326 Mr Forbes's Physical Notices (yf'the Bay of Naples. 



the gills. But as the type of the respiratory organs is both 

 lungs and gills, we must expect to meet, in some of those in 

 which the lungs only are developed, with elements more or less 

 remarkable, of the gills. Now such are the hyoid bones, which 

 are in truth the branchial arches. 



Part IV. — Theory of those organs whose functions have never 

 been explained, viz. the spleen, thymus, thyroid, and su^ 

 pra-renal capsules; they are supposed to be rudiments of 

 organs whose developement, so as to perform obvious and 

 perhaps important J'unctiojis, took place only in those ani- 

 mals whose fossil remains proclaim the vestiges of an an- 

 tediluvian world : they are supposed to be the rudimentary 

 organs of a former world. 



Speculating on the principles which have been laid down, 

 may we not explain the existence of certain mysterious organs 

 found in animals, such as the supra-renal capsules, thymus 

 gland, &c. which, as far as we know, have no function either 

 in the embryo or adult state, by supposing that they are the 

 undeveloped elements of the type of a peculiar structure which 

 existed in the animals of the antediluvian world ; for we may 

 infer from the peculiarities of the skeleton of those animals, 

 and more particularly of the Sauria, that there had been pecu- 

 liarities in the soft parts to fit them to live on the earth's sur- 

 face, which, in all probability, was different at that time from 

 what it is now. T. W. J. 



Art. XXII. — Physical Notices of the Bay of Naples. By 

 James D. Forbes, Esq. Communicated by the Author. 



No. VII. — On the Islands of Procida and Ischia. 



«' Turn Prochyta alta tremit durumque cubile 



Inarime, Jovis impcriis imposta Typhoeo " 



^n. ix. 



My last paper brought the reader to the Capo di Miseno, 

 which terminates the continuous stretch to the westward of 

 the shore of the Bay of Naples. It is, however, virtually pro- 

 longed by the two islands of which I propose now to give some 



