320 



ANNELIDA 



Key to the families of Gnathobdellida : 



! Three toothed jaws present .............................. 1. HIBUDINIDAE 



o 2 Three unarmed muscular ridges present in place of the jaws. 



2. HEBPOBDELLIDAE 



FAMILY 1. HIKUDINIDAE. 



Leeches with 3 toothed jaws; segment contains 5 rings; 5 pairs of 

 eyes: several genera. 



1. HIRUDO L. Elongate, flattened leeches with about 95 annula- 

 tions; margin of body serrate; crop with about 10 pairs of lateral 



pockets; teeth very numerous, over 100 in 

 number; body contracts and does not roll 

 up: numerous species. 



H. medicinalis L. The medicinal leech. 

 Body yellowish-brown, 10 to 20 cm. long: 

 an European animal which has been intro- 

 duced into some ponds and streams in the 

 eastern United States; used for blood- 

 letting. 



2. HJEMOPIS Savigny. Body rather thick, 

 with smooth margins; crop with 1 pair of 

 caeca but without lateral pockets; teeth few, 

 about 20; 5 pairs of eyes. 



H. marmoratis (Say). The horseleech. 

 Body 10 cm. long or more, 15 mm. wide, 

 smooth, and very soft; color variegated, 

 being blackish or brownish, blotched with 

 irregular spots: in the mud at the side of 

 pools and streams and also occasionally 

 on the land; will occasionally suck blood but usually eats worms, 

 snails, etc. 



H. grandis (Verrill). Body 20 cm. long or more, specimens 45 cm. 

 having been found; color yellow, mottled with black; the largest 

 American leech: New England, the Great Lakes, and westward. 



3. MACROBDELLA Verrill. Body strongly annulated, broad and flat- 

 tened, and tapering but little; about 65 teeth on each jaw; male orifice 

 between segments 26 and 27 and the female orifice between segments 

 31 and 32: 3 species. 



M. decora (Say). Body up to 30 cm. long and 25 mm. wide, brown 

 or olive green in color, with a median row of about 20 red spots and a 

 row of black spots near each margin; lower surface reddish: very com- 

 mon in fresh water, a fierce blood sucker, attacking men, cattle, fish,, 

 frogs, etc., but also eating other animals, 



Fig. 504 



Fig. 505 



Fig. 504 Herpobdella punc- 

 tata (Moore). Fig. 505 Her- 

 pobdella fervida (Moore). 



