ANATOMICAL SYSTEMS. 323 



the same sum of systems of organs as Man," and the whole 

 of his system is intended to impress emphatically this 

 view. The separation of Man from the animals, not 

 merely as a class but as a still higher division, is especially 

 maintained upon that ground. 



The principle of classification adopted by Ehrenberg 

 is purely anatomical ; the idea of type is entirely set 

 aside, as is shown by the respective position of his 

 classes. The Myeloneura, it is true, correspond to the 

 branch of Vertebrata, and the Sphygmozoa to the Articu- 

 lata and Mollusca ; but they are not brought together on 

 the ground of the typical plan of their structure, but 

 because the first have a spinal marrow, and the other a 

 heart or pulsating vessels with or without articulations 

 of the body. In the division of Tubulata it is still more 

 evident how the plan of their structure is disregarded, as 

 that section embraces Eadiata, (the Echinoidea and the 

 Dimorphsea,) Mollusca, (the Bryozoa,) and Articulata, (the 

 Turbellaria, the Nematoidea, and the Eotatoria,) which 

 are thus combined simply on the ground that they have 

 vessels which do not pulsate, and that their intestine is a 

 simple sac or tube. The Eacemifera contain also animals 

 constructed upon different plans, united on account of the 

 peculiar structure of the intestine, which is either forked 

 or radiating, dendritic or racemose. 



The limitation of many of the classes proposed by 

 Ehrenberg is quite objectionable, when tested by the 

 principles discussed above. A large proportion of them 

 are, indeed, founded upon ordinal characters only, and 

 not upon class characters. This is particularly evident 

 with the Eotatoria, the Soniatotoma, the Turbellaria, the 

 Nematoidea, the Trematodea, and the Complanata, all of 



which belong to the branch of Articulata. The Tunicata, 



Y 2 



