Development of the Teeth of the Soricidio. 605 



Fiflus : hodij-lenyth aJ>out 13 mm. 



The tootli-band has not completely lost its connection with 

 the buccal cpithelinm ; also in this specimen it is continuous, 

 but its anterior part is here somewhat reduced. 



The tooth-rudiments of 1' and P are distinctly differen- 

 tiated, but show obvious traces of reduction. As regards P, 

 a thin layer of dentine is formed. Here, too, the free (lee[) 

 end of the tooth-l)and forms a bud on the lingual side. 1* is 

 bell-shaped and 1' cup-shaped. 



The germ of C is not distinguishable at this stage. 



As to the degree of development, the premolars differ but 

 little from those of the above stage. Only P" is a little more 

 differentiated, though still retai'ded in its development as 

 compared with the other premolars. 



On the lingual side ot P' the free deep end of tbe tooth- 

 band is swollen like a bud. 



The molars are all differentiated : M' and M-' are bell- 

 shaped and ^P is represented by a bud. 



VouHf/ Sovt'x : body-length about 33 m)ii. 



Unfortunately I could not pursue this investigation on 

 fcetal specimens. The next stage which I have examined is 

 therefore that of a young Soi'ex, blind and almost hairless. 



The tooth-band is totally absorbed. No traces of the 

 rudimentary teeth I^, P, and C are to be seen. 



Of the permanent dentition all the functional teeth are 

 developed, i. e. three incisors — tlie morphological 1^, I', I', — 

 the four premolars, and the three molars. They are all 

 calcified, but none of them, not even the enormous P, has 

 cut the gums. . 



2Vie lower jaw. 



Feet as : body-length about 11 mm. 



The tooth-band forujs a continuous curve, as in the upper 

 jaw, i. e. the two halves are connected in the middle. 



In front of the enamel-organs of the large functional 

 incisors the tootli-band is swollen, to give rise most probably to 

 three rudimentary^ tooth-germs — Ij, lo, I3. These rudiments, 

 being more differentiated in the older foetal specimen, are 

 described below. 



The enamel-organ of the morphological I4 — i. e. the func- 

 tional first incisor — is bell-shaped and much in advance of 

 the other teeth. On the lingual side of this tooth the free 



