334 
PALEONTOLOGY OF NEW YORK. 
at the base of the chamber of habitation, but no traces of the furrows are 
observed over the walls of the air-chambers. 
A fragment, preserving the chamber of habitation and five attached air- 
chambers, has a length of 105 mm. The chamber of habitation shows a 
length of sixty-five mm., with a lateral diameter at the base of nearly ninety 
mm., and a ventro-dorsal diameter of seventy-three mm. 
This species is distinguished by the characters of the chamber of habitation 
and form of the dorsal and ventral sides, in which it differs from G. eximium , 
G. mitra and G. impar. From G. gomphus it is distinguished by the point of 
greatest transverse section, the curvature of the dorsal and ventral sides, its 
smaller aperture, the absence of the low undulations of the tube, and its smooth 
chamber walls in the cast. The specimen described is imperfect, but preserves 
several of the minor specific features not observed in specimens from the 
coarser limestones. 
Formation and locality. In the cherty beds of the Corniferous limestones, at 
Lexington, Scott county, Ind. 
Gomphoceras gomphus, n. sp. 
PLATE — SUPPLEMENT. 
Shell large, straight, exogastric. Transverse section oval; lateral diameter 
the longer. Plane of greatest transverse section through the chamber of hab¬ 
itation, distant from the last septum one-third the length of the chamber. 
Ventral and dorsal sides convex, with the curvature of the ventral side 
somewhat greater than the dorsal. Tube gradually enlarging to the point 
of greatest gibbosity, and contracting slightly toward the aperture. Apical 
angle about 23°. 
Chamber of habitation large; length equal to the greatest diameter of the 
tube, or about one-third the apparent length of the entire shell; slightly 
expanded at the aperture. The sides are convex, and slope gradually 
toward the aperture. The crenulated zone in the cast forms a broad, gentle 
constriction at the base of the chamber of habitation, and consists of shallow, 
