17 



tions ; thus, seven revolving stria? only are mentioned on the 

 lower whorl, while my specimens have twelve. But they do 

 not differ materially from a few large specimens which I 

 dredged in New Bedford Harbor. 



In Boston Harbor it occurs at the depth of three fathoms, 

 attached invariably to the margin of the Crepidula fornicata^ 

 where it is fixed on stones and shells. Several occur together. 

 They produce much mucus, and in confinement suspend them- 

 selves from the surface of the water by a thread formed from it. 



Pleurotoma violacea Adams and Ivligh. I have dredged 

 specimens of this shell in two and three fathoms on muddy 

 bottoms in the harbors of Salem and Boston. It seems most 

 abundant among dead and decaying Zostera, but I have never 

 found it about that plant when alive. 



The name P. violacea has since been applied by Hinds to a 

 species from New Guinea, which must receive a new desig- 

 nation. The name of another of our species, P. deciissata, 

 Couthouy, 1838, is equally unfortunate, having been since ap- 

 propriated by Macgillivray to a British species. 



Natica flava Gould. This species was found in our Bay 

 by Mr. Joseph True, of Salem, and subsequently by myself. 

 Both specimens were young, and possessed a very distinct 

 umbilicus. I have also a full grown umbilicated specimen from 

 the Grand Bank. The operculum is corneous, resembling that 

 of N. heros. If a genus Glohularia is to be separated from 

 Natica, this species cannot belong to it. 



Philine sinuata, nob. Three specimens have occurred in 

 Boston Harbor. 



Philine Formosa, nob. Frequent in deep water in many 

 parts of the Bay. 



Bulla puncto-striata Migh. The single specimen of this 

 species found and described by Dr. Mighels must have been im- 

 mature. I have taken about twenty specimens of all ages from 

 fishes caught in deep water off Cape Ann, some of which exceed 

 in size twice the dimensions given by him. Two specimens are 

 three fourths of an inch in length and seven sixteenths of an 



proceedings B. S. N. H. 2 JULY, 1851. 



