Terminology applied to the carapace and chela of the first pair of pereiopods. A: grooves, ornamentation and structures commonly found in erymid lobsters; B: regions of the carapace; C: morphology of a chela of the first pair of pereiopods. Abbreviations: a: branchiocardiac groove; an-r: antennal row; ar: antennal region; as: antennal spine; b: antennal groove; b₁: hepatic groove; br: branchial region; c: postcervical groove; c_ve: ventral extension of the postcervical groove; cr: cardiac region; d: gastro- orbital groove; e₁e: cervical groove; gr: gastric region; hr: hepatic region; i: inferior groove; ip: intercalated plate; on: orbital notch; or-r: orbital row; os: orbital spine; PoA: post-orbital area; pr: pterygostomial region; χ: attachment site of adductor testis muscle; ω: attachement site of mandibular muscle. Line drawings: J. Devillez.