184 BIVALVES. 



means rendered stationary ; the silky filaments 

 produced by some of the species are entwined 

 in the coralines and stones at the bottom of the 

 sea, and securely anchor the group of muscles 

 found there. Others of the species perforate 

 rocks or even large shells, and form for them- 

 selves at once their residence and grave. The 

 Mytili which have their beaks nearly terminal 

 and pointed, and are of a dark colour, much 

 resemble a mouse, and from the circumstance of 

 a few species being like this animal the genus 

 has received their name, which is derived from 

 /zimAoj (mutilos) the diminutive of ^ (a mouse.) 

 Some of the species have their base elongated 

 with lobes on each side, and bear a resemblance 

 to a bird in full flight.* 



MYTILUS EdutisJ 

 COMMON MUSCLE. 



Specific character. Shell oval, pointed at the 

 beaks ; sides much sloped, flattish on the anterior 

 and rather angular and carinate at the posterior 

 end; hinge terminal; beneath the margin are 

 several tooth-like crenulations ; colour often of a 

 rich blue when deprived of its epidermis which is 

 brown ; inside blue about the margin, and whitish 

 in the middle, length from two to three inches, 

 and about half as broad. 



* Plate X. figure 3. f Plate X. figure 2 



