GENUS DOLIUM. JJ 



to belong to females, are more ventricose ; the right lip is less 

 thickened, the teeth situated within are less apparent, whilst, 

 on the contrary, those which are found upon the edge, are very 

 distinctly seen, particularly towards the base. 



A variety of this species, which we have represented, pi. IV, 

 fig. 6, does not exhibit teeth at the inner edge of the right lip, 

 nor brown bands upon the convexity of the whirls. The trans- 

 verse ribs are also more distant in this specimen, particularly 

 towards the upper part of the two lower whirls, which is caused 

 by the almost total disappearance of the second rib at that part, 

 which leaves only a slight indication of coloring. 



7. DOLIUM POMUM, LAM. The Helmet-formed Tun. 

 (Collect. MASS. LAM.) LIST., Conch., pi. 792, fig. 45. 



Pi. V, fig. 8. 



D. test& ovato-inflata, crassiuscula, alba, luteo-maculata ; costis convex- 

 iusculis, latis, confertis ; spira brevi ; apertura coarctata, utrinque dentata ; 

 labro crasso, exttis marginato. 



Shell ovate, inflated, somewhat thick, of a whitish color, 

 varied and spotted with square spots, of a yellow more or less 

 reddish, alternating upon the transverse ribs, with other spots 

 of a dull white ; spire short, composed of six convex whirls, 

 slightly flattened above, banded with ribs equally convex, 

 wide, not distant, and divided by narrow, shallow furrows. 

 The aperture is somewhat narrow, toothed upon both edges, 

 colored yellow within. The right lip, dilated, particularly 

 towards the base, forms externally a very thick convex mar- 

 gin, the external part of which is sharp, undulated, and its in- 

 ternal surface furnished with ten or twelve transverse, distant 

 teeth, resembling folds. The left lip consists of a smooth 

 plate, convex and white, which partially covers the body of 

 the shell. The columella presents a pretty deep emargina- 

 tion, above which are observed several transverse thick folds, 

 and some others, less numerous, more oblique, and less dis- 

 tinctly marked. 



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