y08 ON SYSTEMATIC ZOOLOGY. 



MOLLUSCA 



A. Branchiopoda /O^ReptUia \ 



ACRITA ) T' VERfEBRATAJ 



ntestina / ', V m^ i-'-'o/ 



/ > \ Mammalia y 





(262.) This diagram fully explains our author's 

 meaning in the foregoing passage, when he supposes 

 that " opposite points of a circle may possibly meet each 

 other," and consequently unite. Now, if this, in the 

 sense here taken, and in the instances here stated, were 

 true, the inevitable consequence would be, that the 

 Acrita, the Mollusca, and the Vertehrata, would form 

 one great circle of their own, by the union of the intes- 

 tinal Acrita with the Annelida, while the circle of Ver- 

 tehrata would be divisible in the first instance into two, 

 by Ornithorhynchus uniting the reptiles with the qua- 

 drupeds {Mammalia). It is somewhat surprising, 

 therefore, that our acute author did not perceive the 

 inevitable consequences which would result to his own 

 theory, by admitting the possibility of such a principle 

 of affinity : for either it would, if correct, entirely 

 overturn his own theory on the animal kingdom being 

 first resolvable into five large and five smaller circles ; 

 or it would show that circles of affinity could be ex- 

 pressed in more ways than one, — in other words, that 

 there was more than one natural system. The truth, 

 however, appears to be, that some of the foregoing 

 resemblances are relations of affinity, while others are 



