l8o AN INTRODUCTION TO THE STUDY OF FOSSILS 



or primary, cup (protoecium) secreted by the sexually produced 

 zooid budded off two cups ; each of these gave rise to others. 

 Continued budding produced the mature colony. 



Fig. 72. — Fenestella filistriata Ulrich, from the Burlington limestone (Mississippian) 

 of Iowa. A , inner surface of a colony showing the two rows of zooecia. B, outer 

 surface of a colony ; note absence of zooecia. Each X 6. (After Ulrich.) 



1. Sketch the upper side of a portion of a colony ; indicate the 

 zooecia, median ridge, cross bars. 



2. Sketch in outline the probable shape of the entire colony. 



3. Outline its development. 



4. What is the significance of the name ? 



Order b, Phyladolcemata 



Fresh-water inhabitants ; lophophore horseshoe-shaped ; 

 an epistome overhangs the mouth (whence the name from Greek 

 phylassein, to guard, -{- laimos, the gullet). Unknown in the 

 fossil state, with the possible exception of Plumatellites from 

 the Cretaceous of Bohemia. 



