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Figs. 27 and 28. Temnocheilus (Naut.) subtuberculatum (sp. Sandberger), 

 Hyatt ; Loc , Wissenbach ; Coll. Mus Comp. Zoology ; Devonian. 



Fig. 27, side view of ana-, meta- and paranepionic and perhaps beginning of 

 ananeanic substages before the whorls touch. It will be observed that the apex 

 is not enveloped even in this closely coiled form and that the dorsal furrow is not 

 present at the end of the volution, Fig 27, which is given in the section Fig. 28. 



Figs. 29-31. Apheleceras (Naut.) mutabile (sp. D'Orb.), Hyatt; Loc., Car- 

 boniferous; after D'Orbigny, Pal. Universe lie, PI. lxxxviii, Figs. I, 2 and 4. 

 Show the free apex and moulding of the dorsum to fit the hollow venter of this 

 species. Fig. 31 shows the surface of the shell of earlier substages. 



Fig. 32. Metacoceras cavatiformis (same specimen as Figs. 16-19, p. 496 of 

 this paper) showing the beginning of the impressed zone at contact with the apex. 



Fig. 33. Ccelogasteroceras canaliculatum, Hyatt; Loc, Edmondson Co.,Ky. ; 

 Mus. Comp. Zool.; Carboniferous. A section across the meta- and paranepionic 

 volution showing the large umbilical perforation, comparatively slow increase in 

 size of the first whorl and presence of a dorsal furrow in the paranepionic sub- 

 stage. 



