ANATOMY AND PHYSIOLOGY OF PATELLA VULGATA. 637 



Fig. 39. Muscular fibres of the auricle ( x 250). 



Fig. 40. Pericardium ( x 250). a, superficial clear membrane ; b, subcutaneous connective tissue ; c, 



muscular fibres attaching auricle to the pericardium. 

 Fig. 41. Diagramatic representation of heart and its vessels. b.vn., branchial vein; p., circular 



muscle; b., pericardium;/, left renal papilla; g., anal papilla; a., auricle; v., ventricle; 



d.d'., right and left aortse ; e., left nephridium ; c, aur. vent, valve, 

 Fig. 42. Blood corpuscles. 



Fig. 43. Heart and vessels, pericardium removed. (Letters as in fig. 41.) 

 Fig. 44. Auriculo-ventricular valve. 

 Fig. 45. Muscular fibres of ventricle. 



PLATE CLII. 



Fig. 46. Diagramatic section of shell, showing the arrangement of the lamina?. 



Fig. 47. Section of shell, showing the three layers and lamina?. 



Fig. 48. Do. do., magnified ( x 50). a, upper; 6, r middle; 



c, lower layers. 



Fig. 49. Superficial layer of shell. 



Fig. 50. Nervous system, semidiagramatic. ct., ctenidium; p.s.b., posterior superior buccal ganglion ; 

 a.s.b., anterior superior buccal ganglion; i.b., inferior buccal ganglion; e.g., cerebral 

 ganglion; e., eye; ex., cerebral commissure; c.p., cerebro-pedal commissure; c.v., cerebro- 

 visceral commissure ; v.g., visceral ganglion ; p.g., pedal ganglion ; p.n., pedal nerve ; 

 p., pallial nerve ; m., muscle nerve ; l.s., left splanchnic ; r.s., right splanchnic ; r., recurrent 

 nerve ; I., tentacular ; II., cutaneous ; III., ocular ; IV., posterior pharyngeal ; V., 

 anterior pharyngeal ; VI., labial nerves. The outer dotted and inner dotted lines represent 

 the outlines of the buccal mass and the pharynx respectively. 



Fig. 51. Nerve elements. (1) nerve — c, isolated fibre; (2) cells of a ganglion — a, rounded, b, 

 bipolar. 



Fig. 52. Vertical section through the nuchal tentacle, showing separate origins of tentacular and ocular 

 nerves, and of the cerebral and visceral commissures from the cerebral ganglion, a, super- 

 ficial layer of ganglion cells ; b, visceral commissure ; c, ocular nerve ; d, tentacular nerve ; 

 /, epithelium of tentacle ; e, the ocular mound ; g, cerebral commissure. 



Fig. 53. Semidiagramatic representation of intestinal coils. ph., pharynx; cr., crop; «., anus; 

 /•., rectum ; s. and s'., stomach. 



Fig. 54. Face view of mouth, a, radula ; b, palate ; c, inner lips ; d, outer lips. 



Fig. 55. Section of the lower plate, a, cuticle ; 6, stratified columnar epithelium ; c, connective 

 tissue ( x 50). 



Fig. 56. Same, magnified ( x 250). 



Fig. 57. Section of liver ( x 150), showing hepatic tubes cut in transverse section. 



Fig. 58. Liver cells, connective tissue ( x 450). 



Fig. 59. Liver cells, isolated ( x 500). 



Fig. 60. Eadula, two rows of teeth. 1 and 2, lateral teeth ; 3, median tridenticulate ; 5 and 4, central 

 unidenticulate. 



PLATE CLIII. 



Fig. 61. Pharynx and salivary glands, dorsal neck wall removed, a.b, ducts of salivary gland of right 

 side, d ; c, pharynx ; e, buccal mass ; /, lobe of pharynx ; g, intestine. 



Fig. 62. Vertical section through neck, a, inner lip ; b, upper (palatal) plate ; c, lower (ventral) 

 plate ; d, pharyngeal wall ; e, anterior cartilage ; /, radula ; g, ventral protractor muscle ; 

 h, superficial transverse muscle ; Jc, longitudinal muscle ; I, deep transverse muscle ; m, 

 posterior cartilage ; n, muscles of the subradular membrane ; o, nuchal body cavity. 



Figs. 63. and 64. Dorsal and ventral views of the upper (palatal) plate. 



Fig. 65. Ventral view of buccal mass. a, ventral protractor reflected ; b, terminal radular plate 

 reflected ; b', radula ; c, longitudinal muscles ; d and e, superficial and deep transverse 

 muscles. 



VOL. XXXII. PART III. 5 N 



