Fig. 2. Calveria hystrix. Wyville Thomson, two-thirds the natural size. 

 (From p. 156, fig. 27.) 



Fio. 3. Calveria ~hystrix, Wyville Thomson. 



Inner surface of a portion of the test showing the structure of the ambulacral and 



inter-amhulacral areas. (From p. 157, fig. 28.) 



