i^ CONCUYUA—DITHYRA. 24: 



Shell twb inches and a half long, and nearly three broad, thin, 

 Brittle, dirty white with a rufous tinge, and marked with regular 

 pale testaceous r^ys: beaks prominent, rather oblique: hinge 

 with a depression in the middle, and the rudiment of a small 

 oblique denticle, with a small lateral tooth on each side. 



We are unacquainted with this shell, and have consequently no 

 ihi^dti^ of determining its prbper place in our present arrange- 

 itteht. 



24. GOODAhLlA—TURTON. 



Testa trigona, tcquivalcis, incequilateraUs, clausa. Cardo 

 tuhce alten'us dentihiis duohus vnmfoved trigona interposUd, 

 alterins dente unico : lateralihus obsohtis. Ligametitum 

 internum. 



Shell triangular, equivalve, inequilateral, closed. Hinge with 

 two teeth in one valve aind a triangular cjlvity betit^en thertr, 

 in the other valve a single tooth : lateral teetli obscure. Liga- 

 ment internal. 



The minute shells of this gehiiS differ materially from tlie 

 the Maclrai both in the form and disposition of the teeth ; fhfe"' 

 lateral ones consisting of a I'ather' i^eniote simple tooth in eiich 

 valve on the more produced side : the valves are also closed. 



