ASHFORD : ON THE DARTS OF BRITISH HELICID^. 73 



afforded by the appearance of a swelling on each side of the 

 intervening passage, when the shell is not quite half grown. 

 As these increase into hemispherical knobs a septum is distin- 

 guishable through the transparent masses, and later the free 

 end of each becomes notched. These indentations gradually 

 increase in depth, apparently by the "outward growth of the two 

 lobes, till each teliferous sac is fully formed and furnished. 

 Such at least are the appearances presenting themselves in the 

 examination of a series of individuals of different ages, for after 

 opacity of the shell has set in, it is manifestly impossible to trace 

 progressive growth of an internal organ in the same individual. 



The Dart. Dard, Pfeil, Love-dart, Fleche d'amour, 

 Liebespfeil, Spiculum amoris, Hasta amatoria, Telum Veneris... 

 of authors. 



Structure. Around the tubercle, already referred to as 

 rising from the inner base of the sac, is formed a small conico- 

 cylindrical annulus, about as broad as long, composed of 

 numerous (12 to 20) calcareous rods held together by animal 

 matter (fig. 5). These rods are arranged longitudinally like the 

 cane or whalebone in a cricketer's "leg-guard," and their 

 projecting extremities form two denticulated circular margins, 

 the one resting upon the circumference of the inferior part of 

 the tubercle, the other encircling but not concealing its apex. 

 I'he sides of the tubercle are furrowed with corresponding sulci, 

 in which the rods rest with some slight adhesion, and where 

 they are in all probability secreted. According to Perez, 

 attention was first called to this annulus by A. Schmidt in 1849, 

 but I find it well described and figured by Verloren in his 

 " Preisschrift," published twelve years earlier. Schmidt called it 

 the " crown " (Krone), a term well descriptive of its pretty 

 coronet-like appearance, but hardly suitable to our language, 

 inasmuch as we always apply the term "head" to that part of a 

 spear or arrow that carries the blades or barb. For the same 

 reason the part of the dare attached to the annulus and called 

 by German writers the " head," I shall have to call the " base." 



