GASTBEOPODA OF THE EOCENE MARLS. 231 



moderately marked suture lines dividing them, but usually wider than high; 

 shell quite thin, judging from the spaces left by its removal from between 

 the volutions on the casts; surface on the shell marked by eight or nine 

 sharply elevated, salient spiral ridges on each volution between the sutures, 

 the number on the last volution not ascertained; these ridges are divided 

 by concave interspaces, and are moderately regular, though in several cases 

 the two next above the suture are somewhat more distant than those above; 

 this feature, however, does not hold good in all cases. There are also faint 

 indications in the matrices of fine transverse lines of growth crossing the 

 ridges, and strongly directed backward in passing from the suture down- 

 ward on the matrix, indicating a broad sinuous lip in the shell. Form of 

 the aperture, columella, and base of lip unknown. 



The species is represented by numerous examples, both of internal 

 casts and matrices, but always flattened to a greater or less extent. Some of 

 these indicate specimens of not less than 2^ inches in length, probably con- 

 siderably more, and have a breadth across the lower volution of over half 

 an inch, with probably half the number of volutions absent. It is just 

 possible that these casts represent a thin-shelled Turritella with rounded 

 volutions; still the stirface striae or ridges are much more like those of 

 Mesalia, but the form of the aperture and lip being unknown, the final 

 determination of their true generic relations must be left for future discov- 

 ery. The spire differs so totally in its great elevation and very moderate 

 increase in diameter from that of any other species I know, that there 

 seems no difficuly in distinguishing it. 



Formation and locality: In the upper layers of the Upper Green Marls, 

 at Shark River, New Jersey. Collections at Rutgers College and Am. Mus. 

 Nat. Hist. 



