4'14 DR KNOX on the Dentition of the Dugong, and on the 



following are the few brief remarks I have been able to make re- 

 garding it. 



In accordance with the language of all or most anatomists, I 

 shall speak of this species of the Cetaceaas having four stomachs, 

 this being the usual language held with reference to the sto- 

 machs termed complex. My own opinion, as explained more 

 fully in a memoir I had the honour to submit to the Royal So- 

 ciety of Edinburgh, on the Structure of the Stomach of the La- 

 ma, is, that no animal possesses more than one stomach, divided 

 more or less by compartments, and thus assuming the appear- 

 ance of one or more cavities, which anatomists have unhappily 

 spoken of as being one or more stomachs. Now, in accordance 

 with this language, which, however inaccurate, demands respect 

 from its universality, I shall speak of the second cavity in the 

 stomach of the porpoise as being the second stomach. 



The gullet of the porpoise, composed of the usual membranes 

 or tunics common to it with other Mammalia, terminates in a 

 somewhat elongated, tolerably capacious pyramidal-shaped bag, 

 known by the name of the first stomach. In this we find, ex- 

 ternally, and immediately invested by the peritoneal tunic, a 

 strong coat of muscular fibres, spread uniformly over the sur- 

 face, continuous upwards with the muscular layers of the gullet, 

 and downwards with those which, in a similar fashion, envelope 

 the second stomach, occupying the same situation relatively to 

 the peritoneal tunic in it as in the first. This muscular tunic 

 of the first stomach is composed of two layers, separated from 

 each other by a layer of cellular membrane ; the fibres are chief- 

 ly longitudinal and circular. Within these there is the usual 

 vasculo-cellular layer, and it has within it a mucous membrane, 

 covered by a strong epidermic covering. By maceration a double 

 epidermic covering may be separated from the mucous surface of 

 the gullet, but one only seems to invest the first stomach. 



