DEVONRN FOSSILS 



87 



Soleniscus ( Macrocheilus of older 

 publications) is higher than wide, with a 

 spindle-shaped shell. The aperture is very 

 narrow at the top. S. hebe (fig. 195) is 

 found in the Columbus limestone. 



Palaeotrochus is higher than wide, but 

 Fig. 195 not much; its top-shaped shell with a strong 



basal Keel and coarse growth lines is characteristic. P. 

 kearneyi (fig. 196) occurs in the Columbus limestone. 



Fig. 196 



Fig. 197 



higher than wide. 



Acanthdnema ( Bellerophon and Orthonema in older publi- 

 cations) is small, with keeled whorls and a rounded base; A. 

 newberry i (fig. 197) is found in the Columbus lime- 

 stone. 



Loxonema and the next three genera are much 

 Loxonema (fig. 198) has strongly rounded whorls that give 

 the shell the appearance of a short string of beads. 

 Several species have been recorded for the Columbus 

 limestone. 



Fig. 198 



Fig. 199 



Coelocaulus (see fig. 118) has a long, thin shell also 

 but unlike Loxonem a, it has flat-sided whorls. C. 

 strebloceras is found in the Columbus limestone. 



Murchisonia (fig. 199) is like the last two but has 

 keeled whorls. Several species have been recorded 

 from the Columbus limestone. 



Bembexia ( Pleurotomaria in older publications) 

 and the next four genera are about as high as wide. 

 Bembexia is distinguished by its strong middle keel and the finer ones 

 above and below it. B. adjuto r (fig. 200) is found in the Columbus lime- 

 stone. 



Fig. 200 



Trepospira has a strong keel on top of the 

 whorl (not in the middle, as in Bembexia ) and in addition, the keel is 

 broken up into a series of wart-like bumps. T. rotalia ( Pleurotomaria 



in older publications) occurs 

 in the Olentangy and Plum 

 Brook (fig. 201). 



In Elasmonema 

 ( Callonema of older publica- 

 tions) the whorls are not keel- 

 ed and the aperture is less 

 than half the height of the shell. 



Fig. 201 



202) is found in the Columbus limestone. 



Fig. 202 



E. bellatulum (fig. 



Fig. 203 



Ptvchospirina ( Strophostylus in older publications) has a large 

 aperture, more than half the height of the shell, and coarse growth lines. 

 The figures for Elasmonema . Ptvchospirin a. and Naticopsi s 

 should be carefully compared before a specimen is re- 

 ferred to one of these genera. The most obvious feature 

 is the size of the aperture which is large in all three but 

 larger in Ptychospirina than in Elasmonema and largest 

 of all in Naticopsis . Ptychospirina varians (fig. 203) 

 occurs in the Columbus. 



In Naticopsis (fig. 204) the aperture is larger than in 



Fig. 204 



