NATURAL HISTORY OF THE SHIP-WORMS. 231 
Fre. 60. Nervous system of adult, dorsal view, except that the pedal ganglion is shown more from 
behind. 
Fries. 61 and 62. Diagrams to show the relations of the ends of the kidneys, genital duct, pericardial 
cavity, and visceral ganglion. Figure 61 lateral and figure 62 dorsal view. 
PLATE XXI. 
Fre. 63. Transverse section of the anterior ganglion and genital duct, to show the connection between 
the cerebro-visceral connective and anterior ganglion and the origin of the sensory nerve 
and its distribution to the genital duct. Only a part of the sense organ was included in 
the section, which is from 7. navalis, though it might represent XY. gouldi equally well. 
x 272. 
Fic. 64. Longitudinal section of the genital duct to show its extent and character and the sense organ 
of the genital duct. The end of the ovary is shown, as also the folded kidney near its 
pericardial opening. 272. 
Fic. 65. Section of the osphradium, vertical to the surface, to show the structure of the osphradium 
and the two types of sensory cells, with their brushlike terminations. 1210. 
Fic. 66. Tangential section of the osphradium, to show the distribution of the processes of the sensory 
cells among the nuclei of the epithelial layer. > 950. 
