MOLLUSCA. 35 



Teacher. The variety exhibited in the works of 

 nature cannot fail to delight us, and the resem- 

 blances observable in them enable us to classify 

 and arrange them. 



There is still one point with respect to shells 

 which we have not considered ; I mean the situ- 

 ations which they occupy. Where are shells 

 found ? 



Child. Most of them in the sea, but some on 

 land, and others in ponds and rivers. 



Teacher. Those which live on land are 

 called terrestrial, from the Latin, terr a, earth. 

 These rnollusca feed on vegetables, and have 

 always four tentacula, and their eyes are placed 

 at the tips of these organs. The shells which 

 are found in fresh water, are called fluviatile, 

 from the Latin fluvi us, a river. Their rnollusca 

 have only two tentacula, which are flat, and have 

 eyes at the base. These shells are generally of 

 a corneous colour, and are semitransparent. 

 The shells inhabiting the sea are termed marine, 

 from the Latin, mar e, the sea. They are much 

 the most numerous, the most beautiful, and the 

 most highly prized. I will now recapitulate to 

 you the substance of the lesson to-day, and you 

 must write it on your slates.* 



Shells resemble the hard coverings of insects ; 

 the principal difference between them is, that 

 the former are only attached to the animal in 

 one or two places, while the hard case of insects 



* It would be desirable before the recapitulation that the teacher 

 should question the pupils upon the points that have been dis 

 cussed, as in a preceding lesson. 



