56 THE AMPHINEVURA 
II. ANATOMY. 
Digestive Tract—The mouth is anterior and ventral, and is 
frequently surrounded by papillae, probably sensory in function. 
It opens into a muscular and sometimes protractile pharynx lined 
by a thick cuticle. The salivary glands and radular sac open into 
the pharynx. The radula (Fig. 36), when present, comprises several 
rows of teeth, and may be (1) polystichous, with a continuous line 
of teeth in each row (Proneomenia and Macellomenia), in which case 
a basal membrane may be present, forming a true continuous 
polyserial radula (Proneomenia acuminata, P. sluiteri, P. gerlachet), or 
absent, forming a discontinuous polyserial radula (P. vagans) ; (2) 
distichous, with two separate teeth (Paramenia, Pararhopalia, Ismenia, 
gp 7A 
ip 
ge : 
Fia. 36. 
Radula (transverse rows) of various Neo- 
meniomorpha. A, Proneomenia (Hubrecht) ; 
b, Lepidomenia (Kowalewsky and Marion); 
C. MUU C, Macellomenia (Pruvot); D, Amphimenia 
(Thiele) ; 2, Stylomenia (Pruvot). 
Lepidomenia, Dinomenia); (3) monostichous, with a single tooth 
(Stylomenia, Dondersia, Amphimenia, Proparamenia). The radula is 
entirely absent in the Neomeniidae, in Rhopalomenia, Pruvotia, 
Strophomenia, and Notomenia. 
The salivary glands form a symmetrical pair, lying on the 
ventral side, and opening on a subradular prominence ; their ducts 
sometimes unite before opening into the pharynx. They correspond 
to the subradular glands of the Polyplacophora and the posterior 
salivary glands of the Cephalopoda. In some forms there is a 
second pair of salivary glands, dorsal or dorso-lateral in position, 
opening by a single duct into the mid-pharynx (Paramenia, some 
species of Proneomenia: Fig. 37, gl.s.d). Several genera, among 
them NVeomenia, are devoid of salivary glands. The oesophagus is 
generally short, and leads into a cylindrical and rectilinear stomach, 
which frequently sends forward a caecum dorsad of the oesophagus, 
and is provided with symmetrical lateral caeca, giving to the organ 
the appearance of regular segmentation. The whole surface of the 
