PLATE XV. 



From the Loioe.r Greensand. 



Fig. 1 a. PsEUDODiADEMA FiTTONii, Wriffht, test natural size, cabinet of Dr. Wright, 

 F.R.S.E. (P. 90.) 



1 fj. Upper surface magnified one half. 



1 c. Under surface do. do. 



1 rJ. Lateral view do. do. 



1 r. Ambulacra, poriferous zones, and interambulacra, magnified four times. 



1 /. Portion of an ambulacra, magnified four times. 



1 ,y. One tubercle and pores, magnified six times. 



Frow the JJpjier Greensand. 



Fig. 2 a. PsEUDODiADEMA Benetti^, Forfjes, magnified one half, British Museum, and 

 cabinet of Dr. Wright, F.R.S.E. (P. 101.) 



2 fj. Upper surface of the same test do. do. 



3 c. Latei'al view of do. do. do. 



2 d. Ambulacra, zones, and interambulacra, magnified four times. 

 2 p. Ambulacra seen in profile do. do. 



2/. Inter-ambulacral plate and tubercle, magnified six times. 



