2i}S J\'c'H' SjK'cies iif Fos!<Hx fi'oiii Oliui. 



chamber. The shell bears the appearance, also, of having- been curved, as 

 jnflicated principally by the obliquity of the septa, which are numerous*, 

 rather deeply concave, and arranged at a distance of about one-fourth of an 

 inch in the largest part of the specimen, and decreasing in distance below 

 and above ; while near the base of the outer chamber there are about six 

 septa closely crowded together. Position of the siphuncle not determined. 



The species^'roiemtn'es G. exiiniunu Hall, of the same fonua- 

 tion, in the lower pai"t of its leugth, aJthoi\gh more rapidly ex- 

 panding, but in the npj)er part, and especially near the aperture, 

 differs entirely from any other si)eeies known. 



Formation and Localifii. — In the limestones of the U])i)er 

 Helderberg grotip, in Marion Co.. Ohio. Collection of Columbia 

 College, X. Y. 



Ooinplioeeraiii l!»('i<>teiise. n. sp. 



Pal. O., V'ol. Ill, Plate 4, Fig. 4 ; PI. ."i. Fig. 2 ; PI. ti. Figs. (5 and 7. 



Shell of mediiun size oi' snudler, short obcouical in form, or rapidly ex- 

 panding from the apex upward ; slightly flattened in a dorso-ventral dii'ec- 

 tion, giving a broadly oval transverse section, which is a little more flattened 

 on the dorsal than on the ojiposite side, in the more perfect specimen, but 

 may not be constantly so in all individuals. Septa shallow, arranged at 

 nearly equal distances from each other in the larger parts, and numbering 

 about seven in an inch, except near the outer chamber, where there are usu- 

 ally one or two more closely arranged. The outer chaml^er is proportion- 

 ally short, and rapidlj' contracted in the upper part to about one-half the 

 diameter below, to form the transversely sub-triangular or obscurely tri- 

 lobed aperture, which is rounded at the lateral extremities, straightened on 

 the dorsal side, and provided with a moderately deep but rather narrow 

 sinus on the ventral margin. Siphuncle proportionally small, and situated 

 close to the dorsal side. 



Only two individuals liave thus far been observed, and these 

 show some slight variation in the form of the transverse section 

 and in the proportional length of the outer chamber ; the one 

 retaining the chambers being shorter nbove, and more flattened 

 on the dorsal side than the other. Li this specimen, the, septa 

 are somcAvhat obliquely arranged, being highest on the dorsal 

 side, which may, however, be owing to ol)lique compression in 

 the matrix. The individuals, being ])oth internal casts, huve 

 afforded no opportunity of observing the surface structure. 



Formation and Locatit/f. — In tlte liniestonc of the Upper 



