70 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



two palatal folds, the lower compressed, the upper large, elongate, 

 and usually serrate ; a few supra-palatal denticles generally occur 

 above these. The subgenus Spixia, Pils. & Van., contains about 

 thirty species, ranging from the Argentine to Brazil. The shells 

 are less strong but more turreted, and usually have five folds in the 

 aperture — one compressed parietal lamina, one oblique columellar, 

 one basal, one compressed palatal, and one small supra-palatal fold ; 

 the basal and supra-palatal folds are sometimes obsolete or absent. 

 The subgenus Plagiodontes, Doering, with about seven Argentine 

 species, is somewhat peculiar in having a composite parietal barrier, 

 formed by the fusion of three laminae, i.e. the angular, parietal, 

 and infra-parietal, it is outwardly trifid ; there are besides two 

 -palatal folds — the upper twisted, two supra-palatal, a small 

 compressed basal, and a columellar fold, the latter being largest of 

 all. With the exception of V. -patagonicus, all the species of this 

 subgenus have in addition a high transverse lamella behind the 

 lower palatal fold. 



Genus Tomigerus, Spix. 



Contains some seven known species occurring in South America, 

 and is divided into two subgenera : Tomigerus, s.s., with one 

 species, T. gibherulus, having two lamellae on the outer lip, and 

 Pilsbryella, Ihr., comprising the remainder, with only one 

 lamella on the outer lip. A typical example is T. clausus. Spix, 

 which exhibits two oblique, entering, parietal lamellae, with a small 

 denticle between ; three entering, compressed lamellae on the baso- 

 columellar margin, the middle one the strongest, and a high, flexuous, 

 oblique lamina on the outer lip, bidentate near the upper extremity ; 

 a corresponding scrobiculation is found behind the lip. A minute 

 shell, 1"5 mm. X 1'5 mm., from St. Helena, perexilis, Smith, has 

 been doubtfully referred to this genus ; in this the upper edge of 

 the peristome is notched, having the appearance of being the 

 termination of a tube. 



Genus Strobilops, Pilsbry. 



This genus has a peculiar distribution, being found in North 

 America — one species also occurring in Jamaica — extending 

 through Mexico and Central America to Venezuela, The mainland 

 of China produces one, the island of Korea another, and a species has 

 also been discovered in Japan, while the Philippine Islands con- 

 tribute two. These two last were originally described as forms 

 of Plectopylis by von MoellendorfE, but Dr. Pilsbry has referred them 

 to the present genus. S. quadrasi, Mlldff., from Luzon, is, like all 

 the members of the genus, a minute species, measuring only 3' 5 mm. 

 in diameter. It bears two parallel, horizontal folds on the parietal 

 wall (see Fig. 6c and e), extending over nearly half the whorl, 

 the upper one the stronger and united to the ridge at the aperture, 

 the lower one thinner and not reaching quite so far ; at their 



