24 



LEECHES 



regularly interrupted by papillae bearing sense organs. On the 

 ventral surface the posterior sucker is clearly marked off from the 

 rest of the body, but the anterior sucker is only a small depression 



&:^,mm-:,^^i 



5mm 



Fig. 13. Dorsal view of Glossiphonia complanata. 



on the under side of the head. The male pore is between annuli 25 

 and 26, and the female between 27 and 28. The general arrange- 

 ment of the internal organs is shown in Fig. 14. The proboscis 

 and proboscis sheath are of ectodermal origin, and are lined with 

 a fine cuticle. The endodermal gut begins with the crop, which has 

 six pairs of diverticula, the last pair being elongated and bent 

 posteriorly. The intestine, also endodermal in origin, has four 

 pairs of small lateral diverticula, and leads via the rectum (of ecto- 

 dermal origin) to the anus which is placed dorsally, at the junction 

 of the body with the posterior sucker. 



The female reproductive system, which is the simpler, consists 

 of two ovisacs lying lengthwise in the body in ventral coelomic 

 lacunae. Each contains a single thread-like ovary, and the two 

 sacs have a common opening at the female pore. The male repro- 

 ductive system consists of ten pairs of spherical testes lying 

 between the gut diverticula. Short vasa efferentia join these to a 



