PLA.TE XXXVII. 



Froijc the Lower Grey Chalk. 



Fig. 1 a. SajJ'INIa Ai'stem, Forbes. Test, natural size. British Museum. 



,, ,, Under surface, showing peristome magnified two 



diameters. 

 ,, ., Upper surface, showing disc magnified two dia- 



meters. 

 ,, ,, Lateral view, showing periprocte magnified two 



diameters. 

 „ Inter-ambulacra, entire, magnified four diameters. 



,, „ Ambulacra, do.,. do. do. 



Single plate of ambulacra, do. si.x do. 



,, ,, Single tubercle in profile, do. do. 



,, ,, Apical disc detached, do. four do. 



„ ,, Test, natural size, do. do.. Royal 



School of Mines. 



