*26b' TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



crop folds. Sec.F.Gr. = Radial secondary folds 



on the transverse crop folds. x 15. 

 Fig. 19. The bend of the stomach (Yin fig. 10a) showing the 



opening of the duct of the hepato-pancreas 



(D.H.P.). St.Gr. — Groove in stomach wall. 



V.St. = Valve hindering back flow of the secretion 



of the hepato-pancreas. x 3. 

 Fig. 20. Transverse section of ridges and groove in stomach 



wall of a young specimen (after Haller). Highly 



magnified. 



Plate III. 



Fig. 21. Transverse section across the rectal papilla, x 20. 



Fig. 22a — ■/. A series of transverse sections of gullet and crop 

 (the posterior faces of the sections are drawn) 

 showing the migration of the points of attach- 

 ment of the longitudinal folds {D.F.G. and 

 V.F.G.) through an angular distance of over 270°. 

 D.F.G. = Dorsal fold of gullet. V.F.G. = Ventral 

 fold of gullet, x 10. 



Pig. 23. Nervous system of Patella vulcjata ; — Buc. = Buccal 

 commissure. Buc.G. = Buccal ganglion. Cer.= 

 Cerebral ganglion. Cer.C. — Cerebral commis- 

 sure. C.-Pcd. — Cerebro-pedal connective. C.-Pl. 

 = Cerebro-pleural connective. Lab. = Labial 

 commissure. L. Osph. G. = Left osphradial 

 ganglion. Op.N. = Optic nerve. Ot.N. — Otocyst 

 nerve. Ot. = Otocyst. Fed. = Pedal nerve-cord. 

 PI = Pleural ganglion. Pl.-Ped. = Pleuro-pedal 

 connective. Peel. Anas. = Pedal anastomoses. 

 There are two such anastomoses. B.Osph.G. — 

 Right osphradial ganglion. Subces.C. = Sub- 

 cesophageal connective of the visceral loop. 

 S/ipinl. — Supra-intestinal ganglion of the 

 visceral Loop. T.N. — Tentacular nerve. V. = 

 Visceral loop. V.G. = Visceral ganglion. x 2. 



