WORMS. 309 



jaws are fixed on each side, all facing the medial line. 

 When it is projected, however, the two margins of 

 the longitudinal cleft become transverse in separating, 

 and the jaws follow the same movement, and diverge 

 in the ratio of their forwardness. A kind of lower lip' 

 which is affixed to the under side of the proboscis, is 

 composed of two horny blades united towards their 

 front extremity, and prolonged behind into points. 

 The jaws are to the number of seven ; three on the 

 right and four on the left ; the two upper ones are per- 

 fectly alike, and mutually opposed ; they are large, 

 narrow, pointed recurved hook-wise at the tip, and 

 jointed at their hinder ends on a double horny stem 

 shorter than themselves. The second pair of jaws are 

 large, broad and flat, mutually alike, and jointed on the 

 lower side of the first pair ; . . . their internal edge is 

 straight and cut into deep teeth. The third pair are 

 small, thin, concave, and notched ; they are affixed by 

 their inferior edge outside and in front of the second 

 pair, which they conceal during repose. Finally, the 

 supernumerary jaw, which is found on the left side 

 only, is small, semi-circular, toothed, and placed be- 

 tween the second and third pairs. All these pieces are 

 surpassed by the margin of the proboscis, which is 

 often hard and black." * 



From this complex and formidable mouth we will 

 pass to one of quite another form, not less effective, 

 perhaps more formidable, but ordained by the goodness 

 of God to be a most valuable agent in the relief of hu- 

 man suffering. I mean the Medicinal Leech, of which 

 we can readily procure a specimen from our friend the 

 apothecary. 



* Litt. de la France, ii. 138. 



