INVERTEBRATE PALEONTOLOGY. 433 



Morton's figure and description. It differs from the typical form of S. Con- 

 rad/, in being a little moi-e gibbous and in having two or three rows of tuber- 

 cles less on each side. The deflection and widening of the non-septate por- 

 tion of its outer whorl are also less distinctly marked, and the eosta^ on that 

 part of the shell, instead of gradually growing finer and more crowded, 

 become entirely obsolete toward the aperture. In the smaller number of its 

 lateral tubercles, its rather narrower whorls, and, as far as we have been able 

 to see, in the characters of its septa, it somewhat approaches S. Cheyennensis, 

 Owen, but it differs remarkably from that form in the very small size of its 

 umbilicus. 



Mr. Conrad has figured and described under the name Scaphite.s iris 

 (cited above), Ik in the Cretaceous of Mississippi, a fragment of a form very 

 like this, lint he states that its septa are very different. 



Locality and position. — Fox Hills, Long Lake, Moreau River, &c. ; from 

 the Fox Hills group of the Upper Missouri Cretaceous series. 



Scaphites Conradi, v a r . intermedins. 



Plate 34, figs. :•!. a, h, c. 



Shell oval-subcircular, much compressed; volutions so deeply embracing 

 as to leave only a very narrow umbilicus, all rather distinctly compressed 

 laterally, inner ones narrowly rounded on the periphery ; last, or deflected 

 half of outer turn so very short as not to become free at the aperture, some- 

 what widened and straightened near the umbilicus above, and narrowly 

 flattened on the periphery, the flattening sometimes also continued less dis- 

 tinctly defined around on the inner half; aperture oval, being longer than 

 wide, and more or less sinuous on the inner side; surface ornamented by 

 numerous, somewhat flexuous costa?, which increase by division and the 

 intercalation of shorter ones between, so as to number about five times as 

 many around the periphery as at the umbilical side — those of each side of the 

 inner volutions, as well as the inner half of the outer, being provided with 

 about five revolving rows of small tubercles, exclusive of the row of rather 

 larger ones around each side of the narrow periphery ; costse of the last half 

 of the outer volution becoming very fine, crowded, and nearly or epiite desti- 

 tute of tubercles, excepting the two peripheral rows, which are largest and 

 most widely separated on the lower side of this part. 



Septa rather deeply divided into four lobes and four sinuses on each side 

 ."•") n 



