Lacalli: 1995If the link doesn't work, try Amphioxus PDFs .
Antecedents of Vertebrate Eye and Brain: Evidence from serial EM studies of amphioxus larvae.
No electronic link available and so far no hard copy.
Int J Dev Biol. 2000 Dec;44(8):903-6.PMID: 11206331
Cell morphology in amphioxus nerve cord may reflect the time course of cell differentiation.