7^ Bui,i,BTiN 39 250 



shorter than the narrow aperture; nucleus of about 3^^ smooth, 

 convex whorls, the last Y2 turn being very finely and closely rib- 

 bed; there are 3^^ post- nuclear whorls; sculpture consists of 

 narrovv^ slightlj^ oblique ribs which pass across the spire-whorls 

 from suture to suture and on the last whorl follow down on the 

 anterior canal to its tip; there are 8 ribs on the last whorl; the 

 spaces between the ribs are wide, fiat and smooth; the tops and 

 sides of the ribs themselves are carved or etched with fine, sub- 

 obsolete spiral lines; aperture linear-elliptical, the outer lip some- 

 what thickened by the last rib, but smooth within; anterior ca- 

 nal long straight. 



Height 9, diameter 3.50, last whorl 7mm. 



Gatun Stage: Port Limo7i. 



Genus BORSONIA Bellardi 



Borsonia cocoenGis, n. sp. Plate 5, figures 23, 24 



Shell small, bicouic; v/horls about 7; nucleus of 2, nearly 

 smooth whorls, follovi^ed by 5 strongly shouldered post-nuclear 

 whorls, the angle of v/hich on the spire-whorls comes just 

 above the lovv^er suture; above the shoulder, the vv-horls 

 are fiat or slightly concave to the upper suture; sculp- 

 ture with a double or triple beaded cord on the peri- 

 phery and with alternating beaded spirals both above and below; 

 on the last whorl, the primary spirals number 15 or 16, above 

 the shoulder 3 or 4; the suture is bordered in front by a strong 

 cord; pillar long, slightlj^ twisted in front and with 2 sharp, pli- 

 cations; the anal sinus lies on the peripheral angle as in typical 

 Turris. 



Length 16, diameter 8, last whorl 11 mm. 



The present species is based on two specimens from Coco 

 Plum about 30 miles east of the city of Bocas del Toro. The 

 B. varicosa Sovv^erb}^ from the Dominican Miocene, is a related 

 species, differing in its porportionately longer spire. 



Gatun Stap-e: Coco Plum. 



