134 AN INTRODUCTION TO THE STUDY OF FOSSILS 





sess no hard skeleton, either in adult state or at any time 

 during their development. They are not known in the fossil 



state. The brown sea anemone {Metri- 

 dium marginatum) extends from New Jersey 

 to Labrador ; a large specimen measures 

 3 inches wide by 4 inches high. The 

 orange-streaked anemone {Sagartia lucice), 

 especially abundant from New Jersey to 

 Massachusetts, is marked by twelve longi- 

 tudinal orange streaks. It is about one- 

 quarter inch wide by three-eighths inch 



high. 



Madrepora (Fig. 51) Tertiary to present. 



Coral compound, branching, with small, 

 tube-shaped corallites embedded in abun- 

 dant vesicular coenenchyme. Each cor- 

 allite has from six to twelve septa, which 

 are sometimes imperfectly developed. The 

 corallites terminating each branch are 

 the largest. (Name from Latin mater, 

 mother, + porus, a pore, — i.e. a light, 

 friable stone.) 



Fig. 51. — The ter- 

 minal portion of a 

 branch of a madre- 

 pore coral. The in- 

 dividual polyp at the 

 tip was the largest. 

 cor., corallites, each 

 occupied during the 

 life of the colony by 

 a separate individ- 

 ual polyp. ( X i|.) 



1. Sketch five or six corallites at the tip of a branch, enlarging 

 two times. Label corallites, septa, coenenchyme. 



2. How was the coenenchyme produced ? 



3. Account for the branching of Madrepora. 



4. Outline a single polyp in place upon the above sketch. 



5. How does Madrepora aid in the formation of coral reefs ? 



