Note 155 — Order III.—APODA.

This may be partially seen in the section, fig. 1, of Balanus, on the same plate (25) with the figure of Proteolepas; here (bearing in mind that Balanus is a much modified form) (z) shows the pupal antennæ, within which, whilst young, the cement-ducts are included, and are directly continuous with the layer of branching ovarian cæca (g), which are prolonged up to the ovaria as a pair of simple tubes (only one being here represented), entering the body above the upper margin of the prosoma (c). The prosoma of Balanus, I may add, answers to the segment 2 t in fig. 7 of Proteolepas; (e) the mouth in Balanus, of course corresponding with (m) the mouth of Proteolepas; the segment 1 c and 2 t of the latter, are in Balanus aborted or confluent, at least on the ventral surface; and, lastly, the whole great shell of Balanus, the sack with its muscles and the branchiæ, and the opercular valves with their muscles, are all represented in Proteolepas merely by the outer membrane of the two threads (g), which enter the pupal antennæ!