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still his chief pursuit to the end of his life was comparative anatomy, 

 with occasional excursions into the neighbouring fields of zoology 

 and palaeontology. Fishes and marine invertebrata were his favourite 

 subjects. The chief fruits of his inquiries were his memoirs on the 

 myxinoid fishes ; his systematic description (in association with Henle) 

 of the Plagiostomata ; the reintroduction into zoology of the pla- 

 centiferous shark of Aristotle ; his essay on the Ganoids and on the 

 natural arrangement of fishes ; his papers on Rhizopoda ; and his 

 remarkable succession of memoirs on the embryology and structure 

 of the Echinoderms. It will not have been forgotten by the Fellows 

 of this Society, that for the last-mentioned discoveries in particular, 

 in addition to his previous labours in physiology and comparative 

 anatomy, Professor Miiller received the Copley Medal in 1854. 



Of the memoirs on the myxinoid fishes, we may observe, in the 

 language of the President's address on the occasion mentioned, that 

 their title conveys but a faint idea of their scope and importance ; 

 for while the anatomy of a particular family of fishes may be said to 

 form the text, there is an ample commentary, rich in new and original 

 matter, in which the structure is compared in other tribes, and the 

 facts sagaciously applied to the elucidation of great questions in 

 animal morphology. Referring to the researches on the Echino- 

 dermata, the President thus continued: " Professor Miiller early 

 applied himself to the study of the structure and economy of the 

 Echinoderms. After describing, in a special memoir, the anatomy of 

 the Pentacrinus, so interesting as a living representative of the ex- 

 tinct Crinoidea, and publishing, in conjunction with M. Troschel, a 

 systematic arrangement and description of the Asterida, he was at 

 length happily led to investigate the embryo life of this remarkable 

 class of animals. The field of inquiry on which he entered had 

 scarcely been trenched upon before, and he has since made it almost 

 wholly his own by persevering researches carried on at the proper 

 seasons for the last nine years, on the shores of the North Sea, the 

 Mediterranean, and the Adriatic. In this way he has investigated 

 the larval conditions of four out of the five orders of true Echino- 

 derms, and has successfully sought out and determined the common 

 plan followed in their development, amidst remarkable and unlooked- 

 for deviations in the larval organization and habits of genera even of 

 the same order; and his inquiries respecting these animals have 



