852 



RODENTIA 



Eliiiinj^ 



Fir;. 173. 

 (tllu.'<. C'licuk-tt 



the outer tubercle nearly as large as U, and only a little anterior 

 to it in position, both small tubercles well deiiued from Vl, the 

 re-entrant angles deep and without supplemental folds ; second 

 lamina essentially like first, not connected with it by longitudinal 

 ridges, <6 entire ; third lamina completely distinct from second, 

 /,9 well developed, about as large as /3, tl absent. Second upper 

 molar with first lamina represented by large t\ ; second and third 

 laminte essentially as in m^, the third with well developed <9 

 nearly as large as that of preceding tooth and marked off from 

 /8 by a distinct re-entrant angle. Third upper molar with large, 

 distinct, terete /I, small ti and <5, the 

 latter joined by an obsolete ^6 to outer 

 extremity of i(8, the only remnant of 

 the third lamina ; as the crown wears 

 away the second and third lamina^ 

 assume the form of a narrow loop, the 

 twu limbs of which are separated by a 

 deep re-entrant angle. Anterior lower 

 molar with crown scarcely as long as 

 tliose of the two succeeding teeth, its 

 area also less ; first lamina narrower 

 than second, its posterior border nearly 

 straight, its anterior border with deep 

 re-entrant angle on outer side of 

 middle ; second and third lamime essentially alike, more strongly 

 Curved ^posteriorly than anteriorly, the division into two tubercles 

 ill defined ; terminal heel small, compressed ; a small terete 

 tubercle usually present at outer edge of space between second and 

 third laminib, and a similar though smaller tubercle occasionally 

 present in that between lirst and second. Second lower molar 

 essentially like first without anterior lamina, the outer border with 

 small supplemental tubercle at anterior base of first lamina, and 

 another usually less well developed in space between lamina;. 

 Third lower molar with two laminse, the anterior of which shows a 

 faint indication of division into two tubercles, the posterior similar 

 to the posterior heel of the other teeth but considerably larger. 



lieniarks. — Though now so completely intermingled in many 

 localities that exact determination of specimens is often im- 

 possible, there seems no good reason to doubt that two geo- 

 graphical races of Epuiiys ratliia have established themselves in 

 western Europe. True raltiia, the blackish, slaty-bellied form, 

 is a northern animal, normally occurring in a climate similar 

 to that of central and northern Europe. The buff-bellied 

 form, Eplmijs rattus alexandrinm, is normally more southern in 

 its range, finding its optimum conditions, so far as Europe is 

 concerned, in the Mediterranean region."' Individuals of each 



" In the United States it appears never to become naturalized north of 

 the limits of the Lower Austral life zone, while E. rattus is or has been 

 locally common in the Transition and Canadian zones. 



