348 
Fig. 2 
EXPLANATION OF THE FIGURES. 
Figure 1 shows the form and arrangement of the plastral elements (reduced in 
size) of an adult Trionyax spinifer, epi., epiplastron; ento., entoplastron; hyo., 
hyoplastron; hypo., hypoplastron; xiph., wviphiplastron. 
Figure 2 is a graphic reproduction, magnified ten times, of the plastral elements in 
embryo Trionyx spinifer with a carapace length of 14 mm. umb., umbilicus; 
ent., paired entoplastra. 
