380 JOURNAL, BOMBA Y NA TURAL HISTORY SOCIETY. Vol. XVIll. 



From the end of the pyloric ossicle on each side runs down to meet 

 the pterygocardiac another broader ossicle, the zygwardiac (Gr. zygon, 

 a yoke or crossbar), the ventral portion of which appears from the 

 interior of the stomach as a rough file-like surface and in front 

 terminates in a large curved yellow lateral tooth. 



Below the lateral tooth on each side is found a small pointed tooth 

 borne on an ossicle, the inner aspect of which is setose. There 

 are many other ossicles or sclerites in the stomach , but the above are 

 the most important. 



The transverse ossicles are acted on by muscles arising from the 

 carapace in front and behind, as well as by muscles passing between 

 them, which by their alternate action cause the teeth to clash 

 together and again separate so as to thoroughly chew the food. 



The passage from the cardiac to the pyloric chamber is narrowed 

 by lateral folds and a large tongue-like valve covered with hairs on the 

 ventral floor ; further back the pylorus is narrowed to a mere three- 

 rayed chink by the pushing in of its roof and the presence 

 of cushions on its sides, the whole being covered with hairs through 

 which only very finely chewed food can filter. With the pylorus the 

 cuticular lining ends, and the food passes into the mid-gut, the only 

 part of the canal lined with cells of hypoblastic origin. 



These cells are secretory in character and continuous with those 

 lining the two hepatic ducts which are seen opening on the floor of 

 the midgut. The large solid-looking yellow liver is in fact a tubular 

 diverticulum or off-shoot of the mid-gut, which in the earliest embry- 

 onic condition is only a small pouch or tube on each side, but later 

 on branches into an immense number of short blind tubes or cceca 

 (Latin, blind), which being closely packed together form the apparent- 

 ly solid mass of the liver, or hepato-pancreas. The cells are of two 

 kinds, liver-cells containing yellow oil globules and ferment cells which 

 produce the digestive secretion. 



The secretion is a slightly acid, yellowish fluid, containing many 

 oil-globules, and possesses the power of — 



(a) converting proteids into peptones, 



(b) turning starch into sugar, 



(c) emulsifying fats. 



The short mid-gut is followed by the straight hind-gut or procto- 

 doeum which as already pointed out is lined with cuticle, which forms 



