Development of the Teeth of the .Suricitluj. 



GOT 



No traces of P^ aiul P3 arc to be seen. 

 M, and Rio are not yet calcified. M3 is represented by a 

 large swcllin" of the tooth-band. 



Fit 



Fig. 4. 



Fiff. 6. 



Sorex araneus. — Foetus (13 mm.). Lower jaw. Transverse section 

 Fig. 4. I,. Fig. 5. I2. Fig..O. I3. X 220. The left side of the 

 figui'e represents the lingual, the right the labial side of the jaw. 



Young Sorex : body-length about 33 mm. 



The tooth-band is absorbed. Only a few cells in the 

 middle remain. The anterior rudimentary incisors, I,, I2, I3, 

 are represented by highly vestigial but distinct structures 

 (Pn XIX. figs. 1, 2). They are connected with the remains 

 of the tooth-baud by a few cells. 



As to the other teeth, what is said of the upper functional 

 ones is also true about them : the functional lower teeth — 

 I4, Pj, P4, Ml, M2, M3 — are all calcified, but none of them 

 has cut the gums. 



A vestige of the bud-like free deep end of the tooth-band 

 on the lingual side of I4 is distinguishable. 



TJie milk-teeth. 

 The presence of a milk-dentition has hitherto been a 



