The Ajiatoniical Characters of Arion Jlagellus. 317 



describe — but wliich Dr. Scharff should have seen, — as I was 

 doubtful as to what amount of importance should be attached 

 to them. The two most important are the position of attach- 

 ment of the tentacular muscles, and the length and position of 

 the genital retractor. 



I purposely stated that the alimentary and nervous systems 

 agreed very closely with A. cmpiricorwn. For. — I do not mean 

 A. ater, L. — and to now find such classed as A. subfusctis 

 surprises me indeed. 



When Dr. Scharff had seen the specimens he wrote: — "in 

 some measure it approaches.-^. /?(j5//^7^/«^5 . . . The con- 

 strictions, as you remark, are not due to ova actually passing 

 down the oviduct, but they probably did so recently before the 

 specimens were captured. ... As for the flagellum . . 

 from a superficial examination, I should be inclined to take it 

 for a strongly contracted muscular mass." 



On receipt of his letter I made a further dissection of the 

 oviduct and found the constrictions internally as w^ell. I have 

 never seen a specimen in which the internal wall of the ovi- 

 duct showed distinct constrictions of the epithelial and 

 muscular layers, and I do not think Dr. Scharff has either — 

 I speak with a tolerably wide acquaintance with the form of 

 this organ in the Armiidce and slugs generally. 



As to Dr. Scharff 's idea that the flagellum is a portion of 

 the muscle, I purposely dissected the muscle away {Ann. and 

 Mag., 1893, pi. ix., fig. 3,) so as to show the flagellum. 



Further differences from subfusctis are seen in the form of 

 the receptacular duct, hermaphrodite gland, and in the whole 

 of the generative system. 



If Dr. Scharff can show me specimens bred from A. stibfuscus 

 or any other Arion, except this species, in which the general 

 anatomy shows the above features, then A. flagellus is not a 

 valid species, but seeing that it is far removed from subfuscus 

 and much more closely related to A. lusitanicus, I can only 

 regard his criticism as based upon a hasty examination of the 

 specimens in which the salient features were overlooked. 



