From my perspective, a malacologist does research on mollusks as organisms. To put it another way, a malacologist is a zoologist specializing in the phylum mollusca. A conchologist studies/collects shells. Though the title malacologist is typically reserved for professionals in the field, an amateur who investigates the biology, natural history, systematics, physiology, anatomy, population dynamics, biodiversity, etc. of mollusks is also working in the field of malacology, and can often make significant contributions to the body of knowledge in that field. Such an individual, I feel, can rightfully be described as an "amateur malacologist". The term amateur does not designate a person of little knowledge or experience - it simply means a person who does not make his/her living in this particular discipline, that is, a non-professional. I think the principal criterion separating malacologists from conchologists is research. One who collects shells, and reads/studies in an effort to learn that which is already known and published about shells is a hobbyist, and therefore a conchologist. One who seeks to discover new knowledge by original investigation is working in the capacity of a scientist (whether professional or amateur), and is therefore a malacologist. Paul M.