592 



RODENTIA 



portion arising from under side of alveolus of incisor, its lower 

 border not angulated ; tibia and fibula joined ; cheek-teeth never 

 more than i;"?, rooted or rootless, the crowns tuberculate or 

 prismatic. 



BcmarJiS. — The cosmopolitan family Muridse is more abun- 

 dantly represented in genera, species and individuals than any 

 other similar group of mammals. About a dozen sub-families 

 are currently recognized, three of which occur in Europe. 



KEY TO THE EUROPEAN SUB-FAMILIES OF MURIDM. 



Molars prismatic, hypsodont or rootless, their crowns 



liat (Voles and Lemmings) Microtinx, p. 610. 



Molars tuberculate, brachyodont, rooted. 



Tubercles of maxillary molars arranged in two primary 



longitudinal series Cricetiniv, p, 592. 



Tubercles of maxillary molars arranged in three 



primary series Murinie,'p. 191. 



Sub-Family CRICETIN^. 

 1866. Cricetinge Murray, Geogr. Distrib. Mamm., p. 358. 



Geographical distribution. — Entire American Continent ; cen- 

 tral region of Asia from eastern China west into south-eastern 

 and centi-al Europe ; southern Africa. 



Characters. — As in the sub-family Murinse, but tubercles of 

 maxillary teeth arranged in two primary longitudinal rows. 



Bemarks. — The sub-family Cricetinse, though characteristically 

 American, is represented in the Old World by about six genera, 

 three of which occur in Europe. 



KEY TO THE EUROPEAN GENERA OF CBICETINM. 



General external and cranial characters essentially 

 murine ; fur with no special colour pattern (a 

 narrow dark dorsal stripe in some oriental 

 species) ; form of rostrum and brain-case about 



as in Apodemus (Dwarf Hamsters) Cricetulus, p. 593. 



General external and cranial characters not murine, 

 the body heavy and thick- set ; fur with specialized 

 colour-pattern of contrasted dark and light areas ; 

 rostrum broadened and brain-case narrowed, the 

 parietal bones reduced in size (True Hamsters). 

 Anteorbital foramen with well-developed forward- 

 projecting external plate ; flattened area on 



dorsal surface of brain-case approximately 



parallel-sided ; tail evident, longer than hind 



loot ; mammse 8 (Central Europe, west into 



Belgium and France) Cricekis, p. 596. 



Anteorbital foramen without forward-projecting 



external plate ; flattened area on dorsal surface 



of brain-case truncate diamond- shaped ; tail 



nearly concealed in the fur, shorter than hind 



foot ; mammse 16 (Eastern Europe, west into 



Roumania and Bulgaria) Mesocricetus, p. 605. 



