586 NEW SPECIES OF BRACHIOPODA. 
SPIRIFER EURUTEINES. 
(Tab. IIL, figs. 2, 2 a, 6, and 6 a.) 
Specific character.—Shell nearly semi-elliptical ; cardinal area very wide, slightly concave and finely 
striated; narrow perforation ; beaks sometimes more than half an inch apart, smooth, with eighteen to 
twenty ribs on either side of the bourrelet, finely striated longitudinally, sometimes studded with small 
granulz, bourrelet rather narrow, with a shallow sinus in the median line, finely striated, and crossed by 
fine concentric lines of growth, and sometimes by fine granule. Sinus of the dorsal valve, also some- 
times finely granulated. Length, one inch, breadth one and a half inches. 
This is one of the most common species of Spirifers in the limestones of the Red Cedar and Iowa 
Valleys, as well as the hydraulic limestone near the Falls of the Ohio. It was figured in the Report of 
1839, but without any detailed description. 
SPIRIFER CEDARENSIS. (N. 8.) 
(Tab. IIL, fig. 5.) 
Specific character.—This Spirifer is much deeper from the beak to the circumference than either of 
the preceding, and, though very acute at the angles, it is much less produced along the hinge line. It 
differs, moreover, in the sulcus having small, longitudinal ribs. On either side of the mesial fold there 
are from twenty-three to twenty-five ribs; those on the angle are so fine that it is difficult to count them 
with precision. Shell considerably gibbous, especially towards the umbo. A few concentric wrinkles 
near the angles and border. From the limestones of Cedar Valley, two and a half miles below Rocking- 
ham, Iowa, of the age of the Hamilton Group of New York. 
SPIRIFER INEQUICOSTATIS. (N. 8.) 
(Tab. V., fig. 6.) 
In general shape this fossil resembles 8. semicircularis, it differs, however, from that Spirifer, as well 
as from the bisudcatus, which De Koninck gives as a synonym, in several essentials, which appear to 
indicate a distinct species. 
The ribs, though simple, are very unequal in size, some being exceedingly fine, others coarse ; no 
distinct sulcus on the mesial fold other than the simple grooves between the ribs; the mesial fold or 
bourrelet is sharper and more divergent, by which it is much narrower near the beak. 
Phillips does not give the number of ribs either on the mesial fold or general surface. This species has 
nine ribs on the mesial fold, and seventeen on either side of it, which is nearly the same as on the Lisul- 
catus, according to De Koninck. 
Dimensions.—,§, long, 1,%5; wide. Locality, carboniferous limestone of Iowa. 
FORAMINIFERA. 
SELENOIDES. (N. G.?) 
Generic character.—It was supposed at first that this singular fossil from limestones of Lower Silurian 
date, F. 3, a (and 67), of Towa, would fall into the genus Orbitulina. But as D’Orbigny regards this 
genus as unequal-sided Orbitolites, in which one side is conyex, incrusted, and having concentric lines ; 
the other concave, not incrusted, and showing numerous cells in oblique lines around the sides ; it can 
hardly be grouped with it, as the Iowa fossil is umbilicated on one side, and the cellular, ring-shaped 
surface, instead of being concave, is so convex as to form nearly a coiled cylinder. The other side being 
partly defaced in splitting it out of the rock, it is difficult to say whether it had a cellular surface similar 
to that shown on fig. 13, Tab. II. B, or concentric lines; what portion of it is visible rather indicates that 
the fossil was unequal-sided, not being umbilicated on the other surface ; probably cellular, and not with 
concentric lines. There are no cup-shaped cells opening round the periphery, as in Orbitolites, which are 
said to be equal-sided Orbitulinas. 
For the above reasons, I think it will constitute a new genus, peculiar to the Lower Protozoic rocks. 
The horizontal section seems to present an internal arrangement of cells similar to those of Orbitoides. 
