268 



DISCOVERY REPORTS 



The oesophagus is at first thin and small. It expands in the region of the brain into 

 the stomach. Far back there is an anterior caecum with two short forward branches. 

 The vascular system is normal and the excretory tubules occur just posterior to the 

 brain. 



The proboscis as far as the armature is almost half the length of the body. The 

 accessory armature and proboscidial nerves vary greatly, though there is always a main 

 stylet mounted on a brownish pear-shaped base (Fig. 45 B). The following range of 

 variation has been found : 



It seems evident that no specific value can be given either to the armature or to the 

 proboscidial nerves. There is a possibility of increase with size or age. 



The brain is fairly large but does not show any peculiarity. In one series of sections 

 the lateral nerves left the brain by a sharp twist outwards, but this is merely the effect 

 of contraction. The cerebral organs open by two very small pores ventro-laterally behind 

 the opening of the rhynchodaeum. The organs are small and do not reach the brain. 



Some of the specimens were males, some females. The gonads are shed laterally both 

 above and below the nerves (Fig. 45 D). Eggs were ripe in November and December. 



In view of the extreme variation in the accessory armature and proboscis nerves the 

 distinctions that have been drawn on these characters cannot hold. I therefore feel 

 justified in bringing together the species described by Burger and Joubin under 

 A. spinosus, Burger. 



