JOURNAL OF CONCHOLOGY. 69 



THE DARTS OF BRITISH HELICID^. 



PART I., INTRODUCTORY. 



By CHARLES ASHFORD. 



Very little descriptive detail is to be found in English 

 publications, whether devoted exclusively to our mollusca or to 

 natural history in general, respecting the curious organ of the snail 

 known as the Dart. The student must gather his information 

 by one of two methods, either by dissection or by reference to 

 the writings of foreign — more especially of German — naturalists. 

 For the first, he may lack sufficient leisure, for the second, the 

 requisite knowledge of the language. The present paper, 

 therefore, will not, it is hoped, be superfluous. It will aim at 

 embodying the principal matters of interest concerning the 

 weapon and its sheath, and distinguishing the various forms in 

 the several species. 



The presence of the organ in question — by no means to be 

 confounded with the "crystalline stylet" found in or near the 

 stomach of certain acephalous molluscs — appears, so far as 

 investigation has been carried, to be nearly confined to the 

 genus Helix. The known exceptions (six or eight in number) 

 occur in the border-land common to Helix and its allies, with 

 one outlier, the American slug — Tebennophorus Carolinensis. 

 It must not be supposed, however, that all species of Helix have 

 a dart. Scarcely two-thirds of the British representatives of that 

 genus are so furnished, and the extra-helicine dart-bearing species 

 are, in this country, confined to the genus Zonites. 



It will be convenient to offer first some general remarks, 

 and afterwards to take up the species seriatim. 



The Dart-sac. This is a short, ventricose pouch, general- 

 ly club-shaped or oval, opening into the inferior [)ortion of the 

 vaginal tube, a little above the common vestibule (pi. i., figs. 

 I and 2*). It takes a position in the anterior part of the 



* Fig. I is from a fresh preparation, but the disposition of the various parts 

 is imitated from Schinidt's " Stylomniatoplioren " to facilitate comparison. 



