CORELLA. 21 



bottom at the right side of the mouth. These, the 

 oral papillae, agree in number with the transverse 

 rows of spirals, or rather with the primary vessels 

 which divide them. The branchial tubercle is large 

 and very little complicated in its structure. It is in 

 the form of a simple loop, with its right extremity 

 projecting upwards considerably above the other, which 

 is turned inwards. The endostyle reaches from one 

 end of the sac to the other. Both the anterior and 

 posterior cords in connexion with its extremities are 

 well developed. The tentacular filaments at the base 

 of the inhalant tube are numerous, long, delicate, and 

 simple ; they are nearly of uniform size. The nervous 

 ganglion is minute, and is of the usual elongated form. 

 The nerves, which cannot be traced very far, go to 

 supply the mantle or inner tunic and the respiratory 

 tubes. 



The heart, unlike that of Ascidin, is stretched along 

 the anterior border of the stomach, and lies within a 

 pericardial chamber which is situated in the thickness 

 of the mantle or inner tunic on the left side of the 

 branchial sac. From the dorsal extremity of the 

 organ a branch is given off which divides immediately 

 into two branches, one of which passes upwards, the 

 other downwards in connection with the endostyle, 

 and both go to form the great dorsal, branchial sinus 

 or channel. Another branch also leaves this extremity 

 of the heart and becomes at once associated with a 

 branch of equal size which seems to come from the 

 right-hand side of the stomach. These two vessels 

 thus associated pass into the test within which they 

 ramify. From the ventral extremity of the heart a 

 vessel is apparently given off to each side of the 

 cardiac end of the stomach. Further than this the 

 blood-system has not been traced, though there is no 

 reason to suppose that it differs in any important 

 respect from that of Ascidia. 



The digestive system is considerably modified. The 

 mouth is large and circular, with a wide fleshy lip or 



