OF POLYPES. 
38 
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 fibrogelatinous 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 FI us tree, Cellarise and Sertulariae are similar to those of Lobularia ! Coral. 
Flex. p. 832. 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. 65. 
* Blainville’s Actinologie, p. 675. 
C 
