214 MISS DOROTHEA BATE ON A NEW GENUS 



longitiulinal sections the enamel rods (or fibres, as Sir John 

 'J'omes designates them in his classical memoir) leave the surface 

 of the dentine with a slight curve and then proceed outwards, 

 slightly flexuous, at an angle of about 70° with the dentinal sur- 

 face for about half the thickness of the enamel, where they bend 

 sharply and abruptly to proceed in a straight course to the 

 svu'face. 



" There is appearance of serrations of the margins such as is 

 usually seen in the Dormice. 



" Thus the course of the rods is as in Myoxidse, whilst their 

 form is as in Sciuridse, 



"In transveise section altei'iiate groups of rods cross one 

 another at an angle of about 120°, and when half-way through 

 turn sharply outwards and run paiullel out to the enamel surface 

 Avhich they i-each at right angles, the pattern assumed resembling, 

 though not identical with, that seen in a transvei'se section of the 

 incisor of Eliomys." 



While the palate is almost uniform in width, the rows of cheek- 

 teeth appear curved owing to their inner borders being practically 

 in a straight line, so that all the differences in the sizes of the 

 teeth, especially that of the premolar, alfect only the outer 

 border of the rows, which thus have a curved outline. The plane 

 of wear of the premolar is almost horizontal, while that of the 

 molars lies at a considerable angle, the inner border being the 

 higher ; this character will be refeired to again later. (Some 

 scarcely worn upper molars are slightly concave and their enamel 

 ridges incline towards being cuspidate, but in most of the specimens 

 obtained the worn surfaces of the crowns are nearly flat. The 

 molariform uppei- premolar is bluntly triangular in outline and 

 the molars snbquadrate in shape, the second being very little 

 larger and the third not much smaller than the first. In the 

 above characters these teeth somewhat resemble those of Leithia, 

 those of Eliomys differing markedly in the concavity and greater 

 comparative width of their crowns. 



In the Balearic molars the ridges are low, and in those of aged 

 individuals, of which a number were obtained, these become 

 almost entirely woi^n away. In little-worn specimens (PL I. 

 fig. 1) it can be seen that in each of the upper cheek-teeth the 

 crown is crossed by four complete and one incomplete transverse 

 ridges, with the addition of one or moi-e further incomplete 

 ridges in the second and third molars. The second complete 

 ridge in the first and second molars runs from the inner border 

 in an anterior direction for more than half its distance before 

 turning to reach the outer margin. The two posterior complete 

 ridges run more or less parallel with the hinder border of the 

 teeth, and it is in the space left between the complete ridges that 

 the incomplete ones occur. The inner edge of the crown surface 

 almost invariably remains unbroken, while the outer border is cut 

 by the valleys between the ridges. In much worn teeth there 

 is found a confluent valley alongside the inner enamel border of 



