1. The neuromuscular mechanism of stridulation has been studied in four species of field crickets.

2. The operation of the exoskeleton has been investigated by direct and neuronastimulation of muscles and by manipulation of the isolated exoskeleton; the wings are closed by lowering the tergum and opened by subalar, basalar and tergopleural sclerites acting outside the wing pivot.

3. Muscle action potentials recorded from freely moving animals during stridulation show the following:

(a) In the calling or aggressive song pulses, the closing stroke is produced by the medial dorsoventral muscles; the opening stroke is produced by the basalars and subalars.

(b) The ‘tick’ of the courtship song is produced by simultaneous contraction of the medial dorsoventral muscles; the subalars and some of the basalars are active during the soft pulse phase of the courtship song but not during the "tick".

(c) Evidently, the first dorsal longitudinal is active during the "tick" and closing; the second is active in opening and in the soft pulse phase of courtship.

4. The upstroke of flight is homologous to the closing stroke of stridulation.

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