PLATE XVI. 



From the Gaiilt. 



Fig. 1 a. PsEUDODiADEMA WiLTSHiRii, Wright, natural size, belonging to the Rev. T. 

 Wiltshire, F.G.S. (P. 94.) 



1 h. Lateral view of the same test, magnified one half. 



1 c. Ambulacra, zones, and interambulacra, magnified four times. 



1 r/, e. Primary tubercle, magnified six times. 



1/. Portion of a spine, magnified six times. 

 Pig. 2. Spine magnified. 

 Pig. 3. Do., natural size. 



From the Grey Chalk. 



Fig. 4 a. PsEUDODiADEMA ORNATUM, GolcJfuss, sp.. Upper surface, magnified one half, 

 belonging to the British Museum. (P. 103.) 



4 b. Under surface of the same, magnified one half. 



4 c. Lateral vieAv of the same, do. do. 



4 d. Ambulacral area, interambulacra! area, and pores, magnified four tmies. 



4 e. Miliary zone and upper portion of an ambulacrum, do. do. 



