(J. E. Beecher — iJevelopment of a Paleozoic Poriferous Coral. 211 



of the corallites, the non-development of the buds consequent upon 

 the adjacent living corallites would naturally result in the produc- 

 tion of mural pores. The basal epitheca limits the fleshy portion of 

 the organisms, and represents an area unfavorable to the acquisition 

 of food or for the natural development of calices. Therefore, it 

 would prevent both tlie maintenance of mural pores and the growth 

 of basal buds.* 



A Favosites in which one or more cells became inactive or dead 

 shows in its subsequent growth the closing over of this area by the 

 budding of the surrounding cells. Each cell is connected with the 

 parent by an apical pore, Plate XIII, figures 3, 4. Without this 

 opportunity to bud afforded by the death of one or more corallites, or 

 by their divergence, the adjacent cells would have developed only 

 mural pores. In the figure of P. problematicwn given on Plate XIII, 

 figure 2, three of the initial poi'es are indicated by dotted lines from 

 23. No distinction can be made between these and the ordinary pores, 

 except that the latter are usually not as large. Tliis difference in 

 size would be expected, as the primary pore represents the bud which 

 succeeded 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 ineffec- 

 tual attempts at budding, resulting only in the perforation of the 

 cell walls. This explanation agrees with the pronounced and per- 

 sistent tendency to gemmation characteristic of the genera men- 

 tioned. 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 classification.! Therefore, 

 the non-tabulate feature of P. lenticulare is without special conse- 

 quence in a discussion of the relations of this species with Favosites, 

 or other tabulate poriferous genera. 



* The presence of basal mural pores or openings through the epitheca has been 

 asserted by Meek and Worthen (Pal. Illinois, vol. iii, p. 409, 1868). The specimens 

 from which this observation was made, are from a friable sandstone, which does not 

 usually preserve minute details with much distinctness. The depressions between 

 the spinules on the septal lines could easily be mistaken in a cast for the filliugs of 

 mural pores, and it is believed by the writer, that this interpretation should be 

 given. P. lenticulare occurs as calcareous or silicified, and in the condition of casts. 

 No basal mural pores are present. Also, none can be observed in the casts of P. 

 pvohlemalicum, from Pelm, Germany. 



f Am. Jour. Sci., vol. iii, p. 187, March, 1872, 



