Note 143 — Genus—ALCIPPE. Pl. 22, 23.

In the genus Lithotrya, as long as the animal continues to bore into the rock, the calcareous discs by which it is attached in its cavity, stand, as in Alcippe (Pl. 8, fig. 2, 2 a′, Darwin’s ‘Monograph on the Lepadidæ’), parallel to the longitudinal axis, but as soon as the animal ceases to bore, and the discs become converted into a cup, they occupy a normal position at right angles to the peduncle. According to Reinhardt, these discs, in Lithotrya, are situated on the carinal or dorsal surface of the peduncle, at which statement I now feel considerable surprise, as undoubtedly the pupa must first permanently attach itself by its prehensile antennæ on its ventral or rostral surface. In Anelasma I failed to discover any cement or cement-ducts; but I am now strongly inclined to believe, considering that the extreme lower or anterior end goes on growing, that the surface of attachment will be found to occur, as in Alcippe, on the rostral surface, a little way below the orifice.