'21)4 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



and the nuchal roof removed. M.T. = Pallial 

 tentacle. Os. = Osphradium. x 1^. 



Fig. 5. The animal seen from the left anterior point of view 

 (diagrammatic and based upon published figures). 

 The nuchal roof has been removed, x 2\. 



Fig. 6. Diagrammatic sagittal section — most of the blood 

 sinuses, also the kidneys and nerves are omitted 

 for the sake of clearness. B.C. — Buccal cavity. 

 D.P. — Dorsal palatal plate. I.L. — Inner lip 

 (not in median section). O.L. = Outer lip. 

 N.B. = Nuchal roof. Oes.P, = Tissue of oeso- 

 phageal pouch. Pap. — Eidged papilla. S.L.P. 

 = Sublingual pouch, x 2J. 



Pig, 7. A small portion of the ventral surface of the mantle 

 showing the circulatory arrangements. VI. — 

 Veinlet from mantle edge. G.V. = Veinlet from 

 pallial gill, x 10. 



Plate If. 



Fig. 8«. Diagrammatic transverse section of a very young 

 specimen to show the lateral streak, the arrange- 

 ment of fibres in the foot, the relations of the 

 kidney cavity, the structure of the mantle skirt, 

 X 35. D.Pal.-QL — Dorsal pallial gland-tissue. 

 Ep.F. = Epithelial fold. Fl. = Flap of Lateral 

 (" Epipodial ") streak. 67/. = Gland tubules of 

 Lateral (" Epipodial ") streak. Lett. St. = Lateral 

 ("Epipodial") streak. PaLGl. = Pallial ^gland- 

 tissue. PaLM. = Pallial muscle. Pal.N. = Nerve 

 in mantle tissue. Ped.S. = Pedal sinus. Sub- 

 Ep.N.L. — Sub-epithelial nervous plexus. S.Z. = 

 Sensory zone of mantle epithelium. Vac.E. = 

 Vacuolated epithelium beneath the lateral streak. 



Fig. fib. Epithelium of one of the folds of a pallial tentacle in 

 cross-section (after Haller). Highly magnified. 



