Edible Snail. 51 



United States ; see also Semper, in Siebold and Kolliker's 

 Zeitschrift fur Wiss. Zool._, viii. 1857, p. 340; and for the 

 points of difference between the reproductive apparatus of the 

 Old and New World Pulmonata, see Leidy, 1. c. p. 229. 



For a monograph of Helix Pomatia, see Cuvier, Memoires pour 

 servir k THistoire et k 1' Anatomic des MoUusques, 1817, or 

 Annales du Museum, torn, vii., 1806. 



For the reproductive apparatus, see Owen, Comp. Anat. Inverte- 

 brata, p. c^6%; Baudelot, Ann. Sci. Nat. Ser. iv., tom. xix., 

 p. 170, pi. ii. fig. 17, 1862. The identifications of the various 

 organs adopted by the two latter authors, differ from those 

 adopted by Cuvier and Leidy, but are doubtless more correct. 



16. Edible Snail {Helix Pomatia), 



Dissected so as to show the position of the heart, and the respiratory cavity. 



The greater part of the shell has been removed, but a part of 

 the spire has been left in situ. An incision has been made trans- 

 versely through the roof of the pulmonary sac, and its cavity 

 has been exposed by turning forward the anterior flap. The vessels 

 have been injected with a red-coloured fluid from the auricle. The 

 bilocular heart is seen, as in dextral molluscs, on the left side, and 

 posteriorly, and, in this preparation, inferiorly to it is seen the 

 triangular pale-coloured kidney. Along the front border of the 

 posterior section of the roof of the pulmonary sac, the pulmonary 

 vein is seen passing towards the apex of the pyramidal auricle. 

 Just before entering it is joined, as not rarely in mollusca, by 

 the efferent renal veins. The right half of the roof of the re- 

 spiratory cavity is covered by vascular ramifications ; the anterior 

 part of the left half is destitute of them, the posterior corresponds 

 to the kidney, or is constituted by the ' pericardium." The non- 

 vascular floor of the respiratory cavity is seen to be formed by 

 muscular fibres, arranged somewhat after the fashion, and doubtless, 

 during Hfe, performing some of the functions of a diaphragm. 

 A more delicate muscular layer enters into the formation of the 

 roof of the sac, taking origin from a thickened band which runs 



E 2 



