THE LARVAL DEVELOPMENT OF BRITISH COLUMBIA BRACHYURA I. XANTHIDAE, PINNOTHERIDAE (IN PART) AND GRAPSIDAE1

The larval stages of four species of crabs inhabiting British Columbia are described from series obtained by hatching eggs in the laboratory. In the development of Lophopanopeus bellus (Stimpson) there are found to be four zoeal stages, of Pinnotheres taylori Rathbun two, and of Hemigrapsus nudus (Dana) and H. oregonensis (Dana) five. There is only one megalopal stage in each of the species. Knowledge of the life history of Pacific coast decapod Crustacea is very-limited. The free-swimming larvae form an important part of shallow water plankton, and as such are a component of the food of fish and macro-plankton. Although the larvae occur in great numbers near the shore, comparatively little is known of their development, owing perhaps to the fact that it is usually necessary to rear the stages to be at all sure of correct identification, as the larvae are so unlike the adults and in many cases so like one another. They are difficult to rear in artificial conditions, and as far as the writer ha