14 
Atrypa. Section I. 
Without longitudinal striae, and with the edges of the 
valves upon one plane. ( u Cardinal area none.”) 
ATRYPA pectinifera. 
TAB. DCXVI. 
Spec. Char. Transversely obovate ; surface covered 
with concentric ciliated fringes. 
The valves of this shell are moderately and equally con- 
vex, the larger beak is only slightly prominent, and the 
internal septa are obscure. 
Very abundant in the magnesian limestone of Humble- 
ton Hill, near Sunderland. It is one of the Terebratulae 
spoken of by Professor Sedgwick in his paper on the mag- 
nesian limestone (Geol. Trans. New Series, Vol. III. 
pt. I. 1 19), and several other shells there mentioned as 
Terebratulae have spiral appendages, and belong also to 
the genus Atrypa. 
The three middle figures are magnified. 
ATRYPA expansa. 
TAB. DCXVI I. — -jig. 1. 
Spec. Char. Orbicular, becoming* transversely oval 
with age, convex ; front even ; surface covered 
with broad, striated, imbricating fringes; beak 
small, produced, incurved. 
Syn. Spirifera expansa. Pliill. Geol. Yorks. Pt. 11. 
220. Pl.X.f. 18. 
