A histological examination has been carried out of the spines of ten species of ophiuroids. Eight species proved to have mucous glands in the spines. The glands were of two types (1) multicellular aggregations of pyriform cells with elongate necks (Amphiura filiformis, A. chiajei, Acrocnida brachiata), (2) glands of varying shape but with distinctly fibrillar contents (Amphipholis, Ophiactis, Ophiopholis, Ophiothrix). All of the glands exhibited the staining reactions of an acid mucopolysaccharide with the exception of the fibrillar glands in Ophiopholis which were strongly PAS positive but negative for acid mucopolysaccharide. Ophiopholis was unique in possessing scattered single pyriform acid mucopolysaccharide secreting cells in addition to the PAS positive fibrillar glands.

The two species of Ophiura which were examined did not have glands in the spines. Possible functions of the gland secretions are discussed.