616 Dr. A. Arnback-Christie-Linde on the 



its development. How highly P' is iu advance of P^ in size 

 is shown by the reconstruction figure (PI. XVIII. fig. 3). 



In the youngest specimens there is between P^ and P* a 

 thickening of the tooth-band, no doubt representing P% 

 which, as a rule, is suppressed in the adult animal, but in 

 rare cases is developed ■^. 



As to the notation of the premolars, I refer to what is 

 said above about the notation of the corresponding teeth in 

 Neomys. 



In stage III. M^ is about to be calcified ; M- and AP are 

 bell-shaped. 



The lower jaw. 



The tooth-band is divided into two halves not connected 

 in the middle. The tooth-band between the teeth, though 

 reduced, is distinguishable. 



There is no definite trace of a suppressed lo or I3, but I 

 have observed that in front of I4 — the large procumljent 

 incisor — the buccal epithelium forms two not very deep 

 rather broad ingrowths in front of the germ of the last- 

 mentioned tooth. How these ingrowths are to be inter- 

 preted, whether they are remains of the tooth-band or not, 

 may be an open question. By the examination of younger 

 foetal specimens this point may possibly be decided. 



The large functional incisor, being in all probability 

 homologous with the corresponding large teeth in Sorex 

 and Neomys, is flesignated in the same way as these, i. e. I4. 

 This tooth is about to calcify. The free deep end of the 

 tooth-band is swollen on the lingual side. 



I have found no trace of a canine. Pi and P4 are in the 

 bell shaped stage, and on the lingual side of these two teeth 

 the free deep end of the tooth-band is swollen. 



In stage I. a rudiment of Po, still more vestigial than 

 in Sorex diwdi Neomys, is distinguishable; in stages II. and 

 III. it is already absorbed. 



Of P3 no trace can be seen. 



The lower molars have reached the same degree of develop- 

 ment a3 the upper ones, i. e. in IMj the calcification has 

 begun ; ]\l2 and ^[3 have the bcU-shaped form. 



It should be especially pointed out that there is a gap 

 between the lower P4 and Mj and that the tooth-band shows 

 3, distinct sAvelling between these teeth, suggesting the 

 possible presence of the last trace of a suppressed tooth. 



* Dobson, G. E., ' A Monog-raph of the Insectivora, Svstoiuatie auJ 

 Anatomical,' part iii. fasc. 1 (London, 1S90). 



