94 



Bui^IvKTlN 39 



^66 



fine, denticles in the middle and few, more oblique plaits below; 

 the base is obliquely encircled by a lighter colored band; outer 

 lip sharp, smooth within. 



Length 10.5, diameter 4.75, last whorl 9, spire 2.25 mm. 

 This is a common shell in the coralline phase of the Gatun 

 at Port Limon. The middle of the last whorl is usually dark col- 

 ored, with the spire and the encircling basal band and callus on 

 the inner lip white. 



Gatun Stage: Port Liinon, 



Olivella ilmonensis var.bocasensis, n. var. Plate 7, figures 24, 25 



A much smaller shell than the Ilmonensis and possibly a dis- 

 tinct species. The spire is somewhat higher and the shell less 

 cylindrical and pump. Dimensions as follows: 



Length 6.5, diameter 2.75, last whorl 6, spire 1.5 mm. 



7> 3-25, 6.5 1.75 mm. 



Gatun Stage: Bocas del Toro, Panama. 



Genus ANCSLLARIA Lamarck 

 Ancillaria aquaensis, n. sp. Plate 7, figure 10 



Shell of medium size, solid; spire elevated, composed of about 

 5 whorls, the sutures of which are concealed by a wide band of 

 callus this band of callus commences on the body-whorl, a 

 short distance below the suture, and extends to the apex; where 

 this band covers the sutures, it forms just above, a depressed or 

 constricted band on the middle of each whorl; the last whorl is 

 large, with a basal band of callus, which commences near the 

 upper end of the inner lip, descends obliquely across the back of 

 the last whorl to the anterior tips of the outer and inner lips; a 

 short distance above this basal band, the shell carries a single, 

 incised line; a small umbilical pit is found just behind the mid- 

 dle part of the inner lip; aperture broadly sub-elliptical with a 

 sharp outer lip. 



Length 18.5, diameter 7.5, last whorl 12.5, spire 10 mm. 



