208 C. E. Beecher — Developmoit of a Paleozoic Poriferous Coral. 



aperture of the corallite. The apical portion is smooth for about 

 one-fourth the length of the cell. Then the concentric lines of 

 growth become apparent, and over the distal half, radiating ribs are 

 also developed. The interior of the apex is granulose. At about 

 the middle of the cell, the granules are arranged in rows, forming 

 the beginnings of the septal lines. 



The simple growth of the initial cell continues until the entire 

 procumbent portion is completed. A thickening of the margin then 

 takes place, and an upward growth of the corallite is initiated. At 

 the commencement of this upward growth, the first bud starts out 

 from the lateral edge of the initial calyx, either to the right or left 

 of the axis. This condition represents the first nealogic stage. The 

 bud resembles the parent cell in all particulars, and reaches consider- 

 able size before the second appears, as shown in Plate IX, figures 9, 10. 

 The visceral cavities are confluent, as the initial apex of the bud 

 opens into the calyx of the first cell. 



The succeeding nealogic stages, to the completion of the first 

 circle of peripheral calices, have been observed mainly from the 

 epithecas of mature or nearly full grown corallums, rejjresented on 

 Plate X, figures 1, 2. In these examples, the lines of growth are so 

 perfectly shown, that all the stages are distinctly marked, and may 

 be satisfactorily studied. 



What is here considered as the second nealogic stage is repre- 

 sented on Plate IX, figure 3, showing the initial corallite, with the 

 fii'st and second buds on opposite sides. This process of alternate 

 gemmation from the parent cell continues until the circlet of calices 

 is completed, as shown in figures 4, 5, and 6. In this species, the 

 normal number of peripheral calices is seven, making eight corallites 

 in the completed nealogic corallum. The last cells to be formed are 

 (1) the sixth and seventh budding from the anterior side of the first 

 calyx, and (2) the eighth or posterior cell. Plate IX, figure 12, repre- 

 sents the completed nealogic corallum, with the initial cell and six 

 well developed peripheral calices. The eighth has just begun to 

 fill up the space between the second and third. It will be noticed 

 that there is a direct correspondence in the size of the calices to 

 their relative age. The first calyx is much the largest. Then, de- 

 creasing serially, come the second, third, fourth, fifth, sixth, and 

 seventh, while the eighth is undeveloped. An inspection of the 

 upper surface of a mature corallum will thus usually determine the 

 order of successive calical additions. After the ajjpearance of the 

 posterior, or eighth calyx, the corallum commonly grows to double 



