HELICIGONA. 297 



The true limits of this genus were first indicated by Schmidt, and 

 have been confirmed by the researches of numerous later authors. 

 The two-bladed type of dart, the broad diverticulum bound to 

 uterus by a wide membrane traversed by blood-vessels, and the two 

 mucus glands, which are either simple and vermiform or once split, 

 are all characters unlike Helix or other genera of Belogona. The 

 shell is never five-banded as it is in Helix, but has either two bands 

 above, one below the periphery, or only the middle baud is retained, 

 or it is bandless. 



The form of the dart is not alone diagnostic, for Eremina and 

 some Iberus approach the two-bladed type. Helicigona is the only 

 genus known to me in which the diverticulum is a constant generic 

 character ; and here it seems to be much more highly developed 

 than in any other group. 



The shell shows a considerable range of mutation in form and 

 sculpture, sometimes being acutely keeled as in H. banatica, canth- 

 ensis and lapicida, and again globose or subgloboseas in arbustorum, 

 ehingensis and the Tacheocampylseas. In some forms, such as H. 

 lepidotricha and ehingensis, the margin of the umbilicus is obtusely 

 angular, as in some Chloritis ; and high authorities have indeed re- 

 ferred the former species to this genus. In my opinion such reference 

 is wholly uncalled for. I would as soon consider Lysinoe ghiesbre- 

 ghti or Epiphragmophora rtmondi species of Chloritis on account of 

 the similar angled umbilicus and quincuncial sculpture. We must 

 have better evidence than these unstable and frequently repeated 

 characters, before admitting Chloritis to the European fauna. The 

 claim of Metafruticicola (p. 276) to a place in the genus Chloritis 

 is far better than that of H. lepidotricha and its allies. The variety 

 of sculpture found in Helicigona is equally remarkable ; some species 

 being quite smooth, others, as gobanziand hemonica, heavily ribbed ; 

 and still other forms, such as lepidotricha, rahtii, setosa, benedida 

 have bristles or their papilla? arranged in regular quincunx or 

 oblique sweeps, besides a still more minute granulation of the whole 

 surface. In some species this regular sculpture extends to the very 

 apex, being exactly like that of Chloritis, Moellendorffia and a few 

 other Helices of very diverse groups. 



Synopsis of subgenera and sections. 

 RECENT GROUPS. 



1. Aperture oval or lunate ; lip 1-toothed or toothless. 

 a. Spire convex or conoidal ; mucus glands tubular. 



