314 REPORT UNITED STATES GEOLOGICAL SURVEY. 



concave between the base of the first and the extremity of the outer 

 process. Anterior canal and beak short ; no posterior canal ; inner lip 

 apparently without a callus. 



Surface of the volutions of the spire marked by numerous vertical or 

 slightly oblique folds or ridges, which disappear upon the body-volution, 

 its surface, like that of the wing, being marked with comparatively strong 

 wrinkles of growth ; the folds of the spire are crossed by numerous fine 

 revolving, raised lines, which are hardly visible without the aid of a lens, 

 except those adjacent to the sutures, which are stronger ; these revolving 

 lines are perceptible upon the body-volution, but are absent or obsolete 

 upon the wing. No carina passes out from the body-volution to either 

 of the processes of the wing, but the inner process is the more convex 

 of the two, its convexity being continuous with the greater convexity of 

 the body- volution. 



Extreme length from the point of the canal to the apex of the spire, 

 nearly 4J centimeters $ breadth across the wing and body-vohition, 29 

 mdlimeters ; diameter of the body- volution, 15 millimeters. 



The difficulty of assigning the species of the Aporrhaidce found in our 

 Western Cretaceous rocks to rigidly defined genera has already been 

 referred to, and this species not only presents no exception to that rule, 

 but it possesses some unique features, notably that of a second expansion 

 of the outer lip, and it is apparently without the usual sinuosity of the 

 front margin near the columella. With these exceptions, it would con- 

 form well with the diagnosis of the subgenus Drepanocheilus Meek. It 

 is, however, apparently without the callous inner lip possessed by all the 

 species of that subgenus known to me. Its reference as above is of 

 course provisional. 



Position and locality. — Cretaceous strata, probably of the age of the 

 Colorado Group; Upper Kanab and Sink Spring, Utah, where it was 

 collected by Prof. J. W. Powell. I also saw examples of it from the same 

 localities in the collection of Professor Barfut, Salt Lake City, Utah. 



Genus TUEEITELLA Lamarck. 



TURRITELLA MARNOCHI (sp. nOV.). 



Plate 7, figs. 5 a and i. 



Shell of usual size, elongate conical, gradually tapering, with slightly 

 convex, nearly straight sides, apical angle from 20° to 25°, but varying 

 somewhat in different specimens and in different portions of its length, 

 in consequence of the slight convexity of the sides of the spire ; volu- 

 tions ten or twelve, flattened-convex, the last one rounded below ; suture 

 impressed, at the bottom of a moderately distinct channel ; surface of 

 the volutions of the spire marked by five (sometimes six) moderately 

 elevated, revolving, nodulose carinas, the distal one being a little larger 

 than the others, and the nodules being sometimes so arranged as to form 

 obliquely longitudinal rows across the volutions. These nodules appear, 

 in some examples, to be a little elongated, the longer axes of those upon 

 the carinas that occupy the distal half of the volution being directed 

 obliquely to the sinistral skle of the shell, and the others to the dextrai 

 side ; the surface between the carinas marked by from three to five fine, 

 raised, revolving lines ; similar ones also marking the carinas between 

 the nodules. Besides the carinas just described, visible upon the spire, 

 there are several others of similar size, but a little more sharply raised, 

 and a little less broken into nodules, on the proximal side of the last 



