44 TRANSACTIONS LIVEEPOOL BIOLOGICAL SOCIETY. 



and the right lateral lobe of the testis until it reaches the 

 ventral surface between the stomach and the anterior end 

 of the ovary (PL I. fig. 9). It now turns forwards, reaches 

 the base of the tail, enlarges to form the caudal ganglion, 

 and then continues onwards through the length of the 

 tail lying on the left side of the notochord. 



I have not discussed specially those detailed points in 

 which the preceding account differs from those of Fol, 

 Eisen and other authors. The new method of investigation, 

 serial sections in place of transparent objects, might be 

 naturally expected to yield some new results in matters of 

 detail : besides I cannot be certain that my form is speci- 

 fically identical with any of those previously described. I 

 may mention, however, as perhaps the most interesting 

 points shown in my figures : — the condition of the endo- 

 style as a diverticulum to a great extent shut off from 

 the branchial sac, the presence of a genital duct, the distri- 

 bution of the enlarged ectoderm cells and the cuticular 

 test, the exact course of the nerve cord through the pos- 

 terior part of the body, and finally the shapes and relative 

 positions of the alimentary and reproductive viscera. 



Explanation of the Plates. 



All the figures with the exception of fig. 9 on PI. IV. 

 were drawn from the sections, which were placed so that 

 right and left sides of the figure represent right and left 

 sides of the animal. With the exceptions of figs. 4, 5, and 

 8 on PI. I. figs. 9 and 10 on PL III. and figs. 6 and 8 on 

 PL IV. which show more highly magnified details, all the 

 figures were drawn under a moderate magnification, about 

 115 diameters. The following abbreviations are used : — 



