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 cateniilaria (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 

 halysis, 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 ? 



