During the Biocyarise 1984 cruise in the area of deep-sea hydrothermal vents of the East Pacific ridge at 12 degree -13 degree N, Brachyura were collected on various sites. Cyanagraea praedator is represented by two large adult females, caught on the Pogonord site. Bythograea thermydron , and Bythograea microps are also recorded. The very rich precocious stage material permits the formulation of hypotheses concerning regression of the eyes in both Bythograea species from the young and juvenile stages to the subadult and adult stages. The systematic position of the Bythograeoidea is discussed.