Branchioplax is an extinct genus of crab which existed in Alaska and Washington during the Eocene period. It was first named by Mary Rathbun in 1916, and contains ten species , including Branchioplax washingtoniana from the Hoko River Formation,  Branchioplax carmanahensis, and Branchioplax ballingi.

Branchioplax is an extinct genus of crab which existed in Alaska and Washington during the Eocene period. It was first named by Mary Rathbun in 1916, and contains ten species , including Branchioplax washingtoniana from the Hoko River Formation,  Branchioplax carmanahensis, and Branchioplax ballingi.