DEVELOPMENT OF PALEOZOIC PORIFEROUS CORAL 425 



central position, and forms the boss or apex of the basal 

 epitheca. The first bud is nearly on a plane with the base of 

 the initial cell, and is the one nearest the apex. The second 

 and successive buds are respectively more distant and at a 

 higher level. Specimens having broad surfaces of attach- 

 ment to foreign objects have these distinctive features of the 

 epitheca obliterated, and the only guide to the order of the 

 corallites then lies in their comparative size and position on 

 the upper surface of the corallum. 



General Conclusions. 



The first feature to be noted in the development of a 

 poriferous coral, as here described, is the simple cyathiform 

 character of the initial corallite. This nepionic stage is 

 without mural pores, and has an epitheca over the entire 

 exterior of the cup. The septal lines become developed 

 toward the end of this stage. These features are in harmony 

 with the young of many Paleozoic corals, such as Cladochonus, 

 Aulopora, or Syringopora, and clearly indicate a primitive, 

 simple, and imperforate ancestry for the Perforata. A simi- 

 lar origin and development obtains in Favosites, as may be 

 seen from the figure of a young colony of F. Forlesi, var. 

 occidentalis^ given by Professor Hall.* 



The first neanic stage, represented by the primitive coral- 

 lite with one bud, is the first transition toward both a com- 

 pound and a perforate coral (Plate XXVII, figure 9). This 

 stage has two calices making it a compound coral, and has 

 an opening through the cell walls or connecting channel 

 between the corallites, forming the first mural pore. The 

 manner of growth and the structure of the corallum at this 

 stage are suggestive of Aulopora, and should be given con- 

 siderable significance. The visceral cavities in Aulopora are 

 confluent, and rudimentary septa or lines of spinules are 

 often present. Romingeria has a growth resembling Aulo- 



* Indiana Geol. and Nat. Hist., llth Rept. of the State Geologist, pi. i, fig. 12, 

 1881. 



