PATELLA. 267 



Fig. 24. Dissection of mantle nerves in posterior region to 

 show the anastomosis (Z) between the posterior 

 pallial nerves (P.Pal.N.) of the two sides. The 

 dissection is supposed to be made from the 

 ventral surface, and a small portion of the skin is 

 left to show the pallial tentacles (see also Fig. 8). 

 X 8. (After a drawing by J. T. Jenkins). 



Fig. 25. Longitudinal section of the cephalic tentacle. T.N. — 

 Tentacular nerve, x 15. 



Fig. 26^. Section of eye epithelium, x 800. 



Fig. 266. Pigment cell of eye epithelium, x 1,500. 



Fig. 26c. Sense cell of do. S.G. = Sense cell. P.O. = Pig- 

 ment eel!. P.Z. = Pigment zone, x 1,500. 



Fig. 27«. Section of otocyst and nerve (after de Lacaze- 

 Duthiers). x 15. 



Fig. 27fr. Epithelium of otocyst cavity. 



Fig. 28. Section of osphradium, etc. Osph.G. = Osphradial 

 ganglion. Os.E. — Osphradial epithelium. E.G. 

 — Rudimentary gill (ctenidium). x 180. 



Plate IV. 



Fig. 29. Heart of Patella. N.B. V. = Veins from the nuchal 

 roof. Ant.Ao. = Anterior aorta. L.Au. — 

 Auricle (morphologically left). Post. A. = 

 Posterior artery. Vn. — Ventricle, x 3. 



Fig. 30. Eight kidney (after Lankester). A.-D.Lobe = Antero- 

 dorsal lobe. P.-V.Lobe = Peri-visceral lobe. 

 S.-B.Lobe — Sub-rectal lobe. V.Lobe = Ventral 

 lobe, x 1J. 



Fig. 31. Diagrammatic transverse section showing the position 

 of the renal aperture (B.B.P.) of the renoperi- 

 cardial canal of the right kidney. The anterior 

 face of the section is drawn, x 80. 



Fig. 32a. Diagram illustrating the structure of the kidney. 

 K.C, = Kidney cavity, x 300. 



