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 sht-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 (Pl. II., fig. 17). 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 (zc.d.), which opens into a duct 
common to the mass of cells (¢.d.). This duct is probably 
