34b Bulletin 39 306b 



Shell rather large, moderately solid; outlines subcylindrical 

 but a little wider about the anterior half of the shell; the spire 

 is short, composed of 4 or more whorls, and a small nucleus of 

 the usual type, as in canaliculata ; sutures channelled; the sur- 

 face appears smooth, until slightly magnified when it is seen to 

 be covered with very fine spiral lines; columella carries a single 

 strong fold. 



Height 10, diameter 3, aperture 9 mm. 



The Costa Rican fossils are related to the recent A. bullata 

 Kiener, of the West Indies but differ in their shorter spire and 

 are somewhat more expanded about their anterior half. It is the 

 largest species in the Costa Rican Miocene, often reaching a 

 length of 10 mm. Its surface is covered with fine, spiral lines 

 and the columella carries a single, strong plication. 



Gatiin Stage: Middle Creek. 



Coll. ^, East Grape Point Creek. 



Acteocina recta d'Orbigny 



■ Bidla recta d'Orbigny, 1845, De las Sagra, Hist. Pol. y Nat. Isla de 

 Cuba, vol. 5, p. 67, no. 55; Atlas 8, pi. 4, bis, figs. 16-20. 

 Tor?tatina recta Gabb, Trans. Phil. Soc, vol. 15, p. 246. 

 Torn.atina coix-lacryma Guppy, 1876, Quart. Journ. Geol. Soc. Lon- 

 don, vol. 22, p. 518. Probably not of Guppy, 1867. 

 Acteocina recta Maury, 1917, Bull. Amer. Pal., vol. 5, p. 178, pi 3, 

 fig- 3- 

 A small species, t}^pically with a short exserted spire and a 

 broadly C3dindrical form. The Costa Rican examples are all 

 less than 3 mm in height. There is considerable variation in 

 the height of the spire, which may be sunken in some cases as 

 illustrated bj^ the larger coix-lacry?7ia Guppy from the Miocene 

 of Venezuela and Martinique, to others with high spires and 

 strongly descending whorls as in the recent canaliculata Say. 

 However they all appear to belong to the same species. From 

 the young of bullata var. costarica?ia, they are at once distinguish- 

 ed by their smooth, plain surface. 



Gatun Stage: Coll. 7, Estrella River. 

 Coll. 5, Red Cliff Creek. 



