FOSSILS OF THE SILURIAN AND DEVONIAN ROCKS. 179 



L. rectistriatum, with which it is also associated, and has no constriction of the 

 upper part of the volution as in that species. 



A specimen preserving nine volutions, including the last one, measures about 

 one inch and a quarter. 



Formation and Locality. Occurs in the cherty layers above the hydraulic limestone of the Devo- 

 nian formation, at and around the Falls of the Ohio, in Kentucky and Indiana. Not as abundant as its 

 associate, the Lox. hydraulicum. 



Loxonema rectistriatum. HALL. 



Loxonema rectistriatum, Hall. Pal. N. Y., Vol. 5, pt. 2, p. 131 1879. 



Shell elongate terete ; volutions probably twelve and more in number; mod- 

 erately convex, very gradually increasing in size ; the last one being scarcely 

 more ventricose than the preceding ; each volution is distinctly contracted a 

 little below the close suture, and then expanding, gives the greatest convexity 

 near the lower third. Suture line close ; aperture ovate, with the columella 

 extending below. 



Surface marked by slender, gently curving, longitudinal striae, which bend 

 backward from the suture to bottom of constriction, and then continue to 

 the base of the volution, those of the last one curving gently forward to the 

 columellar lip. The spaces between the striae are from one and a half to twice 

 the width of the ridges. 



This species may be distinguished from any other described of the genus 

 Loxonema, by the finer longitudinal striae, which are scarcely curved on the 

 body of the volution, and also by the constriction of each volution just below 

 the suture-line. The striae are stronger on the upper volutions, gradually be- 

 coming finer and less prominent on the lower ones, though continuing distinct 

 throughout. A specimen, which preserves about eight volutions from the 

 aperture, measures a little more than one inch in length. 



Formation and Locality. Found associated with Lox. hydvaulicum and Lox. laeviusculum, in the 

 cherty layers superimposed upon the hydraulic limestone of the Devonian formation at and around the 

 Falls of the Ohio, in Kentucky and Indiana. Prof. Hall's descriptions and illustrations of this species, and 

 of those just mentioned as its associates, were made from specimens belonging to the cabinet of the late Dr 

 James Knapp, who collected them at the Falls of the Ohio on the former Corn Island. 



Genus Macrocheilus. 



Phillips. 



Macrocheilus, Phillips. Pal. Fossils 1841. 

 Etymology: macros, long; and cheilos, a lip. 



Synonym: Polyphemopsis, Portlock. 



Shell thick, ventricose, buccinoid ; aperture simple, effuse below ; outer lip 

 thin, inner lip wanting; columella callous, slightly tortuous. Type: Macro- 

 cheilus arculatus of Schlotheim. (Copied from Woodward's Manual.) 



