• Limulus is commonly known as king-crab.

• Body consists of anterior prosoma and a posterior opisthosoma terminating in a long spike-like telson.

• Prosoma is covered by an unsegmented, semi-circular, or horse-shoe-shaped carapace.

• Prosoma is convex above with sloping sides and bears three longitudinal ridges one median and two laterals.

• A pair of simple median eyes and a pair of lateral compound eyes are placed on the dorsal surface of prosoma.