THE POLYPES. 199 



in the kindred species. The motions are exactly 

 the same in both cases. I observe that sometimes the 

 place of the bird's head is occupied by an oval or 

 pear-shaped body, which is probably an early stage of 

 its development; and when perfectly formed there 

 is much dilFerence of size, some of these curious 

 organs being twice as large as others on the same 

 specimen. 



Now let us come to the polype itself. It is when 

 we get a good lateral view of a single inhabited cell, 

 that we obtain a knowledge of the structure of the 

 tenant. The summit of the cell is then seen to pro- 

 trude, diagonally towards the inner side, — (i. e. to- 

 wards the axis of the spire) a tubular mouth, which 

 is membranous and contractile. When the animal 

 wishes to emerge, this tubular orifice is pushed out 

 by evolution of the integument, and the tentacles are 

 exposed to view, closely pressed into a parallel bun- 

 dle (See fig. 4); the evolution of the integument, that 

 is attached at their base, goes on till the whole is 

 straightened, when the tentacles diverge and assume 

 the form of a funnel, or rather that of a wide-mouthed 

 bell, the tips being slightly everted (See fig. 5j. 

 They are furnished with a double row of short cilia 

 in the usual order, one set working upward, the other 

 downward. Their base surrounds a muscular thick 

 ring, the entrance to a funnel-shaped sac, the substance 

 of which is granular, and evidently muscular, for its 

 contractions and expansions are very vigorous, and 

 yet delicate. Into this first stomach passes with a 

 sort of gulp any animalcule, whirled to tbe bottom of 

 the funnel by the ciliary vortex, and from thence it is 



