12 



PERIPATUS 



largest part of the alimentary canal. It is a dilated soft- walled 

 tube, and leads behind into the short narrow rectum (K), which 

 opens at the anus. There are no glands opening into the 

 alimentary canal. 



Nervous System. 



ain 



pc. 



The central nervous system consists of a pair of supra- 

 oesophageal ganglia united in the middle line, and of a pair of 

 widely divaricated ventral cords, continuous in front with the 

 supra-oesophageal ganglia (Fig. 9). 



The ventral cords at first sight appear to be without gangli- 

 onic thickenings, but on more careful examination they are 

 found to be enlarged at each pair of legs (Fig. 9). These enlarge- 

 ments may be regarded as imperfect ganglia. There are, there- 



FiG. 9. Brain and anterior part of the ventral nerve- 

 cords of Peripatus capensis enlarged and viewed 

 from the ventral surface. (After Balfour.) Tlie 

 paired appendages {d ) of the ventral surface of the 

 brain are seen, and the pair of sympathetic nerves 

 {sy) arising from the ventral surface of the hinder 

 part. From the commencement of the oesopha- 

 geal commissures pass off on each side a pair of 

 nerves to the jaws {Jn). The three anterior 

 commissui-es between the ventral nerve-cords are 

 placed close together ; immediately behind them 

 the nerve-cords are swollen, to form the ganglionic 

 enlargements from which pass off to the ornl 

 ])apillae a pair of large nerves on each side {orv). 

 Behind this the cords present a series of enlarge- 

 ments, one pair for each pair of feet, from which a 

 pair of large nerves pass off on each side to the feet 

 {pn). atn, Antennary nerves ; co, commissures 

 between ventral cords ; d, ventral a])pendages of 

 brain ; J, eye ; en, nerves passing outwards from 

 ventral cord ; F.g.1, ganglionic enlargements from 

 which nerves to feet pass off ; jn, nerves to jaws ; 

 org, ganglionic enlargement from which nerves to 

 oral papillae pass off ; orn, nerves to oral papillae ; 

 ''^ pc, posterior lobe of brain ; pn, nerves to feet ; 



sp, sympathetic nerves. 



fore, as many pairs of ganglia as there are pairs of legs. There 

 is in addition a ganglionic enlargement at the commencement of 

 the oesophageal commissures, w^here the nerves to the oral papillae 

 are given off (Fig. 9, or.g). 



The ventral cords are placed each in the lateral compart- 

 ments of the body cavity, immediately within the longitudinal 

 layer of muscles. They are connected with each other, rather 

 like the pedal nerves of Chiton and the lower Prosobranchiata, 

 by a number of commissures. These commissures exhibit a 



