ROTIFERA 789 



attached to themselves, and to the interior of the mastax. that the 

 imci rise and fall at the same time that the rami open and shut. 

 The food is torn by the unci, crushed by the rami, and then passes 

 between the latter down a short oesophagus (ce) into the stomach (s). 

 This has thick cellular walls, and is lined with cilia, especially at its 

 lower third, which is often divided by a constriction from the upper 

 part, and is often so different in its shape and contents as to merit 

 the name of an intestine (i). The lower end of the intestine gene- 

 rally expands into a cloaca (cl), into which open the ducts of the 

 ovary (oy\ and contractile vesicle (cv). Just above the mastax, 

 and sometimes just below it, on the oesophagus, are what are sup- 

 posed to be salivary glands ; while ttached to the upper end of 

 the stomach are two gastric glands^ 

 (gg), often possessing visible ducts. 

 There are two further glands (fg) 

 in the foot, which is itself a prolon- 

 gation of the ventral portion of the 

 trunk below the aperture of the cloaca. 

 These foot-glands secrete a viscid sub- 

 stance which is discharged by ducts 

 passing to the tips of the two toes (t) 

 and which serves to attach the animal 

 to one spot when it is using its frontal 

 cilia to procure food. FIG. 602. Malleate type of jaw. 



Longitudinal muscles (Im) for with- < U s, uncus. 



drawing the head and foot within the 3 r>nm - > manubrium. 



lorica can be readily seen, and these is, incus | ^ r ^^ m 



parts are driven out again by the 

 pressure of transverse muscular fibres acting on the fluids of the 



On either side of the body is a tortuous tube commencing in a 

 plexus in the head and running down to open on the contractile 

 vesicle (cv). These tubes bear little tags (vt), each of which appears 

 to contain a vibrating cilium. The real structure of these bodies is 

 uncertain, and the use of the whole apparatus is much disputed ; 

 but the tags are possibly very minutely ciliated funnels, their free 

 ends open to the body-cavity ; and it seems probable that the fluids 

 of the body-cavity are conducted through them, along the tortuous 

 tubes, into the contractile vesicle, and are by it discharged into the 

 cloaca. The apparatus would therefore be mainly an excretory one. 1 



There is a bilobed nervous ganglion (gii) between the buccal 

 funnel and the dorsal surface. Above it is the eye (e) a refracting 

 sphere on a mass of crimson pigment. From the ganglion pass 

 nerve-threads to a dorsal antenna (a) and to two lateral antennce (a f ) 

 on either side of the dorsal surface. These latter organs are rocket- 

 headed terminations of the nervous threads, and have each a bundle 

 of fine hairs passing through a hole in the lorica. The dorsal 



1 But see Dr. Hudson's Presidential Address, Journ. of the Boy. Microsc. Soc. 

 Feb. 1891, p. 13, in which reasons are given for suspecting that the contractile vesicle 

 may also have a respiratory function, and the vibratile tags and longitudinal canals 

 an excretory one. 



