468 PALEONTOLOGY OF NEW YORK. 



Septa thin, somewhat regular in their arrangement ; the margin* moder- 

 ately thickened, and slightly imbricating j distant from each other, at their 

 origin on the umbilical side, from three to five mm. in the last fourth of 

 the outer volution, the last two being closer than any of the preceding. 

 From the umbilical side the septa proceed in a generally transverse direction, 

 making several abrupt curves, the posterior ones of which are angular, and 

 describing four saddles, of gradually increasing height and dimensions, and 

 three shallow, angular lobes on the inner half of the width of the volution : 

 on the outer half of the volution there are deeper and more abrupt curves; 

 and leaving the base of an angular lobe at about the centre, the septa describe 

 a wider semi-elliptical saddle, a deeper elongate subangular lobe, and a 

 still more elongate and more elevated saddle, which has its apex near the 

 periphery. On the outside of this there is a narrow lobe, and an abrupt 

 turn of the septum to the periphery, upon which its course has not- been 

 observed. This arrangement gives six lobes on the lateral face of the volu- 

 tion, each one of which has an increasing depth from the umbilical margin. 

 There are likewise six saddles, each successive one of which is higher and 

 wider than the preceding, except the last which is much higher, but not 

 quite so wide as the one preceding it. Suture-lines narrow, moderately 

 impressed upon the cast, and more strongly marked at and near the extremi- 

 ties of the lobes and saddles. Siphuncle unknown. 



Test entirely unknown. The surface-markings cannot be satisfactorily 

 determined on the cast of the interior or upon the weathered impression of 

 the ixterior, which are the only portions preserved. 



The cast of the interior is marked by nodulose annulations, which are 

 nearly continuous on the inner half of the volution, and interrupted on the 

 outer half: the median line of the volution being marked by a row of 

 depressed nodes, which become obsolete toward and upon the chamber of 

 habitation. The intermediate spaces are essentially smooth, or marked only 

 by a peculiar pitted or indented surface, which has not been identified with 

 any external marking. The fossil has had a lateral diameter of nearly 

 eighty mm., and perhaps more than that in its entire condition. 



