BROWN, RUGOSE CORALS 
79 
stages of development of this species are studied, it is seen that the form 
arises from a Streptelasma-like stem. Duerden has studied the early 
stages of other species of this genus and found specimens in which there were 
only six septa in the youngest stage observed. 1 In figure 22a is shown a 
stage from the polished tip of a specimen in which eight septa are present. 
Two pairs of secondary septa have already arisen in the counter quadrants. 
Figure 22b, from the fractured tip of another individual, shows a later 
stage in which there are three pairs of secondary septa in the cardinal quad- 
Fig. 22. Hadrophyllum, orbignyi. X 4. 
rants and four in the counter quadrants. The pinnate arrangement of the 
septa is already distinctly accentuated and the three fossulse clearly defined. 
Figure 22c is a view from above the calyx of a small individual. Two more 
pairs of secondary septa have been added in each set of quadrants. The 
cardinal septum does not show T in this specimen, but as the cardinal fossula 
was somewhat poorly defined, probably its absence was due to imperfect 
fossilization. Figure 22d is a similar view from a still larger individual. 
Another pair of secondary septa has been added in the counter and in the 
1 Science, Aug. 24, 1906. Annals and Magazine of Natural History. Sept., 1906. 
