limulus

Patten considers the Pteraspids as derived from primitive arachnid or spider-like forms having a bony carapace as Limulus has.

It is especially significant that in Limulus they are already partially degenerated.

Fortunately, there is still alive on the earth one member of this remarkable group—the Limulus, or King-Crab.

Limulus, like other water-dwelling arthropods, breathes by means of gills attached to its appendages.

Lankester and Bourne have divided the eyes of scorpions and Limulus into two kinds, monostichous and diplostichous.