:mouth of the whale. 1.3J) 



them closes over, and after a short time can no 

 longer be seen. For the discovery of this 

 curious fact we are indebted to Geoftroy St. 

 Hilaire.* In connexion with this subject, an 

 analogous fact which has been noticed in the 

 parrot may here be mentioned. The young of 

 the parrot, while still in the egg, presents a row 

 of tubercles along the edge of the jaw, in ex- 

 ternal appearance exactly resembling the rudi- 

 ments of teeth, but without being implanted 

 into regular sockets in the maxillary bones : 

 they are formed, however, by a process precisely 

 similar to that of dentition ; that is, by depo- 

 sition from a vascular pulp, connected with the 

 jaw. These tubercles are afterwards consoli- 

 dated into one piece in each jaw, forming by 

 their union the beak of the parrot, in a manner 

 perfectly, analogous to that which leads to the 

 construction of the compound tooth of the ele- 

 phant, and which I shall presently describe. 

 The original indentations are obliterated as the 

 beak advances in growth ; but they are per- 

 manent in the bill of the duck, where the 

 structure is very similar to that above described 

 in the embryo of the parrot. 



* Cuvier, Ossemens Fossilcs, 3iue edition, torn. v. p. 3(i0. 



