T'NIO.— Plate LVI. 



gill sloping upwards, middle undulated near the j Swainson. 



umboes, umboes depressed ; posterior side large, i Hub. River Ohio. 



expanded, obliquely biaugular, dorsal margin ele- tt • • .n- r r- ; / i „ •, c .. 



'.''•' o > t- xhis species diilers from I . nmpl anal tin by its lar 



"ated. winged, lateral margin sloping, end between , ■ , i » • i i i c 



" a 1 s' I rnorc triangular and posteriorly-produced lorni. 



the angles produced 



