Hancock, but has in many cases escaped the observation of later zoologists.
In the south-western part of Pittsfield, on the boundary between it and Hancock, is Shaker Village, settled about 1790 by Shakers.
Hancock, Gratiolet and others to be connected with the opening and closing of the valves, or with their attachment to or movements upon the peduncle.
Two other pairs have been termed divaricators by Hancock, or cardinal muscles (" muscles diducteurs " of Gratiolet), and have for function the opening of the valves.
The divaricators proper are stated by Hancock to arise from the ventral valve, one on each side, a little in advance of and close to the adductors, and after rapidly diminishing in size become attached to the cardinal process, a space or prominence between the sockets in the dorsal valve.