121 Morgan Hexpeditions. 
concave; it rounds somewhat abruptly to the ventral margin below, which 
is moderately curved anteriorly, but becomes nearly straight and subpar- 
allel with the dorsal margin along the middle of the shell. Posteriorly 
the ventral margin appears to round up more or less strongly toward the 
dorsal margin, but in none of the specimens obtained, is the posterior ex- 
tremity of the shell perfectly preserved. From a line, extending obliquely 
across the valves, from just behind the beaks to the lower posterior ex- 
tremity of the shell, and forming an angle of about 30° with the dorsal 
margin, the surface curves moderately and quite regularly to the anterior 
margin, and is traversed by about 10 or 12 low, wide, rounded, concentric 
undulations, which decrease in size from the ventral margin toward the 
beaks, where they are quite small. The lower ones round up quite ab- 
ruptly in front, but are more gently curved along the middle. Posterior 
to the oblique line, above mentioned, the surface descends abruptly, and 
with a concave slope, to the hinge line and the posterior extremity, and is 
smooth in the moulds. Length, about 16™™ ; height, 10.6 ™™ ; depth of 
each valve, 3™™, ; 
Prof. Hall has identified this Brazilian form with his G'ram- 
mysia parallela of the Hamilton group, New York, Joc. cit. ; 
but he expresses a doubt as to whether the species is a true 
Grammysia, or belongs to his new genus Pholadella, pub- 
lished in 1869. 
Only a few specimens of this pretty form were obtained 
from the Devonian sandstone of Ereré, Prov. of Para, Bra- 
zil, associated with Spirifera Pedroana, ete. 
Genus EDMONDIA, De Koninck. 
Edmondia Pondiana, sp. nov. 
Shell below the medium size, elongate, nearly two-thirds as high as 
long, sub-elliptical in outline and moderately ventricose, with the great- 
est convexity in the lower posterior part of the umbonal region. An- 
terior end much narrower than the posterior, well rounded and prominent, 
the margin uniting by a moderate curve with the ventral margin, which, 
along the middle one-half of the shell, is quite straight and nearly par- 
allel with the dorsal margin; posterior end strongly rounded, and appar- 
ently slightly truncate in its lower portion; dorsal margin straight 
and about one-half the length of the shell. Beaks situated at a little 
less than one-third the length from the front, broad, very prominent, 
and strongly incurved toward the hinge margin and the front, nearly or 
quite contiguous, and projecting a moderate distance above the hinge. 
The umbonal region is obliquely flattened, the flattened surface inclining 
anteriorly. This flattening, which commences on the beak, appears to 
