XXI 



velopxnent of the Mollusca, the first published memoir from his pen 

 which appeared in the " Annales des Science N"aturelles," for 1835, 

 being upon the genus Dreissena. Numerous other papers followed 

 one another in rapid succession, chiefly in the " Memoires " or 

 " Bulletins " of the Belgian Academy, and his researches soon 

 extended into other branches of zoology, but mainly the aquatic, and 

 especially marine forms of invertebrates (as Hydrozoa, Bryozoa, 

 Turbellaria, Ascidians, Archiaimelides, Crustacea, Hydrachnida, and 

 Pentastomida), which frequent residences at Ostend during his 

 academic vacations gave him opportunities of observing. For this 

 purpose he established at his own expense in 1843 a marine labora- 

 tory and aquarium, which was one of the first, if not quite the first, 

 of these now familiar institutions. He also greatly advanced the 

 knowledge of the development, transformations and life-histories of 

 the parasitic worms, and their relations to their respective hosts, one 

 of his principal memoirs on this subject obtaining in 1858 the 

 " grand prix des sciences physiques " of the Institute of France. A 

 summary of his researches into a branch of zoology which he made 

 peculiarly his own, was published in a popular form, as one of the 

 International Scientific Series, under the title of " Les commensaux et 

 les parasites dans le regne animal" 1875. Of this, English and 

 German translations were issued. 



It is singular that throughout nearly the whole of his long and 

 industrious scientific career he was engaged more or less in two quite 

 independent and very distinct lines of work, the one which has been 

 referred to above, and another by which to many he was almost 

 exclusively known, and which in his later days became of such 

 absorbing interest as to give him little leisure for any other. Very 

 early in life he was attracted by the discoveries of fossil bones of 

 whales made during the excavations carried on in the formation of 

 the fortifications at Antwerp, and this led to a systematic study of 

 this group of mammals, then, owing to the want of materials in 

 museums, most imperfectly known. With an extraordinary per- 

 tinacity and zeal, which was continued to the end of his life, he 

 gathered from all available sources everything that could be known 

 of the Cetacea, both existing and extinct, and published the 

 knowledge he acquired in innumerable short papers and memoirs, 

 and in several great and handsomely illustrated works, of which one, 

 the '* Osteographie des Cetaces vivants et fossiles," 1868-80 (written 

 in conjunction with Paul Gervais), will long remain the standard 

 work of reference on the subject. Others especially relate to the 

 extinct species found in the neighbourhood of Antwerp, and are in- 

 cluded in a series, which also contains a description of the fossil seals 

 from the same locality, published in the "Annales du Musee Royal 

 d'Histoire Naturelle de Bruxelles" 



