PLATE IX. 
PyoNASTER ANGUSTATUS, Forbes, sp. (Page 21.) 
From the Upper Chalk. 
. Abactinal aspect; natural size. (Coll. Brit. Mus.) 
. Lateral view of the margin ; natural size. 
Metopaster Parxkinsont, Forbes, sp. (Page 31.) 
From the Upper Chalk. 
. Actinal aspect; natural size. (Coll. Brit. Mus.) 
. Lateral view of the margin ; natural size. 
An infero-marginal plate ; magnified. 
Mirraster Hunreri, Forbes, sp. (Page 59.) 
From the Upper Chall. 
,. Abactinal aspect of a small example with four supero-marginal plates; 
natural size. (Coll. Brit. Mus.) 
. Actinal aspect of the same ; natural size. 
Lateral view of the margin; natural size. 
. A supero-marginal plate; magnified. 
. An infero-marginal plate ; magnified. 
