CLASSIFICATION. 387 



' Tracheata (Peripatus, Myriapods, Insects). 



,, ,^^- . ,, , Arachnids. 



" (13) Arthropods ^ ^ ^ 

 ^ ^ Crustacea. 



Pycnogonida. 

 *'(14) Mollusca. 



"(15) Polyzoa (Including Phoronis). 



"(16) Brachiopoda. 



" (17) Chordata (Includes Balanoglossus and Tunicates. Some 



continental zoologists do not admit Balanoglossus)." 



[This last phylum of course includes the Vertebrata.] 



Though under present conditions, as above implied, it 

 would be absurd to attempt a definite scheme of relation- 

 ships, yet it has seemed to me that the adumbration of a 

 scheme, presenting in a vague way such relationships as are 

 generally agreed upon and leaving others indeterminate, may 

 be ventured; and that a general impression hence resulting 

 may be useful. On the adjacent page I have tried to make 

 a tentative arrangement of this kind. 



At the bottom of the table I have placed together, under 

 the name " Compound Protozoa/' those kinds of aggregated 

 Protozoa which show no differentiations among the members 

 of groups, and are thus distinguished from Metazoa; and I 

 have further marked the distinction by their position, which 

 implies that from them no evolution of higher types has taken 

 place. Eespecting the naming of the sub-kingdoms, phyla, 

 classes, orders, &c., I have not maintained entire consistency. 

 The relative values of groups cannot be typographically ex- 

 pressed in a small space with a limited variety of letters. 

 The sizes of the letters mark the classificatory ranks, and 

 by the thickness I have rudely indicated their zoological im- 

 portance. In fixing the order of subordination of groups 

 I have been aided by the table of contents prefixed to Mr. 

 Adam Sedgwick's Student's Text Book of Zoology and have 

 also made use of Prof. Eay Lankester's classifications of 

 several sub-kingdoms. 



Let me again emphasize the fact that the relationships of 

 these diverging and re-diverging groups cannot be expressed 



