Alimentary System of Gryllotaljya aitstralis. 123 



The cell wall is composed of a single layer of epithelial cells, 

 and the tunica propria is surrounded by scattered radial and 

 longitudinal muscle fibres. The general shape of the cells is 

 columnar, but in parts they are cubical, and the whole internal 

 face is covered by a very thin hyaline cuticle. The cell-wall 

 frequently leaves the muscular bed and infolds transversely and 

 longitudinally, thus forming little spaces where I have sometimes 

 found " wandering " blood cells. Normally, the blood would 

 always be present in these spaces, but unless entangled among 

 the muscles or trachete, any cells would be lost in the prepara- 

 tion of sections. 



On the ventral floor of the posterior two-thirds there is 

 a fundamental change of structure ; the epithelial cells are 

 altogether wanting, and there exists only a thin nucleated 

 structureless membrane, over which the cuticle lies. This area 

 is much wrinkled, and here and there are short longitudinal 

 folds, forming low ridges, which rise into the lumen, w^ith 

 spinous processes pointing posteriorly ; also there are villi 

 of varying length, which at first are few and scattered, but 

 gradually become crowded together towards the narrower end 

 of this part of the canal. These villi (Fig. 10) have the 

 appearance of minute fox-tails, which stretch into the lumen; 

 they vary in length somewhat, but generally are about -25 mm. 

 long. They are formed by ingrowth, or invagination of the 

 chitinogenous layer, with the result that little hollow finger- 

 shaped crypts or follicles are formed, into which the blood 

 can enter. Each villus has several deep radial folds or pleats, 

 with their anticlinal axis bordered with spinous processes which 

 project into the cavity of the canal, and between these folds are 

 consequently little furrows into which the digested food material 

 can enter, but the granular material is prevented from so doing 

 by the spinous guards. 



However, I have not proved that they function in this manner. 

 I have observed "wandering" blood cells in their cavity (Fig. 

 11), but whether they carry excretory products, or receive 

 digested food, I am unable to definitely say. 



The termination of the villous area marks the posterior limit 

 of the mid-terminal canal. 



