LEUCOCHROA. 233 



and terminating in a globular spermatbeca (pi. 57, fig. 53, duct 

 dissected away from uterus and straightened). Ovo-testis very large 

 and compact, completely occupying the earlier H ivhorls. 



Distribution, circum-Mediterranean region. The area occupied 

 by this genus is the same as that of Otala plus Levantina, 

 being coincident with the region where the olive grows. A3 in 

 Macularia one species (vermiculata) extends throughout the range 

 of the group, so in Leucochroa, L. candidissima has an equally wide 

 distribution, occurring in Palestine (v. hierochuntina), northern 

 Africa and westward in Europe to southern Spain. The other spe- 

 cies are all local. Many of them show not only much individual 

 variation, but also numerous well-marked local varieties ; and the 

 complete tale of these has not yet been told. 



This genus is distinguished by its cretaceous solid shell, conspic- 

 uously tripartite sole, smooth jaw and the teeth and genitalia of 

 Helix, except that the dart sack is wholly absent, the mucous ap- 

 pendages reduced to one straight or coiled sacculated gland, and 

 the ovotestis not enveloped in the digestive gland. 



The group has had a varied literary existence, Moquin-Tandon, 

 in 1848, removing it from the Helices to Zonites on account of the 



o 



smooth jaw ; and later system at ists, Martens, Westerlund, Kobelt 

 and others have adopted this view in their several works. Binney, 

 upon examining the teeth of L. boissieri, declared it a Helix, and 

 has been followed by Fischer and Tryon. It only remains to say 

 that there can be no doubt that Leucochroa belongs to the belogo- 

 nous Helicidte, and has not the slightest affinity to the Zonitidse. 

 It is more nearly allied, in the peculiar position of the eye retractor, 

 to Helicella than to other genera, but differing in the loss through 

 degeneration of the dart and its sack, and in the smooth jaw both 

 of these being purely secondary modifications. I have retained the 

 genus in Belogona euadenia on account of the sacculated mucus 

 gland of candidissima ; but a careful dissection of some species with 

 elongated mucus gland, like bcctica, should be made, with histologi- 

 cal examination of the mucus gland and the minute spur ac its mid- 

 dle (see pi. 36, fig. 15), to ascertain more certainly the place of the 

 genus. Probably the spur mentioned is a remnant of the dart sack. 

 The anatomy is known by Schmidt's figures representing Candidis- 

 sima, boetica, cariosa and cariosula (= hispanica), and the writer's 

 dissection of candidissima. 



