SCIUKOPTERUS 



945 



cut l)y a deep posU'rior re -entrant fold, so tliat its inner 

 extremity stands as a nearly free subterete cusp; inner cusp 

 relatively higher, obscurely trilobed owing to the presence on 

 palatal border of two well marked depressions extending from 

 apex nearly to base of crown (these become obsolete as the tooth 

 wears away) ; in nt^, m? and m^, a short process extends outward 

 from base of inner cusp into space between tirst and second 

 transverse ridges, while in pm:^, ni^ 

 and )ir a similar but less developed 

 process lies in space between second 

 and third ridges ; third and fourth 

 ridges of ni-^ smaller than in the 

 other teeth, but well developed, so 

 that there is no indication of a pos- 

 terior basin-shaped area on surface of 

 crown. Mandibular teeth like those 

 of Sciurus vulgaris in relative sizes 

 and in general form except that j/;., 

 is longer and more narrowed pos- 

 teriorly. The pattern of enamel 

 folding, while essentially like that of 

 S. vulgaris in its main features, is 

 more complicated, owing to the greater development of all the 

 smaller cusps and folds ; main cusps relatively higher and more 

 slender, their bases extending further inward toward middle of 

 crown, this together with the greater development of cusp and 

 ridge coiniecting inner portion of bases of outer main cusps 

 greatly reducing area of median crushing surface, which is 

 scarcely basin-shaped and which occupies less than half area of 

 crown ; antero-external ridge well developed in the three molars, 

 terminating in a distinct cusp-like elevation at middle of anterior 

 border of crown ; a deep depression at anterior base of postero- 

 external cusp ; a similar but larger depression behind base of 

 postero-internal cusp of m.^, the cingulum rising back of it so 

 as almost to form a supplemental cusp. 



3Ieasiiremeuts. — Adult male from Finland : head and body, 

 170; tail, 109; hind foot, 35; ear, 19. A second adult from 

 the same region : tail, 128 ; hind foot, 37. For cranial measure- 

 ments see Table, p. 940. 



Specimens examined. — Two from Finland (B.M. and U.S.N.M.) ; also 

 one from Russia, and a stuffed specimen from unknown locality. 



Sci'uropterus russicus. 

 Cheek-teeth, x 5. 



1. Finland. 

 1. Russia. 

 1 st. Europe. 



Dr. H. Schulman (p). 

 Purchased (Parzudaki). 

 Purchased (Brandt). 



1. 6. <J. 1. 

 53. 12. 6. 29. 

 42. 5. 16. 11. 



3 p 



