APPENDIX. 



CLASSIFICATION. 



It was my wish to have given in tabular forms some slight outlines 

 of the various systems of classification adopted by Professors Grant, 

 fiaechel, Huxley, Ray Lankester, Macalister, Nichohon, Packard, and 

 Sir Wyville Thomson, adding a few remarks on their disliuctive 

 features. 



But it is found easier to concentrate the attention on a single plan, 

 and to notice the chief divergencies, than to compare a series of plans. 

 I have therefore selected the Stammhaum des Thierreichs of Professor 

 G. V. Koch, as a central scheme. The names and numbers in the 

 Stammhaum denote closses. 



Classes 1, 2, 3, 4, 5, (5 constitute the Sub-kingdom Protozoa, dis- 

 tinguished by the absence of cell-formed tissue. 



Most authors include Class 7, Infusoria. 



The Gregarinidie are omitted, though retained by Lankester as 

 forming Class Corticata. 



The same ^author gives Noctiluca as an example of a distinct Class, 

 Proboscidea. 



Class 8, Spongife, treated by Grant as constituting Class Porifera = 

 Sub -kingdom Polystomata, Huxley. 



Classes 0, 10. 11 form the Sub-kingdom Coelenterata ^ Phylum 

 Nematophora, Lankester. It includes Class Hydrocoraliinae, Moseley. 



Classes 7, 12, 13, 14, 15, 10, 17, 18, 19, enclosed within a dotted 

 line, represent the Sub-kingdom Vermes . 



Each of the Classes 12, 13, 10 and 18 forms a distinct Phylum or 

 Sub-kingdom, Lankester. 



The same author places Class 17, Tunicata, under the name 

 Urochorda, amongst the Vertebrata. 



Class 14, Polyzoa, he inserts between the univalve and bivalve 

 MoUusca. 



The remaining Classes, 15 and 19, are referred by him to the Plijdum 

 Appendiculata, which also includes Gnathopoda=Arthropoda, i.e., the 

 whole of the boneless animals with jointed limbs. 



Classes 19, 20, 21, 22, 23 constitute the Sub-kingdom Echinodermata, 

 which in most of the recent systems of classification immediately 

 succeeds the Ccelenterate Sub-kingdom. 



Such an arrangement seems to be essential in either of two cases. 



