428 GEOLOGY OF OHLO. 



The specimen from which the description is taken is an internal 

 cast, not retaining any portion of the shelly structure; but it appears to 

 have been destitute of strong surface markings. It measures about seven 

 inches in length by nearly four inches in transverse diameter at the widest 

 part, which is near the lower part of the outer chamber. The lower 

 end is imperfect, and measures one and a half inches in transverse diam- 

 eter. It is with some hesitation that I place the species under the genus 

 Gomphoceras, owing to the strong curvature of the shell and the struc- 

 ture of the aperture, which is reversed in its relation to the curvature of 

 the shell as compared with most species of the genus; the widest por- 

 tion being on the inside curvature, instead of on the outer side. The 

 general triangular or trj-lobed form of the aperture, together with the 

 greater lateral diameter, would seem to overbalance the fact of the curva- 

 ture. 



Formatio7i and Locality. — In limestone of the Upper Helderberg 

 group, at Smith and Price's quarries, near Columbus, Ohio. Named in 

 honor of Mr. E. Hyatt, from whose collection it was obtained. 



Gomphoceras amphora. 



Plate hi, fig. 9. 

 Gomphoceras amphora Whitf., Ann. N. Y. Acad. Sci., March, 1882, p. 207. 



Shell of large size, elongate-ovate or short sub-fusiform, somewhat rapidly 

 expanding from below upward to within a short distance of the base of the outer 

 chamber; from which point it again contracts more rapidly to about one-half the 

 height of the outer chamber, and is then drawn out into a narrow neck, resembling 

 the neck of a bottle, of a width but little exceeding one-third of the diameter of 

 the larger portion of the shell. Aperture not distinctly traced, but on the side 

 figured, there is an appearance of a deep, rather narrow sinus, extending nearly one- 

 half the depth of the outer chamber. The shell bears the appearance, also, of hav- 

 ing been curved, as indicated 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 about six septa closely crowded 

 together. Position of the siphuncle not determined. 



The species resembles G. eximium Hall, of the same formation, in 

 the lower part of its length, although more rapidly expanding, but in the 

 upper part, and especially near the aperture, differs entirely from any 

 other species known. 



Formation and Locality. — In the limestone of the Upper Helderberg 

 group, in Marion county, Ohio. Collection of Columbia College, New 

 York. 



Gomphoceras Sciotense. 

 Plate IV, fig. 4 ; Plate V, fig. 2 ; Plate VI, figs. 6 and 7. 

 Gomphoceras Sciotense Whitf., Ann. N. Y. Acad. Sci., March, 1882, p. 208. 



Shell of medium size or smaller, short obconical in form, or rapidly expanding 

 from the apex upward ; slightly flattened in a dorso-ventral direction, giving a 

 broadly oval transverse section, which is a little more flattened on the dorsal than 



