100 LUCINID^. 



This shell, so remarkable for its universal dispersion, as well in a 

 fossil as in a living state, is not unfrequently thrown upon our ocean 

 shores in such a state as to indicate a neighboring residence. At 

 Nantucket it is far from rare. It is found on every Atlantic shore, 

 even to the Southern Ocean. Vineyard Sound (^Desor^. 



It varies considerably in the development of the lateral teeth, and 

 in the approximation of the striae. 



[There can be no doubt that this shell is not the divaricata of 

 Linna3us, as was supposed in the first edition ; that name referring, 

 as shown by Forbes and Hanley, to a smaller European species. Dr. 

 Stimpson has applied to it — rather unfortunately, I think — the 

 name strigiUa, which had been previously given as a generic name 

 to a group which is sufficiently peculiar to justify a distinguishing 

 name, and which he himself also uses as such. I have rather 

 adopted the prior and more appropriate name of Wood. 



Oeiius CRYPTODOIV, Turtox. 1822. 



Rounded, thin, nearly equipartite ; valves with a depression bor- 

 dering the hinder end ; a minute cardinal tooth in the right valve. 



Cryptodon Gouldii. 



Fig. 52. 



Shell small, globose-triangular, white, interior with minute radiating lines. 



Lucina flexuosa, Gould, Inv. Mass. 1st ed. 71, fig. 52. 



Cryptodon flexuosus, Adams, Gen. pi. 114, figs. 2, 2 a. 



Lucina Gouldii, Philippi, Zeitsch. f. Malak. 1845, 74. 



Thyastra Gouldii, Stimpson, Shells of New England, 17 ; Invert. Gr. Manan. 21. 



Cryptodon Gouldii, Stimpson, Check List, 2. 



Shell minute, white, ovate-globose, or somewhat triangular, near- 

 ly equilateral ; beaks prominent, inclined forwards, and having a 

 rounded depression in front of them ; behind them, a re- 

 Fig. 406. markable widened groove runs near the margin to the 

 posterior base, producing a deep indentation in the out- 

 line of tlie margin at that part ; elsewhere regularly 

 c Gouldii I'ounded ; surface smooth, dead white. Hinge with only 

 2 the vestige of a cardinal tooth, and no lateral ones. Lig- 



ament long and rather large, partly concealed. Interior 

 glossy white, with minute radiating lines. Length, three tenths 

 of an inch ; height, somewhat more ; width, one tenth of an inch. 



