Io8 JOURNAL OF CONCHOLOGY. 



THE DARTS OF BRITISH HELICID^. 



By CHARLES ASHFORD. 



PART II. 



In the last article on this subject a general description was 

 given of the form, structure, and economy of the dart and its 

 sheath. I will now proceed to the peculiarities of the organ in 

 the different species, and in doing so shall not attempt any par- 

 ticular arrangement beyond that of considering first our two 

 dart-bearing species not included in the genus Helix. 



I. Zonites nitidus Miiller, pi iii. figs, i — 4. Dart-sac 

 long, slender, with a single reflected or pendent lobe at 

 the free end; whitish, semi-transparent. DARTfiliform, 

 curved, twisted, without blades or annulus ; length not 

 quite 2 mm. 



This was the first European species of Zonites ascertained 

 to possess a dart, and the fact was published by Dr. Lehmann 

 in a communication to the ' Malakozoologische Blatter' for 1862, 

 but without a figure. On the ground of the peculiarity Leh- 

 mann proposed to constitute a separate genus for the reception 

 of this species under the name of" Zonitoides." 



In its organization it forms a link between Helix and 

 Zonites, showing its alliance to the former by the dart and long 

 spermatheca-duct, and to the latter by the teeth of the lingual 

 ribbon, which resemble those of Z. crystallinus (Goldfuss), by 

 the form of the shell and jaw and by the absence of mucous 

 glands. In the place usually occupied by mucous glands when 

 a dart-sac is present, is a small oval fold of a dirty greenish-grey 

 and spongy appearance, overlying the vagina and lower portion 

 of the spermatheca-duct. This fold occurs also in several 

 members of the genus Zonites not provided with darts — notably 

 in Z. cellarius — and is considered by Moquin-Tandon to be the 

 analogue of the mucous glands. 



J.C., iv., Oct., 1883. 



