70 PHILOSOPHICAL TRANSACTIONS. [aNNO 1744. 



Observations concerning the Salt-Marsh Muscle, the Oyster- Banks, and the Fresh- 

 fValer Muscle, of Pennsylvania. By Dr. John Bar tram. 1^° ATA, p. 157. 



There is something of an extraordinary nature in our salt-marsh muscle : by 

 its fibrous roots, which strike deep into the soil, it seems to be of a vegetable na- 

 ture; for, it is highly probable, the animal draws some part of its nourishment 

 through them : they are fixed by these two thirds of their length in the sand, with 

 their broad ends uppermost, which open at every return of the tide, to be re- 

 plenished by the salt-water : when it is retreated, they are found lodged in the 

 grass, sedge, creeks, and banks, singly and together in plenty. 



On viewing one of them, we plainly observe the ligaments draw their origin 

 from the principal parts of the animal, and unite near the extremity of the shell, 

 which they pass through on that side of the muscle that opens to let in the water; 

 then they divide again into many capillary roots or fibres, which penetrate and 

 extend themselves into the mud or soil of the marsh; which, by long obsei-vation, 

 seem intended for two uses; first, as I have above observed, to convey part 

 of their nourishment; which seems probable, by their being dispersed through 

 the body of the muscle. 



The other use of these fibrous roots, for so I must call them, by their striking 

 deep into the mud or sand, is to secure the creature from being carried away by 

 the rapidity of the tide : so that, in this circumstance, they are somewhat ana- 

 logous to plants, whose roots both nourish them, and secure them from the in- 

 juries of wind and flood. 



Our oysters are of an oblong figure; they grow at the sides and bottoms of 

 creeks, rivers, and bays, near the sea; but mostly in such a situation where they 

 are near or quite dry at low water : they have the power of opening and shutting, 

 like the muscle, to take in and retain the salt-water, which is their principal 

 nourishment: though they stick in the mud, they are not so secured as the salt- 

 marsh muscle beforementioned ; and though these oysters grow in great clusters 

 or heaps, commonly called oyster-banks, yet every one that is alive has free com- 

 munication with the air and water, and liberty to open and shut. If the oyster's 

 way of growing may be compared to that of a plant, I think there is great simili- 

 tude between it and the opuntia, or Indian fig; a leaf produces and supports a 

 leaf, and so on. thus the young oysters grow on the sides of the old one, which, 

 by degrees, is so deeply immerged in the mud, that it dies; but yet it serves to 

 support the young ones upright, till they come to maturity to produce others ; 

 and then those by degrees, subside; so that, by this method, banks of dead and 

 living oysters are extended of an inconceivable length and breadth through all 

 our coasts. 



Our common fresh-water muscles differ from our salt-marsh muscle, in that 



