PLATE XIX. 



From the Grey Chalk. 



Fig. 1 a. PsEUDODiADEMA ORNATUM, Gold/uss. Test, natural size, in the cabinet of 

 Dr. Wright, F.R.S.E. (P. 103.) 



1 h. Same test restored and magnified half a diameter, showing the base. 



1 c. Lateral view of do. do., do. 



1 d. Portion of the ambulacra, inter-arabnlacra, and zones, magnified four times. 



1 e. Inter-ambulacra, plate, and tubercle, magnified six times. 



From the Tipper Greensand. 



Fig. 2 a. PsEUDODiADEMA MiCHELiNi, Agassiz. Upper surface, magnified one half. 

 In the cabinet of Dr. Wright, F.R.S.E. (P. 99.) 



2 b. Under surface of the same test, do. Do. 

 2 c. Lateral view of do., do. Do. 

 2 d. Portion of ambulacra, inter-ambulacra, and pores, magnified four times. 

 2 e. Do. magnified four times. 



2 /. Base of the ambulacra, do. 



