I Fig. 32. Four-sided prism, acuminated on both extremities by four planes, which are set on the lateral edges. 33. Six-sided prism, accuminated on'both extremities by three planes, which are set on the alternate lateral planes. 34. Six-sided prism, acuminated on both extremities by three planes, which are set on the alternate lateral edges. 35. Double eight-sided pyramid, accuminated on both extremities by four planes, which are set on the alternate lateral edges. ERRATA. Fagf. 6, line io, for arfenical pyrites read arfenic pyrites, 9, line 29, for feladon read celadon. 13, line 19, for principal colour read characterillic co lour. 14, line 7, for fundamental colour read characterillic colour. 29, line 13, for Fructicofe read Fruticofe. ■37, line 3, for later read lateral.