Sends specimens of 'Hirudo nigra', observes their different colour from some collected a few months ago. Anxious that his relative lack of knowledge could compromise his paper. Also sends a species of 'Cicada' that swims on its back, like 'Notonecta', would like to write his next paper for "Linnean Transactions" on it if [Thomas] Marsham has not already seen it before receiving it from Kirby.