[NTERNAL ANATOMY OF SQUILLA. 
415 
cells of tlie bladder- wall and at the lower end with the cells of 
the hypodermis (the hypodermis has shrnidv away from the 
cuticle all round the opening of the duct to the exterior). This 
clump of cells thus does not appear to form an ordinary 
sphincter muscle^ since the muscle-fibres are not disposed 
Text-fig. 8. 
C.P.Co!. 
Opening of the gland. Bl. Lower portion of bladder. Op. 
Opening of duct. F. Col. Patch of columnar epithelium at duct 
opening, the lower cells of which are, in life, connected {C. P. Col.) 
with the two curious plug-like bodies situated in the cuticle 
{Cut.). Gl. Transverse section across one of the numerous 
small multicellular seta glands (driisenzellen) . The hypodermis 
has shrunk away from the cuticle. ( X 384). For other 
reference letters see p. 429. 
circularly round the narrow duct and they are only developed 
in the inner wall. If this clump of cells be examined carefully 
it is seen that the outer ends of most of these cells (containing 
denser cytoplasm) are in close contact with a thick strip of 
cuticle which extends up the inner wall of the duct and 
nowhere else, and that those cells situated at the extreme end 
