III. Preliminary note upon the brain and skull of Amphioxus lanceolatus

The singular little fish Amphioxus lanceolatus has been universally regarded as an extremely anomalous member of the Vertebrate series, by reason of the supposed absence of renal organs and of any proper skull and brain. On these grounds, chiefly, Agassiz proposed to separate it from all other fishes, and Haeckel, going further, made a distinct division of the Vertebrata (Acrania) for its reception; while Semper, in a lately published paper, separates it from the Vertebrata altogether.