SEA-MATS AND SHELLY CORALLINES. 65 



like that of a bird, only stretching to an enormous width 

 of gape, and then closing with a strong and sudden snap. 

 Now and then the whole head sways backward and for- 

 ward on its joints ; and these movements, combined with 

 the fitful and apparently spiteful snappings, performed by 

 many birds' heads scattered about the branch, are highly 

 curious and amusing. 



The birds' heads, however, are not the living inhabi- 

 tants of the cells ; they are not integral parts of them. 

 The cells have their proper inhabitants, each dwelling in 

 its own ; and each essentially formed on the same plan as 

 the " baby with the tucked-up knees," that makes the 

 Sea-mat for his cradle-house. 



In order to get a good view of the tenant here, you 

 must move the stage about till you find that the branch is 

 presented to your eye sidewise. Directing your attention 

 then to the lateral edge of a single inhabited cell, its 

 summit is seen to protrude diagonally, towards the inner 

 side (i.e., towards 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 

 unfolding the integument, and the tentacles are exposed 

 to view, closely pressed into a parallel bundle ; the un- 

 folding 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 turned out. 

 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 sto- 

 mach passes, with a sort of gulp, any animalcule whirled 

 to the bottom of the funnel by the ciliary vortex ; and from 

 thence it is delivered, through a contracted, but still rather 



p 



