526 ANNELIDA. 



enable them to store up a large quantity of food, and many of 

 them are able to go without food for a long period. 



Fam. 1. Rhynchobdellidae. With colourless blood, with a protrusible pro- 

 boscis, without jaws. Each typical segment consists of 3, 6, or 12 rings. The 

 6 -ringed forms are all marine except Haementaria. Organs concerned in the 

 formation of blood corpuscles (so-called valves) are often present in the dorsal 

 vessel. Without botryoidal tissues. 



Sub-fam. 1. Ichthyobdellidae. Marine and fresh-water leeches, parasitic 

 for the most part on fishes. With cylindrical body. The proboscis is not 

 longer than the preclitellum. Ichthyobdella Blainv. , on marine fish ; Pis- 

 cicola Blainv., on fresh-water fish ; Pontobdella Leach, marine, on sharks 

 and rays ; Branchellion Sav., with foliaceous lateral appendages; B. tor- 

 pedinis Sav. ; Callidbdella v. Ben. and Hesse ; Ozobranckus Qfg., with 

 branchiae, in the mouth of tortoises, crocodiles, pelicans. 



Sub-fam. 2. Clepsinidae. Fresh-water leeches, generally parasitic on 



snails, but also on fish. With dorsoventrally compressed, never cylindrical 



body. The proboscis is longer than the preclitellum. Clcpsine* Sav., 



common fresh-water form. They brood over their eggs, which are attached 



to some foreign body. In two species bioculata and heteroclitn the eggs 



are attached to the ventral surface of the body. After hatching the young 



attach themselves to the ventral surface of the mother. Batrachobdclla 



Viguier, on Batrachians, Algeria ; Haementaria de Fil. ; 2f. mexicana de Fil. , 



H. officinalis de Fil, both in the lagunes of Mexico, the latter used for 



medicinal purposes ; H. Ghilanii de Fil., in the Amazon. 



Fam. 2. Gnathobdellidae. Fresh-water and land leeches with jaws, without 



protrusible proboscis, with red blood ; the complete segments have five rings. 



With botryoidal tissue. 



Sub-fam. 1. Nephelidae. With 19 complete segments; the sexual 

 openings are separated from one another by two rings. Eyes are never 

 present on the 6th segment, 4 pairs only. Ncphelis Sav. (Herpobdclla 

 Blainv.), without hard jaws, feeds on snails and planarians ; Liostomum 

 Wagler ; L. lumbricoidcs, lives in the earth after the fashion of earthworms, 

 which it resembles, Brazil. Macrobdclla Phil.; Trochctia Dutroch., jaws 

 vestigial, without teeth, 4 pairs of eyes ; it is a water-leech, but leaves the 

 water to feed on earthworms, continent of Europe, has been introduced into 

 England ; Archacobdella 0. Grimm, A. esmonti 0. Grimm, from the mud 

 at the bottom of the Caspian. 



Sub-fam. 2. Hirudinidae. With 16 complete segments ; sexual openings 

 separated by 5 rings ; 5 pairs of eyes. Hirudo Ray and Linnaeus, with 

 102 rings ; eyes on the three anterior rings, and on the fifth and eighth ; 

 male opening between rings 30 and 31, female opening between rings 35 and 

 36. The three jaws are finely serrated, and can be moved like a circular 

 saw in a manner well-adapted to make a wound, which readily heals, in 

 the external skin of man ; aquatic, but deposits its cocoons in damp earth. 

 H. Mcdiciixtlis Ray, with the variety distinguished as officinalis, possesses 

 80-90 fine teeth on the free edge of the jaws, and attains a length of about 

 6 inches. They were formerly common in Germany, and are still frequently 



* The genus Glossiphonia Johnson has priority over Clepsine, but whether it 

 is advisable to give up a name so well-known as Clepsine is a doubtful question. 



