CLASS AXNKL1DA. 31 



terranean tunnels, come to the surface of the water, and 

 there swim about. Some species reach eighteen inches 

 in length. 



The famous Autolytus (a tol'i tus) is also a marine 

 Annelid, and a closely related form. The young of this 

 animal have a general resemblance to the Clam-worm, 

 though they are of much smaller size. After the worm 



FIG. 42. 



Au tbl' y tus cor nu' tus, subdividing into two individuals. 



wanders about for some time, one of its middle segments 

 begins to take on the appearance and structure of a 

 head and the posterior part of a body, and finally breaks 

 away, a complete animal, free to move about and to de- 

 posit eggs. These eggs will produce other worms, which 

 will, in their turn, go through the same process of self- 

 division. 



ORDER DISCOPHORI (clis kof'o rl). 



The Leeches generally have the mouth surrounded by 

 a sucking disk, while there is also a similar disk on the 

 posterior end of the body. Dissection reveals a metam- 

 erous (me tam'er us) (in parts or segments) arrangement, 

 for the digestive, nervous, and excretory systems. The 

 Leeches used in medicine, are imported from France, 

 where they are raised in large numbers.* The mouth is 



* The Leeches grown in our own waters, especially the genus that furnishes 

 the large variety, serve also for medicinal purposes ; and, if baited by applying a 

 little blood to the inflamed part, will attach themselves as readily as the imported 

 ones. When gorged, they let go their hold of their own accord. If then a little 

 salt be put upon their sucking disk, they at once disgorge themselves and are 

 again ready for service. 



