348 



Tig- I 



Fig. * 



EXPLANATION OF THE FIGURES. 



Figure 1 shows the form and arrangement of the plastral elements (reduced in 



size) of an adult Trionyx spinifer, epi., epiplastron; ento., entoplastron ; hyo., 



hyoplastron; hypo., hypoplastron ; xiph., xiphiplastron. 

 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. 



