THRACIA. 71 



Like many others of our shells, this has had the misfortune to 

 have several names applied to it which it cannot claim. It is 

 Ijcautifullj and accurately figured by Mr. Conrad, but his synonymy 

 is entirely erroneous. In the " Catalogue of Animals and Plants 

 of Massachusetts, 1834," it is referred to under the name of Atia- 

 tina convexa. In Dr. Storer's Translation of Kiener's " Iconog- 

 raphy," &c., it is alluded to under the supposition that it was 

 T. corbu/oides, to which species it is, indeed, closely allied. But 

 it is more equipartite, more rounded, proportionally narrower be- 

 hind, and its surface has not the shagreen roughness of that 

 shell. 



Mr. Couthouy has fully pointed out its distinctive characters, 

 and established it as a species, and for more minute particulars 

 his article in the Boston Journal may be referred to. 



Thracia myopsis. 



Shell small, solid, rounded oval, beaks sub-central, broadly truncate behind, 

 ossiculum very minute. 



Thracia mijopsis, Beck, Moll., Ind. Moll. Grocnl. 18 (1842). — Mokcii, Fortegn. over 

 Gronl. Bloddyr in Beskrivelse af Gronl. 90 (1857). — Stimpsox, in Sillim. Journ. 

 1858; Inv. Gr. Manan, 21. 



Thracia Cuuthoui/i, Stimpson, New England Shells, 23 (1851) ; Proc. Best. Soc. iv. 1.3. 



Shell small, white, orbicular-ovate, compressed ; beaks nearly me- 

 dian, narrowed and rounded in front, more pointed 

 and truncate behind, gaping ; surface with rather ^'"' ^^^" 



elevated concentric lines ; hinge callus thickened 

 backwards, without any distinct spoon-cavity. Os- 

 siculum very minute. 



Length, one inch ; height, seven tenths of an r^'Z^is* 

 inch. 



Found in Massachusetts Bay and Eastport, Me., in the Coralline 

 zone ; Grand Manau {Stimpson) ; Greenland { Mailer) ; Labrador 

 {Packard). 



Animal with the mantle closed ; foot large and tongue-shaped ; 

 siphons free, long, fringed at aperture ; branchias unequal, the ex- 

 ternal comb smallest. 



* I am indebted to the kindness of Dr. Stimpson for an opportunity of figuring this 

 species. — W. G. B. 



