a: 
b. 
PLATE XII. 
MerTopASTER ParkINsoNi, Forbes, sp. (Page 31.) 
From the Upper Chalk. 
Abactinal aspect; natural size. (Coll. Brit. Mus.) 
Lateral view of the margin; natural size. 
A supero-marginal plate ; magnified. 
. The madreporiform body ; magnified. 
e. Abactinal intermediate plates; magnified. 
oa. 
Mevopaster zonatus, Sladen. (Page 45.) 
From the Upper Chalk. 
. Abactinal aspect; natural size. (Coll. Brit. Mus.) 
. Lateral view of the margin; natural size. 
The madreporiform body ; magnified. 
Mitraster Hunteri, Forbes, sp. (Page 59.) 
From the Upper Chalk. 
Actinal aspect ; natural size. (Coll. Brit. Mus.) 
Lateral view of the margin; natural size. 
A supero-marginal plate ; magnified. 
. An infero-marginal plate ; magnified. 
. Actinal intermediate plates ; magnified. 
CaLLIDERMA MosatcuM, Forbes, sp. (Page 9.) 
From the Lower Chalk. 
. Actinal aspect ; natural size. (Coll. Brit. Mus.) 
. Lateral view of the margin ; natural size. 
. Mouth-plates ; magnified. 
. An infero-marginal plate ; magnified. 
