EVOTOMYS 



631 



lowev inolar with a narrowly crescentic, somewhat unsym- 

 metrical posterior transverse loop, three inner and three outer 

 closed or partly open triangles, and a short rounded anterior 

 loop ; outer side with three well defined salient angles and the 

 same number of re-entrant angles, inner side with four well 

 defined salient angles and four re-entrant angles ; the number 

 of salient angles on either or both sides may be increased by 

 one through the assumption of a distinctly angular form by the 

 base of the anterior loop, this occurring more frequently on the 

 outer than on the inner side. The folds are moderately angular, 

 those of inner side slightly the larger, but the contrast in size 

 and form is much less evident than in the upper teeth. Second 

 and third lower molars essentially alike in form, each consisting 

 of three transverse loops, three inner and three outer salient 

 angles, and two inner and two outer re-entrant angles, these last 

 better developed in ui.^ than in m.,, in which the anterior re-entrant 

 angle is sometimes obsolete. The first and second loops of m., 

 and the second loop of mg often show a tendency to become 

 partly or almost completely divided into two triangles, a 

 peculiarity more evident in the second tooth than in the third. 



Bemarks. — Evotomys glareolus is the common, widely-dis- 

 tributed European representative of the genus. It is divided 

 into nine geographical races. The forms inhabiting Great 

 Britain and the central portion of the Continent are small, 

 while those of western Norway, the Alps, Pyrenees and the 

 mountains of southern Italy are noticeably larger. There seems 

 little doubt, however, that intergradation between the small 

 and large forms takes place in every instance, though as yet it 

 can be satisfactorily demonstrated in the case of glareolus and 

 nageri only. 



