3(, 



V- 



A PHYLOGENETIC CLASSIFICATION OF 

 ANIMALS. 



In the following account of the probable Phylogeny of 

 Animals — exhibited diagrammatically in the Table opposite 

 page 76 — I have begun with the lowest Protozoa and 

 worked upwards. The Metazoa have been discussed in the 

 following order (the number refers to the page on which 

 the group is commenced) : — Porifera (15), Coelenterata (16), 

 Platyelmia (25), Mollusca (29), Enteropneusta (40), Echino- 

 dermata (40), Nematelmia (44), Gephyrea (44), Brachiopoda 

 (44), Polyzoa (45), Chsetognatha (45), Rotifera (45), Crusta- 

 cea (46), Tracheata (51), Discophora (54), Chsetopoda (55), 

 Tunicata (58), Cephalochorda (61), Cyclostomata (62), 

 Pisces (62), Amphibia (64), Reptilia {jq^), Aves do^), Mam- 

 malia {^^)^ 



At the base of the Table all Animals and Plants are 

 represented as having arisen from a single organism of 

 extreme simplicity, to which the name Protamoeha is attached. 

 The simplest form of life known to science is Haeckel's 

 Protamoeha primitiva/^^ (fig. 1) and it is probable that the first 



^ ^ 



i^m ^^^v 





^^^m^^^ jfe^^S^ A^f^^M^ 



Fig. 1. Protamoeha primitiva, Haeckel. Three stages in the life-history, showing 

 reproduction by fission. 



formed organism was a particle of unmodified protoplasm, 

 * Haeckel, Studien iiber Moneren, Leipzig, 1870, p. 43. 



