. Annals of the Carnegie Museum. Carnegie Museum; Carnegie Museum of Natural History; Natural history. Raymond : Gastropoda of the Chazy Formation. 181. convex and the outer whorl concave, or the whole upper surface may be convex and the spire somewhat elevated. The lower part of the shell is usually rather long, the sides meeting the upper surface always at less than a right angle ; in young shells, in rather an acute angle. The umbilicus is large in the cast, but in perfect specimens it is filled by the shell. The surface is marked by lines which make a double curvature in crossing the upper
. Annals of the Carnegie Museum. Carnegie Museum; Carnegie Museum of Natural History; Natural history. Raymond : Gastropoda of the Chazy Formation. 181. convex and the outer whorl concave, or the whole upper surface may be convex and the spire somewhat elevated. The lower part of the shell is usually rather long, the sides meeting the upper surface always at less than a right angle ; in young shells, in rather an acute angle. The umbilicus is large in the cast, but in perfect specimens it is filled by the shell. The surface is marked by lines which make a double curvature in crossing the upper surface of the volution. They are interrupted at the middle by a raised line. At the edge of the shell, which is acute, there is a raised band on which the striae curve sharply back. Beneath, the striae curve sharply forward, then backward to the columella. In young shells the surface markings consist of fine impressed lines which are often more or less gathered into fascicles, as is shown in figure 13, Plate XLVII, and on Plate XLVII, figure 1. On mature shells the surface of the body is covered with coarse striae or undulations, parallel to the successive positions of the outer lip. This character of the surface of the adult shell is shown in figures 5-8, Plate LV. In fully adult shells the columella is somewhat drawn out, twisted to the right, and slightly excavated. (See figure 8, Plate LV.) Some shells show a hint of an umbilical perforation, as is seen in figure 7 on the same plate, but in almost all cases this is covered by the columellar lip. The outer lip seems always to be thin. Its form can be seen on Plate LV, figures 5 and 6. For characters distinguishing this species from the last, see Rapliis- toma striatum. Locality. — Shells of this species are common at Crown Point, Val- cour Island, Valcour, and Chazy, New York, and Isle La Motte, Ver- mont. The specimen represented on Plate XLVIII, figure 1 is in the Carnegie Museum, figures n-13, Plate XLVII, and figures
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