A detailed examination of the alkaloids of the cactus Lophocereus Schottii has resulted in the isolation of two new alkaloids, piloceredine and lophocerine in addition to the previously described pilocereine; quaternary alkaoloids were not encountered. Piloceredine (C30H44N2O4) was shown to be diastereoisomeric with pilocereine and potassium-liquid ammonia cleavage of its methyl and ethers yielded the same cleavage products as the corresponding derivatives of pilocereine. Lophocerine was obtained in impure form from the phenolic alkaloid fraction and is assigned the structure 1-isobutyl-2-methyl-6-methoxy-7-hydroxy-1,2,3,4,-tetrahydroisoquinoline since upon methylation it afforded the known 1-isobutyl-2-methyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline. Lophocerine appears to be the biogenetic precursor of pilocereine and piloceredine. © 1958.