382 Proceedings of the 



terior part of the mouth. The inter-maxillary bone is principally in 

 relation with the organs of taste and smelling ; and, like most of the 

 cranium bones, its principal purpose is to furnish partitions and assist 

 in forming the cavities in which the organs of the senses are placed. 

 It is true that these bones also furnish sockets for the teeth, but that 

 is quite a secondary function. The teeth, stony and crystallizable sub- 

 stances, have a structure and system of formation which render them 

 wholly unconnected with the structure and form of the osseous tissue. 

 Deposited at first on the maxillary arcades, they do, it is true, hollow 

 out a socket for themselves there ; but this intercalation is wholly 

 determined by the accident of proximity, and is not produced by any 

 marked predilection for a particular bone. In those animals which 

 have long jaws, the teeth, not meeting with any obstacle to their 

 development, are regular in form and position all along the bone. 

 This could not be the case in man, because the extreme develop- 

 ment of the encephalos rendered a corresponding reduction in the 

 face necessary. As, however, the nerves and vessels which pass 

 through the jaws are not less numerous, and each of these bundles 

 must terminate in a tooth, it follows that the number of the dental 

 germs is not less considerable, but their arrangement is less regular. 

 In the parts nearest the origin, these bundles are formed into 

 groups of four, whence result the teeth with four fangs ; further on 

 they are only two and two, and the teeth have two fangs ; while it is 

 only towards the extremity that the germs are developed in an iso- 

 lated manner and produce single teeth. It is only in those mam- 

 miferee which have the cerebrum large and the face short, that we 

 find those teeth with several fangs, which must be considered as 

 being produced by dental germs, heaped, and, as it were, soldered 

 together. These explanations M. St. Hilaire considers as strongly 

 confirming his theory respecting the teeth of the mammiferse ron- 

 as above developed. 



Snail's Eggs. On the 15th of August, a letter was read from 

 M. Turpin, containing some particulars of the microscopic analysis 

 of the egg of the garden snail (Helix hortensis). When the exterior 

 of this egg is viewed through a strong magnifying glass, the shining 

 surface presents an infinity of white points, which appear, as it were, 

 drowned in the soft mucous and transparent envelope of the egg. 

 When an egg is crushed between two plates of glass, all the viscous 

 and albuminous liquid which it contains is scattered abroad, and the 

 torn membrane remains empty. If the whole be then viewed through 

 a microscope having a two-hundred times magnifying power, a pro- 

 digious quantity of very beautiful pointed white and translucid rhom- 

 boidal crystals, regularly formed in their angles and sides, are clearly 

 distinguished. These rhomboids are of unequal dimensions, the largest 

 being about 100th part of a millimetre (.0004 of an inch). Some are 

 single, and others grouped together by two, three, four, five, and six ; 

 all are fixed or glued against the interior surface of the envelope of 



