14 



HISTORY OF THE OYSTER. 



course be only observed by dissection. It will be 

 necessary to understand, however, in the first place, 

 what relations two of the organs bear to one another, 

 namely the bronchise and mouth. The latter is fur- 

 nished on each side with two lobes, called the labial 

 palpi (PI. II. c) : the former, in the process of respira- 

 tion, collects on its delicate surface numerous animal- 

 culse, upon which the animal feeds : these are col- 

 lected by the palpi, and transferred to the mouth. 

 These palpi also serve another purpose at the time of 

 reproduction. 



We will suppose the Oyster to be deprived of its 

 lower shell, as in Plate I. : we observe the adductor 

 muscle (a) severed, the ovaries (b b) extending over 

 the liver and stomach, and the upper lobe of the 

 mantle (c), all visible. Upon turning back the edge 

 of the mantle, we shall discover the four lobes of the 

 bronchiae (d), and below them, again, the lower folds 

 of the mantle Hning the opposite shell. On returning 

 two of the bronchial lobes back, so as again to cover 

 the lower fold of the mantle, we shall find, situated at 

 the end towards the hinge, between the four lobes, the 

 mouth, having a pair of somewhat ovate labial palpi 

 (PI. II. c), situated one on each side, and extending 

 downwards. We shall also observe, unless the ani- 

 mal is very full of spawn, some dark olive marks 

 appearing through the cuticle of the ovaries : these 

 are the stomach and liver. 



