PLATE XII. 



Hemipedinas from the Great Oolite, Coral Rag, and Kimmeridge Clay. 



Fig. 



1 a. Hemipedina Corallina, Wright, p. 163. Portion of the base and jaws in situ. 

 h. Fragment, with plates and spines, from the Coral Rag, Wilts. 



c. One inter-ambulacral plate, magnified three times. 



d. A primary spine, from fragment b, magnified three times. 



2 a. Hemipedina Morrisii, Wright, p. 166. A fragment of the test, natural size. 



h. Ambulacral area, poriferous zones, and inter-ambulacral plates, magnified four 



times. 

 c. A primary spine, magnified four times. 



3 a. Hemipedina Cunningtoni, Wright, p. 167. A fragment of the test, natural size. 

 h. The same, magnified four times. 



4 a. Hemipedina micrograbima, Wright, p. 159. Upper surface of the test, natural size. 

 h. A lateral view of the test, natural size. 



c. One inter-ambulacral plate, a portion of the ambulacra, and poriferous zones, magnified 

 four diameters. 

 4.* CiDARis spiNOSA, Agassiz, p. 53. Spine, natural size. 



5 a. CiDARis Boloniensis, Wright, p. 53. A flattened spine with prickly ridges. 

 b. A spine with thorny prickles, resembling C. sjnnosa. 



6 a. Hemipedina Davidsoni, Wright, p. 156. A lateral view of the test, natural size. 



b. The upper surface of the test, natural size. 



c. The under surface of the test, natural size. 



d. One inter-ambulacral plate, a portion of the ambulacra, and poriferous zones; 



magnified six diameters. 



7 a. Hemipedina WooDWARDi, Wright, p. 158. A lateral view of the test, magnified 



twice. 



b. Upper surface of the test, magnified twice. 



c. Under surface of the test, magnified twice. 



d. One inter-ambulacral plate, ambulacra, and poriferous zones, magnified six times. 



8. PsEUDODiADEMA MAMMiLLANUM, Boemer, p. 133. Primary spine, magnified three 



times. 



9. PsEUDODiADEMA VERSiPORA, FhilU^s, p. 124, Primary spine, magnified three times, 



10. Rabdocidaris MAXIMA, MUnster, p. 65. Primary spine, natural size. 



