IN the note on missing nebulæ in NATURE, vol. xix. p. 221, I find the nebulæ G. C. 132, 4570, and 5051 mentioned together with the Merope nebula as being diffused objects which are 'overlooked in very large telescopes, though obvious in much smaller ones'. This alludes, no doubt, to the occurrence of these objects in the list of nebulæ not found with Lord Rosse's 6-foot reflector (Phil. Trans., 1861, p. 745)