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THE AMERICAN NA TURALIST. [Vol. XXXVI 1 1. 



the right into the left margin, it is widely rounded ; and the 

 widest part of the shell is below the middle." 



A. A. Gould, in his rnvcrtcbrata of Massachusetts ('41), con- 

 siders Bulla insculpta and Bulla solitaria identical : he concludes 

 his description of Bulla iusculpta with the following paragraph : — 

 " The differences between s.)litaria and insculpta, if there be 

 any, must be very slight Xor do I see that the two descrip- 

 tions (Totten and Say) are at all inconsistent with each other. 

 Still it is true that the shells from Martha's Vineyard are pre- 

 cisely Hke. those from Charleston, S. C, and accord with Mr. 

 Say's solitaria ; and those from Roxbury are precisely like those 

 found by Col. Totten at Newport, R. I., and described by him. 

 The observable differences are, that the first are of a more dead 

 white, are more cylindrical, the summit has a more square 

 appearance, the revolving lines are less distinct, and there is 

 always a perceptible opening in the region of the spire. These 

 differences may be ascribed to age or locality." 



Verrill ('73) describes solitaria as occurring along the Atlantic 

 coast from Massachusetts Bay to South Carolina and makes no 

 mention of insculpta except to assume that it is the same species 

 as solitaria. The shells of insculpta and solitaria as figured by 

 Totten, Gould, and Verrill seem to be identical. 



The size of the shells which I have found at Wood's Moll, 

 Mass., varies to a considerable degree ; one shell found was only 

 one-fourth as large as the average, the shape of a large number 

 of shells which were examined varies in regard to the width and 

 length of the lip. All of the shells examined were dextral. 

 The distinctness of the revolving lines seems to depend on 

 the age, the larger ones being the 

 more distinctly marked. The state- 

 ment that the shells of insculpta 

 FIG. ..-//<z„»w« shov^i„g seem to be more of a dead white 



lar disk^'^'rheTrrlpodi^ "^^^^ ^^^^ '•^^^ J^^;//■^^;7■^^ is easily 



conceal the anterior part of the explained. Thc shcll of ' the liviug 



teriortoit. Naturafsbe.^" ^ """^ animal is a golden gray; the golden 

 tinge being given by the thin struc- 

 tureless membrane, the periostracum, which completely co\ ers 

 the shell (Fig. i). When this membrane has suffered disinte- 



