332 TRANS. OP THE ACAD. OP SCIENCE. 



above. Productus muricatus only exists in the lower 

 measures and generally in calcareous or bituminous sbale. 

 Productus aurictdatus (Sw.) is rare, — only has been found 

 near middle of the series in Caldwell Co. Productus Nor- 

 woodii (Sw.) occurs in argillo-calcai'eous shales, and is 

 often much compressed. Spirifer cameratus ranges through- 

 out, although in the lower series it more rarely resem- 

 bles the /Spirifer striatus ; in the upper series its ribs are 

 more angulated and fasciculated.* Sptirifer Kentuckensls 

 occurs throughout, but is not abundant anywhere. /Spi- 

 rifer plano-convexus seems to be gregarious, and is gen- 

 erally found in calcareous shales ; it ranges through- 

 out. Orthisina umbracidum occurs from the lowest to the 

 highest of the series, and is more often found in shales, 

 either calcareous or bituminous, and in different rocks 

 varies a little in its general appearance. Fusidina cylin- 

 drica, although abounding in Group "I," is rarely seen 

 again until found abounding in the rocks of the upper 

 series. 



Crinoids are not common in the Coal Measures of Mis- 

 souri. 



/Spirigera subtilita is found everywhere. Specimens of 

 genus Archceocidaris are rare ; species occur in upper por- 

 tion of "H," in limestone, just above the Lexington coal 

 bed; in lower members of "F," and in the upper part of 

 " B," they abound. 



Fossil fish bones are rare ; teeth are found in bituminous 

 shales in lower series. 



The interior of some of the fossils, especially Producti, 

 in the upper series, is pure crystallized carbonate of lime. 

 In the bituminous shale of lower series, (particularly Group 

 "I,") many fossils are composed of iron pyrites. The py- 

 ritiferous shales often abound in plants and shells. 



Changes. — Beds of rock are occasionally found much indu- 

 rated In Caldwell County some of the limestones occupying 

 the lower part of group " G" are very hard and close grained, 

 and appear to have been indurated ; they are silicious and 

 ferruginous. Similar limestones are found in Group " H," 

 on Yellow Creek, Linn Co., Muscle Fork, Macon Co., &c. 



Some sandstones are much indurated and resemble alter- 

 ed or metamorphosed rocks; for example, the sandstone 

 showing cross lamination near Princeton, Mercer Co. 



Disturbance. — The local disturbances are not important, 

 do not seriously affect the relation or general dip of the 

 rocks, or their practical economy. During the early periods 

 of their existence they have evidently been subjected to 

 undulations, oscillations, and sometimes to violent disturb- 



* Spirifer cameratus, var. Kansasensis of Prof. Swallow. 



