GASTEEOPODA OF THE MIDDLE GREEN MAELS. 177 



Cavoscala annulata. 



Plate XXII, Figs. 1-5. 



Scalaria annulata Morton : Synopsis, p. 47, PI. iii, 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. 398. 

 Scala (Opalia) annulata (Mort.) Gabb: Ibid. 



Shell above a medium size for shells of this group, the largest individ- 

 ual, if perfect at the apex, would measure fully If 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 deejjly 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 



