134 



ZOOLOGY 



cuius, which in Rirudo is enormous, and produced into eleven 

 pairs of lateral caeca — it serves as a storehouse for the blood ; 

 (iii.) the digestive stomach, usually very small ; (iv.) the intes- 

 tine ; and (v.) the rectum. Sections (i.) and (v.) are formed by 

 epiblastic invaginations. The ahmentary canal of Aulostoma 

 is ciliated ; an interesting peculiarity, since this leech does not 

 live on blood, but on small water-worms, etc. The Rhyn- 

 chobdellidae have a protrusible proboscis. 



The nephridium in PontoMella (Fig. 85, 1.) is a continuous 



PiQ. 85. — Diagrams of the ne- 

 phridia in (I.) PontoMella and 

 (II. ) Hirudo, A. G. Bourne. 



I. 



1. Funnels. 



2. Branched network. 



3. Caeoal tubules. 



4. External opening. 



II. 



1. Funnel. 



2. Ducts in testis lobe. 



3. Ducts in main lobe. 



4. Ducts in caecal end of main 



lobe. 



5. Ducts in apical lobe. 



6. Unbranched tube passing to 



exterior, 



7. Vesicle. 



8. External opening. 



network of fine tubules, which is spread through the greater 

 part of the body. This network opens at intervals into a blood 

 sinus by 1 pairs of internal funnels occurring in the segments 

 9-18. The lumen of the funnel is usually occluded, a condition 



