Carapace with median and sub-median lobes developed. Antero-lateral margins of carapace with seven broadly rounded to truncate lobes, postero-lateral margins with two anterior lobes. Chelipeds equal, sometimes slightly unequal in large males, and smooth; second to fifth pereiopods stout with rows of short stiff setae longitudinally placed, dactylus styliform. Male chelipeds slightly more robust than in female.
Carapace length male up to 60 mm; female up to 98 (160) mm.
Depth range up to 91 metres. Ovigerous November-August, larvae from April-December.
Carapace reddish brown (young specimens purple brown), pereiopods lighter, distal parts of dactylus and propodal prolongation of chelipeds black.
Shetland, Orkney, Aberdeen, Firth of Forth, Northumberland, Yorkshire, Wash, Thames, East Channel, Wight, Portland, Channel Isles, Plymouth, Scilly Isles, North Cornwall, Bristol Channel, Cardigan Bay, Anglesey, Liverpool Bay, Solway, Isle of Man, Dublin, Belfast, Clyde & Argyll, Lewis, Donegal Bay, Mayo, Galway Bay, Fastnet, Cork.