Mr. H. J. Carter on the Growth of Stromatopora. 105 



Dr. F. E. Schulze, of Gratz, subsequently found this in the 

 Adriatic Sea, where the hydroid polyp &c. designated by him 

 Spongicola jistularis was found to be the denizen of several 

 different kinds of sponges ; and his representation (Archiv f. 

 mikroskop. Anatomie, Bd. xiii. Taf. xlii. fig. 8) might, the 

 sponge being replaced by Stromatopora, pass for a specimen 

 of Caunopora with the tubes much branched. 



Again, it should be remembered that in commensalism the 

 host is hardly ever without its guest ; so that it becomes the 

 habit of the latter to dwell with the former even from the 

 commencement of life, and, while the guest may never be seen 

 without its host, the latter is occasionally seen without its 

 guest. In a beautiful preparation which Dr. F. E. Schulze 

 has just kindly sent me, the guest, viz. Oscillaria spongetia}, 

 is already present in the embryo of Spongetia pallescens, which 

 it afterwards pervades throughout life (Zeitschrift f. wiss. 

 Zool. Bd. xxxii. p. 149, Taf. v. fig. 7). So that it is not 

 surprising that Caunopora, i. e. the host and its guest together, 

 should be occasionally found surrounding Corals also together 

 in the way above mentioned. 



I am aware that all but Roemer and Rosen (that is, all 

 English authors on the subject) have, from Lonsdale down- 

 wards, viewed Caunopora as a distinct species of Stromatopora ; 

 but I myself now cannot help, from the facts above mentioned, 

 regarding it as an instance of commensalism ; and in this I am 

 supported by Mr. Champernowne. 



The fact, however, that Caunopora may thus be found to be 

 a compound of two organisms does not invalidate what I have 

 stated respecting Millepora alcicornis, in which there are dis- 

 tinct tubes among the Stromatoporoid coenenchyina rising 

 from an axial structure of a different form. Millepora alci- 

 cornis, too, overruns every thing in its way ; thus, in the 

 British Museum there is a large Murex, together with reticu- 

 lated Gorgonice, covered with it. Ellis notices that it is one 

 of the commonest corals in Jamaica, where it is principally used 

 for burning into lime (Nat. Hist. Zoophytes, 1786, p. 142), 

 and afterwards mentions a bottle that became incrusted with it ; 

 so that, as the branches coalesce between themselves, and 

 in like manner this species of Millepora attaches to itself 

 every foreign body that comes in its way, a reef-accumulation 

 may be thus produced, similar to that which was built up by 

 Stromatopora. By eliminating Caunopora, therefore, the 

 description of Stromatopora is not only more simplified, but 

 Millepora alcicornis and the Hydractiniie are brought together, 

 which, as Mr. Champernowne observes, afford the best key 

 to a right understanding of what Stromatopora really was. 



