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Bull. U. S. B. F., 1924. (Doc. 968.) 
Fig. 42. — Segments of the branchial sieves of three common fishes that feed on plankton, a. Menhaden, Brevoortia 
tyrannus; b, herring, Clupea liarengus; c, mackerel, Scomber scombrus; d, mackerel, side view of gill raker, with 
gill spines. X 25 
