Development of (he 7 Vc/// o/ ///e Soricida?. 615 



(>. There arc two dentitions in A'eomys fodiens, tlic milk and 

 permanent dentitions. The former is reduced and 

 f nnctionless. The milk-teeth arc probalily never dcve- 

 lojjcd, and disappear in all probal)ility before birth. As 

 in Sore.r, the possibility of a postpennanent dentition is 

 not exclnded. 



7. The results of the tooth-development in Neomys fodiens 

 may be thns expressed : — 



(P) r I' I' — P' r- 1" W W W 



Id' Id^ — Pd^ Pd^ Pd' 



Cd Pd, Pd, (Pds) Pd, 



I. la I. C P, P, P, P. M, ^r, M ,. 



The functional set of teeth consists of : — 

 I" V V P' P^ P ' W W W 



iv p, I', mtmtm;' 



Crocidura russula. 



The germs of the permanent dentition. 



As already mentioned, I liave examined five foetal speci- 

 mens. Though not varying mncli in size, they represent 

 three stages of development of the teeth — I., II., III. 



The ujiper jaw. 



In the specimens representing stages I.-II. the tooth-l)an(l 

 is continuous, but its anterior part, in front of I^, is highly 

 reduced. 



In the specimen representing stage HI. the anterior 

 part is about to be absorbed, which is also true of the buds 

 situated on the lingual side of several teeth. 



In the specimens examined I have found no definite trace 

 of reduced anterior incisors. In this respect Crocidura 

 differs from Sore.e (and Neoimjs). These tooth-rudiments 

 seem to have been totally suppressed in Crocidura. 



As to V, a layer of dentine has been formed. I^ is in the 

 bell-sliaped stage. The development of I'^ is retarded ; it is 

 in all three stages represented by a thickening of the 

 tooth-band. 



There is no trace of a canine. 



The two other functional teeth ought in all probability to 

 be regarded as P' and P'*. The tooth-germ of P^ is bud- 

 shaped in all the three stages, and consequently retarded in 



