DESIGN IN THE ORGANIC WORLD. 



451 



Fig. V. 



Diagram illustrating the Pedigree of the Complex type of Orbitolite, 



Simple undivided Spire of Coniuspii-a. 

 Partially interrupted Spire of Spiroloculina. 

 Spire of Peneroplis, divided by partitions into chambers. 

 Spire of Orbkiilina, its chambers divided into rows of chamberlets. 

 Disk of "simple" Orbitolite, showing first-formed spire, surrounded by 

 concentric rings. 



6. Disk of "duplex" Orbitolite, showing earlier passage from spiral to 

 cyclical plan of growth. 



7. Central portion of Disk of "complex" Orbitolite, in which the cham- 

 bered nucleus alone shows an abbreviated spire, the very first row of chamber- 

 lets forming a complete ring. 



I. 



2. 



3- 



4- 

 5- 



