Blue clay. Rare.
Pl. [6], Fig. 3.
A cruciform variety occurs at Pensauken, N. J., artesian well (Coll. F. J. Keeley).
BIDDULPHIA GRANULATA ROPER
Valve elliptical-lanceolate, convex, with diagonal rows of puncta 12 in 10 µ and sometimes with small scattered spurs. Processes inflated at the base, obtuse at the ends, which are curved outward toward alternate sides. Near each process and on opposite sides of the longitudinal axis is placed a stout spine bent or curved inward near the middle. Connective zone with diagonal rows of puncta smaller than those on the valve.
Pavonia, N. J., artesian well. Fossil in the Pleistocene. Along the coast. Not common.
Pl. [7], Fig. 6.
BIDDULPHIA RHOMBUS (EHR.) WM. SM.
Valve rhomboidal, sometimes triangular, with subconical processes. Surface convex with hexagonal reticulations, 7-9 in 10 µ, irregular at the centre and radiating to the circumference. Minute spurs are scattered over the surface, and on each side are usually two or three short spines.
Common along the coast and fossil in the Miocene and later deposits.