26g Costa Rica- Miocene — Olsson 97 



inella conifonnis has been figured by Guppy in the Quarterly 

 Journal and similiar shells were collected in abundance by the 

 Maury expedition to Santo Domingo. It is a larger and more 

 cylindrical form. 



It is an abundant shell in the quarries west of the Gatun 

 locks at Gatun. A single, large shell figured as figure i was 

 collected from the Banana River beds. 



Gatun Stage: Gatu7i, C. Z. 



Banana River, C. R. 



iVIarginella avena Valenciennes Plate 7, figures, 21, 28 



Marginella avena Valenciennes, 1814, in Kiener, Coq. Viv. Marginella, 



p. 17, pi. 6, fig. 24. 

 Marginella avena Gabb, 1881, Journ. Acad. Nat. Sci. Phila., vol. 8, 



2nd series, p. 355. 



A common, recent species along the Caribbean coast of 

 Panama and Costa Rica. As a fossil, it occurs plentifully in the 

 coralline phase of the Gatun at Port Limon and Bocas del Toro. 

 The fossil shells do not differ materially from their recent repre- 

 sentative. 



The shell is elongate-cylindrical in outline, with a low, but 

 slightly projecting spire. The aperture is norrowl}' linear, 

 slightly wider in front. Outer lip thick, smooth within. The 

 columella is provided with 4, obliquely descending plications. 



A series of specimens from I^imon and Bocas measure as fol" 

 lows. 



Length 11.75, diameter 4.25, spire 2. 

 11.50 4.25 1.5, 



12.50 4.50 2. 



Gatun Stage: Port Limon, C. R. 



Bocas del Toro, Panama. 

 Coll. 4., Red Cliff Greek. 



Marginaila collina, n, sp. Plate 7, figures 26, 27 



Shell of the general form and size of M. avena, but more 



