Manual of the Paleontology of the Cincinnati Group. 



67 



MANUAL OF THE PALEONTOLOGY OF THE 

 CINCINNATI GROUP. 



By Joseph F. James, M. D., M. Sc., F. G. S. A., Etc. 



Part VI. 



(Continued from Vol. xvi, p. 208.) 



Group IV. Laminar or Fron descent: Expanded or flattened, 

 sometimes formed of two layers of corallites diverging from a central 

 axis; sometimes more or less irregular. 



a. Surface with conspicuous monticules. 



* Interstitial cells absent; monticules with larger calices than 



average 41 



* Interstitial cells few. 



t Monticules with calices of average size 42, 43 



f Monticules with cells larger or smaller than average. 44 



b. Surface with small monticules or stellate maculae. 



* Interstitial cells absent 45 



* Interstitial cells few. 



f Stellate maculae with angular cells 46 



f Monticules with cells smaller than average 47 



f Monticules with cells larger than average 48 



* Interstitial cells numerous. 



f Maculae with cells smaller than average 49 



f Monticules with cells of average size 50, 51 



f Maculae with cells larger than average 52, 53, 54 



c. Surface smooth. 



* Interstitial cells absent 55 



* Interstitial cells few 56, 57 



* Interstitial cells numerous 58, 59, 60 



Note. — Keys of this kind are necessarily more or less defective and artificial, 

 but they are believed to be of use to the student in tracing out some form which 

 he may have found. It should, of course, be understood that only the salient 

 characters of each are given, and for the more detailed description attention must 

 be given to the text. 



