"Section through an early embryo of Limulus longispina, showing seven transverse divisions in the region of the unsegmented anterior carapace. The seventh, VII, is anterior to the genital operculum, op, and is the cavity of the praegenital somite which is more or less completely suppressed in subsequent development." — The Encyclopedia Britannica, 1910

Limulus Longispina

"Section through an early embryo of Limulus longispina, showing seven transverse divisions in the region…