DEVELOPMENT OF CALLOPORA 363 



figures 16 and 38. These sections cut at about the same level as the 

 section of Peronopora (figure 14) and present a very similar appearance. 



THE PRIMARY BUDS 



The lateral and median buds are shown in figure 8. Some sections 

 indicate that the median bud sometimes failed to develop. Tliis I be- 

 lieve to be the case in figure 16. The lateral buds were attached to the 

 under side of the neck of the ancestrula, as in the recent Cyclostomata 

 (cf. figure 30), and at once diverged rather widely from the ancestrula 

 and from each other — that is, the radial arrangement of the zooecia, 

 seen in cross-sections of the stems of Callopora, is very quickly attained 

 (figure 38). The posterior wall of the ancestrula and primary buds lias 

 the same appearance and structure as in the case of Prasopora and 

 undoubtedly for the same reason. 



The section shown in figure 17 is from a specimen which coidd not be 

 definitely referred to any genus, owing to the fact that the mature por- 

 tion of the zoarium had been entirely broken away. It was a small 

 ramose form, with rounded zooecia, diaphragms, and mesopores, found 

 associated with Prasopora and Phylloporina corticosa at Cannon Falls, 

 Minnesota. It is interesting in the fact that no buds whatever are in 

 contact with the posterior portion of the ancestrula, and also in the fact 

 that evidently four buds rather than three issued from the ancestrula. 



Developmicnt of Phylloporina corticosa 



The initial stages of this species are so nearly identical with those of 

 Prasopora that they do not need extended description. A comparison of 

 figures 29 and 25 will satisfy any one of this. The protoecium is large, 

 and beautifully shown in figure 29 (see also figure 18), which is drawn 

 with the utmost possible fidelity to the original section. The ancestrula 

 and primary buds are all very prone, more so than in any other form 

 studied. The arrangement of the primary and secondary buds is the 

 same, point by point, as in Prasopora. 



The chief interest attaching to Phylloporina corticosa is in the com- 

 plicated fenestriate zoarium which it builds. So aberrant is it in this 

 respect that Ulrich very naturally referred the species to the Cryptosto- 

 mataj placing it in the genus Phylloporina. In 1904 (6) I stated that 

 the species belongs to the Trepostomata. In 1905 (7) I figured the sec- 

 tion of the initial region, shown here again in figure 29, and called 

 attention to the presence of the protoecium. The identity of the initial 

 growth stages with those of Prasopora is sufficient to show that the spe- 

 cies is a true trepostome. In figure 19 of another specimen is indicated 



