1878.] 33 (Rathbun. 
The entire length of the shell is 28 mm., width 26 mm., depth of 
the dorsal valve 15 mm., width of fold at the front about 11 mm. 
Only a single specimen of this large species of Rhynchonella was 
obtained; this is the cast.of a dorsal valve, with a portion of the ven- 
tral valve attached. It is readily distinguished from the other species 
recorded in this paper, by its larger size, greater proportionate 
length, and the more extended, pointed beak of the dorsal valve. 
From the Devonian sandstone of Ereré. (Geol. Comm., 1876.) 
Rhynchonella (Stenocisma) dotis (?) Hall. 
Rhynchonella (Stenocisma) dotis Hall, Paleont. of New York, rv, p. 
344, pl. trv, 1867; Rathbun, Bull. Buff. Soc. Nat. Sci., 1, no. 4,_p. 
246, pl. virr, 1874. 
This species was first recorded from Brazil in the report of the 
Morgan Expeditions referred to above. At that time only two speci- 
mens were known from the Devonian sandstone of Ereré. These 
were both dorsal valves, which agreed quite closely in their charac- 
ters with Rhynchonella dotis of the Hamilton group of New York. 
The Geological Commission discovered no more specimens of this 
species at Ereré; but in the sandstone beds of the Rios Mecurt and 
Curud were found many specimens of Rhynchonella, representing 
several varieties, of which the most are closely connected together 
and to the Ereré variety, by intermediate forms. Some of the varie- 
ties, however, present differences which may necessitate their being 
separated eventually from the commoner form. ‘The result of the 
studies made on these varieties of Rhynchonella indicate that this 
species from Brazil may prove to be as closely related to some other 
of the N. American species as to R. dotis; but I was unable to make 
comparisons with a sufficiently large collection, and thus it has 
seemed best to retain the species as it is for the present. 
Asa rule, the shell of the Brazilian form is more or less trans- 
verse, or has the length and breadth nearly equal. Ventral valve 
short-ovate in outline; dorsal valve very short-ovate or transversely 
subelliptical. Of the ventral valve the beak is small, quite sharply 
pointed, and strongly incurved. The posterior margins diverge at an 
angle of about 105° to 115°, and are nearly straight. Anterior mar- 
gin broadly, but not deeply, indented by the sinus. The surface of 
the valve is generally much flattened toward the front, and curves 
rapidly downward toward the front and lateral margins. 
Dorsal valve very convex, the surface rising regularly and rapidly 
from the beak to near the anterior margin, toward which it curves 
PROOEEDINGS B. 8. N. H. = VOL. XE. 3 JANUARY, 1879. 
