314 INVERTEBRATA OF MASSACHUSETTS. 



brown ; surface covered with equal and regular revolving lines, 

 interrupted by as many as fifteen smooth, obtuse folds or ribs 

 running lengthwise of the shell ; and as the folds extend only half 

 the length of the lowest whorl, the remaining half is marked by 

 the revolving lines only ; whorls six, nearly flat, forming an 

 elevated, pointed spire ; suture distinct, and somewhat scolloped 

 by the folds ; aperture narrow-oval, about one third the length of 

 the shell ; very little contracted by the thickening of the middle 

 of the outer lip ; this lip is simple, somewhat thickened externally, 

 and having a series of lengthened teeth just within the margin ; 

 inner lip invested with a plate of callus, which is also toothed in 

 a similar manner, in mature shells ; operculum horny. Length | 

 inch, breadth | inch, divergence 33°. 



Sent me from Martha's Vineyard by Dr. L. M. Yale. Pro- 

 fessor Adams says it is common at New Bedford and vicinity, 

 also at Fahnouth and Nantucket. Cape Cod, however, seems to 

 be its northern limit, though a solitary, worn specimen is oc- 

 casionally found within the Capes. It lives below low-water mark. 

 It is abundant on the shores of the Southern States. 



Mr. Say referred this shell, somewhat doubtfully, to the genus 

 CoLiJMBELLA ; and as it still remains equivocal between Columbella 

 and BuccixuM, it is best to let it remain where he placed it. It varies 

 much in its length and coloring, being in general longer than described 

 by Say. It is usually covered with a dirty-brownish pigment. The 

 middle of the last whorl is frequently angular, especially in immature 

 shells ; in these too, and, indeed, in a majority of the shells I have 

 seen, the denticulations of the aperture are wanting. There is, how- 

 ever, no other shell resembling it on our coast, and it is easily recog- 

 nised. 



This concludes the account of the Testacea. I have endeav- 

 oured to describe them fully and definitely, and to arrange them as 

 nearly in accordance with the present state of science as my 

 means of information would enable me to do. 



