MARYLAND GEOLOGICAL SURVEY 163 



ones above; longitudinal costae variable in distribution and develop- 

 ment, often entirely absent; month widest above; labrum strongly 

 crennlated; columella with three plaits, of which the upper is the larg- 

 est, the middle the most oblique, and the lower is obsolete in the whorls 

 of the spire. 



This species differs from C. lunata in being much more constricted 

 at the suture, and in having less distinct longitudinal ribs. 



Length, 23 mm.; diameter, 13 (?) mm. 



Occurrence. — Calvert roRMATiON. Plum Point. 



Collections.— Mar jlaiid Geological Survey, Johns Hopkins University, 

 U. S. National Museum, Philadelphia Academy of Natural Sciences, 

 Cornell University. 



Cancellaria lunata Conrad. 

 Plate XLIII, Fig. 5. 



Cancellaria hmata Conrad, 18."0, Jour. Acad. Nat. Sci. Phila., voL vi, 1st ser., p. 



222, pi. ix, fig. 4. 

 Cancellaria lunata Lyell, 184.5, Quart. Jour. Geol. Soc. London, vol. i, p. 421. 

 Cancellaria hmata Lyell, 1846, Proc. Geol. Soc. London, vol. iv, p. .5.55. 

 Cancdlaria lunata Conrad, 1868, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. .567. 

 Cancellaria lutiata Meek, 1804, Miocene Check List, Smith. Misc. Coll. (183), p. 17. 

 Cancellaria scalarina Conrad, 1866, Amer. Jour. Conch., vol. ii, p. 68, pi. iv, fig. 17. 

 Cancellaria {Solatia) ZMna<aCossmann,1899,Essais de Paleoconch.Comp.,vol. iii,p. 12. 

 Not Cancellaria scalarina Lamarck. 



Descripition. — " Shell turreted, with longitudinal oblique ribs ; trans- 

 versely sulcated; whorls of the spire narrowed at the base and flattened 

 on the summit; apex acute; right lip regularly toothed within; colu- 

 mella with three plaits, the upper one large and distant, and the last 

 plait uniting with the base of the columella; aperture lunate." Con- 

 rad, 1830. 



Some individuals resemble C. alternata. This species differs from 

 alternata essentially in being proportionally longer, having a sharper 

 spire, thinner shell, longitudinal ribs not as strong, and the tops of the 

 whorls somewhat fiat. In these characters it is intermediate between 

 aliernala and engonata but is sharply separated from both. 



Conrad could not have intended his figure and description for C. 

 scalarina Lamarck, which is a Trigonostoma somewhat resembling T. 

 hiplicifera. Conrad's description of scalarina applies to our speci- 



