334 



The following is a summary of the fresh points I have observed in 

 the nervous system: 



(1) Immediately underneath the oesophagus the oesophageal com- 

 missures dilate and form a pair of ganglia equivalent to the annelidan 

 and arthropodan suboesophageal ganglia. These ganglia are closely 

 approximated and united by 5 or 6 commissures. They give off large 

 nerves to the oral papillae. 



(2) The ventral nerve cords are covered on their ventral side by a 

 thick ganglionic layer 5 ), and at each pair of feet they dilate into a mall 

 but distinct ganglionic swelling. From each ganglionic swelling are 

 given off a pair of large nerves 6 ) to the feet ; and the ganglionic swel- 

 lings of the two cords are connected together by a pair of commissures 

 containing ganglion cells 7 ). The other commissures connecting the 

 two cords together do not contain ganglion cells. 



The chief feature in which the nervous system of Peripatus was 

 supposed to differ from normal Arthropoda and Annelida, viz. the ab- 

 sence of ganglia on the ventral cords, does not really exist. In most 

 particulars, as in the amount of nerve cells in the ventral cords and 

 the completeness of the commissural connection between the two 

 cords, etc., the organization of the nervous system of Peripatus ranks 

 distinctly high. The nervous system lies within the circular and longi- 

 tudinal muscles, and is thus not in proximity with the skin. In this 

 respect also Peripatus shews no signs of a primitive condition of the 

 nervous system. 



A median nerve is given off from the posterior border of the supra- 

 oesophageal ganglion to the oesophagus wich probably forms a rudi- 

 mentary sympathetic system. I believe also that I have found traces of 

 a paired sympathetic system. 



The organ doubtfully spoken of by Mr. Moseley as a fat body, 

 and by Grubeasa lateral canal, is in reality a glandular tube, lined 

 by beautiful columnar cells, which opens by means of a non-glandular 

 duct into the mouth. It forms a perfectly simple tube close above the 

 ventral nerve cord in a lateral compartment of the body-cavity, and ex- 

 tends backwards for a varying distance. 



This organ may perhaps be best compared with the simple salivary- 

 gland of Julus. It is not to be confused with the slime-glands of Mr. 



5) This was known to Grube, loc. cit. 



6) These nerves were noticed by Milne-Ed wards, but Grube failed to ob- 

 serve that they were much larger than the nerves given off between the feet. 



7) These commissures were perhaps observed by Saenger (loc. cit.). 



