BLOCH, MARK ELIEZER (c. 1723-1799), German nat uralist, was born at Ansbach, of poor Jewish parents, and died at Carlsbad Aug. 6, 1799. Af ter taking his degree as doctor at Frankfurt-on-Oder he established himself as a physician at Ber lin. He is best known by his important work on fishes. Mark Eliezer Bloch was 56 when he began to write on ichthy ological subjects. He wrote Allgemeine Naturgeschic/ite der Fische (1782-95, 12 pts., 432 coloured plates), and left an un finished Systema icjithyologiae (ed. Schreiber, 18o1). His collec tion of fishes was bequeathed to the Berlin Museum.