130 THE BERMUDA ISLANDS. 



The identification of this form depends mainly on the 

 coloration, which Professor Heilprin informs me is sufficiently 

 similar to Lesueur's description. 



The polyps form encrusting masses,'and are so deeply im- 

 bedded in the coenenchyma, that in contraction a slight de- 

 pression alone indicates the position of the various individuals, 

 or in some cases a slight annular elevation. The species is by 

 this peculiarity readily distinguishable from C. ocellata, as 

 well as from C.flava of the Bahamas, which stands in an inter- 

 mediate position as far as the projection of the polyps above 

 the coenenchyma is concerned. The form described from the 

 Bermudas by Erdmann, and named C. lutea by Hertwig, re- 

 sembles C. glareola in this respect, but appears to differ from it 

 in other points. 



The mesogloea is, with the exception of a narrow band im- 

 mediately adjoining the endoderm of the polyps, richly sup- 

 plied with imbedded foreign bodies, so that the entire colony 

 is very hard, almost stony in its consistency. C. ocellata is 

 much less richly provided with foreign particles, and the same 

 is the case with Hertwig's C. lutea. Whether this is a charac- 

 teristic of sufficient importance for specific distinction can 

 only be ascertained by the examination of numerous speci- 

 mens of some species, obtained from different localities and 

 living under different conditions. In fact, our knowledge of 

 the histology of the Zoanthidse is not yet sufficiently advanced 

 to enable us to ascertain what features are of systematic im- 

 portance and what are liable to extensive individual variation. 



The sphincter muscle resembles closely that of Hertwig's 

 C. lutea. It is imbedded in the mesogloea and is single, con- 

 sisting of a single row of cavities which are entirely confined 

 to the portion of the column which is invaginated during con- 

 traction. All the cavities contain muscle cells, and there are 

 none of the empty spaces with clearly defined walls such as oc- 

 cur in C. flava. 



The mesenteries are arranged on the microtypus, and in the 

 specimens examined there were about eighteen pairs only. 



