42 SHELLS AND SHELL-FISH. PART I. 



intervals between the existing races, and which,, were 

 they now living, would render all her groups equally 

 perfect. All analogy, drawn from theory or from facts, 

 compels us to embrace this latter conclusion. PERFEC- 

 TION in all His works is one of the attributes of the 

 Creator; it is therefore clear that nothing imperfect 

 could have entered into the plan of the creation. 



(36.) An attentive consideration of the vertebrated 

 classes of animals, both collectively and separately, will 

 convince the philosophic inquirer, that in every instance 

 nature begins, as it were, from a small rudimentary 

 group, a point, so to speak, in existence, which 

 seems to contain such animals as have the very least 

 affinity to those which, standing at the head, exhibit 

 the typical structure ; they possess only the rudiments 

 of the perfection to which they gradually, but ulti- 

 mately, lead; and their structure is often so exceed- 

 ingly simple, that, in such as may be termed the germ, 

 even these rudiments are scarcely perceptible. One such, 

 or at most two, are all we can expect to find. Hence 

 it follows, that such imperfectly formed beings, although 

 found in every large division of animals, must neces- 

 sarily possess a strong resemblance to each other ; al- 

 though, in reality, they belong to classes widely distinct, 

 when we trace them up to their full developement. 

 This theory, although in some respects not new, for it 

 has been tacitly or indirectly admitted in a general way, 

 has never received that attention it deserves. It has 

 consequently resulted, that nearly all those authors who 

 overlook the important differences between analogy and 

 affinity, have naturally supposed these rudimentary 

 animals, as they may be called, were closely connected 

 to each other by affinity, and have accordingly classed 

 them as such. This seems to be the true cause why we 

 have such a heterogeneous assemblage of animals under 

 Cuvier's class of Intestina, and even in those of Mac- 

 Leay's Acrita and Vermes. They agree, indeed, in one 

 respect, that is, of being the most simple of all others 

 in structure; but this is altogether more a negative 



