586 



COMPOUND ASCIDIAXS '. — AMAROUCIUM. 



Fig. S02. 



T-n~ 



Wilt 



IP'' 



iA 





!T& 



h 



C 



Vw, 



Compound mass of Amaroucium pro- 

 liferum, with the anatomy of a single 

 Zooid : — a, thorax ; b, abdomen ; c, post- 

 abdomen : — c, oral orifice ; e, branchial 

 sac ; /, thoracic sinus; i, anal orifice ; 

 i', projection overhanging it ; j, nervous 

 ganglion ; k, oesophagus ; /, stomach sur- 

 rounded by biliary tubuli ; m, intestine ; 

 n, termination of intestine in cloaca ; 

 o, heart ; o', pericardium ; p, ovarium ; 

 p' , egg ready to escape ; q, testis ; r, sper- 

 matic canal ; ?•', termination of this canal 

 in the cloaca. 



slits, which allow part of the water 

 to pass into the space between the 

 branchial sac and the muscular mantle, 

 where it is especially collected in 

 the Thoracic Sinus /. At Jc is seen 

 the (Esophagus, which is continuous 

 with the lower part of the pharyngeal 

 cavity ; this leads to the Stomach Z, 

 which is surrounded by Biliary fol- 

 licles ; and from this passes-off the 

 Intestine w, which terminates at n in 

 the Cloaca, or common vent. A cur- 

 rent of Water is continually drawn-in 

 through the mouth by the action of 

 the Cilia of the branchial sac and of 

 the alimentary canal ; a part of this 

 current passes through the fissures of 

 the branchial sac into the thoracic sinus, 

 and thence into the cloaca ; whilst 

 another portion, entering the stomach 

 by an aperture at the bottom of 

 the pharyngeal sac, passes through 

 the alimentary canal, giving up any 



