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- 



1 quarter inch wide by three-eighths inch 



%>. high. 





M^ Madrepora (Fig. 51) Tertiary to present. 



^ Coral compound, branching, with small, 



tube-shaped corallites embedded in abun- 

 minal portion of a dant vcsicular coenenchyme. Each cor- 

 branch of a madre- ahjte has from six to twelve septa, which 



pore coral. The in- . r ^i j 1 j ^u 



divadual polyp at the are sometimes imperfectly developed. 1 he 

 tip was the largest, corallites terminating each branch are 



cor., corallites, each 



occupied during the the largest. (Name from Latin mater, 

 life of the colony by mother, + porus, a pore, — i.e. a light, 



a separate individ- . . , , x 



ual polyp. (xi|.) friable Stone.) 



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

 two times. Label corallites, septa, coenenchyme. 



2. How w^as 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 ? 



