344 Prof. Dr. F. Roemer—On the Genus Caunopora. 
least as essential organs of the species. So long ago as 1844 I 
expressed the opinion’ that Caunopora placenta of Phillips was 
nothing else than Stromatopora concentrica, which has surrounded 
and overgrown the stems of Syringopora. In a recent elaborate 
memoir on the minute structure of Stromatopora and its allies,* by 
Professor H. Alleyne Nicholson and Dr. James Murie, these authors 
deny that the tubes could belong to Syringopora, because they have 
decidedly not the infundibuliform tabulz so characteristic of Syringo- 
pora, and come to the conclusion that the tubes essentially belong to 
the Stromatopora-like body, which is therefore entitled to generic 
distinction as Caunopora. 
My own observations confirm entirely the statement that the tubes 
have not the internal structure of Syringopora, but are hollow, and 
can therefore not belong to that genus; but the inference drawn 
from this fact, viz. that the tubes are an essential part of the 
Stromatopora-like body, is erroneous. A number of specimens of 
Caunopora placenta from the Devonian beds of Gerolstein in the 
Hifel, which exactly agree in structure with those from the lime- 
stones of South Devon, show distinctly that the tubes belong to 
Aulopora repens. This little creeping Coral attached itself on the 
surface of Stromatopora concentrica, and when a new concentric 
layer of Stromatopora was forming, it extended its calices upwards 
in tubes to prevent itself from being entirely covered, and finally 
killed by the Stromatopora. When other layers of the latter 
followed, the calices of Aulopora continued to grow upwards. On 
the surface of the uppermost layer of Stromatopora the calices of 
Aulopora appear as circular openings with a distinct and projecting 
rim. This relation in growth of the two species is particularly 
obvious in such specimens from Gerolstein which show a mass of 
Alveolites suborbicularis, with a network of Aulopora repens, on 
the surface, and which are besides partly covered with a thin layer 
of Stromatopora concentrica. The network of Aulopora is, in such 
specimens, occasionally partly free and partly covered with the thin 
layer of Stromatopora. Where it is covered, the calices of Aulopora 
appear as circular openings with a projecting rim on the surface, 
just as H. A. Nicholson and Dr. J. Murie® have figured them in 
Stromatopora (Caunopora) perforata from the Corniferous Limestone 
of Ontario. I have no doubt that in this Canadian species the 
circular openings are equally the calices of Aulopora, as in the Eifel 
specimens. 
In thick masses of Caunopora the vertical tubes do not necessarily 
all belong to the same individual of Aulopora, but different colonies 
of these little creeping corals attached themselves repeatedly to the 
surface of the succeeding concentric layers of Stromatopora, and were 
covered by the following one. In fact, on vertical sections of Cauno- 
pora the same vertical tubes can never be followed up through the 
whole mass, but they are mostly only a few lines in length. 
1 Das Rheinische Uebergangsgebirge, p. 5. 
2 Journ. Lin. Soe. vol. xiv. Zoology, pp. 211 and 219. 
3 jc. p. 218, fig. 4. 
