CEPHALOPODA OF THE OEETAOEOUS MAKLS. 251 



compressed discoidal, with a proportionally small umbilicus, the volutions 

 have been sharp on the dorsal edge and marked by a series of undulations 

 which gave rise to the specific name. The sides are ornamented by two 

 lines of nodes which divide the surface into three nearly equal spaces, also 

 by transverse ridges which are low and rounded, and pass from the margin 

 of the umbilicus almost directly across the volution to a node one-third of 

 its breadth from the margin, and are then bent sharply forward, their con- 

 vexity giving rise to the undulations on the dorsal carination. Some of 

 the ridges bifurcate at the inner line of nodes, each branch reaching the 

 margin as independent ridges, but the fragment is too small to show how 

 frequently this feature occurs. 



The septa of this specimen from New Jersey appear to be as nearly 

 like that figured by Dr. Roemer, above cited, as could be expected in any two 

 individuals from the same locality, consisting of a proportionally large 

 dorsal lobe and three lateral lobes, visible on the side of the volution, with 

 another just within the limits of or on the side of the umbilicus. The dorsal 

 lobe has the main divisions bifurcating, forming two nearly equal branches, 

 with numerous slender digitations ; the other is single, slender, elongate, and 

 with five or six digitations. The' first lateral lobe is large and somewhat 

 complicated, having five principal divisions with numerous digitations. The 

 other lobes are much smaller and less complicated, but all have slender, 

 narrow digitations. Between the dorsal and first lateral lobe there is a long 

 slender intermediate lobe with three to five digitations on a side. The 

 sinuses are less complicated than the lobe, and have the terminations usu- 

 ally rounded, while those of the digitations of the lobes are usually sharply 

 pointed and narrow. 



The specimen bears no evidence of the siphon. 



Formation and locality: The specimen, which is a small fragment only 

 of a single volution, is entirely a cast in a hard ferruginous sandy clay, 

 with a few grains of glauconite scattered through it, and may have come 

 from the white limetone nodules near the base of the Lower Green Marls, 

 at Holmdel, Marlboro, or some of the other outcrops of this material 

 within the State. As it is the only fragment of the species yet noticed, 

 there may be some question as to its locality until others are found. 



