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 Ilelderberg limestone, near Jamesville, 
Onondaga county, N. Y. 
Murchisonia micula. 
PLATE XXI, FIG. 11. 
Murchisonia turricula,* Hall. Descriptions of New Species of Fossils, etc., p. 22. 1861. 
“ “ “ Fifteenth Rep. N. Y. State Cab. Nat. Hist., p. 50, pi. 4, fig. 13. 1862. 
“ micula, “ Miller. Arner. Palaeozoic Fossils, p. 244. 1877. 
Shell small, turretiform. Yolutions 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 strife 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 strife 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 Billings in Report of Progress of the Geological Survey of Canada for 1857. 
