CLASSIFICATION OF ZOOPHYTES. 



107 



troid polyps, illustrate the same principles, and are as nearly allied to 

 the Tunicata as the Rotifers to the Crustacea. It is a side-deve- 

 lopement from the imaginary line, which connects the Infusoria 

 with the Tunicated Molluscs. The Entozoa afford other examples, 

 one branch of them passing into Crustacea, through the Lernseidse 

 and Caligidae, and the other into the Annelida. The LernaBoid divi- 

 sion appears to reach the Polygastrics in the Acephalocyst. 



These remarks are intended to support no monad or Lamarckian 

 theory, but only to elucidate the established principle that there are 

 in nature certain distinct systems or types of developement. Each 

 species is developed with some reference to one or the other of these 

 systems, but, through the agency of the vital forces peculiar to it, — 

 forces which, there is reason to believe, only creative power can change. 



107. In accordance with these principles, the several orders of 

 animals may be arranged as follows : 



I. Vertebrata. 



III. Articulata. 



Insecta, Myriapoda, 



Arachnida, 

 Crustacea, Annelida, 



Rotilera, Entozoa, 



IV. Radiata. 



Echinodermata, 

 Zoophyta, Acalephae, 



II. MoLLUSCA. 



Cephalopoda, Pteropoda, 



Gastropoda, Conchifera, 



Tunicata. 



Bryozoa. 



V. Protozoa or Infusoria. 



108. A radiated structure characterizes the simplest form of animal 

 life.* Passing up from the monad globule, this structure has its 



* As suggested in the close of § 98, it appears to be more than a plausible conjecture, 

 that we may attribute the radiated structure to the ordinary uncontrolled principles of 

 cellule budding ; the results of which are seen in the varied forms of zoophytes and 

 vegetation. It gives origin to the radiated form of the flower; and the spiral arrangement 

 of the leaflets, — the result of a succession in the developements, — is one of the conse- 

 quences of it (§ 86). The nervous system, in its lowest condition, conforms to this cha- 

 racter; but, as it becomes more perfect, it has a peculiar mode and direction of develope- 

 ment, — as the zoophyte has its peculiar characteristics in this respect, — and thus developing, 

 it guides all the other elaborations ; for it seems to be the channel along which vital 

 influences operate. The developement of nerves, therefore, carries the animal structure 

 more or less widely from the radiate type. This is well illustrated in the relation of the 

 Rotifers and Crustacea, the former, as shown above, having the general structure of the 

 latter under a radiate form. The Rotifers have, as organs of motions, a series of plates 

 arranged in a circular series around the mouth at one extremity of the animal. In the 



