Max W.C. Weber, a versatile German-Dutch zoologist, had a German father, Hermann Weber, and a Dutch mother, Wilhelmina van der Kolk. While still at school he developed an interest in natural history and a teacher trained him in field botany. From 1873 he studied medicine and natural history at the University of Bonn and for some time in Berlin. After qualifying in medicine he returned to Bonn in 1877 and was awarded a doctoral degree in zoology for a thesis on Die Nebenorgane des Auges von einheimischen Lacertiden (The subordinate organs of the eyes of indigenous Lacertidae - a family of lizards). After two years in Amsterdam as an assistant in zoology and two years lecturing in zoology at Utrecht he was appointed professor of zoology and comparative anatomy in Amsterdam in 1883. That same year he became a Dutch citizen and married the Dutch algologist Anne A. van Bosse (see A.A. Weber*). They had no children.
During 1880-1881 Weber accompanied an expedition on the Willem Barents to the northern ice seas and published (in German) an introduction to the scientific results of the expedition, and descriptions of its collection of Isopoda (an order of the crustaceans), in the journal Bijdrage tot de Dierkunde (1884). For several years after their marriage the Webers went to Troms?, Norway, each summer, he to disect whales and she to study algae. Max published mainly in German, but aso in Dutch, French and English, on a variety of zoological topics, but mostly on the anatomy of both vertebrates and invertebrates. In 1888 the Webers went on an expedition to the Dutch East Indies and made extensive collections on the islands Java, Sumatra, Celebes and Flores (now part of Indonesia). At this time Max developed an interest in the geographical distribution of organisms. He, and others, published extensively on the material collected during this expedition. One of his comprehensive publications dealt with the anatomy and development of the genus Manis (Pangolins; 1891, 110p).
Weber and his wife visited South Africa from July 1894 to January 1895. He collected the local freshwater fauna and studied the anatomy of the genus Chrysochloris (golden moles) and some other mammals. The visit resulted in a series of papers on the fauna of South Africa, by different authors, in the Zoologischer Jahrb?cher, Abteilung f?r Systematik, Geographie und Biologie der Thiere. Weber himself provided an account of the freshwater fishes he had collected, including seven new species (1897). J.C.C. Loman described eight new species of Arachnida collected by Weber at Knysna and in Natal (1898), while his crustaceans were studied by J.C.H. de Meijere. Later F.A. Jentink described his South African mammals (1909). One of Weber's important discoveries in South Africa was a new species of the freshwater fish genus Galaxias in the southern interior. This genus is not otherwise represented in the African fish-fauna, but occurs in Tasmania, New Zealand and Patagonia. The discovery was announced in the Tijdschrift der Nederlandsche Dierkundige Vereeniging in 1895.
Weber was an expert on the functional anatomy and adaptive variety in the mammals. As early as 1885 he published the first volume of his Studien ?ber Saugethiere (Studies on mammals), followed by a second volume in 1898. This wok culminated in his most important book, Die S?ugetiere. Einf?hrung in die Anatomie und Systematik der recenten und fossilen Mammalia (Jena, 1904, 866p), which dealt with the anatomy and systematics of both living and fossil mammals. A much enlarged edition appeared in 1927-1928.
In 1899 he resigned his professorship and, with his wife, went on another expedition to the East Indies in the Dutch government vessel Siboga. He published an introduction and description of the Siboga expedition (in French) in 1902, followed by more specific publications on the zoology of the Indo-Australian archipelago. These included his monograph on the fishes of the Siboga expedition (1913, 710p) a paper on the marine mammals encountered (1923) and a number of papers on the region's marine and freshwater fish fauna. The series of Siboga reports that appeared under his editorship for many years constitute a record of one of the great historic voyages of exploration.
Among others Weber studied the geographic distribution of many species, particularly on Celebes (now Sulawesi, Indonesia), to determine the boundary between the Indian and Australian faunal regions. He showed that Celebes had a very limited freshwater fish-fauna compared to Sumatra, Borneo and Java, probably because it was formerly divided into several smaller islands with short and insignificant rivers. He was also the first to stress the great differences between the fauna of the north and south parts of the island. Among others he discovered over a hundred new fish species. In his later years he published extensively on the whole Indo-Australian fish fauna, a project that was interrupted by his death in 1937.
Weber was a recorder of innumerable observations, but refrained from theorising. He was a man of charm and dignity and was awarded the order of Orange Nassau, the knightly order of the Lion of the Netherlands, and several foreign decorations. He was a member of several academies, and a Fellow of the Royal Society of London.