Morgan Expeditions. 121 



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 mm ; height, 10.5 m,n ; depth of 

 each valve, 3 mm . 



Prof. Hall has identified this Brazilian form with his Gram- 

 my sia par allela of the Hamilton group, New York, loc. 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 Erere, Prov. of Para, Bra- 

 zil, associated with Spirifera Pedroana, etc. 



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 

 May, 1875- 9 Ann. Lyc. Nat. Hist., Vol. xi. 



