71 



/?.i?.P. = Renal aperture of reno- 



pericai'dial canal of right 



kidney. 

 B.S. = Radular sac. 

 S.C. = Sense cell of eye. 

 Scc.F.Cr. = Radial secondary 



folds on the transverse crop 



folds. 

 Scc.G. = Secondary or pallial gills. 

 S.L.P. = Sub-lingual pouch. 

 S.M. = Shell muscle. 

 S.-E. Lobe. = Sub-rectal lobe of 



right kidney. 

 S.R.M. = Sub-radularniembrane. 

 ,S7. = Stomach. 



Sl.Gr. = Groove in stomach-wall. 

 Sub-Ep.N.L. = Sub-epithelial 



nervous layer. 

 Sitb-Oes.C. = Sub-oesophageal 



connective of visceral loop. 

 Sup.-Int. = Supra - intestinal 



ganglion of visceral loop. 

 S.Z. = Sensory zone of mantle 



epithelium. 

 T. = Tentacle. 

 J'.N. = Tentacular nerve. 



r. Visceral loop. 



Vac.E. = Vacuolated epithelium 



beneath lateral streak. 

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

 V.G. = Visceral ganglion. 

 V.U. = Visceral hump. 

 I '. Tj.C. = Ventro-lateral cartilage 



of the odontophore. 

 V.-l.F. = Ventro-lateral folds of 



wall of rectum. 

 17. = Veinlet from mantle edge. 

 V.-Lobe. = Ventral lobe of right 



kidney. 

 Vn. — Ventricle. 

 I'.-S7. = Valve hindering flow of 



secretion of hepato-pancreas 



into anterior part of gut. 

 X is the point of connection 



between Int. 1 (Fig. 10a) and 



Int. 2 (Fig. 106). 

 Y. is the point at which the 



stomach folds on itself 



(Fig. 10«). 

 Z. is the anastomosis between 



the posterior pallial nerves 



of the two sides. 



The terms ri(//t^ and left are always used to signify post-torsional 

 relations unless otherwise specified. 



Plate I. 



Fig. 1. Extreme forms of shell of Patella vnlgata. Froni 

 specimens collected in the GoiUiot Caves, Bark. 



Fig. 2. Section through the shell, -i Thin brown external 

 layer, /i Thick middle layer: (a) outer part 

 traversed by branching canals ; (h) clear inner 

 part. C Internal laminated layer. ' x 15. 



Fig. 3. The animal in its shell — Ventral surface. H. — Head. 



Fig. 4. Dorsal view to show positions of organs. The 

 pigment layer of the mantle has been rubbed off 



