68 BRITISH TUNICATA. 



by inter-vascular communications. Radiating vessels, 

 however, which are sufficiently numerous to prevent 

 engorgement, pass from the apex of each cone to the 

 transverse or primary vessels, and are the principal 

 interruptions to the continuity of the spiral stomata. 



The oral lamina is a plain, simple membranous band 

 which reaches from one end to the other of the branchial 

 sac, on the right side of the mouth ; it is widest about 

 the centre or just below the mouth, which in this genus 

 is placed much further forward than usual, in a wide, 

 smooth space extending along the ventral margin 

 between the two sides of the gill. There are similar 

 wide, smooth spaces extending a^ng each side of the 

 endostyle, which is almost white, and reaches from 

 the top to the bottom of the branchial sac. The 

 anterior and posterior cords in connection with the 

 endostyle are well developed. 



The tentacular filaments are much branched ; they 

 are about fifteen in number with one or two small ones 

 between them. 



The alimentary tube is wide throughout ; it bulges 

 from the rio-ht pallia! wall into the pallia! chamber, 



o 1 1 



and is bent upon itself, so as to form a large transverse 

 loop which extends to the dorsal border. After follow- 

 ing the loop it turns downwards, and, on reaching the 

 anterior portion of the tube, advances upwards ; 

 passing in contact with the stomach and oesophagus, 

 it forms a second short open loop, and then terminates 

 in the cloaca at the base of the excurrent tube. 



The anus, which is large, has a wide, bilobed, 

 reflected, papillose margin. The oesophagus is short 

 and somewhat constricted. The stomach is wide in 

 front, elongated downwards and backwards, and sub- 

 sides gradually into the intestine so that the pyloric 

 extremity is ill defined. 



The liver is of a tawny-brown colour, and forms a 

 compact mass which lies mostly at the ventral margin 

 of the stomach, and is spread over the left side of that 

 organ, partially enveloping it. 



