the Shells of Maine. 323 



owing to their habit of boring deep into the mud, the dredge 

 slips over them, capturing those only which happen to be near 

 the surface. 



The whole animal is of an uniform, light flesh color — it is 

 very active and sprightly, — is very tenacious of life, and will 

 often leap about in an astonishing manner, for half an hour or 

 more, after being removed from its shell. When at rest, the 

 foot is nearly lancet shaped. In making a leap, it suddenly 

 thrusts forward this living stiletto to the extent of an inch or 

 more. — when extended to its utmost, the beholder for the 

 first time, is astonished to see it suddenly transformed into a 

 kind of parasol, and his astonishment instantly merges into 

 admiration, when, at that moment, he sees the shell darting 

 forward with the rapidity of an arrow. When the animal is 

 undisturbed, these evolutions are performed very rapidly and 

 for a considerable length of time. It is thus manifest how 

 perfectly it is adapted to its situation, and with what facility it 

 is capable of cutting its way through its muddy habitation. 



J\'. thraciceformis, Storer. This species is very rarely found. 

 I have obtained a few small specimens from haddock's stom- 

 achs taken in Casco Bay, but have never had the good fortune 

 to find it full grown. 



N. proxima, Say. Plentiful. 



N. minuta, Gmelin, Turt. Considerably plentiful. 



N. tenuis, Mont. Turt. Common. 



N. myalis, Couth. This species is often found, but is not 

 plentiful in Casco Bay. In the northern part of the Gulf of 

 St. Lawrence it is more abundant and considerably larger. 



N. navicularis, Couth. Very rare in Casco Bay. 



N. sajwiilla, Gould. Often found, but not in plenty. 



N. rostrata, INIont. I have detected this species among 

 other shells from the Gulf of St. Lawrence. Ii is readilv dis- 

 tinguished from N. minuta, Turt., by being shorter, and more 

 inflated anteriorly. It is rare. 



N.jacksonii, (fossil,) Gould. This rare species is occa- 

 sionally found in the post-tertiary formation at Westbrook, 

 and Mr. True informs me that he lias found it in a clav bank 

 at Gardiner. 



