WORMS. 



157 



Fio. 90. 



with one another; the intestine terminates on the back 

 at the base of the posterior sucker; in these chambers 

 the creature stores the blood which it takes in at its 

 anterior sucker. Like all worms, the leech is made up 

 of rings, of ^hich it has ninety-five. Powerful muscles 

 are attached to the skin, and enable it to contract with 

 great force. It then takes the form of an olive, while 

 when the muscles are relaxed it stretches out like a long 

 ribbon. 



As in all worms, the nervous system consists of a gan- 

 glionic chain united by an 

 cesophageal band with a 

 bilobar anterior ganglion. 

 The eyes are ten in number, 

 being ocular points situated 

 on the upper lip. 



Certain creatures that 

 were long considered to be 

 infusoria are* properly con- 

 sidered among the worms : 

 they are the rotatoria. 

 These are microscopic crea- 

 tures, furnished in front 

 with two or more ciliary 

 lobes. Cilia are a sort of 

 very fine hairs animated 

 with a continual motion, 

 which, however, can be ar- 

 rested at the will of the ani- 

 mal ; the movements of the 

 cilia are called vibratile movements. These creatures 

 can support a state of great desiccation and also, after 

 drying, a tolerably high temperature, and yet, when a 



14 



HYDATINA SEUTA (Rotifera, Hudson 

 and Gosse). a, female, dorsal 

 view; b, male, ditto. 



