- 77 - 



MnTensions .- length, 5.8 inm.; alt., 6.2 mm.; seraidiam., 1.5 nun, 

 Hem arks .- This form is considered, after some hesitation, 

 a variety of I. ovalis C^abh (1), described from the Oligooene of 



(1). Trans. Am. Philos. Soc, newser., vol. 15, p. 255, 1873. 



Santo Domingo. The typical ovalis reaches a lar^^er size and is 

 slightly less oblique. Adult shells do not display the obliquity 

 for which "this shell is remarkable", acjordii^g to the original 

 description: on the contrary, they are but slightly obliciie. 

 On the largest of his specimens the concentric sculpture is exagger- 

 ated, 7^ile the others have a sculpture closely resembling that of 

 supracaneellata . Guppy (2) has described a very closely related 



(2). Proc. U. S. ITat. I'us., vol. 19, p. 525, pi. 50, fig. 2, 1096. 



form, I_. Gubangularis. from the Oligocene Ditrupa bed at Point- 

 apier, Trinidad; ir. fact, it is so close to the previously des- 

 cribed ovalis that it, too, should rjrobably be considered a var- 

 iety. The Trinidad variety differs from supracan eel lata by being 

 smaller, slisrhtly more oblique, less c onver and by having the con- 

 centric sculpture usually more accentuated than the radial, so that 

 the cancellated effect- so conspicuous on supracancella.ta - is 



