Tegumental Glands in the Cirripedia Thoracica.1

Abstract

ABSTRACT In the Cirripedia the exo-skeletal integument consists of a thick layer of chitin with a thin superficial layer of cuticle. The cuticle agrees in properties with that of the Decapod Crustacea, and is also secreted by tegumental glands. Unicellular or compound glands, here first described, secrete the cuticle of the outer surface of the peduncle and capitulum; the labial and suboesophageal (‘salivary’) glands secrete that of the surface of the mantle cavity. In the Operculata the labial glands also secrete between moults, the cuticular material serving to entangle excess material which enters the mantle cavity and so assist in its rejection. The restriction of this accessory function to the Operculata may be correlated with their abundance in frequently turbid waters between tide-marks. The cement is identical in properties with the cuticle and the cement glands are regarded as modified tegumental glands. In the Pedunculata all the gland-cells regenerate after secretion. The labial and suboesophageal glands secrete only at the moult, in the other glands some of the cells are always active. In the Operculata secretion is confined to the moult apart from the secretion produced by the labial glands in connexion with rejection of particles. In the Operculata the cells of the cement glands degenerate after secretion, new cells developing from the walls of the duct. The specializations of the tegumental glands are correlated with the sessile habits of the Cirripedia.