PLATE XVIIJ—Continued. 
PLEUROTOMARIA NODOMARGENATA: 6 a aieiemiem ae nei ae lel a oh oe a te at 
Fig. 15. Enlargement to three diameters of a typical specimen, from the lower portion of the 
Carboniferous Group. 
METOPTOMA PEROCCIDENS © << -<2 2 0-200 weno wn wee ene eee ees wens conse owner acs ssen ee aees ee 
Fig. 16. Summit view, showing the outline and the radiating dark lines and fine concentric 
strie. 
QORTHOCERAS /RANDOULPHENSIS Mea jaja)ee meals eee ele ee ee ee See mpcdos 
Fig. 17. View of a crushed fragment of the tube. 
yan oy ss Oso. ONOH Ch Soo 6 cogcte ceciboe GaSe Co UaO Set eSee bys s5c Dec on owas Hao edoo ConpSESsosse 
Fig. 18. View of broken specimen, showing the surface characters and general form. 
EUOMPHALUS (S.) SUBRUGOSUS. ......---. ---- .----- --- 2-2 none conn ne =e ncansacc socoscomeccos 
Fig. 19. Summit view of a small characteristic specimen. 
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