 and fourth sub-equal and longest, fifth extending nearly to 

 middle of fourth, first not quite to base of second ; claws 

 essentially like those of front feet : sole naked, the pads 

 arranged as in Mus musculus ; postero-internal tubercle extended 



