300 
AUG. F. FOERSTE 
the lower part of the funnel of the septum beneath at a point 
about 4 or 5 mm. below the general concave curvature of this 
lower septum. The septal funnels contract slightly about 2 
mm. before reaching contact with the funnels next beneath, and 
continue downward to a point slightly more than half the length 
of the second camera beneath the septum at which the funnel 
originates. The diameter of the siphuncle is one-third of that 
of the conch, and its ventral side is distant one-fifth of the 
diameter of the conch from the ventral wall. 
The annulations of the conch are low and broad, rising only 
1 mm. above the intermediate grooves. They cross the conch 
obliquely, descending from the dorsal toward the ventral side 
a distance slightly exceeding the height of one camera, at an 
angle of about 12 degrees with a horizontal line. The interior 
of the siphuncle of the type exposes only a single endocone 
having a length between 100 and 110 mm. 
Locality and Horizon. — From the Trenton limestone at 
Middleville, New York. Type, numbered 811, in the American 
Museum of Natural History in New York city. 
Remarks . — Cyclendoceras annulatum probably is confined to 
the typical Trenton of New York and of the immediately adja- 
cent states. Similar species occur in approximately similar 
horizons in adj oining geological provinces. The species described 
and figured by Whiteaves (Trans. Royal Soc. Canada, 9, 1891, 
p. 77, pi. 5, figs. 1, la) from the Trenton (Black River ?) between 
the second and third rapids of the Nelson River, west of Hudson 
Bay, enlarges much less rapidly and has much more oblique 
annulations. It is a distinct species. 
In typical Cyclendoceras the annulations usually are distinctly 
more prominent on the ventral than on the dorsal side of the 
conch. The sutures of the septa curve slightly downward both 
on the ventral and on the dorsal side. The most striking feature 
usually is the strong downward curvature of the annulations 
along the ventro-lateral sides of the conch, and their relatively 
broad concave curvature across the ventral side. Across the 
dorsal side of the conch their course may be nearly straight or, 
slightly curved either in an upward or in a downward direction. 
