.^Ofi JTeic Species of Fossils from Ohio. 



time, leaving a perforation to be closed by a deposit of shell from 

 the mantle as it approached the lower ])art of the chamber of 

 habitation. Many species of Orthoeeras have been observed, 

 having a raised line, or rather markings, along the dorsal side ; 

 but none, so far as I am aware, presenting these evidences of a 

 series of separate openings, which I consider a feature worthy 

 of generic distinction. 



Treniatoceras Oliioeii§e, ii. sp. 



Pal. O., Vol. Ill, Plate 6, Figs. 3 and 4. 



Shell of medium size, straight, and somewhat rapidly tapering from 

 below upward ; the rate of increase being equal to nearl}' one-sixth of the 

 increase in length. Septa moderately concave, rather closely arranged ; 

 five of the chambers about equalling the diameter of the uppermost of the 

 five counted. Siphon of moderate size, and in the specimen used slightly 

 cxcentric. The surface of the shell, so far as can be determined from the 

 internal cast, has been smooth. Perforations, or nodes i-epresenting them, 

 large and elevated, two to three times as long as wide, and occurring at 

 everj^ third septum beloAV and at every second in the upper part of the 

 specimen. 



Formation and Locality. — In limestone of the Upper Helder- 

 berg group, at Smith and Price's quarry, near Columbus, Ohio. 

 The discovery and preservation of this peculiar s])ecimen are due 

 to the careful observation of Mr. Edward Hyatt, of the State 

 University at Columbus, Ohio. 



Ciomphoccras llyatti, n. sp. 



Pal. O., Vol. Ill, Plate 4, Fig. 1, and Plate 5, Fig. 1. 



Shell large and robust, slightlj^ arcuate throughout, but more strongly 

 curved below than in the upper part ; somewhat rapidly expanding from 

 below upward to near the middle of the outer chamber, where it is sud- 

 denly contracted to the aperture, and on the lateral margins again slightly 

 expanding. The rate of increase in diameter, as compared with the in- 

 creased length, is about as one and two, when measured on the inside curva- 

 ture. Transverse section of the shell obtusely subtriangular, flattened or 

 but slightly convex on the inner surface, rounded on the lateral surfaces, 

 and obtusely rounded on the back ; the dorso-ventral and lateral diameters 

 are about as four and five, and the triangular form is more perceptible in 

 the earlier stages of growth, owing to the greater convexity of the inner 

 face in the upper portion and on the outer chamber. Outer chamber 

 comparatively short, being about two thirds as high as wide. Aperture 

 large, irregularly tri-lobed, straight on the inner face, and about four-fifths 



