ASHFORD : ON THE DARTS OF BRITISH HELICID^. 1 33 



structure. In some cases the lateral edges below the point 

 present concave, in others convex outlines. The distance from 

 the point of the weapon at which the blades disappear is very 

 variable, and the two pair of blades sometimes differ from each 

 other in this respect. Occasionally the flanges, forming the 

 channels already referred to, as they approach the point, dip 

 below the sharp edge of the blade proper, leaving the latter 

 standing out as a ridge in the centre of the channel. A trans- 

 verse section below the point will then present the arrangement 

 shown in fig. 15, which is rather diagrammatic than strictly 

 accurate. In the basal region the outer line of the blades is 

 sometimes straight, sometimes curved in accordance with the 

 enlargement of the shaft. In short, it may almost be asserted 

 that no two darts of H. Pisana are exactly alike, and yet they 

 can never, for a moment be mistaken for those of any other 

 British species. 



Young darts have a narrow, almost cylindrical base ; the 

 annulus is unformed ; the blades are not yet channelled, and 

 their edges are more or less jagged (fig. 12). The last remark 

 applies also to the imperfect flanges at a later stage. 



Of 13 individuals, obligingly procured for me from Tenby 

 by Mr. G. S. Tye, in the month of September, all yielded darts 

 except one which had a shell manifestly not full-grown. Out 

 of a batch obtained from Jersey at the beginning of July, ten 

 adult shells yielded eight darts, two of which were immature. 



The figures 10, 11, 16, are from Tenby specimens, the 

 others from examples obtained from Jersey. 



Helix aspersa Mliller in Tasmania. — I have recently 

 obtained some fine living examples of this species in a garden at 

 Hobart, thus proving its thorough acclimatization in this island. 

 It has been abundant about Melbourne, Victoria, for some 

 years. — W. F. Petterd, Nov., 1883. 



