3i6 The Irish Naturalist 



vinced that a thorough investigation of the marine flora and 

 fauna would well repay students of botany and zoology/ and 

 could, with the means available there, be carried out without 

 much difficulty. 



THE ANATOMICAIv CHARACTERS OF 

 ARION FLAGELLUS, CI^EGE. 



BY WAI^TKR ^. COIvIvINGK. 



Thk anatomical features of this recently-described Arion are 

 so pronounced, and distinct from any other known European 

 species, that I should not have thought it necessary to reply 

 to my friend Dr. Scharff " had he not — most unintentionally, 

 I am sure — misrepresented the published account of its 

 anatomy.3 



It is of little importance, but still I contend that A.flagellus 

 does differ in colour from A. sttbfuscus. The most important 

 external character — which Dr. Scharff entirely overlooks — is 

 the small caudal mucous gland. So constant is the form and 

 size of this gland — as might be inferred from the importance 

 of its function — that not a few malacologists have used it as 

 a feature in generic distinction. I have examined very large 

 series of Arions from almost every part of Europe, but have 

 never in any single instance found it vary, and I am not aware 

 of any published instance either. I, therefore, think the point 

 is one worthy of note in the aggregate characters of this species, 

 which is not described from any single one, but from the 

 general anatomy. 



The exact importance of the myology of the Mollusca as a 

 feature in generic or specific distinction I am as yet undecided 

 upon, but quite recently Et.-Col. H. H. Godwin, F.R.S., has 

 placed great importance upon the position of attachment of 

 certain muscles, e.g., the retractor muscles of the eye, generative 

 organs, &c., and finds that in certain genera these are subject 

 to but slight variation. Now, in A. flagellus there are a number 

 of differences in the form, &c., of the muscles, which I did not 



* I am hoping that Dr. Loftus, of Roundstone, whose acquaintance I 

 made, will become a present-day M'Calla. 

 - Irish Nat., vol. ii., 1893, p. 302. 

 •^ Ann. and Mag. N. ff., 1893 (6th s.), vol. xii., p. 252. 



