"Anterior end of body of Branchiostoma. d, chorda dorsalis; e, spinal cord; f, cartilaginous rods; g, eye; h, branchial rods; i, labial cartilage; k, oral cirrhi." — Encyclopedia Britannica, 1893

Brachiostoma

"Anterior end of body of Branchiostoma. d, chorda dorsalis; e, spinal cord; f, cartilaginous rods; g,…