HIRUDIN E A 137 



selves to her body. Nephdis deposits its cocoons on water- 

 plants, Aulostoma and Hirudo in damp earth. 



Leeches are usually inhabitants of fresh water ; sometimes 

 they live in salt water, and more rarely on land. They 

 usually move in loops by the aid of their anterior and posterior 

 suckers, but they can swim well. The land forms are most 

 common in Asia south of the Himalayas, and in the East 

 Indies and Australia. A gigantic form, Macrdbdella Valdi- 

 viafia, lives underground in Chili, and is said to reach the 

 length of 2-^ feet. They are, with few exceptions, parasitic, 

 living on the blood of Vertebrates. 



The HiEUDiNEA are divided iuto two groups : 



(i.) Rhynchobdellidae.— Cj^MmcZn'ca? or flat, elongated lody 

 with loth suckers well marked, fore part of the lody 

 retractile, forming a proboscis. The vascular and the 

 coelomic spaces are in direct continuity ; the Hood 

 does not contain hcoemoglobin. Pontobdella, Clepsine, 

 Piscicola. 



(ii.) Gnathobdellidae.— ilfoM^/i' sucker-like, pharynx armed 

 with three jaws. No proboscis. The vascular and the 

 coelomic spaces are in indirect continuity. The Hood 

 contains haemoglobin. Hirudo, Aulostoma, Nephelis. 



