396 REPORT ON THE STATE CABINET. 



GENUS MURCHISONIA, Phillips. 



MURCHISONIA CONBADI, N. S. 

 PLATE XV, FIG. 19. 



Shell turreted, somewhat rapidly ascending, consisting of about seven 

 volutions which are distinctly carinated on the middle or scarcely 

 above the middle. Above the carina the surface is slightly concave, 

 and below the carina very slightly rounded ; while the lower side 

 of the last volution is regularly rounded and somewhat ventricose. 



The surface has been finely striated with irregular undulations, cor- 

 responding with the lines of growth where the strise have become 

 crowded. The entire length of shell to the base of the last volution is 

 one inch and nine-tenths, and the diameter near the base nine-tenths of 

 an inch. 



This species is described from an impression in the limestone and a 

 gutta percha cast from the same. It is a well marked species ; differing 

 from every other in these rocks in the sharply carinate volutions and 

 elevated spire. In some characters it is allied to M. xantippe, Billings, 

 but the spire is more elevated : the length of that one, from the carina 

 of the last volution to the apex of the figure, is the same as the length 

 from the same point to the carina of the second volution above, in our 

 specimen ; while the diameters of the lower volutions in the two are 

 about equal. 



Formation and Locality. — ^In limestone of the age of the Niagara group, 

 at Racine, Wisconsin. 



MURCHISONIA LAPHAMI, HaLL. 

 PLATE XV, FIG. 20. 

 Murchismiia laphami, Hall. Report of Prog. Geol. Survey Wisconsin for 1860, p. 36. 1861. 



Shell turritiform, robust ; volutions seven or eight, gradually increasing 

 from the apex, rather ventricose on the exterior, with close sutures ; 

 the upper half of the volutions very slightly flattened ; giving a 

 perceptible angularity in the region of the revolving band. Section 

 of volution broadly ovate, the breadth equal to four-fifths of the 

 height, and the greatest diameter on the lower third. Surface 

 marked near the middle of the volution by a somewhat broad band , 



