7 6 



Invert cbrata. 



FIG. 46- 



*,&*'* 



JsswSWj 



masses of semi-transparent, often gristly material, and 

 of a whitish, pink, or brownish 

 colour. They vary in length from 

 one to six inches. 



In each tunicary there are two 

 apertures on the surface; one of these 

 (c, fig. 46) opens into a large chamber 

 whose wall (e) is a vascular mem- 

 brane, and at the bottom of which 

 is the mouth (/). The digestive canal 

 ends at the bottom of a second 

 chamber (;z), of which the lower or 

 hinder opening (/) is the outlet. Be- 

 tween these two chambers, which 

 thus lie over the digestive canal, 

 there is a partition wall which is 

 pierced by many small holes whereby 

 the water which enters into one can 

 pass into the other, thus bathing the 

 surface of the lining membrane, and 

 enabling the blood contained in the 

 spaces in its texture to become 

 aerated. The first chamber (fig. 46) 

 is called the branchial chamber, the 

 second is called the atrial. 



Between the opening of the 

 branchial chamber and the atrial ori- 

 fice there is a nerve ganglion send- 

 ing a fine loop of branches around 



Amonroncium argits. a tunicated worm. A, Pharynx, or respiratory portion 

 of the body ; B, stomach ; c, egg-producing organ ; a, tunic ; b, branchial 

 chamber ; d, tentacles, non-protrusible ; h, atrial chamber ; /, ganglion 

 beside which are two eye-spots ; /, liver ; in, digestive canal ; o, heart ; 

 / ' > P" > e gg- s in various stages ; q, ovary ; r, vas deferens. 



