1878.] oil (Rathbun. 
about one-fourth the leneth of the hinge. A shallow, rounded me- 
dian depression extends from the beak to the front margin. It is bor- 
dered on each side by a rounded fold of about its own width, which, 
however, descends much more rapidly on the outer side than on the 
inner, to another much less defined depression, reaching quite to the 
cardinal margin. From these lateral depressions outward the valve 
is slightly convex, or forms a low, very broad fold which extends to, 
and includes, the cardinal extremities. The margins of the shell 
are made very sinuous by these foldings of the surface. Length 
and breadth of the ventral valve each about 5.6 mm. Dorsal valve 
unknown. 
This very small species of Spirifera resembles much S. disparilis 
Hall, of the Corniferous limestone of New York. It is readily dis- 
tincuished from the North American form, however, by its smaller 
size, greater proportionate length, flatter hinge-area and different 
character of plications, etc. 
Only a few specimens were obtained; these were all found in the 
sandstone of the Rio Mecurt. (Geol. Comm., 1876.) 
Amboccelia (?) sp. indet. 
There were encountered in the fossiliferous sandstone beds of the 
Rio Curud several very small spiriferoid shells, resembling much in 
shape Ambocelia umbonata Hall, of the Hamilton Group of New 
York State. The specimens were all, however, in too imperfect 
condition to permit of proper identification. 
Cyrtina (?) Curupira Rathbun. 
Bull. Buff. Soc. Nat. Sci., 1, no. 4, p. 242, pl. x, 1874. 
Quite rare in the sandstone at Ereré. (Morgan Exs., 1870 and ’71.) 
Retzia Jamesiana Hartt, MS. 
Rathbun, Bull. Buff. Soc. Nat. Sci., 1, no. 4, p. 243, pl. x, 1874. 
A number of specimens of Retzia, identical with the R. Jamesiana 
of Ereré, were obtained from the Devonian sandstone of the Rio 
Mecurt. From the same locality there are also other specimens, 
differing from the above in having more prominent and subangular 
plications, and a second variety has a much broader shell. it is 
doubtful whether these two latter forms should be included in R. 
Jamesiana or be separated from that species. 
Devonian sandstone, Ereré. (Morgan Exs., 1870 and ’71; Geol. 
Comm., 1876.) Rio Mecurt. (Geol. Comm., 1876.) 
Retzia Wardiana Hartt, MS. 
Rathbun, Bull. Buff. Soc. Nat. Sci., 1, no. 4, p. 245, pl. x, 1874. 
