222 The Molluscan Family Plauorbidae 



Type Locality. Lake Wasliington, Seattle, Washington. 



Type Material. Collected by P. B. Randolph, deposited in United States 

 National Museum, Shimek Collection, Accession no. 504360. Holotype 

 figured on plate 94, fig. 1; paratypes, figs. 2-4; immature, fig. 5. 



Helisoma carihaeum cuhense. New Variety 

 Plate 119, figs. 22-25 

 Shell differing from that of typical caribaeum in having the spire depres- 

 sion much narrower, the whorls, especially the body whorl, increasing 

 more rapidly in diameter. Five full whorls. Sutures not impressed as in 

 caribaeum, the spire whorls flattened, not rounded, and there is often a 

 carina at the edge of the whorls. Nuclear and first whorl rounded as in 

 caribaeum and of the same size. Basal whorls rounded, the umbilical 

 region concave, umbilical opening distinct. Axial height somewhat greater 

 than in typical caribaeum, the body whorl flattened near the spire depres- 

 sion, not evenly rounded as in typical caribaeum. Aperture more nearly 

 auriculate than in caribaeum, the lip sometimes (as in the holotype) 

 thickened by a heavy callus. Sculpture as in caribaeum. 



Shell Greater Lesser Aperture Aperture 



Height Diameter Diameter Height Diameter 



8.7 19.1 16.0 6.0 4.0* Holotype 



7.0 16.0 13.5 6.2 4.0 Paratvpe 



6.1 14.0 12.0 4.5 3.0 Paratvpe 

 6.0 14.1 11.1 4.3 3.1 Paratvpe 



*.A.perture contracted in holotype liy thickened lip. 



The form of the whorls increases like that of tenue, especially like that 

 of tenue sinuosum, but inner whorls are like those of caribaeum in that 

 they are rounded, and are not like those of tenue which are flat and cari- 

 nated at the edges. Some living Cuban specimens have a somewhat nar- 

 rower spire than the typical form here figured but these lack the greatly 

 increased diameter of the body whorl characteristic of cubense and the 

 aperture is not auriculate or thickened by a callus as in mature and nearly 

 mature specimens of cubense. The basal whorls are more concave than in 

 caribaeum. Sutures are not as deep as in caribaeum. Evidently a Pleisto- 

 cene fossil. 



Type Locality. Zapata Swamp, Cuba, in marl between layers of peat. 



Type Material. Eight specimens, collected April 19, 1927, by H. H. 

 Bennett, are deposited in the United States National Museum, Accession 

 no. 404719. Of these, the holotype is figured on plate 119 as fig. 22, and 

 three of the paratypes are shown as figs. 23-25. 



HeXisoma colum\)ie.n&e.. New Species 

 Plate 119, figs. 16-21 



Shell with four to four and one-half whorls, rapidlv enlarging. Spire de- 

 pression flattened, the inner whorls bordered by a sharp carina which be- 

 comes distinctly central in position on the last whorl. The sides of the 

 depression slope sharply downward. Base of shell concave, broadly funnel- 

 shaped, the last whorl with a more or less sharp carina or ridge. Sutures 

 well marked. Sculpture of coarse riblets, widely spaced, as in typical sub- 



