Microscopic data on the internal and external structures of the usually solidly silicified lower parts of Aulocopium aurantium Oswald, 1850 are very scarce, almost lacking. Examination of several of these lower parts reveals that they have a system of prominent canals similar to, and wholly continuous with, that in the upper parts. Lower parts, therefore, are not stalks, but represent a younger developmental stage of the individual as a wh ole. The characteristic differences in preservation of upper parts and lower parts reflect diagenetic rather than biological processes. These features are considered to be fully representative of the whole sponge. The canal system within outer regions of the body in aulocopiids thus appears more complex than was hitherto assumed. This may also hold for other members of the anthaspidellid family. Also, smooth monaxons are demonstrated within skeletal strands of some aulocopiid upper parts, as well as in a lower part specimen. Their distribution within strands may vary considerably.--Modified journal abstract.

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