528 



CILIOBRACHIATE POLYPES ; BOWERBANKIA. 



at once, as in the inferior Polypes, into the stomach ; but it 

 forms the entrance to a wide funnel-shaped tube, which may be 

 termed the pharynx. This soon contracts 

 into a narrower canal, the oesophagus^ which ^ & ^ 



terminates at its lower end in the digestive 

 cavities. The first of these is an organ 

 which seems closely to resemble a gizzard. 

 It is of a globular form, and has two dark 

 spots upon its sides, from which radiating 

 lines are seen. These are probably composed 

 of muscular fibres, the office of which is to 

 effect the trituration of the food, by means 

 of the teeth that project from the inner wall 

 of the cavity. The gizzard opens at its 

 lower end into a larger bag, which seems to 

 be the true digestive stomach. Its walls 

 are thickly studded with spots of a rich 

 brown colour ; these appear to be caused by 

 minute follicles or sacs opening from its 

 cavity, in which bile is secreted for assisting 

 the digestive process. A fluid is poured out 

 from them which tinges the whole stomach, as 

 well as its contents, with the characteristic hue of that secretion; and 

 we may therefore regard these follicles as constituting the simplest 

 form of hepatic gland or liver, which we meet with in the animal 

 kingdom. It is easy for the comparative anatomist to trace the 

 gradual concentration of these scattered elements, up to the con- 

 solidated form in which they present themselves in the highest 

 grades of organisation (ANIM. PHYSIOL. 356). From the 

 upper part of the stomach, and by the side of the entrance from 

 the gizzard, arises the intestine ; the orifice of which is surrounded 

 by vibrating cilia. This passes up as a straight tube by the 

 side of the oesophagus, and terminates by a distinct orifice outside 

 the circle of tentacula. 



1100. The whole of this complex digestive apparatus floats 

 freely in the general cavity, formed by the integument of the 

 animal ; the space between being occupied by a clear fluid, and 



FIG. 624. BOWER- 

 BANKIA. a, oesophagus ; 

 b, gizzard ; c, stomach ; 

 d, orifice of intestine. 



