Dr. Carel Octavius van Regteren Altena has passed away on December 23, 1976. He was born in Amsterdam on December 19, 1907, where he obtained his Ph. D. (cum laude) at the University of Amsterdam in 1937. In the period 1930-1940 Altena worked on fossil molluscs of the then Netherlands East Indies. After an interim period of teaching biology at a ‘gymnasium’ (a type of secondary school), he joined the staff of the Rijksmuseum van Natuurlijke Historie at Leiden in 1941 as curator in charge of the Lepidoptera. Upon the retirement of Dr. Ch. Bayer in 1952 Altena moved to the Mollusca department, which position he held until January 1, 1973. Altena’s deteriorating health forced him to cut down his activities and in 1968 he was relieved of the official duties of curator of molluscs. Dr. E. Gittenberger was put in charge of the department and Altena stayed on until 1973 being allowed to devote all his time to research. Thereafter he continued to work in the museum at regular intervals, much of his work being done at home. From 1946 until his demise Altena was also curator of the geological, mineralogical and palaeontological cabinet of Teyler’s Museum, Haarlem, where he worked one day a week; after his official retirement in Leiden he spent more time in the Haarlem museum. Teyler’s Museum is a very old, but unfortunately comparatively little known, institution with in particular historically very important palaeontological collections. Here Altena made full use of the unique opportunities offered for palaeontological research. Next to his museum duties Altena devoted much time to the Dutch malacological society. He was a foundation member in 1934, served as treasurer in 1934-1940, as president in 1948-1967, and as editor of Basteria in 1945-1968. He was made an honorary member of the society in 1967. Under the Queen’s birthday honours in 1970 Altena was nominated an Officer in the Order of Orange-Nassau in recognition of his scientific work and public service. The scientific work of Altena may be considered to consist of four main subjects, (1) his entomological work (period 1941-1952, last paper in 1959), (2) his palaeontological work (mainly on fossil molluscs of the Tertiary and Quaternary of Indonesia and the Netherlands), (3) his work on land slugs (a series of 25 Notes on land slugs, also entitled Notes sur les limaces, or Mitteilungen über Nacktschnecken, 1953-1977), (4) his work on the molluscs of Surinam, formerly Dutch Guiana (published in 1969-1975). On his 65th birthday on December 19, 1972, the Dutch malacological society dedicated nos. 2-5 of vol. 36 of Basteria to Altena on which occasion his life and work were described in detail by Van Benthem Jutting & Van Bruggen (Basteria 36: 31-54). This paper contains a complete bibliography and a list of new taxa covering the period up to January 1, 1973. In the present paper these lists have been brought up to date and amended where necessary. As easy as it is to describe the life and work of Carel van Regteren Altena, so difficult is it to delineate the man behind it all. First and foremost Altena was an extremely modest man; his modesty was only equalled by his artistic feelings (he was an accomplished musician) and his thorough and varied education. His delightful sense of humor left a lasting impression on all who had occasion to meet him. Moreover, he was one of those fortunate people who know that everything goes by comparison. The last decade or so he particularly felt the responsibility for completing work once undertaken and to do it as well as he could; his physical courage kept him going in times of adversity. His health became increasingly poor and the suffering must have been intense. Yet, he never talked about it, desiring not to burden others with his personal troubles. As a sensitive person he must have appreciated that his colleagues and others treated him as if nothing was the matter. Knowing him was enriching one’s life — may he rest in peace.