AST. 22 MIOCENE GASTROPODS AND SCAPHOPODS MANSFIELD 59 



CALUOSTOMA RHOMBOTUM, new species 



Plate 8, figs. 4, 8 



Shell very small, conic, four and one-half whorled ; whorls rapidly 

 expanding, nearly straight in outline ; sutural area distinct and open 

 on spire whorls, indistinct on body whorl ; base nearly flat. Apical 

 one-half turn small, globular, glazed and pearly, smooth and con- 

 centric. Subsequent whorl much larger, tabulate above and sculp- 

 tured with three small granulose threads, the upper one very small 

 and situated in front of the suture, the second one situated at the 

 upper shoulder, and the lower one marginates the loAver suture; in- 

 distinct axials cross the whorl connecting the granules. Following 

 whorls more prominently sculptured, consisting of three on the two 

 subsequent whorls and four (the basal one being doubled) on the 

 last whorl, beaded spiral cords, the anterior third being a little 

 stronger; beads connected axially by retractive threads giving the 

 whorl a cancellate ornamentation and the interspiral space a rhom- 

 bic pattern. Base of shell with a thin wash of callus but distinctly 

 shows five subequal crenulated spirals lying within a wider, un- 

 dulated and spirally striated peripheral band. About one-fourth 

 of the last volution is broken away. Columella strong and enameled 

 with a wash of callus. 



Dimensions: Type and only specimen (U. S. Nat. Mus. Cat. 

 No. 352689) measures : Altitude 3 mm. ; greatest diameter 2.5 mm. 



Occurrence. — Middle or lower Miocene : In flood-wash, Caroni 

 County, Montserrat Ward, 1 mile south of Brasso, Trinidad. 



Genus LIOTIA Gray 



LIOTIA MACHAPOORIEENSIS, new species 



Plate 8, figs. 1, 3 



Shell large, solid, perforate, diameter a little greater than alti- 

 tude, four whorled; whorls rapidly expanding, later ones well 

 rounded; sutural area excavated; suture close-fitting; base nearly 

 flat. Apical whorl flat and broadly coiled. Sculpture of subse- 

 quent whorl begins with two weakly nodulous spirals situated at 

 the upper and lower shoulder of the whorl. Soon another median 

 spiral appears. In ascending the whorl, these spirals increase in 

 strength and are adorned with strong, j^rotracted nodules. On the 

 upper half of the body whorl, two other intermediate spirals appear, 

 making five in number. Base with five lowly-nodulous spirals. 

 Aperture subcircular in outline. Outer lip strongly crenulate har- 

 monizing with the exterior sculpture. 



