FIFTH REPORT OF THE DIRECTOR I908 



199 



A thick calcareous incrustation is found between the axial canal 

 formerly occupied by the axial cell, or cells, and a thin, carbon- 

 aceous outer film. The axial canal becomes visible in the principal 

 branch of the thallus where the tube is crushed [see pi. I, fig. i] 

 and also an axial canal of the branchlets can be seen in the same 

 specimen on the right-hand side. The calcium carbonate of the 

 fossil contrasts by its dark brown and sometimes amber color with 

 that of the matrix and of other fossils indicating a certain amount 

 of carbonaceous matter still contained in it. In thin sections made 

 through a few joints a deep black thin layer was seen on the out- 

 side and a less distinct one lining the axial canal, showing that the 

 calcareous deposition took place within an outer membrane or 

 gelatinous sheath. The outer black layer fails to show traces of 

 former pores and the calcareous deposition is crystalline and devoid 

 of structure. 



Professor Whitfield describes the branchlets or pinnules as 

 repeatedly bifurcating. The fact, however, that this bifurcation is 

 seen in both the longitudinal and transverse sections of the 

 same specimen suggests that also in the branchlets the division 

 took place in double dichotomies or in whorls of four branches ; 

 and in fact in one place [see pi. I, fig. I at a and b] three branchlets 

 are seen at the second division (at a) and in one three at the 

 third (at b). The thallus is hence composed of a system of verti- 

 cils of branches. The joints of the main stem are cylindrical, little 

 contracted at the articulations, those of the branchlets, however, 

 are clavate, * somewhat bulbous at the distal end and with rounded 

 extremities. The terminal branchlets are pyriform, distinctly 

 pointed at the distal extremity and round and bulbous at the other. 



Thin sections through the few fragments of joints of the main 

 stem and branchlets have not furnished any indication of the pres- 

 ence of cavities suggestive of conceptacles. The fructifications may 

 have consisted of terminal sporangia that were easily detachable 

 and were lost, or we may have only sterile thalli before us, or 

 again, the terminal pyriform branchlets may have contained the 

 conceptacles at their apexes and these may have become obscured 

 by secondary crystallization. It probably will require more material 

 than is available now to discover the fertile branches. 



Professor Whitfield referred this form to the coralline algae 

 (Corallinaceae) , as shown by the name, probably on good ground 

 as long as the verticillate arrangement of the branchlets of the 

 second and third orders was not recognized. A verticillate 



