SWALLOW—DESORIPTION OF FOSSILS. 659 
umbilicus large, deep, cylindrical within, expanding rapidly 
outward; aperture wide and short, much modified by the 
preceding whorl; has a broad sinus in front; septa very 
convex, arched on the outer margin and nearly straight on 
the sides. The cast shows longitudinal strie on the center 
of the outer margin of the whorls. 
Width of aperture, 3.21; length of aperture, 2.05, 
This fine Nautilus was presented to the Geological Survey 
by Col. Wm. Gilpin, who obtained it at Wayne City in the 
Coal Measures. 
GoNIATITES OSAGENSIS, R. Sp. 
Shell small, discoid, moderately convex, having internal, 
transverse strengthening ridges, which vary from four to six 
in the outer whorl, as indicated by the constrictions on the 
cast ; umbilicus small, deep, slightly infundibuliform; septa 
form a broad, shallow, forward curve on the sides, and a more 
abrupt backward sinus on the dorsal margin; constrictions 
slightly curved ; aperture large, 0.25 long and 0.30 wide; di- 
ameter of the shell, 0.88; whorls rounded on the dorsal mar- 
gin, flattened on the sides. 
This beautiful little species resembles @. micronatus of 
Phillips (Geol. York. Pl. XIX., p. 234), but is easily distin- 
guished by the septa. . 
Abundant in the Chemung rocks of Cooper and Moniteau 
counties, 
Gonratites (7) HotmeEsii, 0. sp. 
Shell flattened, discoid, sharply rounded on the dorsal mar- 
gin ; umbilicus rather small infundibuliform ; whorls decreas- 
ing rapidly ; aperture elongate; a rounded sinus in front ; 
septa not seen; no constrictions on the cast. 
eae of shell, 1.02; thickness, .30; length of aperture, 
2; Width of aperture, .38. 
This fossil is ‘eas convex with a greater diameter than G. 
Osagensis above described. 
Rare in the Chemung rocks of Cooper county 5 
have been obtained. 
casts only 
GoNIATITES MorGANENSIS, 0. SP- 
Shell very small, gibbous, subdiscoidal, proadly rounded on 
the dorsal margin; umbilicus small, deep 
iameter, .38; thickness, 213 length of aperture, -10; 
23. 
