MODIOLA. 185 



The animal is oblong, soft, and of a mingled dusky and 

 bright-red and orange colour, more or less speckled with 

 yellowish-white. The mantle, except its edges, is pale and 

 whitish. The base of the foot, and its large and conspicu- 

 ous byssiferous gland, which appears as if a distinct organ, 

 are wrinkled and cylindric ; the finger-shaped portion of 

 the foot is subcorneal, smooth and red, and small in propor- 

 tion to the size of the body. The branchial laminae are 

 tawny. The posterior adductor muscle is conspicuously larger 

 than the anterior. The byssus is strong, and of a more or 

 less shiny yellowish hue : the extremities of the threads 

 are fixed by a small expansion to neighbouring bodies, and 

 being usually arranged in several linear series, cause, when 

 they are broken away, the appearance of rows of zoophytic 

 cells, or peculiar nidi. 



The Horse Mussel, as this fine species is popularly 

 called, is so universally distributed around our coast, that 

 to quote localities would be superfluous. We have met 

 with it in all depths of water between low-water mark and 

 sixty fathoms. It is small at great depths, finest in from 

 seven to thirty fathoms, and frequents gravelly and muddy 

 localities most. In tide-ways it sometimes envelops itself 

 by means of its byssus, in a complete nest or investment of 

 threads and gravel : this habit we have observed in thirty 

 fathoms water, seven miles north of Anglesea (M'Andrew 

 and E. F.). At Rothesay, Mr. Alder informs us, it is 

 common just below low-water mark, and is waded for 

 by women and children at low tides for food. 



It ranges through the North Atlantic ; but seems to have 

 had its origin on the European side, where it is found fossil 

 in the mammaliferous crag. 



VOL. II. 



