24 Proceedings of the Royal Society of Victoria. 



entrance of food into the food cavity of the mastax. Sections 

 show the mastax (Fig. 3, ma.) to be of considerable complexity. 

 Seen from the dorsal in the living animal it appears as a tri- 

 lobed mass, the mallei being imbedded in the lateral lobes, and 

 the incus in the posterior. Sections show that the food enters 

 a cavity of heart-shaped section seen ventrally (Figs. 7 and 8, f.c.) 

 and this extends dorsally, becoming crescentic in section more 

 towards the dorsal portion of the mastax (Fig. 10, f.c). This 

 food cavity, as for convenience T name it, has at the ventral end 

 a membranous floor (Figs. 5, 7, 8, s.m. ) which continues doi'sally 

 and joins the lateral lobes on their anterior surface. More 

 dorsally it is seen as two membranes joining the roof of the food 

 cavity with the lateral lobes, so that each side forms an inclined 

 plane to direct the food particles between the ci;tting points 

 of the unci. Below the unci, in that portion of the mastax 

 dorsal of the fulcrum, there is a lower portion of the food 

 cavity (Fig. 10, f.c). The upper and lower portions of the 

 food cavity are thus separated off when the unci are closed. 

 The food cavity is strongly ciliated at the ventral part on either 

 side of the slit (Figs. 5 and 7, f.c); above the unci on the roof, 

 and below on the doi'sal portion excavated out of the middle of 

 the mastax, are ridges of very thickly packed cilia (Figs. 5, 8, 9, 

 10, cil.m.). The opening into the oesophagus is close to the 

 dorsal surface of the animal. The food cavity at its ventral 

 part is separated on its sides and floor by the separating 

 membrane (Figs. 5, 7, 8, 9, s.m.) from a cavity, portions of 

 which are shown in Figs. 5, 6, 7, 8 and 9 (n\.c.). I was unable 

 to discover any opening into the food cavity or coelom from this 

 mastax cavity. Fig. 10 shows that it does not extend the whole 

 length of the mastax. The separating membrane is exceedingly 

 delicate, and it was by the presence of food particles (Fig. 8, f.p.) 

 always on one side that the food cavity and the mastax cavity 

 were found to be distinct. 



It will be noticed that in all the horizontal sections the 

 mastax cavity appears as two separate portions, but I think 

 it very probable that communication is made by means of the 

 portion m.c (Fig. 5) and have therefore treated it as one. The 

 trophi (Fig. 11) when dissolved out with chlorinated soda are 

 seen to be of the malleo-ramate type, characteristic of the genus 



