Under surface of horseshoe-crab, Limulus polyphemus:. a, abdomen; c, cephalothorax; g, the first gill-bearing abdominal appendage; m, mouth; o, operculum; p, telson; s, metasfoma; 1-6, cephalothoracic limbs
A monograph of the British fossil Crustacea,.
London,Printed for the Palæontographical Society,1866-78..
biodiversitylibrary.org/page/37092624
Yesterday was #NationalFossilDay! See Horseshoe Crab, a living #fossil which has changed little in 445MM yrs, in #bhlib biodiversitylibrary.org/page/37092624