123 Morgan Expeditions. 
Although only a single specimen of this species, which 
has been referred with some doubt to Hdmondia, has been 
obtained, and that is not a very perfect one, it has been pos- 
sible from it to make out the principal characters of the 
species quite accurately. It is readily distinguished from 
all the other species of lamellibranchs yet found at Ereré, 
by the nearly symmetrical valves and sub-central beaks. 
From the Devonian sandstone, Ereré, Prov. of Para, 
Brazil, with Spirifera Pedroana, ete. 
[Named in honor of my friend, Senhor José Gualdino da 
Silva, of Para, to wliom I am under many obligations. C. 
Genus MODIOMORPHA, Hall. 
Modiomorpha Pimentana, sp. nov. 
Shell of moderate size, elongate, sub-quadrilateral in outline. From 
the beaks, which are placed at less than one-fourth the length from the 
front, the height increases very gradually to the posterior end of the 
hinge margin, which last equals about three-fifths the length of the shell 
and is straight; height of shell at beak about five-sixths that at end of 
hinge margin. Anterior margin straight and oblique for about one-half 
its length, forming at the beak an angle of about 135° with the dorsal 
margin. It rounds abruptly to the ventral margin, which, in its posterior 
three-fourths, is nearly straight. The posterior margin is slightly con- 
“vex, and extends obliquely backward from the dorsal margin, with which 
it forms an angle equal to about that at the beaks, and curves abruptly to 
the ventral margin. Beaks very small, obtuse and not produced above 
the hinge line. The valves are quite convex, the surface rising rapidly 
from the ventral and anterior margins on the one side, and from the 
dorsal and posterior margins on the other, toward a line running obliquely 
across the valves from the beaks to the lower posterior extremity. Along 
this line the valves are sometimes angular, at others they are regularly 
and strongly rounded; generally, however, they are angular near the 
beaks and become gradually rounded and flattened posteriorly. Above, 
the surface slopes to the dorsal margin very abruptly and is concave just 
behind the beaks, but the slope becomes more and more gradual toward 
the posterior extremity, and, from very slightly concave at first, it changes 
to very slightly convex posteriorly. The lower and anterior portion of 
the valves is sometimes broadly flattened. Surface marked with numer- 
ous concentric lines of growth. Length, 30™™; height, 16™™; depth of 
single valve, 5™™. These dimensions are of the largest specimen found ; 
most of the specimens are much smaller. 
