aMj It**- 



OF THE UNITED STATES. 241 



This species was found by Mr. Aaron Stone on 

 sea- weed, about low water mark. It is often varie- 

 gated with olivaceous and white, or green and yel- 

 lowish, so as to exhibit a reticulated appearance ; but 

 they are very frequently covered with a greenish, or 

 reddish-brown pigment, which sometimes conceals 

 the reticulated surface ; and sometimes with a plain 

 yellowish white immaculate one. The shell within 

 is very often of a dark reddish-brown colour, with 

 the oral margiu whitish; but the same part is some- 

 times entirely whitish. 



4. T. *obligatus. Shell suboval, not thickened; 

 whirls five, transversely wrinkled, and longitudinally 

 striated with obtuse slightly elevated lines ; spire 

 short, much shorter than the aperture; suture in- 

 dented. 



Length about one-third of an inch. 



Greatest breadth about the same. 



Inhabits Portland, Maine. 



Cabinets of Messrs. Stone, Hyde and Say. 



This species strongly resembles the preceding, but 

 is distinguished by the elevated, obtuse, revolving 

 lines, or acute impressed ones. The colours are 

 greenish, olivaceous, or whitish, with darker, irre- 

 gular, transverse lines or shades, and the throat is 

 dark reddish- brown, the margin of the mouth whitish. 

 It is very possible that it is only a variety of the 

 preceding. 



5. T. *vestita. Shell conic, rather thin ; whirls 



30 



