Monograph of the LamelUhranchiata. 223 



It is fouud from 300 feet above low water-mark, at Cincinnati, to 

 the top of the Cincinnati Group. It attains a much larger size in the 

 upper part of the Group at Versailles, Indiana, than it does in the 

 hills about Cincinnati. 



Genus Amhonyclda — (Hall). 



[See page 14, January Ko. of this Journal.] 



AmhonycMa radiata — (Hall) . 



[See page 15, January No. of this Journal.] 



Amhony cilia bellisiriata — (Hall). 



[See page 14, January No. of this Journal ] 



* Amhonychia costata — (James). 



[See page 15, January No. of this Journal.] 



Genus Anomalodonta — (S. A. Miller). 



[See page 16, January No. of this Journal.] 



Anomalodonta gigantea — (S. A. Miller). 



[See page 17, January No. of this .Journal.] 



■ Anomalodonta alata — (Meek, 1872). 



Shell attaining a moderately large size, subtrigonal in general out- 

 line, compressed posterio-dorsally, and more convex in the umbonal and 

 anterio-central regions ; umbonal slopes ranging at an angle of about 

 fifty degrees below the hinge' line, and broadly rounded ; hinge line 

 straight, very nearly or quite equaling the greatest anterio-posterior 

 diameter of the valves, and ranging nearly at right angles to the 

 anterior side of the same ; posterior alation very large, not separated 

 from the swell of the umbonal and central regions by any defined sul- 

 cus, slightly rounded at its immediate extremity above; posterior 

 margin faintly sinuous a little below its intersection with the hinge 

 margin above, thence sloping forward and downward, and finally 

 rounding into the regularly rounded base ; anterior side more or less 



