52 I'llOCEEDINGS OF TIIK MALACOLOGICAL SOCIETY. 



THE MYOLOGY OF SOME PULMONATE MOLLUSCA CONSIDERED 



AS A DISTINCTIVE FEATURE IN THE DISCRIMINATION OF 



GENERA, ETC. 



Ey Walter E. Collinge, Demonstrator of Zoology and Comparative 



Anatomy, Mason College, Birmingham. 



Eead December Sth, 1893. 



In the careful anatomical descriptions of not a few of Mr. Charles 

 Hedley's valuable contributions to the anatomy of the MoUusca, 

 I have noted that he very rightly describes the chief muscles. More 

 recently Lieut. -Colonel H. H. Godwin-Austen, F.E..S., has stated that 

 the position of attachment of the several retractor muscles of the 

 generative organs, eye, etc., is of "very great importance when studying 

 the differences between generic groups, being an internal character 

 less liable to change than other external ones." ^ 



Eor some length of time I have noted tbe variations in the fonn, 

 number, and position of the muscles of various species of Pulmonate 

 Molluscs, and have resolved in my future dissections to carefully note 

 and draw these in order to determine more exactly the importance 

 that should be attached to the same in generic, or specific distinction. 



For this purpose specimens of Arion empiricorum, Fer., A. subfuscus, 

 Drap., Lhnax maximus, L., Testacella scuhdum, Sby., Helix aspersa, 

 Miill., and Limncea stagnalis, Linn., were chosen ; firstly because 

 I had already made numerous notes and drawings of the muscular 

 system of many, and secondly since they are all common and widely 

 distributed forms, so that it is open for other workers to confirm, 

 amend, or add to the following account. 



Malacologists now, more than ever, seem agreed that wherever 

 possible the distinctions of both genera and species should rest upon 

 something more tlian the colour or form of a shell, or the external 

 markings of the animal. There is hardly a system of organs in 

 the Mollusca which has not at some time or other been advanced 

 as a basis for the classification and division of the various families, 

 genera, and species. The nervous, generative, respiratory, vascular 

 and digestive systems have all found supporters, but the myology 

 seems to have been entirely overlooked. I do not for a moment 

 support the classification, or division, of any group of animals upon the 

 morpholog\- of a single system of organs, but think it necessary that 

 we should know the actual value of each system, in order that we 

 may more accurately judge of its importance in the aggregate 

 characters of the animal or group of animals. 



' I'roc. Make. Sue. 1893, vol. i. p. 8. 



