556 



RODENTIA 



three minute secondary cusps, one in front of tirst main cusp, the 

 others behind second ; surface of crown crossed by four complete 

 transverse ridges, the first, second and third extending from large 

 inner cusp respectively to small anterior cusp, to large anterior 

 cusp and to large posterior cusp, the fourth from small postei'o- 

 internal to small postero-external ; on outer half of crown 

 between the second and third complete cross-ridges occur two 

 incomplete ridges extending inward for a varying distance 

 from posterior base of anterior large cusp and anterior base of 

 posterior large cusp, the outer extremity of one or the other 

 sometimes forming a minute supplemental cusp ; in m^ the third 

 complete ridge is relatively smaller and second incomplete ridge 

 relatively larger than in the other teeth, the first incomplete 

 ridge obsolete or absent. Upper premolar essentially like 

 molars in arrangement of main cusps and ridges, but crown 

 slightly smaller than that of m^, and somewhat distorted by the 

 more central, anterior position of antero-external root, and ridges 

 tending to be incomplete, especially the two anterior ; secondary 

 ridges and cusps essentially absent ; milk tooth much smaller 

 than permanent premolar, its nearly triangular crown with area 

 barely half that of m^, its ridges less regular. The milk tooth 

 remains in place until m^ is fully grown. Lower cheek-teeth 

 much like upper, but with crowns slightly less concave than 

 those of maxillary teeth, and tending, especially that of r)/3, to 

 become basin-shaped, their cusps and ridges less sharply defined, 

 those of 7H3 often very irregular ; outer side of crown with three 

 low but well defined cusps, inner side irregularly crenulate in m.^ 

 and m^, with two rather low but well defined cusps in m^, the 

 posterior of which is decidedly the larger ; main cross ridges 

 four, the first and second tending to be distorted and incomplete ; 

 an incomplete intermediate ridge on inner side of crown between 

 second and third main ridges. Lower premolar triangular in 

 outline, its apex in front, its crown area about four-fifths that of 

 m^ ; a well developed cusp at each corner and an indistinct 

 transverse ridge across middle ; milk tooth smaller than 

 permanent tooth, but discrepancy in size less than in the 

 corresponding upper teeth ; crown of milk premolar essentially 

 like that of succeeding tooth, but with a small cusp at middle of 

 antero-external border, and transverse ridge absent. 



Measurements — Two adult females from Maredsous, Namur, 

 Belgium : head and body, 136 and 137 ; tail, 116 and 121 ; hind 

 foot, 28 and 29 ; ear from meatus, 24 and 24. Adult male from 

 I'Hospitalet, Ariege, France: head and body, 116; tail, 97"6; 

 hind foot, 25*4 ; ear from meatus, 25. Two adult females from 

 the same locality: head and body, 118 and 127; tail, 108 

 and 111 ; hind foot, 26 and 26'4; ear from meatus, 24 and 25. 

 Five adult males from Valescure, Var, France : head and body, 

 125(115-131); tail, 107 (100-111); hind foot, 26-3 (25-27); 

 ear from meatus, 23 "6 (22-25). Five adult females from Silos, 



