Errata. Page 65, lines 17 and 32, for Acanthodrilis read Acanthodrilus. 94, line 22, for Falces read Eyes. 101, line 27, for cocolorous read concolorous. 113, line 31, for lateral read central. 162, line 29, for Debranchiata read Dibranchiata. 162, line 38, for perouii read peroni. 166, line 9, for terrebelloides read terebelloides. 168, line 34, for Italiotidæ read Haliotidæ. 170, line 6, for mangei read maugei. 171, line 22, for Onchadella read Onchidella. 172, line 24, for Aphysiidæ read Aplysiidæ. 172, line 29, for novo-zealandica read novæ-zealandiæ. 174, line 28, for lumbata read lambata. 196, last line, for cathymetrical read bathymetrical. 197, line 31, for quinqualoculine read quinqueloculine. 198, line 4, et seq., for W. and T. read W. and Y.