CHAPTER XIV. 



OF THE MOLLUSCA IN GENERAL. 



862. QUITTING now the Articulated series, which we have 

 seen to terminate in very simple forms of structure, that lead us 

 towards the Zoophytes, we return to a higher point in the 

 Animal scale, to descend in like manner through the Molluscous 

 series. Looking only at the general complexity of structure 

 exhibited by these groups of Animals respectively, we might have 

 some difficulty in deciding which should rank the highest ; since 

 in the Articulata we observe one set of organs far more highly 

 organised than in any of the Mollusca ; whilst the converse holds 

 good as to another set of organs in the Mollusca. But when we 

 look at the respective characters of these organs, we cannot 

 reasonably hesitate longer. It is the organs of animal life that 

 are so highly developed in the ARTICULATA ; whilst it is in the 

 development of the organs of nutritive or vegetative life only, that 

 they are surpassed by the MOLLUSCA. In the Animal scale, 

 therefore, we may justly regard the Articulata as ranking on the 

 whole above the Mollusca. To the consideration of the latter 

 group we shall now proceed. 



863. The range of animal forms comprehended in the sub- 

 kingdom MOLLUSCA is so great, that it would be difficult to 

 include them by any character common to all. We encounter 

 but few traces of the circular disposition of organs around the 

 mouth, which is characteristic of the .Radiated tribes ; and we 

 seldom meet with any thing that even approaches to the elon- 

 gation of the body, still less to the division into segments, which 

 has been noticed among the Articulata. This will be compre- 

 hended, when it is borne in mind that the body of the Mollusca 

 is almost entirely occupied by the organs of nutrition ; and that 

 the organs of sensation and locomotion are entirely subservient to 



