DERMATODIADEMA HORRIDUM. 



71 



7 3 mm. 

 FlO. 117. D. UclliKIDUM. 



advanced stages of growth (Pis. 26, fig. t ; 28, fig. /; 29, figs. 3, 4)- In a 

 young specimen of 7.o mm.. Fig. 117, the primordial plates have been 

 resorbed, and the first pair of interambulacral plates are in contact with 

 the actinal system. There are twelve to thirteen ambulacra! plates, six 



10.5 mm. 

 FlO. US. D. HORRIDUM. 



