78 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
which project into the cavity of the stomach. The dorsal 
wall of the stomach is almost flat, and is continuous 
posteriorly with the mid-gut. The anterior end of 
the stomach is slightly oblique, and when seen 
from the upper surface is semi-circular. The plates 
and “teeth” which form the gastric mill are 
arranged in the following manner. On _ each _ of 
the lateral margins of the anterior end of the stomach 
a bilobed ampulliform triturating ‘ tooth’ (Fig. 15, J.c.t.) 
arises, and meets its fellow of the opposite side above the 
opening of the oesophagus. These lateral cardiac teeth 
are the chief masticatory agents of the gastric mill. 
Between these, on the anterior wall of the stomach, three 
teeth fill up the space, a small median anterior tooth 
(m.a.t.) situated between two antero-lateral teeth (a./.t.). 
Posteriorly, the closure of the entrance to the stomach is 
effected by a ventral transverse setiferous ridge, the 
ventral cardiac tooth (v.c.t.). In the preceding description, 
the word ‘tooth’ has been used to designate a chitinous 
protuberance of the wall of the stomach, which is covered 
with short, closely-set, re-curved setae. On the ventral 
side of the stomach, in the middle region, three tooth- 
shaped processes arise, their apices directed backwards; 
they are the median, ventral and ventro-lateral teeth 
(v./.t.). On each side of the cardiac region of the stomach, 
a narrow lamella, the lateral cardiac lamella (/.¢./.) runs 
in an oblique direction from the antero-dorsal region to 
the ventral side, and terminates near the ventro-lateral 
tooth. In the pyloric region of the stomach, a deep 
invagination of the dorsal surface forms a broad dorsal 
lamella (d./.), which extends across the dorsal side and 
half-way down the lateral sides. Between the lateral 
portions of the dorsal lamella and the wall of the stomach, 
two large lamellae (v.l.p.l.) have their lateral limits; these 
