p. 24




Status: Complete


riot truncation to the posterior extremity of the hinge line - the
meeting of the curved lower and straight upper margin giving
a sub-nasute extremity. Umbones prominent, very full and
rounded, the beaks closely incurved, the apices minute. Sur-
face marked by concentric ridges, of growth parallel to the
margin of the shell.
This species has some resemblance to T. ventricosa, in its
form and general outline: but it is broader in proportion
to length, less attenuate posteriorly, the beaks are the nearest
to the anterior, and the basal margin is destitute of the sinus
which exists in that species,
Length nearly seven-eights of an inch, height three-fourths
of an inch.
Geological Formation and Locality. In limestone of the age
of the Trention limestone; at Mineral Point, Wisconsin.

Description. Shell small, sub-triangular, with the rounded basal
margin; valves depressed-convex. The anterior and posterior
portions of the hinge line are nearly straight from between the
beaks to beyond the muscular impression, and stand nearly at
right angles to each other. The distance from the beaks to the
base of the shell is usually equal or nearly equal to the length.
The muscular impressions are large and moderately distinct;
the posterior one elevated on the dorsal side with a broad, low
ridge (depression on the cast) passing from near the beak to
the scar. The hinge plate is marked by from twenty to twen-
ty-five very small curved teeth on the posterior side, and from
ten to fifteen on the anterior side.
This species differs from T. astartoeformis, (Ctenodonta?
astartoeeformis, Salter, Canadian Organic Remains, Decade I,
page 27,) in the more erect beaks and in the different form of
the posterior basal margin.
Geological Formation and Locality. In limestone of the age
of the Trenton limestone; Dodgeville, Wisconsin. T.J. Hale.

TELLINOMYA VENTRICOSA, (n.s.) [penciled in See Vol 1 p 38]

Description. Shell sub-rhomboidal, extremely ventricose, with
strong incurved beaks, the anterior dorsal and ventral margins
sub-parallel, the posterior and obliquely truncate, the anterior
end broadly rounded, and continuing into the basal margin;
posterior umbonal slope somewhat angular, with a slight sulcus
just anterior to it, which passes from near the beak of the
base. Surface marked by obscure concentric striae of growth.

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