FANGS OF SERPENTS. 147 



is, by the intervention of a connecting bone, pressed 

 forwards whenever the jaw is opened sufficiently 

 wide ; and the fang is thus made to assume an 

 erect position. As these sharp teeth are very liable 

 to accidents, others are ready to supply their places 

 when wanted : for which purpose there are com- 

 monly provided two or three half-grown fangs, 

 which are connected only by soft parts with the 

 jaw, and are successively moved forwards into the 

 socket to replace those that were lost.* 



The tube through which the poison flows is 

 formed by the folding in of the edges of a deep lon- 

 gitudinal groove, extending along the greater part 

 of the tooth ; an interval being left between these 

 edges, both at the base and extremity of the fang, 

 by which means there remain apertures at both 

 ends for the passage of the fluid poison. This struc- 

 ture was discovered by Mr. T. Smith in the Coluber 

 naia, or Cobra de Capello ;t and is shown in Fig. 

 28.3, which represents the full grown tooth, where 

 the slight furrow, indicating the junction of the two 

 sides of the original groove, may be plainly seen ; 

 as also the two apertures (a and b) above mentioned. 

 This mode of formation of the tube is farther illus- 

 trated by Fig. 286, which shows a transverse 

 section of the same tooth, exhibiting the cavity (p) 

 which contains the pulp of the tooth, and which 

 surrounds that of the central tube in the form of a 

 crescent. Figures 287 and 288 are delineations of 

 the same tooth in difterent stages of growth ; the 

 bases of which, respectively, are shown in Figures 

 289 and 290. Figures 291 and 292 are magnified 



* Home, Lectures, &c. I. 333. 



t Philosopliical Transactions, 1818, p. 471. 



