- r.is - 



that are so chars.oteristi t? of the variety. In this connection it 

 is well to reiiifc'iiioer that 3ov;erby desorihed (l) both ribfe -^.j in- 

 terspaces of whst certainly was a rijht valve f. '.imclatiis" . 



(l). r^^uart. JoLir. J-eol. 3oe, Lonoon, vol. G, o. 52, lo"~. 



Ocaurrence_. - Upper Oligocene : Jturacao (Dall, 1898); Isthnius 

 of Darien (Dall, 1898); lower I.'iiocene : Bovjden beris,. Bov/den, Jam- 

 aica (C-npT)^-, 1866, 1874; Ball, 1898). 



