202 INTRODUCTION TO CONCHOLOGY. 



inadequate to contend with either winds or waves ; he is 

 therefore commissioned to abide where neitlier can work 

 him woe. 



FAMILIES OF CEEYICOBEANCHS. 



Look on the wondrous structure of tliat organ 

 Through which the breath of life doth come and go. 

 How strange its form, and yet how fitly made ; — 

 A living channel, with most curious windings, 

 A water-course, yet borne upon the neck 

 Of such as range at will in deepest waters ! 



The CermcohrancUata are so called because the respira- 

 tory organs are situated at the back of the neck, in an ob- 

 lique line, either upon the surface or in a particular cavity. 



A variety of modifications are discovered in the breathing 

 apparatus of such mollusks as pertain to the present 

 order, and their shells are of a very anomalous character. 

 Those of the Siliquarice and Haliotides, for instance, differ 

 materially in their growth, notwithstanding the affinity of 

 their animal inhabitants ; but an analogy subsists between 

 these two genera, which could not have been anticipated 



