THE NAUTILUS. 95 



all over the northern portions of Europe, Asia and America. They 

 are used in Rhode Island for food to a very limited extent, probably 

 on account of the vast quantities of clams, quohogs, oysters and scal- 

 lops which abound here, any of which form a much better quality of 

 food than the mussels ; but they are consumed in large numbers in 

 Europe. The annual consumption in the city of Edinburgh is esti- 

 mated at four hundred bushels, averaging one thousand to the bushel ; 

 the amount collected for bait in various kinds of fishing is enormous. 

 In France, Norway and Russia immense quantities are gathered and 

 used, animal, shell and seaweed together, as a fertilizer for the land. 

 They are found in Rhode Island attached to each other by their 

 strong byssus in great numbers. They are not buried in mud, but 

 cluster together on rocks between tides and form beds in the banks. 

 The young are found in deeper water and attain their growth in one 

 year. 



Mytilus pellucidus, Penn., Mont., Turt., Don., De Kay and others, 

 considered by many as a separate species, I think is only a variety of 

 Mytilus edulis. The shell is thin and transparent, beautifully radi- 

 ated with blue, yellow and green zones. These marks are generally 

 seen in specimens about one inch to an inch and a half in length and 

 they gradually disappear as the shell gets larger; still these zones are 

 sometimes seen in old and solid specimens, while others, one half an 

 inch or less in length, are of a uniform shining black appearance, so 

 that it does not seem to depend at all upon the age or size of the 

 individuals. In every cluster of Mytilus edulis we find from one to 

 a dozen or more of these pellucid, radiating ones, which if they do 

 belong to a separate and distinct species, present an anomaly seldom 

 seen, i. e., a colony of different species of animals living together and 

 firmly bound together by such strong bonds of friendship (or some- 

 thing else) as these mollusca are. 



Genus Modiolus Lam., 1799. 



The horse-mussels differ from the edible mussels in having a shell 

 swollen at the umbos, and in having three pedal impressions in each 

 valve, whereas there are but two in Mytilus. The animal burrows 

 in mud, or clusters together under banks of grass or peat in salt 

 marshes in some species, while others live in deep water. There are 

 three species living in Rhode Island, one of which, however, is not a 

 native, but has become domesticated here within about twenty years. 



