Figure 3. — Development of the egg of the Pacific mackerel, Scomber japonlcus (= Pneumatophorus diego ): a, 

 h, and c^, early embryonic development, c being the early stage immediately before blastopore closure; d, 

 middle-stage, just after blastopore closure; e, middle-stage, dorsal view of head and pectoral region, tail 

 separated from yolk-sac; f, late-stage, tail reaching to head; g, same as f, viewed from opposite pole 

 (adapted from drawing of Mattson, fig. 1 of Kramer, 1960). 



Figure 4. — Late-stage egg and yolk-sac larvae of the Pacific mackerel. Scomber japonlcus (= Pneu- 

 matophorus diego): a, egg immediately before hatching; b, yolk-sac larva, 3.3 mm. long, just 

 after hatching; c, yolk sac larva, 3.5 mm. long, with yolk about two-thirds absorbed (adapted 

 from drawing by Mattson, fig. 2 of Kramer, I960). 



