Fig. 1 



Fig. 2 



EXPI.AXATION OK FIGURES 



Figure 1. P. amerieanus at hatching (3.5 x 0.525 ram.). 



Figure 2. P. amerieanus at twelve days (5.0 x0.724 mm.), 



Figure 3. P. amerieanus at six weeks (5.8 x 1.33 mm.). 



Figure 4. P. amerieanus at eight weeks (6.5 x 2.75 mm.). 



