1. A method for remote identification of a tissue using ultrasound, comprising the steps of: directing ultrasound energy into an unknown tissue; measuring values of a characteristic of echoes of the ultrasound which are scattered from the unknown tissue; accumulating a statistically significant sample of the measured values of the characteristic; filtering the accumulated sample to determine, for each of a plurality of predetermined mathematical models, each of which is associated with a possible tissue type, a signal which is a measure of the likelihood that the accumulated sample of measured values was generated by said mathematical model; applying the the filtered signals as inputs of a predetermined logical decision function which selects one of the models which most likely produced the sample; and assigning the tissue type which is associated with the chosen model as the identity of the unknown tissue.