Chapter 32 THE CLASS OSTRACOPHORI[152]

Ostracophores.-Among the earliest vertebrates actually recognized as fossils belongs the group known as Ostracophori (?στρακο?, a box; φορ?ω, to bear). These are most extraordinary creatures, jawless, apparently limbless, and enveloped in most cases anteriorly in a coat of mail. In typical forms the head is very broad, bony, and horseshoe-shaped, a