Developmental abnormalities of identifiable neurons in the crayfish Procambarus simulans.

We report anomalies of lateral giant neurons in field-caught animals. In one case, both lateral giant neurons arising from the fifth abdominal ganglion did not terminate in the next-most anterior ganglion, but rather continued to the third abdominal ganglion. In another case, an additional large neuron arising in the fifth abdominal ganglion coursed in a posterior direction. All othe CNS structures appeared normal in animals having either anomaly.