Mr. H. J. Carter on Stroraatopora dartingtoniensis. 339 



(fig. 2, A), prove, beyond a doubt, that the canaliculi are 

 entirely confined to the walls separating contiguous tubes, 

 whether these be the proper zooecia or the cancelli. 



So far as I have seen, no " fcabulsB," or but an occasional 

 one, seem to be developed in the outer thickened portion of 

 the tubes ; but it is often possible to recognize the delicate 

 radiating spines or " septa," which are so well displayed in 

 tangential sections. Lastly, owing to the unequal thickening 

 of the walls of the tubes, it is not uncommon for the longi- 

 tudinal section of their cavities to assume a beaded appearance, 

 though this is not constant, and, when present, varies much 

 in amount. 



[To be continued.] 



XLTI. — On Stromatopora dartingtoniensis, n, sp. with 

 Tabulation in the Larger Branches of the Astrorhiza. 

 By H. J. Carter, F.E.S. &c. 



[Plate XVIII.] 



In 1878 I made the following statement, viz. :■ — " Thus in all 

 essential points the structure of Caunopora placenta was the 

 same as that of Millepora alcicornis" &c. (' Annals,' vol. ii. 

 p. 313). I also stated that, in Millepora alcicor?iis, "the 

 axial [structure], which in the transverse fracture only appears 

 to be a cribriform surface, is now [in the opposite direction] 

 found to be composed of longitudinal tubes in juxtaposition, 

 more or less interrupted by tabulae, and more or less pierced 

 with holes by which they communicate with each other " 

 ibid. p. 308). In 1879 I found that neither of these state- 

 ments was tenable, but that the tubes of Caunopora placenta 

 belonged to a separate organism, and that the " axial struc- 

 ture " was Favosites Forbesii (not gothlandicus } as first stated), 

 over which the Caunopora had grown. 



This year (1880) an article by Dr. F. Roemer has ap- 

 peared in the ' Geological Magazine ' for the month of 

 August, in which the author states (p. 345) that " Cauno- 

 pora of Phillips is not a good genus, but is founded on masses 

 of Stromatopora which are perforated by vertical tubes not 

 essentially belonging to Stromatopora" which tubes Dr. 

 Roemer considers a form of Aulopora 7-epens, having previ- 

 ously noticed what he published in 1844, viz. " that Cau- 

 nopora placenta of Phillips was nothing else than Stromato- 

 pora concentrica " (p. 344) ; now, however, he adds, " My 

 own observations confirm entirely the statement that the 



