54 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



occur four denticles, two on the parietal and two on the palatal wall. 

 Again, S. heUgmoidea, Orb., also from Ecuador, has the parietal 

 callus raised and furnished with a compressed fold, which is con- 

 tinued for some distance on the parietal wall and coincident with 

 a tubercle on the upper palatal margin of the peristome corresponding 

 with a scrobiculation, the aperture being in consequence sub- 

 triangular. 



Genus Ennea, H. & A. Adams. 



This has a wide distribution, being found throughout southern 

 and south-eastern Asia from Arabia to Japan and the Philippine 

 Islands ; Madagascar, the Mascarene Islands, and throughout tropical 

 and southern Africa. 



E. mucronata, Mts., a Cameroon species, is provided with an 

 entering, flexuous fold on the parietal wall near the upper part of 

 the peristome, which bears a corresponding tubercle, while on the 

 outer lip are found two flexuous, entering folds, and the columella 

 bears a flexuous, entering fold, bidendate at the anterior end. 

 E. ringens, H. Ad., from Sierra Leone, has a parietal lamina, three 

 profound columellar teeth, and several lamellae within the outer lip, 

 four of which are longer and more prominent than the others. 

 E. infrendens, Mts., a Natal species, has its aperture nearly closed, 

 having a raised, compressed lamella at the parietal angle, a deep- 

 seated, bipartite, columellar plica, two small teeth on the basal 

 margin, and two on the palatal margin of the peristome, the upper 

 one being the larger. E. planti, Pfr., another Natal form, possesses 

 a slight, entering, flexuous fold on the columella, one short, com- 

 pressed lamina on the parietal wall near the insertion of the upper 

 margin of the peristome. 



The next group for consideration is the family Zonitid^. 



Genus Vitrea, Fitz. 

 Of this genus, which has a very wide distribution, only a few of the 

 North American species are provided with armature. F. interna. 

 Say, has two prominent sub-lamelliform white teeth, which do not 

 reach the edge of the peristome. Several other species have radial 

 series of internal teeth on the lower wall of the last whorl. In 

 V. multidentata, Binn., some specimens have these teeth united at 

 their base into barriers, these processes being distinctly visible 

 through the thin shell-wall. 



Genus Gastrodonta, Albers. 

 This is confined to North America, and its members have more solid 

 shells than those of the last genus dealt with. G. gidaris, Say, has 

 a long, revolving fold inside on the base of the last whorl, extending 

 for about two-thirds of a whorl ; some have a strong, raised denticle 

 on the basal margin of the peristome. Immature shells show two 

 folds. G. lasmodon, Phill., is provided on the base with two, nearly 



