164 JOURNAL OF CONCHOLOGY. 



THE DARTS OF BRITISH HELICID^. 



By CHARLES ASHFORD. 



PART IV. 



7. Helix nemoralis L., pi. vii. figs, i — 6. Dart-sac simple, 

 subclavate ; lavender-grey to livid blue when mature, 

 inner coat dark-brown. Dart straight, considerably 

 and somewhat conically expanded at the base; furnished 

 with four sharp-edged blades, of which two are more 

 prominent than the others ; annulus of 15 to 18 rods. 

 Length 7 to 8 mm. 



The colour of the mature dart-sac is some shade between 

 light lavender or French-grey and dull bluish lead-colour, general- 

 ly intensified at each extremity. This, however, is not the hue 

 of either of the two principal coats. The thick outer envelope 

 is greyish-white, pink or light purple ; the inner coat dark-brown, 

 sometimes approaching black, red, or violet. The general livid 

 aspect must be considered due to a modification of one by the 

 other. At an earlier stage the sac is white, and in that state 

 contains no dart. Several adjacent organs, also white at first, 

 gradually assume a reddish-brown colour as maturity is approach- 

 ed, and Paasch states, according to Busch, that the intensity of 

 the prevailing tint is proportionate to the extent and emphasis of 

 the fasciation of the shell, the animals of unicoloured shells 

 exhibiting less development of pigment than others. This 

 opinion has received no support from the more recent observa- 

 tions of conchologists. 



The two mucous glands (fig. i ) spring from the vagina close 

 to its junction with the dart-sac, each generally dividing rather 

 low down into two or more branches. The total number of 

 coeca — in both groups together — is usually 5 or 6, sometimes 4 

 or 7, more rarely so few as three, or so many as nine. I have 

 found the most common arrangement to be as represented in fig. 

 I — two branches to one gland and three to the other. Each 

 coecum is slender and nearly cylindrical, white, or with a tinge of 

 pink. It will be necessary to revert to these particulars when we 

 come to H. horteiisis. 



J.C, iv., April, 1SS4. 



