31 



TAB. LXXVI. 

 HIRUDO circulans. 



Gen. Char. Body oblong, truncate at both ends, 

 unarmed, cartilaginous, and moves by dilating 

 the head and tail, and contracting into an arch. — 

 Turton. 



Spec. Char. Oblong, acuminated towards the head, 

 convex above, flat beneath, dull red. 



I POUND this curious Leech on the Thames side in 1800^ 

 and T believe it is not very rare. It is excellent for showing 

 the circulation of the blood, through a curiously disposed 

 set of vessels about three quarters of its length, at one pulse. 

 The head seems to have two eyes, and the mouth is apparently 

 underneath, being a small roundish aperture. The animal 

 is about an inch long when stretched out, and only half an 

 inch in length when contracted. It is very flexile in its 

 motions ; and, like all leeches, it can attach itself by its 

 posterior end, but at the head has less of that adhesive 

 property, and very seldom uses it. The upper side is 

 convex, and obscurely striated across. The under side is flat, 

 and appears nearly as in the magnified figure in the middle 

 of the plate. 



