DEVELOPMENT OF PALEOZOIC PORIFEROUS CORAL 427 



ceeded in producing a corallite ; whereas the other attempts 

 at budding resulted no further than the production of mural 

 pores. The conclusion to be drawn is that the mural pores 

 in such genera as Favosites, Striatopora, Pleurodictyum, 

 Michelinia, etc., are ineffectual attempts at budding, result- 

 ing only in the perforation of the cell walls. This explana- 

 tion agrees with the pronounced and persistent tendency to 

 gemmation characteristic of the genera mentioned. They also 

 represent compound forms having individualized epithecas, 

 and this feature naturally arises from the same system of 

 budding obtaining in the simple corals. 



Professor Verrill has shown that the presence or absence 

 of tabulae is of little or no importance in a natural classifica- 

 tion.* Therefore the non-tabulate feature of P. lenticulare 

 is without special consequence in a discussion of the rela- 

 tions of this species with Favosites, or other tabulate porifer- 

 ous genera. 



If the preceding interpretations of structure and affinity 

 are correct, a simple, conical imperforate, non-tabulate proto- 

 type, or protocorallum, may be assumed for the Madreporaria 

 Perforata. The next derived form, represented by the early 

 neanic stages of P. lenticulare, has the structure and growth 

 of Aulopora, and consists of the parent cell with one or more 

 buds. At this stage, which may be called the Aulopora 

 stage, the initial corallite has the same number of mural pores 

 as developed buds, for each bud leads into the parent cell by 

 a basal opening or pore. Aulopora may thus be considered 

 as representing a primitive type of a poriferous coral, in 

 which the number of pores in each corallite corresponds to 

 the number of buds given off plus one connecting it with the 

 parent cell. Some species of this genus are free throughout 

 most of their growth (A. subtenuis Hall), agreeing closely 

 with the erect growth of Romingeria and Syringopora. This 

 fact removes one of the important arguments against the 

 relations of Aulopora with these genera. The corallites of 

 Aulopora usually send off buds before turning out of the 



* Amer. Jour. Sci. (3), III, 287, March, 1872. 



