114 G. ST. HILAIRE ON THE F A 1 1 A K A OF THE NILE, 



ON THE STOMACH AND SWIM BLADDER OF THE FAHAKA 

 OF THE NILE. (Tetrodon Physa). 



BY M.G. ST. HILAIRE, PROFESSOR OF ZOOLOGY, AT THE JARDINS DES PLANTES, 



PARIS. 



Figure of the Fahaka. 



I only know two naturalists, the celebrated Bloch and Count 

 Lacepede, who have treated of the pouch in the fahaka. Bloch has 

 shown that it communicates with the cavity of the gills j and my 

 illustrious colleague (Lacepede) has seen that it is formed by a 

 membrane situated between the intestines and the peritoneum. 



The latter observation having been made from the inspection of a 

 dry and ill-preserved specimen, is of course very incomplete 5 but 

 having had the opportunity of examining as many fahakas as I 

 pleased, I am able to complete the description. 



I have opened a great number of these fishes, and have ascer- 

 tained that it is the stomach which, without losing its ordinary 

 functions, serves also the purpose of an air bag, {reservoir atrien). 



This organ, generally occupying but a small space, escapes, if I 

 may use the term in this case, from the cavity in which it is con- 

 tained, and swells out to a size larger than that of the 'animal itself. 

 This is so singular that our first impression is, that it does not de- 

 serve belief. But if we consider that nature never operates by new 

 creations, but simply by modifications of things already existing 

 and that, of all the combinations to produce this pouch, the most 



* Translated by Jacob Dixon, Esq. from " Description cCEgypte, Partie Zoolo- 

 gique," published by the French Government. 



