ASHFORD : ON THE DARTS OF BRITISH HELICIDiE. 1 69 



referred to (var. hybrida of authors) afforded indication of affinity 



to horiensis in regard to the two more variable items of length of 



gland and number of branches : — 



H. NEMORALis length i6'4 mm. total No. of branches 5*49 



H. HORTENSis „ 21 „ „ 8-4 



Variety „ 21-9 „ „ 87 



Immature darts are curved at a very early stage. Fig. 11 

 represents, much enlarged, one now lying before me, about 

 I '3 mm. in length. Its qualities are chiefly negative. The 

 blades follow first, then the flanges at their margin, the base 

 expands before the blade-channels are quite complete, lastly the 

 annulus. 



Of examples of ^ >^<?r/^;zi-w with mature shells examined 

 between March and September, 58 per cent, had the dart 

 present, 31 per cent, had not formed a dart, and 11 per cent, 

 gave evidence of having lost it. I have also found the sac 

 equipped in February, November, and December. 



The figures are from examples collected at Christchurch. 



9. Helix fusca Montagu, \A. vii., figs. 12 — 15. Dart-sac 

 broadly oval, with a well-defined secondary lobe 

 between it and the vagina ; pearly-white. Dart long, 

 narrow, curved and tapering ; furnished with four 

 blunt-edged blades ; base very large, irregularly cup- 

 shaped ; annulus ? Length about 2 mm. 



The roundly ovate dart-sac is for a considerable part of its 

 length attached to the vagina (fig. 12). Between the two, inter- 

 venes an accessory, empty sac or lobe, smaller than the dart-sac, 

 but rising a little higher. There are 7 to 9 simpjle or bifid 

 mucous glands, vermiform or irregularly tumid, whitish with a 

 dash of azure, and 3 to 4 mm. in length (fig. 14). 



The neat little subulate dart (fig. 13) occupies the principal 

 or outer lobe (fig. 15). Its shaft is regularly curved, sharply 

 pointed, enlarging gradually downwards for about three-fourths 

 of its length, when it expands more rapidly but not abruptly into 

 a long irregularly goblet-shaped, puckered base. The four 



