ANATOMICAL SYSTEMS. 327 



The classification with which Owen 1 introduces his 

 " Lectures on Comparative Anatomy" is very instructive, 

 as showing, more distinctly than other modern systems, 

 the unfortunate ascendancy which the consideration of the 

 complication of structure has gained of late over the idea 

 of plan. His provinces, it is true, correspond in the main 

 to the branches of Cuvier, with this marked difference, 

 however, that he does not recognize a distinct province 

 of Radiata coequal with those of Mollusca, Articulata, and 

 Vertebrata, but only admits Radiaria as a subprovince on 

 a level with Entozoa and Infusoria. Here the idea of 

 simplicity of structure evidently prevails over that of 

 plan, as the subprovinces Radiaria, Entozoa, and In- 

 fusoria embrace, besides true Radiata, the lowest types of 

 two other branches, Mollusks and Articulates. On the 

 other hand, his three subprovinces correspond to the first 

 three types of von Siebold ; the Infusoria 2 of Owen em- 

 bracing the same animals as the Protozoa of Siebold, his 

 Entozoa 3 the same as the Vermes, and his Radiaria the 

 same as the Zoophyta, with the single exception that 

 Owen refers the Annellata to the province of Articulata, 

 whilst Siebold includes them among his Vermes. Beyond 



one sub-kingdom called Radiata, in orders and families were only added 



contradistinction of the sub-kingdoms, to the second edition in 1855. I 



Mollusca, Articulata, and Vertebrata, mention this simply to prevent the 



and that sub-kingdom is subdivided possibility of being understood as 



into two groups, Nematoneura and ascribing to Owen all those subdivi- 



Acrita. sions of the classes which he admits, 



1 I have given precedence to the and which do not appear in the sys- 



classification of Owen over those of terns considered before his. 

 von Siebold and Stannius, Milne- 2 The Rhizopoda are considered as 



Edwards, Leuckart, etc., because the a group coequal to Rotifera and Po- 



first edition of the "Lectures on Com- lygastria, on p. 16 of the "Lectures"; 



parative Anatomy" was published in but on p. 59 they stand as a sub- 



1843 ; but in estimating its features, order of Polygastria. 

 as expressed in the preceding dia- 3 The Turbellaria are represented 



gram, it should be borne in mind, as an independent group on p. 16, 



that, in the first edition, the classes and referred as a sub-order to the 



alone are considered, and that the Trematoda on p. 118. 



