THE DAWN OF LIFE 



127 



the deeper parts of the ocean. If in connection with this we 

 consider the rapidity with which the soft, simple, and almost 

 structureless sarcode of these Protozoa can be built up, and 

 the probability that they were more abundantly supplied with 

 food, both for nourishing their soft parts and skeletons, than 

 any similar creatures in later times, we can readily understand 

 the great volume and extent of the Laurentian limestones 

 which they aided in producing. I say aided in producing, 

 because I would not care to commit myself to the doctrine 

 that the Laurentian limestones are wholly of this origin. 

 There may have been other limestone builders than Eozoon, 



FIG. II. Section of a Nummulite, from Eocene Limestone of Syria. 

 S'howing chambers, tubnli, and canals. Compare this and Fig. 12 with Fig. 

 7 and Nature-print of Eozoon. 



and there may have been limestones formed by plants like the 

 modern Nullipores, or by merely mineral deposition. 



Its relations to modern animals of its type have been very 

 clearly defined by Dr. Carpenter. In the structure of its 

 proper wall and its fine parallel perforations, it resembles the 

 Nummulites and their allies ; and the organism may therefore 

 be regarded as an aberrant member of the Nummuline group, 

 which affords some of the largest and most widely distributed 

 of the fossil Foraminifera. This resemblance may be seen in 

 Fig. ii. To the Nummulites it also conforms in its tendency 

 to form a supplemental or intermediate skeleton with canals, 



