344 STEUCTUKE OF THE LA.EVAL POLYPTEEUS. 



PLATE XXXV. 



Fig. 1. A section through the mesonephros of the 24th body-segment, showing the thickened strip of 



peritoneum in section lying to the outer side of the mesentery of the genital ridge (ovary) 



and the more complicated arrangement of the tubules in the anterior region. 

 Fig. 2. A section through the 29th body-segment, showing the thickened ridge lying to the outer 



side of a small projection, which here represents the genital ridge. It also shows the 



accessory tubules on either side and the accessory glomerulus on the right side. The 



arrangement of the older tubules is here less complicated. 

 Fig. 3. A section through the 30th body-segment, showing on the left side a nephrostomic opening 



upon the thickened ridge and communicating with the glomerulus. On the right side 



accessory tubules are shown. 

 Fig. 4. A segment through the 34th body-segment ; on the left side the edge of a nephrostome 



and also of a glomerulus is cut through, while on the right side is shown a single large 



glomerulus from which a kidney-tubule leads. 

 Fig. 5. A section through the 37th body-segment, showing the opening of two kidney-tubules into 



the right and left segmental duct. The thickened strip of peritoneum still persists, though 



the genital ridge does not extend so far back. 

 Fig. 6. A section passing near the hind end of the body-cavity behind the last kidney-tubules. 



The thickened strip of peritoneum is still seen lying under the segmental duct. 

 Fig. 7. A section passing through the very end of the body-cavity ; the segmental duets are now 



turning ventralwards and approaching one another, while the thickened strip lies just 



ventral to them. 

 Fig. 8. A section passing just in front of the vent, behind the point of union of the segmental 



ducts. The body-cavity is seen here to be prolonged backwards in two portions on either 



side divided by a septum. The thickened strip of peritoneum is here seen on the inner 



side of the dorsal portion. 

 Fig. 9. A section through the posterior end of the kidneys of a 9 cm. male specimen, showing the 



genital duct still in connection with the peritoneal epithelium. 

 Fig. 10. A section of the same specimen further forwards, showing the large size of the genital 



duct at the base of the testis. 



(Magnification 80.) 



