1878.] Di [Rathbun. 
and neither much elevated nor strongly incurved. Size of the largest 
dorsal valve found; length 25 mm., breadth 33 mm. 
There seems to be no species of Spirifera in the Devonian of N. 
America: with which the form under discussion can be compared. It 
has the appearance of a much lengthened S. duodenaria. Only 
three specimens have been found, a dorsal and a ventral (¢) valve, 
in the sandstone of the Rio Mecurt,, and a small dorsal one in the 
sandstone of the Rio Curud. (Geol. Comm., 1876.) 
Spirifera Pedroana Hartt, MS. 
Rathbun, Bull. Buff. Soc. Nat. Sci., 1. no. 4, p. 237, pl. vir, 1874. 
Collections made since the original description of this species was 
published have furnished some new forms of Spirifera, very closely 
related to this species, if not identical with it. From the want of 
suflicient material to better characterize these varieties, I have 
placed them provisionally in the species S. Pedroana. We can sepa- 
rate the specimens into two general varieties, in the first of which the 
ventral valve has a rather broad hinge area, very slight curvature of 
the surface from the beak to the front margin, and also well devel- 
oped, rather large and long, dental plates, which sometimes reach 
nearly to the front of the valve. In the character of the dental 
plates this variety approaches S. Elize Hartt, but it always has well 
marked plications, by which the two species can be readily distin- 
guished. In the second variety, which is connected to the first by 
many intermediate forms, the ventral valve is much less convex, very 
slightly curved, with the margins very regularly curved, and the 
cardinal extremities rounded. On either side of the median sinus 
there are at times as many as twenty-four plications, and such exam- 
ples often resemble the flattened forms of S. medialis, of the Hamil- 
ton group of New York. ‘This extreme variety may eventually prove 
to be distinct from S. Pedroana. 
The localities at which the different varieties of this species have 
been found are as follows: Devonian sandstone of Ereré, very abund- 
ant; Rios Mecurti and Curua very rare, especially the typical forms ; 
but several odd varieties were obtained from these localities. In the 
collection from the Curud there is a single large specimen, having a 
width of 70 mm. At the falls of Teuapixima on the Rio Mecurt, 
there is a fine-grained micaceous sandstone, containing S. Pedroana 
and Lhynchonella dotis. ‘The former occurs of small size and is usu- 
ally quite transverse, with a thin shell. 
(Morgan Exs., 1870 and ’71; Geol. Comm., 1876.) 
