13^ Bulletin 39 302 



persistent to the penultimate whorl, but are laking from the 

 last whorl which is smooth and polished; the penultimate whorl 

 has about 15 ribs; the ribs are generally beaded about their up- 

 per extremities; sutures distinct; last whorl large and strongly 

 laterally flattened betv/een a prominent ridge or hump on the left- 

 hand side of the whorl and the large outer lip; aperture sub- 

 eliiptical with a large, expanded outer lip, deeply indented be- 

 hind; canal short and beak-like and spirally striated with about 

 8 threads on the back. 



Length 7, diameter 3.25, spire 3.50, aperture 3.75 mm. 

 A small species abundant in the Gatun beds of Hill la, of the 

 Banana River. The last whorl is rather small and strongly flat- 

 tened dorso-ventrally. The spire is large and about }4 of the to- 

 tal length of the shell. 



Gahni Stage: Hill la Banana River. 

 Hill J, Banana River. 



StromSsina ciiiriquiensis, n. sp. Plate 10, figures 14, 24 



Shell small and in genral characters like the preceding but 

 with a larger body- whorl and a shorter, more conic spire; whorls 

 about 8, of which the first 3 are smooth and belong to the small 

 pointed nucleus; the succeeding whorls until the penultimate are 

 sculptured with fine, straight, longitudinal ribs, there being 19 on 

 the penultimate whorl; the last whorl is rather large, smooth and 

 dorso-ventrall}^ flattened between a hump-like ridge on the left 

 side and the large, expanded outer lip; canal short, beak-like and 

 spirally striated; aperture linear-ovate, deeply indented behind; 

 inner and outer lips are both heavily calloused, especially about 

 their posterior portions; over this callous and between the outer 

 and inner lips passes the small posteriorly directed canal; lower 

 half of the inner and outer lips denticulated with 8 or 9 strong, 

 denticles, heaviest above. 



Length 7.50, diameter 4.25, spire 2.50, aperture 4.50 

 mm. 



Of much the same size and general characters as S. sincola of 



