396 Royal Society. 



I have appended the Stomatoda and the twelve remaining sections 

 of the Invertebrata in the oi'der indicated by their affinities. 



Scheme of Classification of Invertebrata. 



Leading Types of Protozoa, aggregate or compound. 



1. 2. 3. 4. 



Collosphaera. Porifera. Polycystina. Foraminifera. 



Corresponding simple forms. 

 Thalassicolla. Actinophrys. Acaiithometra. Amoeba. 



Gregarina. Gromia. Podocyrtis. Difflugia. 



Derivative types. 

 Cestoidea. Infusoria. Noctilucid®. Coelenterata. 



Trematoda. Turbellaria. Rotifera. Molluscoida. 



Nematoidea. Sipunculidse. Annelida. Mollusca. 



Eehinodermata. Articulata. 



So as not to comphcate the Table, I thought it better to sup- 

 plement it with the definition of the four leading types of compound 

 Protozoa. 



1. In the CoUosphfera type, the sarcode bodies lie at some 

 distance apart and are always distinct. 



2. In the Porifera type the sarcode bodies are closely approxi- 

 mated or confluent. 



3. In the Polycystina type the sarcode bodies are concentric and 

 connected by radiating stolons. 



4. In the Foraminifera type the sarcode bodies are connected 

 by stolons in linear series or some order of juxtaposition. 



If it is incumbent upon the developmental hypothesis to derive 

 the Vertebrata from the preexisting Invertebrata, the only line 

 through which it would be possible to trace their descent is that 

 leading from the Protozoa to the Mollusca proper, or the fourth 

 series of the Table. It would also appear that the Entozoa, 

 Eehinodermata, and Articulata appertain severally to separate 

 series of their owti ; and whateAer may happen by-and-by, it 

 would be difficult to find, in the present fauna of the globe, a single 

 form clearly deducible from any of them. 



The habit of life of the Entozoon, the pecuharity of structure 

 of the Echiuoderm, and the very perfection of organization of the 

 Articulata, as it were, preclude their evolution into any other 

 existing type. To use a common phrase, they may be said to lead 

 nowhere, though they may be easily and, I think, consistently traced 

 back to their possible origin in the Protozoa. 



It would be great presumption to say that even an approach to 

 perfection had been attained in this attempted classification of 

 a whole subkingdom of animals. Nevertheless, in the preceding 

 Table, the relationships existing amongst the members of that sub- 

 kingdom are presented to the eye at a single glance, and in a 

 manner that would be quite unattainable by systems maintaining 

 the original creation of every so-called species, and that in an 

 order perhaps more easily described than understood. 



