THE NATURE OF CAUNOPORA. 115 



Lonsd., and G. ramosa, Pliill. The latter of these has been seen not to be a 

 " Caunopora " at all, but to be the type of the genus Amphipora, Schulz. The 

 former is the Coscinopora placenta of Lonsdale, and it would be difficult or impos- 

 sible, from the figures and descriptions of both Lonsdale and Phillips, to identify 

 it precisely with any particular one of the three or four commoner kinds of 

 " Caunoporce " which occur in the Devonian Rocks of Devonshire. It would, at 

 any rate, in my opinion, be inexpedient to attempt to retain the name of "placenta " 

 as a specific title, unless Caunopora were also to be retained as a genus. My reason 

 for this conclusion is that the presence of " Caunopora-tubes " in the fossil was, 

 of course, the essential feature selected by Lonsdale and Phillips as characterising 

 their Caunopora placenta as a species, whereas these tubes occur in all the so-called 

 Caunopora?, and their presence cannot, therefore, be employed to characterise a 

 species. 



As early as 1844, Professor Ferdinand Roemer expressed the opinion (' Das 

 rheinische Uebergangsgebirge ') that Caunopora, Pliill., was merely based upon 

 examples of Stromatoporoids, which in the course of growth had enveloped colonies 

 of Syringopora, and that the genus consequently must fall to the ground. To this 

 view Roemer has always adhered, so far as concerns the belief that " Caunopora " 

 has no existence as a single organism ; but he has so far modified his original view 

 ('Geol. Mag.,' New Ser., Dec. ii, vol. vii, p. 343, 1880) that he now regards 

 Aulopora rather than Syringopora as the Coral which is associated with Stromato- 

 poroids in the production of " Caunopora " colonies. 



In the series of valuable papers which he has published on the Stromatoporoids 

 Mr. Carter was at first disposed to accept " Caunopora " as an independent organ- 

 ism ; but he subsequently abandoned this view, and expressed the opinion that, 

 as previously asserted by Roemer, the Caunopora} were the result of the commensal- 

 ism of a Stromatoporoid and a Coral (' Ann. and Mag. Nat. Hist.,' Ser. 5, vol. iv, 

 p. 101, 1879). At a still later date, while retaining this view as to the commensal- 

 ism of Caunopora, Mr. Carter expressed the opinion that the Coral which was thus 

 associated with Stromatoporoids was rather to be regarded as Syringopora than as 

 Aulopora, since infundibuliform tabulas could be occasionally recognised in the tubes 

 (' Ann. and Mag. Nat. Hist.,' Ser. 5, vol. vi, p. 339, 1880.) 



Mr. Champernowne, whose opinion upon any subject connected with the 

 Devonian Stromatoporoids is of the greatest value, also arrived at the conclusion 

 that the " commensal theory " was probably the true one, and has consistently 

 opposed the view that " Caunopora " and " Biapora'' are genera of Stromatoporoids. 



On the other hand, many observers have at various times maintained views as 

 to the nature of Caunopora opposed to the preceding. It has, namely, been held 

 by many authorities that the thick-walled tubes of" Caunopora" are not foreign to 

 the Stromatoporoid in which they are found, but truly belong to it, and that the 



