174 CATALOGUE OF THE MOLLUSCA 
Frequent in the coralline zone. Not uncommon in the sto- 
machs of haddocks. 
Faminy. Mytinipm, Fleming. 
84. MYTILUS, Linneus. 
1. M. evuuis, Zinn. (common Mussel.) 
Mytilus edulis, Mont. Test. Brit. 159. 
Var. 1. Thin, with coloured rays. 
Mytilus pellucidus, Mont. Test. Brit. 160. 
Var. 2. Thick and incurved. 
Mytilus incurvatus, Mont. Test. Brit. 160. 
Var. 3. Thick, flattened and subangular. 
Mytilus subsaxatilis, Williamson in Mag. Nat. Hist.* vii. 
354. 
Var. 4. Small, and sometimes rather hispid. 
Within tide-marks, or a little beyond, on a hard or stony 
bottom, and among rocks, very common. 
No species undergoes a greater degree of variation from locality 
than the common Mussel. For its full development a mixture of 
fresh with salt water appears to be necessary ; it is, therefore, 
met with in the greatest perfection at the mouths of rivers. In 
such localities the typical form of the species is to be found, and, 
when left undisturbed, it usually forms large beds. On the 
more rocky and exposed parts of the coast it assumes a stunted 
appearance, running into the varieties of form mentioned above ; 
always small on the exposed surface of rocks, but attaining a 
larger size in hollows and crevices, where it generally takes the 
form called Mytilus incurvatus. A more flattened variety is 
found at the roots of tangle. 
Mussels are much used for bait in this neighbourhood. The 
Cullercoats fishermen make an annual excursion to the mouth 
of the Tees for the purpose of collecting them, the beds at the 
* « J first noticed this variety in 1810, in company with my late valued friend 
Mr. Hancock, of Neweastle, at the mouth of the Tyne, below Tynemouth, ad- 
hering to stones left dry by the tide, in small groups.”—Captain Brown. 
(Illust. Ree. Conch. 77.) 
