Ala>-, I'.'l/J Siluriiui FossiLs from Ohio 251 



seven. Median sinus with three plications. The pHcations are rel- 

 ativel\' low and rounded and are separated by shallow grooves; pos- 

 teriorly they usually are inconspieuous and in some specimens are 

 almost obsolete. The cuncate muscular area of the brachial valve 

 evidently was slightly raised above the general level of the inner sur- 

 face. This muscular area is traversed by a median septum which 

 di\ndes posteriorh' into a narrow spondylium. A similar but broader 

 muscular area, without a median septum, characterizes the pedicel 

 vah'c. The dental lamellae of the pedicel vah'c extend downward so as 

 to rest upon the inner surface. 



From the richly fossiliferous limestone layer about nine feet 

 above the base of the West Union formation, in the valley on 

 the southeastern margin of Hillsboro, Ohio. Named in honor 

 of Miss Katie Roads. 



Camarotoechia roadsi belongs to a group of species charac- 

 terized, by low rotmded plications tending to become obscurely 

 defined or even almost obsolete posteriorly. Compared, with 

 Camarotcechia obtusiplicata, Hall, from the Rochester shale of 

 New" York, the outline is more triangular, the plications are 

 lower and more nearly obsolete posteriorly. 



Rhynchonella pisa. Hall and Whitfield, was described by 

 them as "globular in full-grown specimens" and therefore 

 figures 18 and 19, accompanying the original description, must 

 be regarded as illustrating the type. The angulate course of the 

 plications of the brachial valve in figure 19 explains w^hy "the 

 more ventricose forms resemble very closely small specimens of 

 Rhynchonella nudeolata, Hall," a typical species of Uncinuhis 

 according to the present system of classification. The type of 

 Rhynchonella pisa was obtained from the same horizon as 

 Camarotoechia roadsi, in the lower or Bisher member of the West 

 Union formation, at Danville, southwest of Hillsboro, Ohio. 



Trochurus phlyctainodes, Green. Plate XI, Figs. lA-D. Plate 



XII, Figs. lA-D. 



1837. Calymene phlyctainodes, Green, Amer. Jour. Sci., 32, p. 167. 



Median lobe of glabella most strongly arched from front to rear at a 

 point one-sixth of its length, measured along its surface, from the 

 posterior end; widest one-third of its length from the rear, narrowing 

 to four-fifths of this width anteriorly, and to three-fifths of this width 

 posteriorly. Compound anterior lateral lobes widest slightly anterior 

 to mid-length, equalling in width the immediately adjacent part of the 

 median lobe; strongly defined from the median lobe by deep fiurows 

 at least a millimeter in width, equally well defined from the third lateral 



