[ *57 3 
VI. ExtraB of a Letter from Dr. John Bar- 
tram, to Mr. Peter Collinfon, F. R. S. 
containing fome Obfervations concerning the 
Salt-Marfh Mufcle, the Oyfter-Banks, and 
the Frefh-Water Mufcle, of Penfylvania. 
My good Friend , 
'Read Nov. 8.V HAVE obferved fomcthing of an ex- 
5 744 - traordinary Nature in our Salt-Marfh 
Mufcle : By its fibrous Roots, which ftrike deep into 
the Soil, it feems to be of a vegetable Nature ; for, 
it is highly probable, the Animal draws fome Part 
of its Nourilhment through them : They are fixed by 
thefe two Thirds of their Length in the Sand, with 
their broad Ends uppermoft, which open at every 
Return of the Tide, to be replenifhed by the Salt- 
Water: When it is retreated, they are found lodged 
in the Grafs, Sedge, Creeks, and Banks, fingly and 
together in Plenty. 
I herewith fend you a Specimen, which will give 
you a better Idea of this wonderful Creature. 
There you may plainly obferve the Ligaments 
draw their Origin from the principal Parts of the 
Animal, and unite near the Extremity of the Shell, 
which they pafs through on that Side of the Mufcle 
that opens to let in the Water ; then they divide again 
into many capillary Roots or Fibres, which penetrate 
and extend themfelves into the Mud or Soil of the 
Marfh ; which, by long Obfervation, feem to me for 
two Ufes j firft, as I have above obferved, to convey 
Part 
