AMERICAN MUSEUM NOVITATES Published by Number 612 The AmERICANe MUSEUM OF NATURAL HISTORY May 8, 1933 New York City 59.7, 57 P: 15.6 REPRODUCTION AND EGGS OF POMACENTRUS LEUCORIS GILBERT BY C. M. BREDER, JR., AND C. W. COATES' On May 2, 1930, twenty-six specimens of Pomacentrus leucoris Gilbert collected at the Galapagos Islands on the first 'Nourmahal' expedition2 were brought to the New York Aquarium by Mr. Vincent Astor. This species is at least as quarrelsome in the relatively close confines of an aquarium as its better-known Atlantic relatives, and as a result of this disposition the twenty-six specimens were reduced to two by the beginning of 1932. Even the placing of a relatively large species (Spheroides maculatus Bloch and Schneider) in the aquarium caused such strong resentment that it was necessary to remove the latter in the interests of peace. The two fishes that remained proved to be of opposite sex, and with the aquarium (4' X3' X3%' deep) to themselves they soon engaged in egg-laying. As there is little recorded on the reproduction of the Poma- centridae, and since there is little likelihood of further observations being made on this species in the near future, the reproductive behavior and the physical appearance of the peculiar eggs are here discussed. The actual courtship and "nest building" may be described as follows. Both fishes were observed carrying mouthfuls of sand to a protuberance of rock in the aquarium and blowing it out in a cloud so that some of the sand settled on the rock, and the rest rolled off. After several mouthfuls of the sand had been carried up in this manner, from the floor of the aquarium, the fishes "fanned'" vigorously with their fins, and then with their mouths picked off the few remaining grains of sand from the rock. After several efforts of this kind, they abandoned this site and chose another jutting ledge of rock which was treated to a similar scouring of sand. This, too, proving unsatisfactory, still other sites were selected until a dozen or more had been tried before one was found to suit. All of these abandoned sites were plainly visible for a short while, since traces of sand were left at each one. lOf the New York Aquarium. 2See Townsend, C. H., 1930, Bull. N. Y. Zool. Soc., XXXIII, No. 4, for details of this expedition.