256 PEOCEEDIXGS OF THE MALA.COLOGICAL SOCIETT. 



Leaving; now the consideration of the shell, I will briefly note the 

 sinistral characters of tlie animal of P. corneus. The position of the 

 orifices on the left side has already been mentioned as distinctive of 

 the sinistral Pulmonates, and has been known since the time of 

 Swammerdam ; but the studies of Lacaze-Duthiers have also shown 

 us that, as in Pkysa, the left visceral ganji'lion is larger than the 

 right, and that it gives rise to a left pallial nerve ending in an 

 osphradium on the left side. This osphradium, moreover, possesses 

 but one epithelial coccum, whereas in all dextral Pulmonates, the 

 right osphradium has tivo coeca, and the right visceral ganglion is 

 larger than the left. 



In conclusion I would add that, in studying the literature of this 

 subject, I have been greatly indebted to Prof. G. 15. Howes, Mr, 

 M. r. Woodward, Mr. B. B. Woodward, and Mr. S. Pace. 



Bihliographj. 



CuviER.— Ann. Mus. d'Hist. Nat. Paris, vol. vii, p 194. 1806. 

 QuATREFAGES. — " Eiubryogduie de Planorbis " : Ann. Sci. Nat., vol. ii. 



1834. 

 Des Moulins. — Bull. Soc. Linn. Bord., iv. 1836. 

 Jacquemin. — Nova Acta, vol. xviii. 1836. 

 Naumann. — " Ueber die Conchospirale von P. corneus ^^ : Abh. 



Math.-Phys. Classe der K. Gesellsch. Wiss. Leipzig, i. 1852. 

 MoauiN-TANDON. — Moll, de France, i, ii. 1855. 

 MoKCH. — " Le Planorbis, estil dextre?'': Journ. Conch. Paris, ii. 



1862. 

 PiRE. — Ann. Soc. Malac. Belg., vii. 1871. 



Lacaze-Duthiers. — " Syst. nerv. des Gast." : Arch. ZooL, i. 1872. 

 Fischer. — " Coq. des jeunes Planorbis '^ : Journ. Conch. Paris, xxv. 



1877. 

 Pfeffer. — "Die Windungsverhaltnisse der Sch. von Planorbis'''' : 



Jahrb. Hamb. Wiss. Anstalten, vii. 1890. 

 Vox Jheking. — Bull. Sci. Franc, et Belg., xviii. 1890. 

 Lang. — " Yersuch einer Erklarung der Asym. der Gast." Zurich, 1892. 



