NATURAL HISTORY OF THE MUSSEL 41 



the influences which affect the crops will be 

 taken up. 



[Those who desire a more detailed and scientific treatise 

 on the morphology or embryology of the mussel than can 

 be entered upon here, may be referred to the following : — 



Sabatier. Anatomie de la Moule Commune (Ann. des 



Sci. Nat., Vl^ Serie, 1877). 

 Lacaze - Duthiers. Organes Genitaux des Acephales 



Lamellibranches (Ann. des Sci. Nat, IV^ Serie, 



1854, t. ii.). 

 Wilson. On the Development of the Common Mussel 



(5th Ann. Rep. Fish. Board, Scot. 1887, App. F, 



p. 247). 

 Purdie. The Anatomy of the Common Mussels {Mytilus 



latiis^ edtilis^ and 7nagella?2iciis). Studies in Biology 



for New Zealand Students, Museum and Survey 



Department, Wellington, 1887.] 



The common mussel, along with the oyster, 

 cockle, clam, and other well-known bi-valve shell- 

 fishes, is included in the classification of the group 

 Mollusca, under the class Lamellibranchiata. 



The two shells (or what is more properly 

 described as a right- and left-valved shell, con- 

 nected by a ligament), the large gills, the absence 

 of any well-defined head, and the presence of a 

 bi-lobed mantle, are their distinguishing features. 



The shell is secreted by the outer surface of 

 the mantle. The 'foot' so well marked in the 

 cockle and scallop, and absent in the oyster, is 

 not of great size in the mussel, and has the 



