POLYZOA INFUNDIBULATA. 



PoLYPiARiA INFUNDIBULATA, P. Gervais in Ann. des Sc. Nat.vii. (1837) 79. 



In the preceding class we found reason to conclude that 

 the polypidom of the Hydroida was a sheath disconnected, or 

 at least not in organic union, with the soft pulpous matter 

 which it invests and protects ; that the corresponding part in 

 the Asteroida, become an interior skeleton or axis, held the 

 same relation to its polypiferous crust ; nor was this relation 

 altered when the polypidom had again, in the Helianthoida, 

 assumed an external position, forming an integral part of the 

 epidermis. In all these instances the polypidom appears to 

 be unorganized, and when once formed, beyond the reach of 

 change from either the polypes or its own inherent powers ; * 

 but in the present class, the cell, although pre-eminently en- 

 titled to the name of polypidom from its appearance and use, 

 is a living portion of the animal which it seemingly contains. 

 The cell is in fact the outer tunic of the polype, analogous to 

 the envelope of the compound mollusca, endowed certainly 

 with no very sensible or active properties of life, yet in 

 organic connexion with the interior parts, and liable to or- 

 ganic changes. The relationship in which they stand to one 

 another is nearly, if not precisely, the same as that which the 

 fleshy crust of the Asteroida bears to its polypes, as a com- 

 parison of the Alcyonium with the Alcyonidium or Alcyo- 

 nella will render sufficiently plain ; and it is not less real even 

 in those genera where the cells, when dried, have hard calca- 

 reous, and apparently impermeable parietes. For the proof 

 of this fact, — a very important one in their physiology, and in 

 any question touching their rank in the animal kingdom, — 

 naturalists are principally indebted to Milne-Edwards.f The 



* " Unorganized non-vascular parts are produced by an organized matrix, and 

 grow by the continued deposition of new matter on one surface.^'' — Miiller's Elements 

 of Physiology, p. 384. 



+ Ann. des Sc. Nat. vi. p. 25-31. A translation of Milne-Edwards's remarks is 

 given in the first edition of this work, p. 327, &c, Sec also Couch's Corn. Faun. iii. 

 p. 91. 



