48 ORAL EQUIPMENTS. 



mouth the tooth is forced forwards by the drawing of certain 

 ligaments on the maxillary bones which move with the teeth. 

 This brings the poison tube in the tooth in a line with the 

 canal in the poison-gland ; whence issues the venom directly 

 the tooth is erected to strike, propelled by the pressure of a 

 ligament which tightens over the gland by the movement of 

 erection of the tooth. 



The victim is then swallowed whole, the " quadrate- 

 bone " allowing the snake to open the mouth to an enormous 

 extent; and the "bucket-handle" movement of the joints 

 gives the creature power to, as it were, draw itself over, or 

 " get outside " its food. 



The structure here briefly referred to is well worthy of 

 the careful study of my hearers, to whom I strongly com- 

 mend it. 



Before bidding good-bye to these interesting creatures I 

 must mention a further beautiful provision of nature in the 

 viperine Dental armature. 



At the side of each poison-fang is developed a second or 

 supplemental tooth. If the fang in use gets broken off 

 another immediately springs up beside it so as to take its 

 place. 



SECTION II.— MAMMALIA. 



In the first portion of this paper, which I had the honour 

 of reading before you some months ago, I commenced by 

 explaining as an introduction to my subject the relationship 

 that teeth in man bear to one another, and the various parts 

 of a tooth to each other and to their surrounding tissues, the 

 jaws and gums ; I then followed by a short reference to the 

 attachment of the teeth to the jaws, and their methods of 

 growth and development in all vertebrate creatures; and 

 concluded by describing the oral equipments of a few speci- 

 mens of cold-blooded vertebrates, specially differentiated to 

 meet definite requirements : culminating in that most highly 

 specialized structure the poison fang of a typical venomous or 

 viperine snake. 



For the better understanding of the subject for this 

 evening by those who were not present on that occasion, or 

 others who may not quite have grasped the details, I will 

 very briefly refer to some of the introductory matter. We 

 saw that the teeth of man consist of two sets. The deciduous 

 or milk teeth, twenty in number, which are lost in childhood 

 to give place to another set, better developed, larger and 



