344 
PALEONTOLOGY OF NEW YORK. 
Gomphoceras oviforme. 
PLATES XLV, FIGS. 1-4; XLVI, FIGS. 6, 7; XCIV, FIGS. 6, 7. 
Gomphoceras (Apioceras) oviforme. Hall. Thirteenth Rep N. Y. State Cab. Nat. Hist , p. 105. 1860. 
“ oviforme, Hall. Illustrations of Devonian Fossils: Cephalopoda, pi. 45, tigs. 1, 2. 1876. 
Cyrtoceras? gibbosum, “ Illustrations of Devonian Fossils: Cephalopoda, pi. 47, figs. 3, 4. 1S76. 
Shell small, ovoid, or subg'lobose, gibbous, straight, exogastric. Transverse 
section very broadly oval to subcircular. Longitudinal section regularly 
ovate, sometimes attenuate at the apex. Plane of greatest transverse section 
at the last septum. Tube rapidly enlarging from the apex, with the sides 
concave for a short distance, and becoming convex over the greater portion 
of the tube. Apical angle about 60°. Apex, when present, attenuate, acute. 
Some of the specimens show a subsequent truncation of the apex: the 
transverse strim lose their character, and the test is pitted or roughened. 
This offers an explanation of the adhering matrix around the apex of many 
of the specimens. 
Chamber of habitation comparatively large, having a length of from nearly 
one-half to one-third the entire length of the shell, or about two-thirds the 
greatest transverse diameter. Dorsal side more convex than the ventral, 
and rapidly sloping - to the aperture. The crenulated band forms a very 
narrow fossa around the base of the chamber of habitation; and shows flat, 
shallow furrows continued over the grand chamber, and obscurely over the 
walls of the air-chambers. 
Aperture large, trilobate, width equal to three-fourths the greatest trans¬ 
verse diameter of the tube, or one-fourth more than the length of the entire 
aperture. Minor aperture small, semi-circular, with a diameter of one-fifth 
the major diameter of the large aperture. Large aperture elliptical, and with 
its longer diameter equal to twice the length of the shorter diameter. In 
the small specimens the whole aperture is comparatively smaller, and marked 
by a variable constriction of the tube near the margin on the chamber of 
habitation. 
Air-chambers regular near the chamber of habitation, except the last, 
