760 



The side along which this groove runs I shall term neural, and the 

 opposite side apo-neural, as the question as to which is the true dorsal 

 side of the animal must unfortunately remain open. 



On the apo-neural side of the posterior end there is a much larger 

 and more slender tail. 



In transverse sections the gut and nerve cord run along the whole 

 length of the animal with the exception of a short break indicating the 

 future line of separation between the two individuals of the second order. 



The nerve cord during the greater part of its length consists of a 

 much flattened tube. 



At the anterior end of each individual the nerve cord turns upwards 

 and comes into contact with the wall of the neural groove (fig. 2). 



KG. 



,r -■■■ 



s.o.- 







-^ ft ff" 



nc. 



Int. 



Fig. 3. Next section showing tubular nerve cord and sense organs with their gan- 

 glion. 2 mm. Apochromat. X 4. Comp. Oc. 



Near the anterior end of each individual the nerve cord gives rise 

 by short lateral stalks to two large ganglia which on each side surround 

 a sensory invagination of the epidermis lying on the neural side of the 

 pharynx (fig. 1, 3). 



The pharynx of the younger buds is found on tlie apo-neural side 

 of the animal (fig. 2), as an inpushing of the epidermis, which in later 

 buds comes into communication with the intestine on its apo-neural side. 



These stages of the development of the pharynx are very hke those 



