Fig. 69.—Comparison of Branchial Lamellæ of Limulus and Scorpio with Branchial Lamellæ of Ammocœtes. A, Branchial lamellæ of Scorpio (after Macleod); B, Branchial lamellæ of Ammocœtes (after Nestler). (All references in this work to "Ammocœtes" or "Petromyzon" appear to refer to the European Brook Lamprey, now called "Lampetra planeri".)