Urosome segments 1 to 3 only very slightly raised dorsally, with small groups of slender dorsal spines and only an occasional small seta. Epimeral plates 2 and 3 subquadrate, posterior margin about straight with a few small setules. Head with the lateral lobes broadly rounded, post-antennal sinus deep; eyes slender and elongate kidney-shaped. Antenna 1 much longer than antenna 2, peduncle sparsely setose; accessory flagellum equal to the length of peduncle article 2, and 5 to 7-articulate. Antenna 2 peduncle and flagellum moderately setose, calceoli absent. Mandible palp article 1 devoid of setae, article 3 with one setal group on the outer surface, ventral setae comb-like, not graduated. Male gnathopod 1 propodus narrowly oval, palm weakly convex, median palmar spine well separated from the angle spines, proximal posterior margin with three or four setal groups. Male gnathopod 2 propodus much broader than in gnathopod 1 and the palm less strongly oblique, palm almost straight with the median spine well separated from the graduated row of angle spines. Female gnathopod 1 propodus oval, palm convex; gnathopod 2 propodus rectangular, palm transverse. Pereiopods 3 and 4 slender, spinose and sparsely setose. Pereiopods 5 to 7 basis with the posterodistal angle freely produced, posterior margin with several small setules; merus, carpus and propodus strongly spinose, with few setae, some setae a little longer than the associated spines. Male uropod 3 inner ramus about one-third to one-half of the length of the outer ramus, article 2 of the outer ramus absent; outer ramus with marginal and apical spines and dense setae, few of the inner-marginal setae plumose. Female uropod generally similar to the male one, except spines more elongate and setae less dense. Telson with each lobe with three apical spines and a few short setae, and three lateral spines.
Up to 20 mm in male, female smaller.
Pale brown or yellow.
Intertidal, typically around mid-tide level; often found in tide pools, has a limited tolerance of reduced salinity.
North Atlantic, American and European coasts. Widely recorded on European coasts from north Norway and Iceland to western English Channel.