OF POLYPn:S. 33 



same. Some few species, classed by the predecessors of the 

 latter among zoophytes, had in the meantime been ascertained 

 to be differently constructed, and furnished with less simplicity, 

 but being in consequence removed into a different category, they 

 were not allowed to disturb the received opinions on polype ana- 

 tomy. Still more recent discoveries have shewn, however, that 

 these are very erroneous, and that the animals of even our na- 

 tive polypidoms form at least two classes distinguished by a very 

 remarkable dissimilarity of organization. By the one they are 

 allied to the tunicated and acephalous mollusca, more especially 

 to the compound families of the former, and hence may be de- 

 nominated Ascidian polypes ; by the other they form a link of 

 the chain or circle which associates the radiated animals, and, 

 assuming the hydra for their representative, we shall call them 

 Hydraform polypes. 



The ascidian polypes never occur in a separate and naked 

 form, but are always placed within the cells of a polypidom of a 

 calcareous, membranous, or fibro-gelatinous consistence. The 

 form of the cells in many genera, as Eschara, Flustra and Cel- 

 lepora, suggests a belief that their tenants, although arranged 

 in a close and determinate manner, are each separate from their 

 neighbours and complete in themselves, — an opinion that is 

 held by some of our best naturalists ; but the observations of 

 Dujardin on some allied fossil polypidoms, render it very pro- 

 bable that there are pores of communication between the cells;* 

 while those made by Professor Grant seem to have proved that 

 the polypes of the Flustra are connected together by a living 

 axis, and are hence truly compound beings. Since the Vesiculi- 

 fera also, which are admitted to be composites, belong unques- 

 tionably to this remarkable form of animated entities, it is safer, 



mated nearer than was believed to the mollusca, of which they might at some 

 future time be considered a family. The opinion certainly rested on few and 

 hasty observations, and no anatomical details were given in its support. See his 

 Edit, of Soland. Zoophyt. pref. p. vii. For example, he not only recognizes a 

 relationship between Lobularia and Actinia, but he tells us that the polypes of 

 the FlustriB, Cellariie and Sertularioe are similar to those of Lobularia ! Coral. 

 Flex. p. 332. Such loose observations as these are, have no influence on the 

 progress of discovery. The observations of Savigny were evidently more spe- 

 cific and correct ; but I am not aware that the details have been yet published. 

 — See his Mem. sur les Anim. s. Vert. ii. p. G5. 

 * Blainville's Actinologie, p. 675. 



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