OTANTON.] STEPHANOCERATIDiE. 187 



bifid and digitate; first lateral sinus as large as the siplional lobe, very 

 narrow at its base, and profoundly divided at its extremity into two 

 unequal branches, of which the one on the siphonal side is larger than 

 the other, and, like the latter, deeply bilid, with sinuous and obtusely 

 digitate margins; first lateral lobe as wide as the siphonal lobe, but 

 somewhat shorter, and provided with two nearly equal, bifurcating, and 

 digitate terminal branches; second lateral sinus not more than half as 

 long, and little more than half as wide as the first, and somewhat simi- 

 larly divided and subdivided; second lateral lobe about half as long 

 and wide as the first, but tripartite at the extremity, the divisions being 

 nearly equal and digitate; third lateral sinus small and merely pro- 

 vided with two nearly equal terminal branches, with more or less sinu- 

 ous margins; third lateral lobe hardly more than half as large as the 

 second, and bearing two very short, digitate, terminal divisions. Be- 

 tween the last-mentioned lobe and the umbilicus there is a minute, tri- 

 digitate lobe, very similar to the auxiliary lobe of the third lateral 

 sinus, but smaller. 



"Length, 3.13 inches; height, 2.G5 inches; convexity, 1.90 inch. 



"In the style of its ornamentation this species resembles our 8. War- 

 reni, but it differs, however, remarkably in form and size, being much 

 larger, and proportionally very decidedly more gibbous, with a pro- 

 portionally smaller umbilicus. As the septa of the type of 8. warreni are 

 yet unknown, I have not had an opportunity to compare their struc- 

 ture with those of the form under consideration; but it is probable 

 that they will be found to present differences in their details. Cer- 

 tainly those of the Wyoming form, that I now regard as only a variety 

 of 8. warreni, are quite different." 



Locality and posit ion. — Chippewa point on the upper Missouri river, 

 Fort Benton shales. 



Scaphites MULLANANUS Meek & Hayden (sp.). 

 PL xlv, Figs. 2-4. 



Ammonites mullananus Meek & Hayden, 1SG2, Proe. Acad. Nat. Sci., Pliila., p. 63. 

 Ammonites?? mullananus Meek, 1870, U. S. Geol. Snr. Terr., vol. ix, p?607, PI. 8, Figs. 



la-c. 

 Compare Scaphites subylobosus Whiteaves, 1885, Cont. to Can. Palaeont, vol. I, p. 52, PI. 



7, Fig. 3 and PI. 8. 



Meek's revised description is as follows : 



u Shell eompressed-subglobose; rounded on the periphery ; umbilicus 

 small, deep, and acutely conical, between one-third and one-half as 

 wide as the breadth of the outer whorl from the dorsal to the ventral 

 side, showing about one-third of each inner volution. Whorls increas- 

 ing rather rapidly in size, particularly in convexity, sloping on each 

 side from near the umbilicus (with a slightly convex outline) toward 

 the periphery, and rounding abruptly into the umbilicus on the inner 

 side, each of those within deeply embraced by the succeeding turn. 



