Two species of Euryplacidae were collected in western Mexico. Trizocarcinus dentatus (12 localities) and Euryplax polita (4 localities) were both found in the Gulf of California. In the case of E. polita 11 specimens (5 males, 5 females, one ovigerous female) were obtained, while in the case of T. dentatus 42 specimens (25 males, 10 females, 7 ovigerous females) were collected. The northern distribution limit of E. polita is extended to the northern Gulf of California (28°16′N 111°36′W). Environmental data for both species are provided, including depth range, temperature, dissolved oxygen, and sediment composition.