PRINCIPAL SYSTEMS OF ZOOLOGY 



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five of smaller: these latter being termed osculant, and being intermediate be- 

 tween the former, which they serve to connect; 4. That there is a tendency in 

 such groups as are placed at the opposite points of a circle of affinity "to meet 

 each other;" 5. That one of the five larger groups into which every natural 

 circle is divided, "bears a resemblance to all the rest, or, more strictly speaking, 

 consists of types which represent those of each of the four other groups, to- 

 gether with a type peculiar to itself." These are the chief and leading principles 

 which Mr. MacLeay considers as belonging to the natural system. We shall now 

 copy his diagram, or table of the animal kingdom, and then endeavor, with this 

 help, to explain the system more in detail. 



We must, in the first instance, look to the above tabular disposition of all 

 animals, as forming themselves collectively into one great circle, which circle 

 touches or blends into another, composed of plants, by means of the "least or- 

 ganized beings of the vegetable kingdom." Next we are to look to the larger 

 component parts of this great circular assemblage. We find it, in accordance with 

 the third proposition, to exhibit five great circles, composed of the Mollusca, 

 or shellfish; Acrita, or polyps; Radiata, or star-fish; Annulosa, or insects; and 

 Vertebrata, or vertebrated animals; each passing or blending into each other, 

 by means of five other groups of animals, much smaller, indeed, in their extent, 



