240 RELICS OF PRIMEVAL LIFE 



of sarcode on the surface of the wall, as may be 

 seen in similar structures in modern Foraminifera. 

 In this specimen the canals are beautifully smooth 

 and c}'lindrical, but they sometimes present a 

 knotted or jointed appearance, especially in speci- 

 mens decalcified by acids, in which perhaps some 

 erosion has taken place. They are also occasionally 

 fringed with minute crystals, especially in those 

 specimens in which the calcite has been partially 

 replaced with other minerals. Fig. 3 shows an 

 example of faulting of the proper wall, an appear- 

 ance not infrequently observed ; and it also shows a 

 vein of chrysotile crossing the line of fault, and not 

 itself affected by it — a clear evidence of its posterior 

 origin. Figs. 4 and 5 are examples of specimens 

 having the canals filled with dolomite, and showing 

 extremely fine canals in the interstices of the others: 

 an appearance observed only in the thicker parts of 

 the skeleton, and when these are very well pre- 

 served. These dolomitized portions require some 

 precautions for their observation, either in slices or 

 decalcified specimens, but when properly managed 

 they show the structures in very great perfection. 

 The specimen in Fig. 5 is from an abnormally thick 

 portion of intermediate skeleton, having unusually 



