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, Let.) 

 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.l.t.). 

 Posteriorly, the closure of the entrance to the stomach is 

 effected by a ventral transverse setiferous ridge, the 

 ventral cardiac tooth (y.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.l.t.). On each side of the cardiac region of the stomach, 

 a narrow lamella, the lateral cardiac lamella (l.c.L) 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.L), 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 



