568 MR. M. F. WOODWABD ON [Miiy 5, 



In the lower molar the protoeonid evidently develops first, but 

 it is closely followed by the metaconid, the entoconid, and the 

 hypocoriid, the reduced paraconid being, last, the order being 

 identical with that seen in Erinaceus. 



The relation of the milk and permanent dentitions may be thus 

 used : — 



fl 2 3 ( 1 r? 2 3 4 ri 2 3 



J 1 2 ffl . p J 1. p J 1 g 3 3 . -- ! 

 ■"Si 2 3' W' ""i 1 (i() B 4' 



b 



1^1 23 1^1 11 2 3 4 1^1 23 



SOEEX. 



The Shrews are generally regarded as possessing one dentition 

 only.but both Owen (18)andTrauber (25) stated definitely that there 

 was a minute calcified milk-dentition present, Owen ascribing to 



4 . . 



Crocidura -. milk-teeth, while Trauber states that in S. vuhjaris 



7 . . 6 . 



there are q and in Crossqpiis fodiens q deciduous teeth. Leche 



(9) believes that these authors mistook the calcifying cusps of the 

 replacing teeth for a set of minute milk-teeth — he himself coming 

 to the conclusion, from the material at his disposal, that only one 

 dentition is present in Sorex and Crossopus ; this he regards as 

 the successional set, the milk-dentition having been suppressed. 



My own observations are based on the examination of one stage 

 onl)', but it appears to be in a very interesting condition and show s 

 distinctly traces of two dentitions. 



The specimen measured 32 mm. long, the head length being 

 8 mm., while from the crown of the head to the posterior flexure 

 of the body it was 13 mm., being just 1 mm. shorter than Leche's 

 youngest stage. 



The Incisors. 

 y-j . — These in the adult are two enormous procumbent teeth, 

 and in my foetal specimen are much in advance of the other teeth. 

 The enamel-organs of these two teeth exhibit strong lingual growths 

 of the dental lamina (Plate XXV. fig. 15, d.l.), so large and 

 swollen, indeed, as to suggest the development of a successor ; but 

 such a condition could not possibly have been overlooked for it 

 would involve the replacement of a large tooth at a comparatively 

 late period, w-hereas the only suggested milk-teeth (Owen and 

 Trauber) are said to be minute. 



The 2nd upper incisor is backward in its development, but its 

 enamel-organ exhibits a marked labial growth (fig. 16, di.2 ) ; this 

 latter being swollen at its free end and slightly indented, evidently 

 represented the enamel-organ of a predecessor to i^ in a vestigial 

 condition. A similar but non-indented labial growth is found 

 related to i^ (fig. 17), this condition being repeated in connection 



