GASTEROPODA. 93 



is in such condition that the surface is not well preserved, and it is only in 

 some of the higher volutions that comparatively strong striae are visible. The 

 shell has probably had at least three or four volutions beyond those preserved, 

 making twelve or thirteen altogether. 



Formation and locality. In the Upper Helderberg limestone, near Jamesville, 

 Onondaga county, N. Y. 



MURCHISONIA MICULA. 



PLATE XXI, FIG. 11. 



Mnri-hUonla turrieula,* Hall. Descriptions of New Species of Fossils, etc., p. 22. 1861. 



" " - Fifteenth Rep. N. Y. State Cah. Nat. Hist., p. 50, pi. 4, fig. 13. 1862. 



" ula, " Miller. Amer. Pala-ozoic Fossils, p. 244. 1877. 



Shell small, turretiform. Volutions about eight or nine, angular, flattened 



above and a little convex below the spiral band, rapidly enlarging from the 



, apex — the last one scarcely more ventricose than the preceding. Spiral 



band strongly elevated, distinctly bounded by sharply carinated revolving 



lines, with its upper margin at about the centre of the volutions. 



Surface marked by strong elevated concentric striae above the band, and less 

 conspicuous ones below it. Suture-line sharply marked by the deep con- 

 traction of the shell, and a narrow crenulated carina just outside of the 

 constriction ; on the last volution the suture-line is continued in a slender 

 spiral line beyond the margin of the lip. 



This minute species has a length of about a quarter of an inch. It possesses 

 in some degree the character of M. desiderata, but the volutions are more 

 angular and the suture-line more deeply impressed, with a narrow crenulate 

 carina bordering the constriction; the concentric strise and the spiral band 

 are proportionally much stronger. More than a dozen specimens have been 

 examined, all of which present the same form and surface characters. 



Formation and locality. In the Hamilton group, at Delphi Falls, Onondaga 

 county, N. Y. 



* Name preoccupied by Billinhh in Report of Progress of the Geological Survey of Canada for 1857. 



