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The sea mussel is used extensively by the local inhabitants and is 

 marketed to some extent. In the South tliey are also used as bait in 

 surf fishing. They have been canned on a commercial scale at various 

 points. 



BAY MUSSEL 



Mytiliis cdttlis Linnaeus 

 Plate 3, figure 4 



This form has been called "sea mussel" on the Atlantic coast to 

 distinguish it from the fresh water mussels, but since it is not found 

 on the outer coasts as is M. calif ormatvus the term "bay mussel" is 

 preferred. 



Description— Tliis is a smaller form, seldom exceeding a couple of 

 inches in length, smoother and less elongated tlian M. californiamis. 

 It is found within bays. 



In Europe it is extensively cultivated and is an important food 

 mollusk. It is often seen in the San Francisco markets. 



HORSE MUSSEL 



Modiolus rectus Conrad 

 Plate 4, figure 3 



Description— The species of Modiolm may easily be distinguished 

 from the other mussels of the coast by the fact that the umbo is not 

 at the extreme end and that the color is not black but brownish. The 

 shells are also either bearded or markedly ribbed. Several species reach 

 a size great enougli to make them of importance though none appear 

 to be abundant. M. recUis, here figured, can be told by its elongated 

 form; the others resemble MytiJus edulis in general shape. Modiolus 

 modiolus is a large form found in deep water among gravel and rocks. 

 M. plicatus is a smaller species that has been introduced from tlie 

 Eastern coast to San Francisco Bay ; it is found between tides on the 

 mud flats. The numerous conspicious radiating ribs will serve to 

 distinguish it from both M. rectus or M. modiolus which are without 

 ribs but are bearded. 



Habitat and habits— The horse mussels are generally solitary and 

 ai-e found partially buried in mud or gravel, to which they are anchored 

 by the byssus. This fact will serve to separate them from the species 

 ■of Mytilus, which occur in beds anchored to some solid object between 

 tides. 



Use — The use of the horse mussels as food was not observed. On 

 the Atlantic coast they are eaten though considered inferior to Mytilus 

 edulis. 



Distribution — Modiolus rectus is found, according to Dall, from 

 Bolinas Bay to Magdalena Bay, Lower California. 



