442 



ZOOLOGY 



into the intestine, the first part of which is also covered by 



, the same structures (Fig. 254). The intestine makes a slight 



twist round the ovary, and is then continued into the rectum, 



which runs straight along the dorsal wall of the branchial sac 



Fig. 25". — Mouth of the subneural gland aud neighbouring parts in AsciMa 



After Herdman. 



and opens into the atrial cavity. The internal surface of the 

 first part of the intestine is much increased by the existence of 

 a typhlosole which projects into its lumen. 



The heart is contained in a pericardium situated ventral 

 to the oesophagus in the angle between the posterior limit of 

 the branchial sac and the stomach (Kg. 254). The peri- 

 cardium contains a corpusculated fluid, its cavity is derived 

 from the original coelom of the larva. The heart is a cylin- 

 drical tube bent into the shape of a V, the angle pointing 

 dorsalwards. One arm of the V is continuous with a ventral 

 or branchio-cardiac vessel or sinus which runs along the line 



