MYTILUS. Ill 



spinning strong tendinous threads, by which she moors 

 her shell to rocks and timbers." Pearls too are pro- 

 duced by them in considerable quantities, although of 

 an irregular shape and indifferent lustre. Formerly 

 they were applied medicinally as an absorbent. Great 

 numbers are still collected at the mouth of the River 

 Conway in North Wales, the fish being boiled and trodden 

 out by the naked feet of women. What is done with 

 these " seed-pearls " is a mystery. I have been told 

 that the Jews purchase them for the Birmingham mar- 

 ket; and a correspondent in London's Magazine of 

 Natural History for 1830 mentions a surmise that they 

 are exported to India to be dissolved in the sherbet of 

 the nabobs ! 



This species in a recent and fossil state has received 

 twenty-eight different names. Its variability is coex- 

 tensive with its diffusion. 



2. M. MODI'OLUS *,(Linne.) f^ - 17 



M. modiolus, Linn. Syst. Nat. p. 1158. Modiola modiolus, F. & H. ii. 

 p. 182, pi. xliv. f. 1, 2. 



BODY dark orange, speckled with white and often tinted 

 with brown: mantle having both margins plain throughout, 

 but finely ciliated : foot red on the upper part, and whitish at 

 the base, where it is very thick and strongly wrinkled. 



SHELL oblong, bluntly rounded, nearly square at the smaller 

 end and expanding outwards to a semicircular edge in front, 

 convex, and gibbous towards the beaks, solid and glossy : 

 sculpture, fine concentric lines of increase : colour purplish- 

 yellow : epidermis thick, dark brown or dusky, almost black 

 in the adult, minutely striate lengthwise, foliated in the 

 young and produced into long thorn-like filaments, which are 

 plain at their edges and arranged in concentric rows on the 

 posterior side and in front: margins thick, straight or but 

 slightly incurved on the ventral side, obtusely rounded be- 

 hind and semicircular in front : beaks blunt, divergent and in- 



* The box of a pump. 



