I,t 



THE ANXAI.S 



ANp 



MAGAZINE OF NATURAL HISTORY. 



[EIGHTH SERIES.] 

 No. 54. JUNE 1912. 



LXVr. — On the Develojjment of the Teeth of the Soriciclse : 

 an Ontogenetical Inquiry. By Dr. Augusta Arnback- 

 CiiuisTiE-LixDE (Zootomical Institute, University oE 

 Stockholm) ^. 



[Plates XVHI. & XIX.] 



When examining the teeth of the shrews, one is struck with 

 the enormous developiuent of the anterior incisors in both 

 jaws and with the reduced number of the antemolar teeth, 

 especially iu the lower jaw. One cannot help combining 

 these two facts, the comparative anatomy offering plenty of 

 instances showing that the enlargement of a tooth involv^es 

 the reduction or even the disappearance of neighbouring 

 teeth. The question then arises, how many and which teeth 

 have been suppressed, and, further, how the small antemolar 

 teeth are to be homologized. 



Another question which has not hitherto been definitely 

 decided is whether the shrews have a milk-dentition or not. 

 Some authors are of opinion tliat these animals have no 

 milk-dentition, but others pretend to have found calcified 

 mill^-teeth. 



Through an ontogenetical investigation I hoped to find an 



* This article is a resume of my paper " Der Bau der Soricidep ]imd 

 ihre Beziehimgen zu andern Saugetieren : Part II.," now publishing in 

 Morphol. Jahrbuch, Bd. xliv, 



Ann. (& Mag. N. Hist. Ser. 8. Vol. ix. -^U 



