The methyl, ethyl and normal butyl esters of the acids of menhaden oil and their bromination products have been prepared and analyzed. The presence of more highly unsaturated acids than clupanodonic is indicated.

The analysis of the methyl ester fractions from 5 fish oils indicates the presence of acids more highly unsaturated than clupanodonic.

By esterifying menhaden oil and fractionating the esters 6 times by distillation under diminished pressure, collecting 16 fractions, the presence of acids with 16, 18, 20 and 22 atoms of carbon is indicated.

The unsaturated acids obtained by the lead soap-ether and barium soapbenzene separations have been esterified and fractionated and their bromine addition products analyzed.

The ether-insoluble bromine addition products of the unsaturated acids have been debrominated and fractionated and their bromine addition products analyzed.

We believe that we have demonstrated the presence in fish oils of myris-tic, palmitic, palmitolic (hexadecatrienoic), clupanodonic (octodecate-trenoic), arachidonic, eicosapentenoic, docosapentenoic and docosa-hexenoic acids.