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CHAPTER VII. 

 Functions and Instincts. Tunicaries. 



THE animals we have hitherto been considering 

 \vere all regarded by Cuvier as belonging to his 

 first class, the Zoophytes, and are continued 

 therein by Carus ; the latter, however, allows 

 that the Echinoderms are somewhat removed from 

 the class by the commencement of a nervous 

 system. Lamarck's next Class, the Tunicaries^ 

 which we are now to enter upon, form part of the 

 headless Molluscans 2 of Cuvier, and belong to 

 that section of them that have no shells. My 

 learned friend, Savigny, in his elaborate and 

 admirable work on The Invertebrate Animals, 

 who also considers them as a separate class, 

 denominates them Ascidians, 3 dividing them into 

 two Orders, Tethydans and Thalidans* Many 

 alcyons of Linne and others, are now referred 

 to the Class we are treating of. 



The characters of the class may be thus stated : 

 ANIMAL, either gelatinous or leathery, covered by 

 a double tunic 9 or envelope. The external one, 

 analogous to the shell of Molluscans, distinctly 



1 Tunicatu. 2 Mollusca Acephala. 



3 Ascidia. * Tethydes, Thalides. 



