136 AN INTRODUCTION TO THE STUDY OF FOSSILS 



Medusa, turned all beholders to stone). During the life of 

 the colony a polyp occupied the position of each minute 

 prominence. 



1. Sketch (a) entire colony in outline, (b) a small portion 

 enlarged four times. Note position occupied during life by an 

 individual polyp. 



2. How was the horny axis produced? the calcareous coat- 

 ing? 



3. What in general is the food of Gorgonia ? 



Super-order b, Tabulata 



Composite corals ; walls of corallites, thick, separate. Septa 

 poorly developed or absent. No dissepiments present. Tabulae 



numerous (whence the name from Latin 

 tabulatiis, furnished with tabulcB, — 

 tables). These occur mostly in the 

 Paleozoic, a few only in the Mesozoic. 



Aulopora (Fig. 52). 



Ordovician to Mississippi an. 

 Coral very loosely compound ; all 

 corallites tube-like (whence the name 

 from Greek aulos, pipe, + poros, a pore). 

 Corallites attached to a foreign object 

 by nearly their whole length. Colony 

 produced by submarginal budding. 



Fig. 52. — Aulopora re pens 

 Knorr and Walch. Nat- 

 ural size. A branching 

 coral growing upon a 

 brachiopod shell, from 

 the Jennings formation 

 (Upper Devonian) of 

 Maryland, cor., coral- 

 lites. (From Clarke and 

 Swartz.) 



I. Sketch colony, notmg corallites. 



2. Outline a polyp in place upon sketch. 



3. How did the colony increase in size? 



Favosites (Fig. 53). Ordovician to Mississippian. 



Coral closely compound, with the corallites in contact but with 

 separate walls. Corallites prism-shaped (whence the common 

 name '' honey-comb coral " from Latin favtis, honeycomb). 

 Walls perforated by equidistant pores believed to represent 



