MASTICATING APPARATUS OF ROTIFERA. 



473 



the substance of which these firm structures are composed ; it is 

 not affected by solution of potass, but is instantly dissolved with- 

 out effervescence by the mineral acids and by acetic acid. Besides 

 the muscles already described, a thick, band (j) embraces the upper 



Fig. 245. 



Masticating Apparatus of Euchlanis deflexa : — a, Mastax ; c, ma- 

 nubrium, and e, uncus, of Malleus ; g, rami, and h, fulcrum, of 

 Incus ; i, muscle connecting ramus and uncus ; j, muscle passing 

 from malleus to mastax ; fc, muscle connecting uncus and manu- 

 brium ; m, buccal funnel ; n, salivary glands ; p, oesophagus. 



and outer angle of the articulation of the malleus ; and is inserted 

 in the adjacent wall of the mastax ; and a semicrescentic band (k) 

 is inserted by its broad end into the inferior and basal part of the 

 uncus, and by its slender end into the middle of the inner side of 

 the manubrium ; the former of these may be considered as an 

 extensor, and the latter as a flexor, of the malleus. By these 

 and other muscles which cannot be so clearly distinguished, the 

 unci are made to approach and recede by a perpendicular motion 

 on the hinge-joint, so that their opposing faces come into contact, 

 and their teeth bruise-down the particles of food ; but at the 

 same time they are carried apart and approximated laterally by 

 the movement of the free extremities of the manubria. The rami 

 of the Incus also open and shut with the working of the Mallei : 

 and by the conjoint action of the whole, the food is effectually 

 comminuted in its passage downwards. 



358. The form of the Alimentary Canal varies ; this being some- 

 times a simple tube, passing without enlargement or constriction 

 from the masticating apparatus to the anal orifice at the posterior 

 part of the body ; whilst in other instances there is a marked dis- 



