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"Diagram of the dorsal surface of Limulus polyphemus. oc, Lateral compound eyes. oc', Central monomeniscous eyes. PA, Post-anal spine. I to VI, The six appendage-bearing somites of the prosoma. VII, Usually considered to be the tergum of the genital somite, but suggested by Pocock to be that of the otherwise suppressed praegenital somite. VIII to XIII, The six somites of the mesosoma, each with a movable pleural spine and a pair of dorsal entopophysis or muscle-attaching ingrowths. XIV to XVIII, The confluent or unexpressed six somites of the metasoma." — The Encyclopedia Britannica, 1910

Limulus Polyphemus

"Diagram of the dorsal surface of Limulus polyphemus. oc, Lateral compound eyes. oc', Central monomeniscous…

"Ventral view of the posterior carapace or meso-metasomatic (opisthosomatic) fusion of Limulus polyphemus. The soft integument and limbs of the mesosoma have been removed as well as all the viscera and muscles, so that the inner surface of the terga of these somites with their entopophyses are seen. The unsegmented dense chitinous sternal plate of the metasoma (XIII to XVIII) is not removed." — The Encyclopedia Britannica, 1910

Limulus Polyphemus

"Ventral view of the posterior carapace or meso-metasomatic (opisthosomatic) fusion of Limulus polyphemus.…