52 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 66 



consists of one and one-half whorls; the apical turn is minute, the 

 following much larger, smooth, and inflated. A low indistinct 

 medial carina and minute spiral threads appear on the following 

 whorl, becoming gradually stronger in ascending the spire. On 

 the fourth Avhorl, another primary spiral appears at the base of 

 the Avhorl. At first, this is weak but gradually strengthens and on 

 the later whorls becomes nearly as strong as the medial one. On the 

 anterior whorls, the two primary spirals continue but are not prom- 

 inent. Four or five rather strong secondary spiral lines intervene 

 behind the medial primary and the suture, two or three lie between 

 the primary spirals and about two behind the suture; very fine 

 tertiary spiral threads overrun the interspaces. 



Cotypes (U.S. Nat. Mus. Cat. No. 352678). 



Type locality : In flood-wash, station 9212, Caroni County, Mont- 

 serrat Ward, 1 mile south of Brasso. 



Occurrence. — Middle or lower Miocene; Stations 8302, 9215. 



TURRITELLA MACHAPGORENSIS Maury 



Plate 7. fig. 10 



TurritiUa machapooreusis Mauky, Bull. Amer. Paleont, vol. 10, no. 42, p. 234, 

 pi. 42, fig. 11, 1925. 



Shell acuminate and solid, whorls medially compressed, suture 

 very shallow and indistinct. Early whorls with a broad medial con- 

 cavity, marginated above and below by a rounded raised cord, the 

 lower being a little stronger 'and forming the periphery of the whorl. 

 Another spiral, small at first but gradually increases in size in ascend- 

 ing the whorl until it equals in strength the one above, lies behind the 

 suture. On the later whorls, the three primary spirals continue, the 

 lower two becoming more prominent and the presutural one being a 

 little stronger and forms the periphery of the whorl. Rather close- 

 set, carin'ate spirals intervene the primary, about three lie between 

 the suture and the following primary, three to four lie in the shallow 

 concavity and one between the basal primaries. Very fine irregular 

 spirals overrun the shell, being especially evident on the larger 

 whorls. The anterior part of the specimen is broken away. 



Dimensions: Figured specimen (U. S. Nat. Mus. Cat. No. 352680) 

 measures: Length 29 mm.; gi-eatest diameter 12 mm. 



This species closely resembles Tvnitella tampae Heilprin from 

 the '• silex bed " of the Tampa formation of Florida. The upper 

 spiral whorls on the latter species are more drawn out, the 

 suture more distinct and interval between the basal cords sriiooth or 

 feebly sculptured. The species also resembles Tui^iteUa anguil- 

 Jana Cooke from the Oligocene, Anguilla, but the latter species pos- 

 sesses a stronger paired basal spirals and less ornamentation abo^•e 



