CRETACEOUS FOSSILS. 181 



though it .still has a rather less oblique suture. The body-volution of the 

 adult C. macrospira, howevei", is suddenly, and dispropoitionally enlai'ged, 

 and so oblique as to give a rather different aspect to the whole shell. 

 Locality and. position. — Same as foregoing. 



Campeloma (iindt. sj).). 



Plate 17, figs. 15 a, h, .ind 10 a, b, c. 



Shell ovate, attaining a medium size; volutions about five or six, con- 

 vex, rounded, increasing moderately in size, all without revolving angles; 

 spire moderately prominent; suture well defined, in consequence of the 

 convexity of the volutions; surface showing fine, slightly oblique, some- 

 what sigmoid lines of growth; aperture ovate; inner lip apparently a little 

 thickened, and in adult shells somewhat reflexed beloAv, but leaving a small 

 umbilical pit uncovered. 



Length of one of the larger s])ecimens, about 1.45 inches; breadth, 

 about 0.9o inch. 



Our fig. 15 a does not give a correct idea of the form of the aperture, 

 which, in the specimen figured, is filled with rocky material that laps upon 

 the columella, so as to give an unnatural apparent breadth to the mouth 

 of the shell. The engraving also makes the marks of growth mvch too 

 coarse and too straight on fig. 15; and the specimen is compressed accident- 

 ally, so "as to appear broader than natural. It may, therefore, be only a 

 distorted specimen of the last; and the smaller specimens represented by 

 figs. 16 and 16 a, h, c are probably young shells. 



Locality and position. — Same as foregoing. 



limnj]idj:. 



Genus LIMN^EA, Lamarck. 



LlMN^A (LiMNOPHYSA) NITIDULA, Meek. 



Plate 17, figs. r>, 5 a." 



Melania f nitidula, Meek (1860), Proceed. Acad. Nat. Sci. Pbilad., XII, 314. 

 Limncea nitidula. Meek (1866), in Conrad's Eocene Smithsonian Check-List, 9. 



Shell small, ovate-subfusiform; spire conical, moderately elevated; vo- 

 lutions about six and a half, convex, last one forming two-thirds of the 

 ♦ Fig. 5 a does not give a very correct representation of the aperture of this shell. 



