GASTEROPODA OF THE MIDDLE GREEN MARLS. 177 
CAVOSCALA ANNULATA. 
Plate xxu, Figs. 1-5. 
Scalaria annulata Morton : Synopsis, p. +7, Pl. m1, Fig. 10. 
Scala annulata (Mort.) Gabb: Synopsis, p. 79; Meek, Check List Cret. and Jur. 
Foss., p. 20; Gabb, Proc. Nat. Sci., Phila., 1876, p. 298. 
Scala (Opalia) annulata (Mort.) Gabb: Thbid. 
Shell above a medium size for shells of this group, the largest individ- 
ual, if perfect at the apex, would measure fully 13 inches in length, with 
the aperture probably yet imperfect. Volutions about seven in number in 
the largest specimen, very ventricose and very slightly angular in the mid- 
dle, closely coiled or in close contact; sutures deeply marked and charac- 
terized by a slightly beaded band at the bottom, formed by the edge of a 
broad, flattened, raised, or thickened space, which marks the base of the 
volutions and borders the umbilicus. Umbilicus very large, angular on 
the margin and rapidly sloping within, showing the preceding volutions in 
the cavity. Aperture broadly ovate or subcircular, the inner margin straight- 
ened somewhat, conforming to the slope of the umbilicus. Surface of the 
shell marked by a series-of moderately close, elevated, lamellose, transverse 
ridges or varices, which are directed rather strongly backward in their pas- 
sage from above to the lower margin, and are less conspicuous on the flattened 
space bordering the umbilicus, within the umbilicus they are faintly shown. 
There are also fine transverse rigid lines parallel to the varices, occupying 
the ridges and intervening spaces, also rather strong, rounded, wiry spiral 
lines covering the entire surface of the shell, which are perceptibly directed 
upward in crossing the varices. This gives the surface of the shell a very 
beautifully cancellated structure, easily perceptible to the unaided eye. 
This is the most beautiful shell I have yet seen from the New Jersey 
formations, and is far more attractive in its appearance than Scalaria pretiosa 
of the present seas, which it much resembles, although the more closely 
arranged varices, contiguous whorls, and cancellated structure readilv dis- 
tinguishes it. 
Formation and locality: In the yellow sandy limestones of the Middle 
Marls at Timber Creek, New Jersey, and a single small one from the green 
marls of the same bed at that same locality. The yellow limestone speci- 
MON XVIII——12 
