THRACIA. 71 



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

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

 beautifully and accurately figured ])y 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 Ana- 

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

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

 T. corbuloides, 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. Groenl. 18 (1842). — Morch, Fortegn. over 

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

 1858; Inv. Gr. Manan, 21. 



Thracia Couthoiuji, Stimpson, New England Shells, 23 (1851) ; Proc. Bost. 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 j, myopsis* 

 inch. 



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

 zone; Grand Manan (^Stimpson); Greenland {Moller^ ; Labrador 

 (^Packard). 



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

 siphons free, long, fringed at aperture ; branchia? 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. 



