Vol. 69.] 



THE GEXTTS AULOPHYLLVM. 



65 



Among the forms from the northern localities, the prevalent 

 design of the central column at this stage is that of the mature 

 section of A. fungites mut. redesdalense (p. 69) ; see PI. T, 

 figs. 5 a & 6. In the more southern forms, the design usually 

 closely approaches that of the mutation tenbiense (PI. VIII, fig. 4). 



The design in other in- 

 Pig. 7. — (Natural size.) dividuals, from both the 



northern and the south- 

 ern areas, lies between 

 these two types. 



0) Stage E.— The 

 central column, the 

 tabular vesicles, and the 

 dissepiments are all well 

 developed. The central 

 column is in typical 

 cases subquadrate in 

 section, as well shown 

 in PI. V, fig. 7 a, and 

 also, although not so 

 clearly, in PI. V, fig. 

 5 b ■ this is due to a 

 slight projection at the 

 alar fossula?, in addition 

 to the more prominent 

 protuberance at the 

 cardinal fossula. The 

 septal lamella? are long 

 and numerous, but not 

 crowded : hence a ra- 

 dial symmetry is cha- 

 racteristic of the stage. 

 The tri-arcal plan is at 

 this stage well defined 

 (PI. V, fig. 5 6). 



(/) Stage F.— The 

 adult characters are now 

 complete. The pinnate 

 is replaced by a bilateral 

 symmetry ; the septal 

 and frequently very flexuous ; the column 

 usually oval, in section, except for the 

 projection into the cardinal fossula (PI. V, fig. 5c). 



The above figure of the coral (fig. 7), from which sections (PI. V, 

 figs. 5a-5c) are cut at a.. a, b..h, c.e respectively, is drawn 

 of the natural size, and indicates the relative position of these 

 stages. . 



lamellae are crowded 

 is circular, or more 



Q. J. G. S. No. 273. 



