INVERTEBRATE PAL2E0NT0L0GY. ' 375 



twisted; apertures rhbmbicoval, being angular above, and near the middle 

 of the outer side; surface ornamented with distinct lines of growth, that 

 make a graceful backward curve, parallel to the outline of the outer lip, on 

 • the upper slope of the volutions, and are crossed In well-defined revolving 

 lines, one of which, between the two principal ridges, is larger than the 

 others; suture distinct. 



Length, about 3.22 inches; breadth, 1.82 inches; slopes of the spire 

 nearly straight, with a divergence from the apex of 57°. 



The specimen from which our figures of this shell were drawn has the 

 upper volutions considerably broken and eroded, so that it does not give a 

 correct idea of the ridges and nodes; the first not being near as angular as 

 in well-preserved examples, and the nodes not appearing flattened and trans- 

 verse enough, nor does the figure show the lines of growth above the angle 

 curved enough. Since the drawings were made, I have also cut away the 

 rock about the columella, and find it somewhat more arcuate on the inner 

 side at the middle, and more prominent below than represented in figure 

 6, b. It should also be explained that the position in which both figures are 

 drawn prevents the curvature of the beak from being apparent; its bend 

 being directly backward, and consequently so nearly in the line of view as not 

 to be seen in the figures. 



It is with great doubt that I refer this shell even to a distinct section of 

 the genus Fusus. Unfortunately, none of our specimens show its entire canal, 

 or inner lip. Its similarity of ornamentation suggests possibly closer generic 

 relations to our Pyropsis Bairdi than may be apparent from such specimens 

 as have yet been seen. 



Locality and position. — Long Lake and Moreau River, Dakota; from the 

 Fox Hills group of the Upper Missouri Cretaceous series. 



Fusus? (Scnifnsns) Dakotensis, var. 

 Plato 32, fig. 7, a (aud 7, 6?). 



I have long had this form under consideration, but have never felt epiite 

 sure that it may not be a variety of the last ; and consequently always laid it 

 aside with the hope of getting other specimens for comparison. As none 

 have yet come in, and it is necessary to arrive at some conclusion in regard 

 to its relations to the last, I have decided to view it provisionally as a varietv 

 of the same. If additional collections sIiohM show it to be sufficientlv dis- 



