80 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



of the mid-gut to the posterior end. On the dorsal side of 

 the anterior region, in the median line, a typhlosole (t.y.) 

 is formed by the floor of a groove being re-invaginated ; 

 posteriorly, the sides of the groove widen out into an 

 elongate spoon-shaped structure. The function of the 

 typhlosole is probably not, as is usual, to assist in the 

 absorption of food, but to provide a channel along which the 

 secretion of the hepatopancreas is able to flow to the middle 

 region of the intestine. In the middle region of the mid- 

 gut the epithelial cells exhibit a very regular arrangement. 

 They are arranged in double rows, which run out in an 

 oblique direction from the median line. The rows of cells 

 project into the body cavity, so that grooves are formed 

 between the double rows. In these grooves the muscle 

 fibres are lodged, underneath the blood-vessels from the 

 intestinal arteries. The posterior region is marked by the 

 presence of the sphincter muscle, which separates the mid- 

 gut from the rectum. In the sphinctal region the faecal 

 pellets are formed. 



The rectum is a short uniform tube opening by the 

 longitudinal slit-like anus. 



The salivary glands. There are two pairs of salivary 

 glands situated in the cephalon, on each side of, and 

 opening into, the oesophagus. Each is made up of 

 a large number of rosette-like masses of gland cells, which 

 are very similar to the mucous glands described by Allen 

 (1892) in Palaemonetes. In section, they have the 

 appearance shown in the figure (PI. II., fig. IT). Each 

 acinus is made up of a number of concentric 

 cells, in which two regions can be recognised — a peripheral 

 cytoplasmic region containing the nucleus, and a central 

 glandular region. Each of the cells has at its internal 

 apex an intracellular duct (zed.), which opens into a duct 

 common to the mass of cells (c.d.). This duct is probably 



