The length-force relationship for the circular muscle fiber preparations from near the outer (black symbols) and inner (white symbols) surfaces of the mantle of the long-finned squid D. pealeii. The data were normalized by the preparation length (L0) that produced the highest isometric active force (P0). Thompson, J.T. Shelton, R.M., and Kier, W.M. 2012. Transmural variation in the length-force relationships and in vivo operating length ranges of the circular mantle muscles of squid. Manuscript.