398 
PALEONTOLOGY OF NEW YORK. 
Siphuncle near the convex ventral side, having a diameter at the septa 
of three mm. where the tube measures thirty-five mm. 
Test not preserved. Surface marked by fine, sharp striae of growth, which 
make a distinct sinus on the ventral side. 
Internal mould essentially smooth, with the sutures slightly impressed. 
In three specimens the disc has a diameter of about 100 mm. each, and 
the chamber of habitation has a greatest diameter of fifty mm. 
This species closely resembles T. eugenium, but differs in its more gibbous 
form, less oblique sutures, and more curved and twisted chamber of habitation. 
A fact worthy of notice in connection with the Cyrtoceras, Gyroceras and 
Trochoceras, of the Schoharie grit, is the much greater proportion of specimens 
preserving surface characters than in Orthoceras from the same horizon. 
This would seemingly indicate a much stronger test, with more decided surface 
characters, than in the latter genus. 
Formation and locality. In the Schoharie grit, at Knox, Albany county, N. Y. 
Trochoceras Barrandei, n. sp. 
PLATE CXI, PIGS. 8-10. 
Shell large, nautiloid, gibbous, making about one dextral volution. Spire 
depressed, not elevated above the upper lateral face of the grand chamber. 
Transverse section broadly oval or subcircular; lateral diameter apparently 
the longer. Tube very rapidly enlarging from the apex to the aperture. 
Apical angle about 22° in a specimen somewhat compressed. 
Chamber of habitation large, regularly expanding, with a capacity some¬ 
what less than the volume of the air-chambers, curving in the direction of 
the spiral axis. Crenulated band marked by obscure furrows, and several 
revolving lines at the base of the grand chamber. 
Air-chambers regular, deep, having a depth of twelve mm., measured on 
the convex side of the tube, near the outer chamber, becoming gradually 
more shallow toward the apex. The last one or two chambers, usually 
somewhat shallower than the preceding. Septa smooth, with a concavity 
