SEA-MATS AND SHELLY COEALLINES. Y3 



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 at- 

 tention 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 tu- 

 bular 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 bundle ; the evolution of the integument, that is 

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

 ened, when the tentacles diverge and assume the form 

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

 tips being slightly everted. They are furnished with a 

 double row of short cilia in the usual order, one set 

 •working xipward, the other downward. Their base sur- 

 rounds 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 the bottom of the funnel by the ciliary vor- 

 tex, and from thence it is delivered through a contract- 

 ed, but still rather wide gullet, into an oblong stomach, 

 the lower portion of which is obtuse. An extremely 

 attenuated duct connects this, which is probably the 

 true stomach, with a globular, rather small, intestine, 

 which is again connected by a lengthened thread with 

 the base of the cell. By an arrangement common to 

 the ascidian type of the digestive function, the food is 

 returned from the intestine into the true stomach, 

 whence the effete parts are discharged through a wide 

 4 



