MOLLUSCA IN THE ANIMAL KINGDOM. 5 



and of their highest class to the fishes ; to the cirripedes and 

 other articulate animals, they present only superficial and illusive 

 resemblance. 



And further, we shall find that although it is customary to 

 speak of shell-fish as " less perfect" animals, yet they really 

 attain the perfection of their own type of structure ; indeed it 

 would seem to have been impossible to make any further advance, 

 physical, or psychical, except by adopting a widely different 

 plan from that on which the molluscous animals have been 

 constructed. 



The evidence afforded by geological researches at present 

 tends to shew that the four leading types of animal structure 

 have existed simultaneously from the very beginning of life 

 upon the globe ;* and though perpetually varying in the form 

 under which they were manifested, they have never since entirely 

 ceased to exist. 



By adding to the living population of the world, those forms 

 which peopled it in times long past, we may arrive at some dim 

 conception of the great scheme of the animal kingdom. And if 

 at present we see not the limits of the temple of nature, nor 

 fully comprehend its design, at least we can feel sure that there 

 is a boundary to this present order of things ; and that there has 

 been a plan, such as we, from our mental constitution, are able 

 to appreciate, and to study with ever-increasing admiration. 



* Mr E. Logan, Geological Surveyor of the Canadas, has discovered foot 

 prints of a tortoise, near Montreal, in the "Lingula Shale," or oldest fossi- 

 biferous rock at present known. 



