The course is a study of the life history, habits, origin, development, physiology, anatomy, and taxonomy of the main phyla of invertebrates. A phylogenetic sequence is followed to show interrelationships among the phyla. Special emphasis is given to the Atlantic marine invertebrates. Laboratory and fieldwork deal with collection, preservation, and identification of local species. This course is periodically offered at the Marine Science field station at Wallops Island, Va., only during a summer session. Since this course also is offered for graduate credit, a differentiation of requirements will be made.