I have great pleasure in returning my most sincere thanks to various naturalists, both for intrusting to me their collections of Fossil Cirripedia, and for allowing me, whenever it was advisable, to clear the specimens from their matrix. Although an entire stranger to many of the gentlemen to whom I applied, I have in every instance received the most courteous acquiescence to my demands. To Mr. Fitch, of Norwich, I here beg to return my thanks, for having allowed me to keep, during several months, his unrivalled collection of Cirripedia from the Upper Chalk of Norwich,—the fruit of twenty years' labour. Mr. Bowerbank has given me the freest use of his fine collection, rich in specimens from the Gault. Mr. Wetherell placed in my hands his beautiful and unique specimen of Loricula pulchetta, and other species. Professor Buckman sent me, of his own accord, a fine series of the valves of Pollicipes ooliticus, the most ancient Cirripede as yet known, discovered and named by him. To Messrs. Flower, Searles Wood, F. Edwards, Harris, S. Woodward, Tennant, and other gentlemen, I owe the examination of several species new to me. Mr. Morris and Professor E. Forbes have, in their usual kind manner, supplied me with much valuable information, and with the loan of many specimens.