295 Costa Rico Miocenk — Olsson 123 



Genus ALECTRIOW Montfort 

 Alectrion ranuncula, n. sp. Plate 9, figures 20, 22 



Shell of medium size, with a large body- whorl and a sharp 

 pointed spire; the general form and sculpture recalls the recent 

 A. acuta Say; spire about the same length as the aperture and 

 canal and composed of about 7 whorls, of which the first 2 belong 

 to the small, smooth nucleus; the profile of the spire- whorls is 

 convex with deep, excavated sutures; sculpture of narrow ribs, 

 the tops of which are crossed by spirals and separated by wide, 

 smooth interspaces; the last whorl has about 9 ribs which are 

 large and humped on the ventral face, finer and more numerous 

 on the back; there are 3 spirals on the spire- whorls and 7 on the 

 last with several more on the short canal; aperture subcircular 

 with a large, heavy outer lip, internally denticulated. 



The general form and sculpturing recalls the recent East 

 Coast Aledrion acuta Say, but the Costa Rican shell is much 

 broader as indicated by the following comparative measurements 

 with A. acuta Say, of the same height. 



Height 14.00, diameter 6.25, last whorl 8, aperture 6 mm. 



(Alectrion acuta Say) 

 Height 14.50, diameter 8.25, last whorl 9, aperture 7.5 mm. 



{Alectrio7i ranuncula^ n. sp.) 

 It is not uncommon in the Gatun beds of the Banana 

 River. 



Gatun Stage: Hill la, Banana River. 

 Coll. 7 Estrella. 



Alectrion losquemadica Maury Plate 9, figure 21 



Alectrion losquemadica Maury, 1917, Bull. Amer. Pal., vol. 5, p. 255, 

 pi. 15, figs. 22, 23. 



The Costa Rica fossil is similiar in its sculpturing and form 

 to the common recent West Indian A. ambigua Montfort. As 

 Maury has pointed out in regard to the Dominican examples, the 



