134 ZOOLOGY 
culus, which in Hirudo is enormous, and produced into eleven 
pairs of lateral caeca—it serves as a storehouse for the blood ; 
(ii.) the digestive stomach, usually very small; (iv.) the intes- 
tine ; and (v.) the rectum. Sections (i.) and (v.) are formed by 
epiblastic invaginations. The alimentary 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 Pontobdella (Fig. 85, I.) is a continuous 
Fie, 85.—Diagrams of the ne- 
phridia in (I.) Pontobdella and 
(II.) Hirudo. A. G. Bourne. 
if; 
1. Funnels. 
2. Branched network. 
3, Caecal tubules, 
4. External opening. 
ne 
. Funnel. 
. Ducts in testis lobe. 
. Ducts in main lobe. 
Pon 
Ducts in caecal end of main 
lobe. 
Ducts in apical lobe, 
OK 
. Unbranched tube passing to 
exterior, 
. Vesicle. 
~I 
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 10 pairs of internal funnels occurring in the segments 
9-18. The lumen of the funnel is usually occluded, a condition 
