138 AN INTRODUCTION TO THE STUDY OF FOSSILS 



corallites is a small tube. Budding occurs only from one side, 

 and the young corallites remain in contact with the parent by 



Fig. 54. — ■ The chain-coral, Halysites catenularia (Linne) from the Niagara (Middle 

 Silurian) of New Jersey. A, top view of a portion of a colony, natural size; 



B, longitudinal section ( X 5) showing two individuals {cor.) with their slightly con- 

 cave tabulae (/.), and the small connecting tubes {con.) with their very convex tabulae. 



C, transverse section through the same showing the septa-like spines {sp.) and 

 within the small connecting tubes a section of the highly arched tabulae (/.). 

 (After Weller.) 



a constricted edge, thus forming chains, in which each corallite 

 is a link (whence the common name, " chain-coral," from Greek 

 Italy sis, chain). 



1. Sketch an inch square portion of colony, (a) top view, 

 (b) side view. For side view polish corallites to show tabulae. 

 Label corallites, tabulae. 



2. How did the colony increase in size ? 



3. Account for the chain formation. 



4. What is the significance of the name ? 



5. Did each individual animal possess a separate digestive 

 system or did it share a common one with others ? 



